Modern subsoiling technology is a little ploughing measure in dry land protective farming technology system.The subsoiler can scarify soil,deepen the arable layer,break the plough layer,improve the soil permeability,i...Modern subsoiling technology is a little ploughing measure in dry land protective farming technology system.The subsoiler can scarify soil,deepen the arable layer,break the plough layer,improve the soil permeability,increase soil infiltration speed and amount,and create an arable layer structure with coexistence of fictional and real situation.Also,it can effectively promote development and growth of crop root system and play a favorable role in drought resistance and yield increase of crops.This paper made a simple overview of the subsoiling technology,current development situation of subsoiler both at home and abroad,and classification of subsoilers.展开更多
Since the design of the subsoiler is a complex work,the interaction between the subsoiler and soil was investigated by using Distinct Element Method(DEM)in this study.Based on the traditional discrete element theory,t...Since the design of the subsoiler is a complex work,the interaction between the subsoiler and soil was investigated by using Distinct Element Method(DEM)in this study.Based on the traditional discrete element theory,the 3D model of soil particles and the subsoiler were established after considering the liquid bridge force between soil particles.The operating resistance curves of the subsoiler were achieved after the DEM simulation at a speed of 1 m/s,and three depths of 180 mm,220 mm and 260 mm,respectively.The simulation curves agreed well with the field experimental results based on relative errors of 2.96%,14.95%and 7.15%,respectively,at three depths.All these data proved that it was feasible and favorable to analyze the performance of the subsoiler by using the DEM and it is of important significance for studying and further optimizing the structure of the subsoiler.展开更多
Generally,a subsoiler is comprised of a shank and a point.The point shape has a significant effect on the draft force of a subsoiler.In this study,the draft force of subsoilers with four different points were compared...Generally,a subsoiler is comprised of a shank and a point.The point shape has a significant effect on the draft force of a subsoiler.In this study,the draft force of subsoilers with four different points were compared under the speed of 0.8 m/s and the depth of 350 mm in the soil bin.Discrete Element Method(DEM)was applied in simulating the working process of the subsoiler.The stiffness of soil particles used in DEM was calibrated by comparing the simulated draft force of a standard arc-shaped subsoiler with the experiment.The calibrated soil particle stiffness was 1.1×104 N/m.The validated model was then used to compare the draft force of subsoilers with four different points under the same condition in the test.Results showed that different points would cause different draft forces.The subsoiler with short chisel point caused the smallest draft force(2885 N)while the point with short face and wings had the largest force(4474 N).The relative errors of the simulated results were less than 4%,which proved that DEM was an effective way for predicting the draft force of subsilers.The velocity field and contact force filed could show the movement of soil around the subsoiler.展开更多
Subsoiling is essential in the tillage of banana planting,as banana plants have a fairly sturdy pseudostem and wide row spacing while soil tends to be compacted.In this study,a bionic vibrating subsoiler for banana fi...Subsoiling is essential in the tillage of banana planting,as banana plants have a fairly sturdy pseudostem and wide row spacing while soil tends to be compacted.In this study,a bionic vibrating subsoiler for banana fields was developed,verified,and evaluated.The vibrator was designed based on crank-rocker mechanism while the bionics design was used for subsoiler development.The forces on the susboiler were analyzed to verify the strength of the subsoiler tine.To test the performance of the subsoiler,field tests were conducted to measure the draft force and fuel consumption.There was approximately 14%reduction in the draft force and 22%increase in the fuel consumption in vibrating mode compared with that in non-vibrating mode.In conclusion,the study results could be applied in China’s tropical agricultural regions.展开更多
Understanding soil disturbance behaviors under the impact of the winged subsoiler is critical for designing or optimizing the winged subsoiler(a primary subsoiling tool).In this study,a soil-winged subsoiler interacti...Understanding soil disturbance behaviors under the impact of the winged subsoiler is critical for designing or optimizing the winged subsoiler(a primary subsoiling tool).In this study,a soil-winged subsoiler interaction model was developed and the effects of winged subsoiler on soil disturbance behaviors were investigated using the discrete element method(DEM)simulations and lab soil-bin tests.The results showed that wings mainly affected the disturbance range and fragmentation degree of soil above them.The draught forces of share section(SS),arc section in the hardpan(ASHP),arc section in the top layer(ASTL)and line section(LS)were accounted for 69.53%,25.22%,4.73%and 0.52%of the total draught force of winged subsoiler;the lateral disturbance range from high to low of the soil at different depths followed the ranking:top layer(TL),hardpan disturbed by arc section(HDAS)and hardpan disturbed by share section(HDSS).Wings had the greatest influence on the draught force of ASHP.Adding wings to an arc-shaped subsoiler increased the disturbance areas of HDAS,TL and HDSS by 47.52%,7.74%and 4.59%,respectively,but meanwhile increased the total draught force by 36%.Compared with a non-winged subsoiler,winged subsoiler had higher soil looseness(15.83%),soil disturbance coefficient(58.59%),furrow width(448.65 mm)and soil disturbance area ratio(0.3835),but poorer soil surface flatness(19.79 mm)and lower soil loosening efficiency(39.35 mm²/N).This study provided critical information for optimizing winged subsoilers on aspects of improving soil loosening effectiveness and reducing draught force.展开更多
Soil compaction is a common problem facing conservation fields that restricts crop root growth and causes yield decrease.Subsoil techniques have been developed to break up the compaction layer.However,subsoil implemen...Soil compaction is a common problem facing conservation fields that restricts crop root growth and causes yield decrease.Subsoil techniques have been developed to break up the compaction layer.However,subsoil implement requires large draft power that hampered the development of subsoil techniques for most of developing countries due to lack of large scale tractors.Aiming to optimize the penetration resistance of the subsoiler and create a good working environment for the operators,a staggered vibrating subsoiler was developed.A new staggered vibrating mechanism was designed to generate the staggered vibration of the shanks meanwhile the V-shape shanks arrangement was adopted to keep relative balance for the subsoiler.In order to obtain optimum working parameters of the vibration frequency and forward speed,the trajectory of shanks was simulated by using the MATLAB software.The forward speed of 2-3 km/h with vibration frequency of 12 Hz was recommended to acquire an effective decrease in draft force.Field performance of this subsoiler was evaluated in terms of the draft force,power requirement and tractor wheel slippage.By comparing the two operation modes,staggered vibrating(SV)and rigid(NV)of shanks,the decrease ratios of draft force for SV were determined by 16.97%,12.12%and 9.02%at forward speeds of 2.2 km/h,2.6 km/h and 3.1 km/h,respectively.This is better than the research for the 1SZ-460 vibratory subsoiler that was decreased by 9.09%in draft force.The power requirement for SV was not significantly greater than that for NV.The obviously decreased wheel slippage was observed for SV by decrease of 12.47%,17.96%and 21.79%at forward speeds of 2.2 km/h,2.6 km/h and 3.1 km/h,respectively.In conclusion,the staggered vibrating subsoiler presents preferable working performance and is recommended to be applied in subsoil tillage process for developing countries.展开更多
A new subsoiler with placoid scale microstructure bionic surface was proposed which mimicked shark skin to reduce tillage resistance and soil adhesion during subsoiling cultivation.The contour curves of placoid scale ...A new subsoiler with placoid scale microstructure bionic surface was proposed which mimicked shark skin to reduce tillage resistance and soil adhesion during subsoiling cultivation.The contour curves of placoid scale microstructure on shark skin were fitted,and two kinds of bionic subsoiler with continuous and discontinuous microstructures were designed and fabricated,respectively.The effects of different bionic surfaces on tillage resistance were investigated by finite element simulation and experiment.The results indicated that the bionic subsoiler with discontinuous microstructure reduced the horizontal and vertical force by 21.3%and 24.8%,respectively.The subsoiler with discontinuous microstructure surface can prevent the adhesion between the soil and subsoiler surface more efficiently.展开更多
With the increased use of agricultural machinery in field operations,soil compaction has become increasingly severe,and the plough pan has become deeper.Subsoiling is an excellent way to address this problem.However,i...With the increased use of agricultural machinery in field operations,soil compaction has become increasingly severe,and the plough pan has become deeper.Subsoiling is an excellent way to address this problem.However,it is limited by high energy consumption,which is closely related to tillage force.To investigate the effect of the geometric shape of shanks and tines on tillage force and soil disturbance in loam,a layered soil model in accordance with the actual conditions was established and five different subsoilers were simulated via discrete element modeling.The results indicated that the shank impacted soil disturbance and tine impacted tillage force.The draft force of curved shank and chisel tine was 8%less than that of the straight shank and sweep tine.The straight shank and sweep tine produced a larger furrow profile and a higher furrow width.The subsoiler with curved shank and chisel tine(C-C)exhibited the lowest specific resistance(12.87,17.52,19.46 and 21.18 kN/m^2 in the 30,35,40 and 45 cm tillage depth,respectively)considering the draft force and soil disturbance characteristics.Hence,these results will facilitate in the selection of a suitable subsoiler and design of new subsoilers with lower energy consumption requirements for loam areas worldwide.展开更多
Public urban greenery greatly contributes to the residential and tourist value of cities in the Gulf Region,but due to the hyper-arid climatic conditions,the cost of irrigation and plant maintenance is very high.Exist...Public urban greenery greatly contributes to the residential and tourist value of cities in the Gulf Region,but due to the hyper-arid climatic conditions,the cost of irrigation and plant maintenance is very high.Existing strategies to reduce the monetary and ecological costs involve the cultivation of native xerophytic plantations,and/or the use of soil improvers to increase water-and nutrient-holding capacity of the sandy soils.Various soil improvers based on mineral,organic,or synthetic materials have entered the United Arab Emirates(UAE)market in recent years,but there is considerable uncertainty about how they should best be used in combination with ornamental plant stands involving xerophytic native plants.The present study investigated the effect of soil amendment and deep pipe irrigation on perennial ornamental plant stands involving native plants(Tephrosia appolinea(Gel.)Link in combination with Aerva javanica(Burm.f.)Juss.ex Schult.)and native-exotic plants(T.appolinea in combination with Ruelia simplex C.Wright)either or not topsoil and subsoil amendment with bentonite and hydrophobic sand under the irrigation water supply of less than 50%of reference evapotranspiration(ET0).After one year of cultivation,T.appolinea and A.javanica(native vs.native)produced high biomass and exhibited high water use efficiency(WUE)as compared with T.appolinea and R.simplex(native vs.exotic)combination given that no significant differences were found under the soil amendment treatments.All stands thrived under irrigation water supply far below what is usually supplied to exotic ornamental stands in public parks of the Al Ain City,the UAE.However,subsoil amendment in combination with deep pipe irrigation reduced the occurrence of weeds and increased the overall plant rooting depth.Our results suggest that subsoil amendment and irrigation up to 60-80 cm depth can potentially control ephemeral weed infestation,which is a great challenge in various plant production systems of the Gulf Region.The results of the present study suggest that the impact of soil amendment on the WUE of exotic plants is marginal and might not be economically justified.Replacing exotic with native ornamental plant species seems to have a far greater water-saving potential than the amendment of the soil,while weeds can be suppressed in the absence of topsoil moisture.展开更多
The horizontal to vertical spectral ratio(HVSR)methodology is used here to characterize pumice soils and to image the three-dimensional surface geometry of Guadalajara,Mexico.Similar to other Latin American cities,Gua...The horizontal to vertical spectral ratio(HVSR)methodology is used here to characterize pumice soils and to image the three-dimensional surface geometry of Guadalajara,Mexico.Similar to other Latin American cities,Guadalajara is exposed to high seismic risk,with the particularity of being the largest urban settlement in Latin America built on pumice soils.Methodology has not yet been tested to characterize subsoil depths in pumice sands.Due to the questionable use of traditional geotechnical tests for the analysis of pumice soils,HVSR provides an alternative for its characterization without altering its fragile and porous structure.In this work,resonance frequency(F0)and peak amplitude(A0)are used to constrain the depth of the major impedance contrast that represents the interface between bedrock and pumice soil.Results were compared with borehole depths and other available geotechnical and geophysical data and show good agreement.One of the profiles estimated on the riverbanks that cross the city,reveals different subsoil thickness that could have an impact on different site responses on riverine areas to an eventual earthquake.Government and academic efforts are combined in this work to characterize depth sediments,an important parameter that impacts the regulations for construction in the city.展开更多
The commonly used subsoiling cum rotary tiller machine(SRT)in Northern China is a combination of subsoiler and horizontal rotary tiller,however backfilling of the subsoiling slot,excessive vibration and plant residue ...The commonly used subsoiling cum rotary tiller machine(SRT)in Northern China is a combination of subsoiler and horizontal rotary tiller,however backfilling of the subsoiling slot,excessive vibration and plant residue wrapping on rotary components has been rarely considered.Therefore,the rotary components and assembly were redesigned to address these issues and to an SRT fitted with IT225 short curve rotary blades behind the V-shape subsoiling slots and IIT245 long curve rotary blades between the tines.Long and short blades were fitted on a rotor in a double helix,with optimal spiral angles of 65° and 90°,and phase angle of 147°and 180°,respectively.Compared with the commonly used SRT(CSRT),the additional anti-wrapping cutting blades in the circumferential and axial direction of ASRT could remove hanging residue on the blade holders,wrapping on the rotor and formation of an isolation layer.Moreover,the cutting edge curve of anti-wrapping cutting blades was an exponential curve.Field tests demonstrated that the redesigned SRT with anti-vibrating and anti-wrapping rotary components(ASRT)had was a significant advancement over the CSRT.Moreover,the working depth of rotary tillage was more stable,while other observations confirmed that backfilling of the subsoiling slot was also improved.展开更多
A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen(N), phosphorus(P), and potassium(K) uptake, and grain yield of spring maize. The results indicated ...A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen(N), phosphorus(P), and potassium(K) uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development,increased nutrient accumulation, and increased yield. Compared with conventional soil management(CK), root length, root surface area, and root dry weight at 0–80 cm soil depth under subsoil tillage to 30 cm(T1) and subsoil tillage to 50 cm(T2) were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.展开更多
In order to improve the water use efficiency under conservation tillage, the effects of subsoiling on soil moisture under notillage were studied. An experiment of 40 cm subsoiling in a field kept under no-tillage for ...In order to improve the water use efficiency under conservation tillage, the effects of subsoiling on soil moisture under notillage were studied. An experiment of 40 cm subsoiling in a field kept under no-tillage for 2 years was operated from 2005 to 2006. Based on the data of the soil moisture and crop yield, the physical basis of subsoiling for water conservation and yield increase was analyzed. The results showed that the soil water storage under subsoiling, from the soil surface to a depth of 100 cm was more than that under no-tillage for the growth season. In the 0-100 cm soil depth, the soil moisture in 50-100 cm depth under subsoiling was more compared with no-tillage, which increased when it＇s drought and decreased when it＇s rainy with the increase in soil depth. Compared with no-tillage, subsoiling could reduce the water consumption of oats in the 0-50 cm depth and increase the water consumption in the 50-100 cm depth. Also, subsoiling increased the yield by 18.29% and the water use efficiency by 16.8% in a two-year average. The effects of subsoiling on water conservation and yield increase were affected by precipitation, and a well-proportioned rainfall was better to increase yield and water use efficiency. Meanwhile, subsoiling decreased bulk density, which increased with the available precipitation. Subsoiling under no-tillage is the effective rotation tillage to contain more soil moisture and improve water use efficiency in ecotone of North China.展开更多
High temperature stress（HTS） on spring maize（Zea mays L.） during the filling stage is the key factor that limits the yield increase in the North China Plain（NCP）.Subsoiling（SS） and ridge tillage（R） were intr...High temperature stress（HTS） on spring maize（Zea mays L.） during the filling stage is the key factor that limits the yield increase in the North China Plain（NCP）.Subsoiling（SS） and ridge tillage（R） were introduced to enhance the ability of spring maize to resist HTS during the filling stage.The field experiments were conducted during the 2011 and 2012 maize growing seasons at Wuqiao County,Hebei Province,China.Compared with rotary tillage（RT）,the net photosynthetic rate,stomatal conductance,transpiration rate,and chlorophyll relative content（SPAD） of maize leaves was increased by 40.0,42.6,12.8,and 29.7% under SS,and increased by 20.4,20.0,5.4,and 14.2% under R,repectively.However,the treatments reduce the intercellular CO 2 concentration under HTS.The SS and R treatments increased the relative water content（RWC） by 11.9 and 6.2%,and the water use efficiency（WUE） by 24.3 and 14.3%,respectively,compared with RT.The SS treatment increased the root length density and soil moisture in the 0-80 cm soil profile,whereas the R treatment increased the root length density and soil moisture in the 0-40 cm soil profile compared with the RT treatment.Compared with 2011,the number of days with temperatures 33°C was more 2 d and the mean day temperature was higher 0.9°C than that in 2012,whereas the plant yield decreased by 2.5,8.5 and 10.9%,the net photosynthetic rate reduced by 7.5,10.5 and 18.0%,the RWC reduced by 3.9,5.6 and 6.2%,and the WUE at leaf level reduced by 1.8,5.2 and 13.1% in the SS,R and RT treatments,respectively.Both the root length density and the soil moisture also decreased at different levels.The yield,photosynthetic rate,plant water status,root length density,and soil moisture under the SS and R treatments declined less than that under the RT treatment.The results indicated that SS and R can enhance the HTS resistance of spring maize during the filling stage,and led to higher yield by directly improving soil moisture and root growth and indirectly improving plant water status,photosynthesis and grain filling.The study can provide a theoretical basis for improving yield of maize by adjusting soil tillage in the NCP.展开更多
Compact!on layers are widely distributed in the Huang-Huai-Hai Plain,China,which restrict root growth and reduce yields.The adoption of subsoiling has been recommended to disrupt compacted soil layers and create a rea...Compact!on layers are widely distributed in the Huang-Huai-Hai Plain,China,which restrict root growth and reduce yields.The adoption of subsoiling has been recommended to disrupt compacted soil layers and create a reasonable soil structure for crop development.In this paper,the effects of subsoiling depth(30,35 and 40 cm),period interval(2 or 3 years)and combined pre-sowing tillage practice(rotary cultivation or ploughing)on soil condition improvement was studied on a tidal soil in the Huang-Huai-Hai Plain.Seve n tillage patter ns were desig ned by combini ng differe nt subsoili ng depths,period intervals and pre-sowing.The evaluation indicators for soil condition improvement were as follows:thickness of the plough layer and hard pan,soil bulk density,cone index,soil three-phase R values,alkali nitrogen content,crop yield,and economic ben efits.The results showed that subsoiling can sign ificantly improve the soil structure and physical properties.In all subsoiling treatments,the depth of 35 or 40 cm at a 2-year interval was the most significant.The thickness of the plough layer in creased from 13.67 cm before the test to 21.54-23.45 cm in 2018.The thick ness of the hard pan decreased from 17.68 cm before the test to 12.09-12.76 cm in 2018,a decrease of about 40.07%.However,the subsoiling combined presowing tillage practice,that is,rotary cultivation or ploughing,was not significant for soil structure and physical properties.For all subsoiling treatments,the soil bulk density,cone index and soil three-phase R values of the 15-25 cm soil layer were significantly lower compared to single rotary cultivation.Subsoiling was observed to increase the soil alkaline nitrogen and water conte nts.The tillage patter ns that had subsoiling at the depth of 35-40 cm at a 2-year in terval combi ned with rotary cultivation had the highest alkali nitrogen and water contents,which increased by 31.08-34.23%compared with that of the single rotary cultivati on.Subsoiling can sign ifica ntly in crease the yield both of wheat and corn,as well as the economic ben efits.The treatment of subsoili ng at the depth of 35 cm at an interval of 2 years com bined with rotary cultivation had the highest ann ual yield and economic benefits.For this treatme nt,the arinual yield and economic ben efits in creased by 14.55 and 62.87%in 2018,respectively.In con clusi on,the tillage patter ns that involved subsoili ng at a depth of 35 cm at a 2-year interval along with rotary cultivation are suitable for the Huang?Huai-Hai Plain.展开更多
The soil factors influencing the potential migration of dissolved and particulate phosphorus(P) from structurally-weak sandy subsoils were evaluated by means of soil column leaching experiments. Soil colloids were ext...The soil factors influencing the potential migration of dissolved and particulate phosphorus(P) from structurally-weak sandy subsoils were evaluated by means of soil column leaching experiments. Soil colloids were extracted from two types of soils to make the colloid-bound forms of P solution. Eight sandy soils with diverse properties were collected for packing soil columns. The effects of influent solutions varying in concentrations of colloids,P,and electrolyte,on the transport of P and quality of leachates were characterized. P migration in the soils was soil property-dependent. High soil electrical conductivity values retarded the mobility of colloids and transportability of colloid-associated P(particulate P) . Soil electrical conductivity was negatively correlated with colloids and reactive particulate P(RPP) concentrations in the leachates,whereas,the total reactive P(TRP) and dissolved reactive P(DRP) concentrations in the leachates were mainly controlled by the P adsorption capacity and the P levels in the subsoil. The reactive particulate P in the leachates was positively correlated with the colloidal concentration. Increased colloidal concentration in the influent could significantly increase the colloidal concentration in the leachates. Elevated P concentration in the influent had little effect on P recovery in the leachates,but it resulted in significant increases in the absolute P concentration in the leachates.展开更多
Soil moisture is the most critical limiting factor impacting yields of dryland winter wheat(Triticum aestivum L.) and it is strongly affected by tillage practice and sowing methods. This study was to assess the link b...Soil moisture is the most critical limiting factor impacting yields of dryland winter wheat(Triticum aestivum L.) and it is strongly affected by tillage practice and sowing methods. This study was to assess the link between sowing method and tillage practice during summer fallow and their subsequent effect on soil moisture and grain yield. Furthermore, we sought to identify a more appropriate farming management practice for winter wheat production in Loess Plateau region of China. The experiment was conducted from 2011 to 2013, using a two-factor split plot design, including subsoiling(SS) or no tillage(NT) during summer fallow for main plots, and conventional drill sowing(DS) or plastic film drill sowing(FM) for subplots. Results showed that the maximum soil water storage(SWS) was under SS×FM treatment with values of 649.1 mm(2011–2012) and 499.4 mm(2012–2013). The SWS during the 2011–2012 growing season were 149.7 mm higher than that in the 2012–2013 growing season. And adoption of SS×FM significantly increased precipitation use efficiency(PUE) and water use efficiency(WUE) compared to other treatments for both seasons. Moreover, adoption of SS×FM significantly increased yield by 13.1, 14.4, 47.3% and 25.9, 39.1, 35.7% than other three treatments during the two growing seasons, respectively. In summary, combining subsoiling during summer fallow with plastic film drill sowing(SS×FM) increased SWS at sowing and effectively improved WUE, thus representing a feasible technology to improve grain yield of dryland winter wheat in the Loess Plateau of China.展开更多
Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacen...Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacent rock-stratum. The influence of the coefficient of permeability and loading frequency on the soil displacement at the ground surface were studied. The results showed that higher loading frequency led to more dynamic characteristics; and that the effect of the soil permeability was more obvious at higher frequencies.展开更多
Buckling of submarine pipelines under thermal stress is one of the most important problems to be considered in pipeline design. And pipeline with initial imperfections will easily undergo failure due to global bucklin...Buckling of submarine pipelines under thermal stress is one of the most important problems to be considered in pipeline design. And pipeline with initial imperfections will easily undergo failure due to global buckling under thermal stress and internal pressure. Therefore, it is vitally important to study the global buckling of the submarine pipeline with initial imperfections. On the basis of the characteristics of the initial imperfections, the global lateral buckling of submarine pipelines was analyzed. Based on the deduced analytical solutions for the global lateral buckling, effects of temperature difference and properties of foundation soil on pipeline buckling were analyzed. The results show that the snap buckling is predominantly governed by the amplitude value of initial imperfection; the triggering temperature difference of Mode I for pipelines with initial imperfections is higher than that of Mode I1; a pipeline with a larger friction coefficient is safer than that with a smaller one; pipelines with larger initial imperfections are safer than those with smaller ones.展开更多
Seasonally cold climate and resulting frost action set great demands to railway track substructure in order to maintain Irack geomelry. Chal- lenges culminate on high-speed lines, where the tolerances for roughness ar...Seasonally cold climate and resulting frost action set great demands to railway track substructure in order to maintain Irack geomelry. Chal- lenges culminate on high-speed lines, where the tolerances for roughness are the tightest. Problems may result in highly increased Irack maintenance and need for temporary speed reslrictions. The causes of frost action can be associated with subsoil, subballast or ballast. The major concern in frost protection is to avoid the freezing of frost susceptible subsoil by using sufficient thickness of subballast and relying on non-fi＇ost-susctible subballast material. This paper provides an overview of the main research findings on the role of ballast, subballast and subsoil in frost acedon. In new comlruclion the material specificalions, design procedures and construction methods have been developed to ensure adequate performance of Irack subscatt, but special challenges exist in managing existing Wacks that were not designed for modem requirements. In order to perform cost-effective and sustainable track maintenance, it is necessary to recognize the problem areas and define the root-causes of problems. For locating the problem sections and defining the causes of defects, a sophisticated analysis based on integration of track geometry and ground penetrating radar （GPR） data has been developed and is summarized in this paper,展开更多
基金Supported by Project of National Natural Science Foundation(51105123)Key Science and Technology Program of Hainan Province(ZDXM20120074)
文摘Modern subsoiling technology is a little ploughing measure in dry land protective farming technology system.The subsoiler can scarify soil,deepen the arable layer,break the plough layer,improve the soil permeability,increase soil infiltration speed and amount,and create an arable layer structure with coexistence of fictional and real situation.Also,it can effectively promote development and growth of crop root system and play a favorable role in drought resistance and yield increase of crops.This paper made a simple overview of the subsoiling technology,current development situation of subsoiler both at home and abroad,and classification of subsoilers.
基金This study was funded by the National Science and Technology Supporting Plan(No.2011BAD29B08)the“111”Project(No.B12007).
文摘Since the design of the subsoiler is a complex work,the interaction between the subsoiler and soil was investigated by using Distinct Element Method(DEM)in this study.Based on the traditional discrete element theory,the 3D model of soil particles and the subsoiler were established after considering the liquid bridge force between soil particles.The operating resistance curves of the subsoiler were achieved after the DEM simulation at a speed of 1 m/s,and three depths of 180 mm,220 mm and 260 mm,respectively.The simulation curves agreed well with the field experimental results based on relative errors of 2.96%,14.95%and 7.15%,respectively,at three depths.All these data proved that it was feasible and favorable to analyze the performance of the subsoiler by using the DEM and it is of important significance for studying and further optimizing the structure of the subsoiler.
基金the National Science and Technology Supporting Plan of China(2011BAD29B08).
文摘Generally,a subsoiler is comprised of a shank and a point.The point shape has a significant effect on the draft force of a subsoiler.In this study,the draft force of subsoilers with four different points were compared under the speed of 0.8 m/s and the depth of 350 mm in the soil bin.Discrete Element Method(DEM)was applied in simulating the working process of the subsoiler.The stiffness of soil particles used in DEM was calibrated by comparing the simulated draft force of a standard arc-shaped subsoiler with the experiment.The calibrated soil particle stiffness was 1.1×104 N/m.The validated model was then used to compare the draft force of subsoilers with four different points under the same condition in the test.Results showed that different points would cause different draft forces.The subsoiler with short chisel point caused the smallest draft force(2885 N)while the point with short face and wings had the largest force(4474 N).The relative errors of the simulated results were less than 4%,which proved that DEM was an effective way for predicting the draft force of subsilers.The velocity field and contact force filed could show the movement of soil around the subsoiler.
基金the Special Fund for Agro-scientific Research in the Public Interest from the Ministry of Agriculture,China(Grant No.201503136)the National Natural Science Foundation of China(Grant No.51565010)the National Natural Science Foundation of Hainan Province(Grant No.20163038)。
文摘Subsoiling is essential in the tillage of banana planting,as banana plants have a fairly sturdy pseudostem and wide row spacing while soil tends to be compacted.In this study,a bionic vibrating subsoiler for banana fields was developed,verified,and evaluated.The vibrator was designed based on crank-rocker mechanism while the bionics design was used for subsoiler development.The forces on the susboiler were analyzed to verify the strength of the subsoiler tine.To test the performance of the subsoiler,field tests were conducted to measure the draft force and fuel consumption.There was approximately 14%reduction in the draft force and 22%increase in the fuel consumption in vibrating mode compared with that in non-vibrating mode.In conclusion,the study results could be applied in China’s tropical agricultural regions.
基金The authors gratefully acknowledge the financial assistance received from the National Key Research and Development Program of China(Grant No.2016YFD0200601,2016YFD020060101)and the Key Industry Chain Innovation Project of Shaanxi Province(Grant No.2018ZDCXL-NY-03-06).
文摘Understanding soil disturbance behaviors under the impact of the winged subsoiler is critical for designing or optimizing the winged subsoiler(a primary subsoiling tool).In this study,a soil-winged subsoiler interaction model was developed and the effects of winged subsoiler on soil disturbance behaviors were investigated using the discrete element method(DEM)simulations and lab soil-bin tests.The results showed that wings mainly affected the disturbance range and fragmentation degree of soil above them.The draught forces of share section(SS),arc section in the hardpan(ASHP),arc section in the top layer(ASTL)and line section(LS)were accounted for 69.53%,25.22%,4.73%and 0.52%of the total draught force of winged subsoiler;the lateral disturbance range from high to low of the soil at different depths followed the ranking:top layer(TL),hardpan disturbed by arc section(HDAS)and hardpan disturbed by share section(HDSS).Wings had the greatest influence on the draught force of ASHP.Adding wings to an arc-shaped subsoiler increased the disturbance areas of HDAS,TL and HDSS by 47.52%,7.74%and 4.59%,respectively,but meanwhile increased the total draught force by 36%.Compared with a non-winged subsoiler,winged subsoiler had higher soil looseness(15.83%),soil disturbance coefficient(58.59%),furrow width(448.65 mm)and soil disturbance area ratio(0.3835),but poorer soil surface flatness(19.79 mm)and lower soil loosening efficiency(39.35 mm²/N).This study provided critical information for optimizing winged subsoilers on aspects of improving soil loosening effectiveness and reducing draught force.
基金This work was supported by China’s Ministry of Agriculture,Agricultural Public Welfare Industry Research(201503117)China’s Ministry of Agriculture,Agricultural Public Welfare Industry Research(201503116-16)the Soil-Machine-Plant Key Laboratory of the Ministry of Agriculture of China.
文摘Soil compaction is a common problem facing conservation fields that restricts crop root growth and causes yield decrease.Subsoil techniques have been developed to break up the compaction layer.However,subsoil implement requires large draft power that hampered the development of subsoil techniques for most of developing countries due to lack of large scale tractors.Aiming to optimize the penetration resistance of the subsoiler and create a good working environment for the operators,a staggered vibrating subsoiler was developed.A new staggered vibrating mechanism was designed to generate the staggered vibration of the shanks meanwhile the V-shape shanks arrangement was adopted to keep relative balance for the subsoiler.In order to obtain optimum working parameters of the vibration frequency and forward speed,the trajectory of shanks was simulated by using the MATLAB software.The forward speed of 2-3 km/h with vibration frequency of 12 Hz was recommended to acquire an effective decrease in draft force.Field performance of this subsoiler was evaluated in terms of the draft force,power requirement and tractor wheel slippage.By comparing the two operation modes,staggered vibrating(SV)and rigid(NV)of shanks,the decrease ratios of draft force for SV were determined by 16.97%,12.12%and 9.02%at forward speeds of 2.2 km/h,2.6 km/h and 3.1 km/h,respectively.This is better than the research for the 1SZ-460 vibratory subsoiler that was decreased by 9.09%in draft force.The power requirement for SV was not significantly greater than that for NV.The obviously decreased wheel slippage was observed for SV by decrease of 12.47%,17.96%and 21.79%at forward speeds of 2.2 km/h,2.6 km/h and 3.1 km/h,respectively.In conclusion,the staggered vibrating subsoiler presents preferable working performance and is recommended to be applied in subsoil tillage process for developing countries.
基金This work was financially supported by Natural Science Basic Research Program of Shaanxi(Program No.2021JQ-173)Innovation and Entrepreneurship Training Program of Northwest A&F University(Program No.201910712134).
文摘A new subsoiler with placoid scale microstructure bionic surface was proposed which mimicked shark skin to reduce tillage resistance and soil adhesion during subsoiling cultivation.The contour curves of placoid scale microstructure on shark skin were fitted,and two kinds of bionic subsoiler with continuous and discontinuous microstructures were designed and fabricated,respectively.The effects of different bionic surfaces on tillage resistance were investigated by finite element simulation and experiment.The results indicated that the bionic subsoiler with discontinuous microstructure reduced the horizontal and vertical force by 21.3%and 24.8%,respectively.The subsoiler with discontinuous microstructure surface can prevent the adhesion between the soil and subsoiler surface more efficiently.
基金This study was financially supported by the National Key R&D Program of China(Grant No.2017YFD0701103)the EU H2020 Program(FabSurfWAR No.644971)+1 种基金the 111 Project(Grant No.B16020)of China,the National Natural Science Foundation(Grant No.51805338)the China Scholarship Council,China(CSC).
文摘With the increased use of agricultural machinery in field operations,soil compaction has become increasingly severe,and the plough pan has become deeper.Subsoiling is an excellent way to address this problem.However,it is limited by high energy consumption,which is closely related to tillage force.To investigate the effect of the geometric shape of shanks and tines on tillage force and soil disturbance in loam,a layered soil model in accordance with the actual conditions was established and five different subsoilers were simulated via discrete element modeling.The results indicated that the shank impacted soil disturbance and tine impacted tillage force.The draft force of curved shank and chisel tine was 8%less than that of the straight shank and sweep tine.The straight shank and sweep tine produced a larger furrow profile and a higher furrow width.The subsoiler with curved shank and chisel tine(C-C)exhibited the lowest specific resistance(12.87,17.52,19.46 and 21.18 kN/m^2 in the 30,35,40 and 45 cm tillage depth,respectively)considering the draft force and soil disturbance characteristics.Hence,these results will facilitate in the selection of a suitable subsoiler and design of new subsoilers with lower energy consumption requirements for loam areas worldwide.
基金partly funded by the Al Ain MunicipalityNational Water and Energy Center, United Arab Emirates University。
文摘Public urban greenery greatly contributes to the residential and tourist value of cities in the Gulf Region,but due to the hyper-arid climatic conditions,the cost of irrigation and plant maintenance is very high.Existing strategies to reduce the monetary and ecological costs involve the cultivation of native xerophytic plantations,and/or the use of soil improvers to increase water-and nutrient-holding capacity of the sandy soils.Various soil improvers based on mineral,organic,or synthetic materials have entered the United Arab Emirates(UAE)market in recent years,but there is considerable uncertainty about how they should best be used in combination with ornamental plant stands involving xerophytic native plants.The present study investigated the effect of soil amendment and deep pipe irrigation on perennial ornamental plant stands involving native plants(Tephrosia appolinea(Gel.)Link in combination with Aerva javanica(Burm.f.)Juss.ex Schult.)and native-exotic plants(T.appolinea in combination with Ruelia simplex C.Wright)either or not topsoil and subsoil amendment with bentonite and hydrophobic sand under the irrigation water supply of less than 50%of reference evapotranspiration(ET0).After one year of cultivation,T.appolinea and A.javanica(native vs.native)produced high biomass and exhibited high water use efficiency(WUE)as compared with T.appolinea and R.simplex(native vs.exotic)combination given that no significant differences were found under the soil amendment treatments.All stands thrived under irrigation water supply far below what is usually supplied to exotic ornamental stands in public parks of the Al Ain City,the UAE.However,subsoil amendment in combination with deep pipe irrigation reduced the occurrence of weeds and increased the overall plant rooting depth.Our results suggest that subsoil amendment and irrigation up to 60-80 cm depth can potentially control ephemeral weed infestation,which is a great challenge in various plant production systems of the Gulf Region.The results of the present study suggest that the impact of soil amendment on the WUE of exotic plants is marginal and might not be economically justified.Replacing exotic with native ornamental plant species seems to have a far greater water-saving potential than the amendment of the soil,while weeds can be suppressed in the absence of topsoil moisture.
基金Consejo Nacional de Ciencia y Tecnología of Mexico(CONACyT)under Grant No.1000473。
文摘The horizontal to vertical spectral ratio(HVSR)methodology is used here to characterize pumice soils and to image the three-dimensional surface geometry of Guadalajara,Mexico.Similar to other Latin American cities,Guadalajara is exposed to high seismic risk,with the particularity of being the largest urban settlement in Latin America built on pumice soils.Methodology has not yet been tested to characterize subsoil depths in pumice sands.Due to the questionable use of traditional geotechnical tests for the analysis of pumice soils,HVSR provides an alternative for its characterization without altering its fragile and porous structure.In this work,resonance frequency(F0)and peak amplitude(A0)are used to constrain the depth of the major impedance contrast that represents the interface between bedrock and pumice soil.Results were compared with borehole depths and other available geotechnical and geophysical data and show good agreement.One of the profiles estimated on the riverbanks that cross the city,reveals different subsoil thickness that could have an impact on different site responses on riverine areas to an eventual earthquake.Government and academic efforts are combined in this work to characterize depth sediments,an important parameter that impacts the regulations for construction in the city.
基金The authors gratefully acknowledge that this research was financially supported by the Modern Agricultural Industry Technology System(Grant No.CARS-03)Special Fund for Agro-scientific Research in the Public Interest from the Ministry of Agriculture,China(Grant No.201503136)Innovative Research Team in University of China(Grant No.IRT13039).
文摘The commonly used subsoiling cum rotary tiller machine(SRT)in Northern China is a combination of subsoiler and horizontal rotary tiller,however backfilling of the subsoiling slot,excessive vibration and plant residue wrapping on rotary components has been rarely considered.Therefore,the rotary components and assembly were redesigned to address these issues and to an SRT fitted with IT225 short curve rotary blades behind the V-shape subsoiling slots and IIT245 long curve rotary blades between the tines.Long and short blades were fitted on a rotor in a double helix,with optimal spiral angles of 65° and 90°,and phase angle of 147°and 180°,respectively.Compared with the commonly used SRT(CSRT),the additional anti-wrapping cutting blades in the circumferential and axial direction of ASRT could remove hanging residue on the blade holders,wrapping on the rotor and formation of an isolation layer.Moreover,the cutting edge curve of anti-wrapping cutting blades was an exponential curve.Field tests demonstrated that the redesigned SRT with anti-vibrating and anti-wrapping rotary components(ASRT)had was a significant advancement over the CSRT.Moreover,the working depth of rotary tillage was more stable,while other observations confirmed that backfilling of the subsoiling slot was also improved.
基金supported by the National Key Technology R&D Program of China(2012BAD04B02,2013BAD07B02,and2011BAD16B10)the Special Fund for Agro-Scientific Research in the Public Interest(201103003 and 201303126-4)the Key Technology R&D Program of Jilin province,China(20126026)
文摘A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen(N), phosphorus(P), and potassium(K) uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development,increased nutrient accumulation, and increased yield. Compared with conventional soil management(CK), root length, root surface area, and root dry weight at 0–80 cm soil depth under subsoil tillage to 30 cm(T1) and subsoil tillage to 50 cm(T2) were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.
基金the National Key Technologies R&D Program of China during the 1 lth Five-Year Plan Period(2006BAD02A15,2007BAD89B01)the National Natural Science Foundation of China(30471010).
文摘In order to improve the water use efficiency under conservation tillage, the effects of subsoiling on soil moisture under notillage were studied. An experiment of 40 cm subsoiling in a field kept under no-tillage for 2 years was operated from 2005 to 2006. Based on the data of the soil moisture and crop yield, the physical basis of subsoiling for water conservation and yield increase was analyzed. The results showed that the soil water storage under subsoiling, from the soil surface to a depth of 100 cm was more than that under no-tillage for the growth season. In the 0-100 cm soil depth, the soil moisture in 50-100 cm depth under subsoiling was more compared with no-tillage, which increased when it＇s drought and decreased when it＇s rainy with the increase in soil depth. Compared with no-tillage, subsoiling could reduce the water consumption of oats in the 0-50 cm depth and increase the water consumption in the 50-100 cm depth. Also, subsoiling increased the yield by 18.29% and the water use efficiency by 16.8% in a two-year average. The effects of subsoiling on water conservation and yield increase were affected by precipitation, and a well-proportioned rainfall was better to increase yield and water use efficiency. Meanwhile, subsoiling decreased bulk density, which increased with the available precipitation. Subsoiling under no-tillage is the effective rotation tillage to contain more soil moisture and improve water use efficiency in ecotone of North China.
基金supported by the National Key Technologies R&D Program of China during the 12th Five-Year Plan period(2011BAD16B15)
文摘High temperature stress（HTS） on spring maize（Zea mays L.） during the filling stage is the key factor that limits the yield increase in the North China Plain（NCP）.Subsoiling（SS） and ridge tillage（R） were introduced to enhance the ability of spring maize to resist HTS during the filling stage.The field experiments were conducted during the 2011 and 2012 maize growing seasons at Wuqiao County,Hebei Province,China.Compared with rotary tillage（RT）,the net photosynthetic rate,stomatal conductance,transpiration rate,and chlorophyll relative content（SPAD） of maize leaves was increased by 40.0,42.6,12.8,and 29.7% under SS,and increased by 20.4,20.0,5.4,and 14.2% under R,repectively.However,the treatments reduce the intercellular CO 2 concentration under HTS.The SS and R treatments increased the relative water content（RWC） by 11.9 and 6.2%,and the water use efficiency（WUE） by 24.3 and 14.3%,respectively,compared with RT.The SS treatment increased the root length density and soil moisture in the 0-80 cm soil profile,whereas the R treatment increased the root length density and soil moisture in the 0-40 cm soil profile compared with the RT treatment.Compared with 2011,the number of days with temperatures 33°C was more 2 d and the mean day temperature was higher 0.9°C than that in 2012,whereas the plant yield decreased by 2.5,8.5 and 10.9%,the net photosynthetic rate reduced by 7.5,10.5 and 18.0%,the RWC reduced by 3.9,5.6 and 6.2%,and the WUE at leaf level reduced by 1.8,5.2 and 13.1% in the SS,R and RT treatments,respectively.Both the root length density and the soil moisture also decreased at different levels.The yield,photosynthetic rate,plant water status,root length density,and soil moisture under the SS and R treatments declined less than that under the RT treatment.The results indicated that SS and R can enhance the HTS resistance of spring maize during the filling stage,and led to higher yield by directly improving soil moisture and root growth and indirectly improving plant water status,photosynthesis and grain filling.The study can provide a theoretical basis for improving yield of maize by adjusting soil tillage in the NCP.
基金This work was supported by the Agricultural Public Welfare Industry Research,Ministry of Agriculture,China(201503117)and the earmarked fund for China Agriculture Research System(CARS-02).
文摘Compact!on layers are widely distributed in the Huang-Huai-Hai Plain,China,which restrict root growth and reduce yields.The adoption of subsoiling has been recommended to disrupt compacted soil layers and create a reasonable soil structure for crop development.In this paper,the effects of subsoiling depth(30,35 and 40 cm),period interval(2 or 3 years)and combined pre-sowing tillage practice(rotary cultivation or ploughing)on soil condition improvement was studied on a tidal soil in the Huang-Huai-Hai Plain.Seve n tillage patter ns were desig ned by combini ng differe nt subsoili ng depths,period intervals and pre-sowing.The evaluation indicators for soil condition improvement were as follows:thickness of the plough layer and hard pan,soil bulk density,cone index,soil three-phase R values,alkali nitrogen content,crop yield,and economic ben efits.The results showed that subsoiling can sign ificantly improve the soil structure and physical properties.In all subsoiling treatments,the depth of 35 or 40 cm at a 2-year interval was the most significant.The thickness of the plough layer in creased from 13.67 cm before the test to 21.54-23.45 cm in 2018.The thick ness of the hard pan decreased from 17.68 cm before the test to 12.09-12.76 cm in 2018,a decrease of about 40.07%.However,the subsoiling combined presowing tillage practice,that is,rotary cultivation or ploughing,was not significant for soil structure and physical properties.For all subsoiling treatments,the soil bulk density,cone index and soil three-phase R values of the 15-25 cm soil layer were significantly lower compared to single rotary cultivation.Subsoiling was observed to increase the soil alkaline nitrogen and water conte nts.The tillage patter ns that had subsoiling at the depth of 35-40 cm at a 2-year in terval combi ned with rotary cultivation had the highest alkali nitrogen and water contents,which increased by 31.08-34.23%compared with that of the single rotary cultivati on.Subsoiling can sign ifica ntly in crease the yield both of wheat and corn,as well as the economic ben efits.The treatment of subsoili ng at the depth of 35 cm at an interval of 2 years com bined with rotary cultivation had the highest ann ual yield and economic benefits.For this treatme nt,the arinual yield and economic ben efits in creased by 14.55 and 62.87%in 2018,respectively.In con clusi on,the tillage patter ns that involved subsoili ng at a depth of 35 cm at a 2-year interval along with rotary cultivation are suitable for the Huang?Huai-Hai Plain.
基金the Natural Science Foundation of Zhejiang Province, China (No.R306011).
文摘The soil factors influencing the potential migration of dissolved and particulate phosphorus(P) from structurally-weak sandy subsoils were evaluated by means of soil column leaching experiments. Soil colloids were extracted from two types of soils to make the colloid-bound forms of P solution. Eight sandy soils with diverse properties were collected for packing soil columns. The effects of influent solutions varying in concentrations of colloids,P,and electrolyte,on the transport of P and quality of leachates were characterized. P migration in the soils was soil property-dependent. High soil electrical conductivity values retarded the mobility of colloids and transportability of colloid-associated P(particulate P) . Soil electrical conductivity was negatively correlated with colloids and reactive particulate P(RPP) concentrations in the leachates,whereas,the total reactive P(TRP) and dissolved reactive P(DRP) concentrations in the leachates were mainly controlled by the P adsorption capacity and the P levels in the subsoil. The reactive particulate P in the leachates was positively correlated with the colloidal concentration. Increased colloidal concentration in the influent could significantly increase the colloidal concentration in the leachates. Elevated P concentration in the influent had little effect on P recovery in the leachates,but it resulted in significant increases in the absolute P concentration in the leachates.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest,China(201303104)the earmarked fund for China Agriculture Research System(CARS-03-01-24)the Project Funded by China Postdoctoral Science Foundation(K461501024)
文摘Soil moisture is the most critical limiting factor impacting yields of dryland winter wheat(Triticum aestivum L.) and it is strongly affected by tillage practice and sowing methods. This study was to assess the link between sowing method and tillage practice during summer fallow and their subsequent effect on soil moisture and grain yield. Furthermore, we sought to identify a more appropriate farming management practice for winter wheat production in Loess Plateau region of China. The experiment was conducted from 2011 to 2013, using a two-factor split plot design, including subsoiling(SS) or no tillage(NT) during summer fallow for main plots, and conventional drill sowing(DS) or plastic film drill sowing(FM) for subplots. Results showed that the maximum soil water storage(SWS) was under SS×FM treatment with values of 649.1 mm(2011–2012) and 499.4 mm(2012–2013). The SWS during the 2011–2012 growing season were 149.7 mm higher than that in the 2012–2013 growing season. And adoption of SS×FM significantly increased precipitation use efficiency(PUE) and water use efficiency(WUE) compared to other treatments for both seasons. Moreover, adoption of SS×FM significantly increased yield by 13.1, 14.4, 47.3% and 25.9, 39.1, 35.7% than other three treatments during the two growing seasons, respectively. In summary, combining subsoiling during summer fallow with plastic film drill sowing(SS×FM) increased SWS at sowing and effectively improved WUE, thus representing a feasible technology to improve grain yield of dryland winter wheat in the Loess Plateau of China.
文摘Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacent rock-stratum. The influence of the coefficient of permeability and loading frequency on the soil displacement at the ground surface were studied. The results showed that higher loading frequency led to more dynamic characteristics; and that the effect of the soil permeability was more obvious at higher frequencies.
基金Project(51021004)supported by Innovative Research Groups of the National Natural Science Foundation of ChinaProject(NCET-11-0370)supported by Program for New Century Excellent Talents in Universities of China+1 种基金Project(40776055)supported by the National Natural Science Foundation of ChinaProject(1002)supported by State Key Laboratory of Ocean Engineering Foundation,China
文摘Buckling of submarine pipelines under thermal stress is one of the most important problems to be considered in pipeline design. And pipeline with initial imperfections will easily undergo failure due to global buckling under thermal stress and internal pressure. Therefore, it is vitally important to study the global buckling of the submarine pipeline with initial imperfections. On the basis of the characteristics of the initial imperfections, the global lateral buckling of submarine pipelines was analyzed. Based on the deduced analytical solutions for the global lateral buckling, effects of temperature difference and properties of foundation soil on pipeline buckling were analyzed. The results show that the snap buckling is predominantly governed by the amplitude value of initial imperfection; the triggering temperature difference of Mode I for pipelines with initial imperfections is higher than that of Mode I1; a pipeline with a larger friction coefficient is safer than that with a smaller one; pipelines with larger initial imperfections are safer than those with smaller ones.
基金Finnish Transport Agency for enabling the research
文摘Seasonally cold climate and resulting frost action set great demands to railway track substructure in order to maintain Irack geomelry. Chal- lenges culminate on high-speed lines, where the tolerances for roughness are the tightest. Problems may result in highly increased Irack maintenance and need for temporary speed reslrictions. The causes of frost action can be associated with subsoil, subballast or ballast. The major concern in frost protection is to avoid the freezing of frost susceptible subsoil by using sufficient thickness of subballast and relying on non-fi＇ost-susctible subballast material. This paper provides an overview of the main research findings on the role of ballast, subballast and subsoil in frost acedon. In new comlruclion the material specificalions, design procedures and construction methods have been developed to ensure adequate performance of Irack subscatt, but special challenges exist in managing existing Wacks that were not designed for modem requirements. In order to perform cost-effective and sustainable track maintenance, it is necessary to recognize the problem areas and define the root-causes of problems. For locating the problem sections and defining the causes of defects, a sophisticated analysis based on integration of track geometry and ground penetrating radar （GPR） data has been developed and is summarized in this paper,
