The problem with earth constructions is their low resistance to water. Step by step, the water degrades the exterior facings of the structures and ends up creating zones of weakness through the structures, making them...The problem with earth constructions is their low resistance to water. Step by step, the water degrades the exterior facings of the structures and ends up creating zones of weakness through the structures, making them collapse and creating enormous socio-economic problems, especially in rural areas. The solutions proposed to date, like the use of straw, cow dung, boiled skins, banana leaves, tar, cement soil, have shown their limits. Generally, the poor adhesion between the protected material and the protective layer means that the latter always ends up peeling off. This work, which is inspired by the traditional practice where plant tannins are used to brush the earthen walls to waterproof them, proposes a tri-layer coating composed of soil, powder and hydrolysable tannins extracted from the stem bark of Bridelia. This work focuses on the geotechnical characterization of the soil, the extraction of hydrolysable tannin, the manufacture of the micro-coating, the resistance tests carried out on the micro-coating, the technique of implementation and the test of evaluation of the performance of the tri-layer coating. The results obtained show that not only does the tri-layer coating adhere perfectly to the layer to protect, but it also waterproofs it and protects it against shocks.展开更多
:Earth is the most common and important building material used in the construction industry,since it is found in almost every country in the world.Modern earthen construction is alive and well,and is spread over an en...:Earth is the most common and important building material used in the construction industry,since it is found in almost every country in the world.Modern earthen construction is alive and well,and is spread over an enormous geographical area.This technique utilizes various earthen materials and numerous methods,and features many benefits for both construction in general and buildings in particular.Najran,a city located in the south of Saudi Arabia,is distinguished by its heritage of earthen architecture,which displays many advantages and a marvelous variety of types and exterior designs.Many weaknesses of the material,however,along with a lack of knowledge and rapid development have caused the uplifting and destruction of many of Najran’s mud and heritage buildings during the last few generations.Not all soil types are suitable for every building need.Soil specification is thus very important in order to ensure that the materials used in construction meet all requirements.The main goal of this study was to invistegate the suitability of local soils for the earthen building construction.Thus,available local materials of common quality were taken from local sites in Najran.Laboratory experimentation and testing was then performed to determine the properties of those materials.The results showed that local soil properties are suitable for using in the earthen block construction since they satisified the specifications.The results were then recorded for use in further studies,as well as to explore heritage building and rehabilitation,and to improve modern earthen building materials and techniques.展开更多
Based on model tests of earthen dam breach due to piping failure, a numerical model was developed.A key difference from previous research is the assumption that the cross-section of the pipe channel is an arch, with a...Based on model tests of earthen dam breach due to piping failure, a numerical model was developed.A key difference from previous research is the assumption that the cross-section of the pipe channel is an arch, with a rectangle at the bottom and a semicircle at the top before the collapse of the pipe roof, rather than a rectangular or circular cross-section.A shear stress-based erosion rate formula was utilized, and the arched pipe tunnel was assumed to enlarge along its length and width until the overlying soil could no longer maintain stability.Orifice flow and open channel flow were adopted to calculate the breach flow discharge for pressure and free surface flows, respectively.The collapse of the pipe roof was determined by comparing the weight of the overlying soil and the cohesion of the soil on the two sidewalls of the pipe.After the collapse, overtopping failure dominated, and the limit equilibrium method was adopted to estimate the stability of the breach slope when the water flow overtopped.In addition, incomplete and base erosion, as well as one-and two-sided breaches were taken into account.The USDAARS-HERU model test P1, with detailed measured data, was used as a case study, and two artificially filled earthen dam failure cases were studied to verify the model.Feedback analysis demonstrates that the proposed model can provide satisfactory results for modeling the breach flow discharge and breach development process.Sensitivity analysis shows that the soil erodibility and initial piping position significantly affect the prediction of the breach flow discharge.Furthermore, a comparison with a well-known numerical model shows that the proposed model performs better than the NWS BREACH model.展开更多
Salt weathering leads to destruction of many valuable cultural heritage monuments and porous building material. The present study aims at providing more laboratory evidence for evaluating the effects of salt precipita...Salt weathering leads to destruction of many valuable cultural heritage monuments and porous building material. The present study aims at providing more laboratory evidence for evaluating the effects of salt precipitation on the deterioration process. In view of this, the remoulded soil specimens were mixed with three kinds of salts(i.e., NaCl, Na_2SO_4 and their mixture) with different salt concentrations, and the specimens were kept in environment cabinet for undergoing different wet-dry cycles. After each cycle, the ultrasound velocity measurements were employed to monitor the deterioration process. For the specimens that have suffered three wet-dry cycles, the mechanical properties(i.e. shear strength and compression strength) were determined to evaluate the degree of deterioration. Furthermore, considering the realistic conservation environment of earthen sites, mechanical stability of these specimens against sediment-carrying wind erosion was conducted in a wind tunnel. These experiments results indicate that the overall average velocities of the specimens after the third cycle are significantly lower than those subjected to only one cycle. Ultrasound velocity, mechanical strength and wind erosion rate decrease when salt content increases. However, the internal friction angle increases firstly, and then decreases with the increase in salt content added to the specimens. Na_2SO_4 contributes most of the surface deterioration, while NaCl plays little role in the deterioration. The damage potential of the salt mixture is less obvious and largely dependent on the crystallisation location.展开更多
In this study, six composite reinforcements such as cement composite made of Abandoned Cell Husks (ASH), Stones, Wood chips, Concrete and Bricks have been used along with control specimen. It is known that the materia...In this study, six composite reinforcements such as cement composite made of Abandoned Cell Husks (ASH), Stones, Wood chips, Concrete and Bricks have been used along with control specimen. It is known that the material used in earth reinforcement applications must be safe against tension failure and adhesion failure for its effective utilization in the field and reliable design of earth structures. Single type of material can provide limited reinforcement capability in reinforced earth structures due to its low frictional resistance and poor cohesion. For an optimal response, therefore, composite reinforcement, that fulfils both the requirements such as possess adequate tensile strength and adequate frictional resistance, is getting considerable attention. Slope stability analyses containing six types of reinforcement have been performed. Stability of the slope has been quantified using minimum factor of safety corresponding to critical slip surface. It was observed that the composite reinforcement whose surface treated by brick aggregate enhanced the factor of safety significantly. The paper also depicted the design aids of reinforced slope in terms of embedding lengths and spacing of reinforcements.展开更多
The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets wer...The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets were formulated to contain 0% (A0), 10% (A10), 20% (A>sub>20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM), as partial fish meal (FM) substitutes. Diet A0 without AM served as a control. Fish growth decreased as AM level exceeded 20% in diets (P 0.05). Crude lipid was significantly lower in fish fed A50 and significant differences were also found in crude ash (P 20, A30 and A50. High level of the fern reduces growth without negatively affecting fatty acid in fish. Fish PUFA, especially the (n - 3) fatty acids, are affected positively, even when fed 50% AM, which is good for the quality of the fish produced in regard to the benefits for the health of consumers.展开更多
Murals in Mogao Grottoes consist of three parts:support layer,earthen plasters and paint layer.The earthen plasters play a key role in the preservation of murals.It is a mixture of Dengban soil,sand,and plant fiber.Tw...Murals in Mogao Grottoes consist of three parts:support layer,earthen plasters and paint layer.The earthen plasters play a key role in the preservation of murals.It is a mixture of Dengban soil,sand,and plant fiber.Two different natural fibers,hemp fiber and cotton fiber,were reinforced to earthen plasters in the same percentage to evaluate the influence on hygrothermal performance.The two types of earthen plasters were studied:one containing hemp fiber in the fine plaster(HFP)and the other containing cotton fiber in the fine plaster(CFP).Specific heat capacity,dry thermal conductivity,water vapor permeability,and sorption isotherms were investigated.The results showed that the difference between two natural fibers has much more impact on the hygric properties(water vapor permeability and sorption isotherms)of earthen plasters than on their thermal performance(specific heat capacity and dry thermal conductivity).The CFP with higher density has higher thermal conductivity than the HFP with lower density.But no significant differences of specific heat capacity were observed.Compared with HFP,CFP used in murals can reduce the rate of water transfer and prevent salt from transferring water to the mural surface.The overall findings highlight that all these features of CFP are beneficial to the long-term preservation of murals.The study of the earthen plasters in Mogao Grottoes is of general significance,and the measured properties can be used to obtain coupled heat and moisture analysis of the earthen plasters and to dissect the degradation mechanism of murals.展开更多
To determine and map the subsurface conditions of a dam, a 2D electrical resistivity tomography study was carried out within the two flanks of Zaria dam at Shika. This was done to ascertain if the variations in the vo...To determine and map the subsurface conditions of a dam, a 2D electrical resistivity tomography study was carried out within the two flanks of Zaria dam at Shika. This was done to ascertain if the variations in the volume of water content in the dam is due to an anomalous seepage beneath the subsurface or seasonal effects. On the basis of the interpretation of the acquired data, various zones of relatively uniform resistivity values were mapped and identified. The first zone is characterized by moderate resistivity values of 150 - 600 ohm-m. It represents unsaturated topsoil with thicknesses varying from 1 - 4.5 m. The second (intermediate depth) resistivity zone, with values ranging from 5 - 100 ohm-m and thickness varying from 3.5 - 10 m, represents a silt clay layer with high moisture content. The third resistivity zone represents fairly weathered granite and is characterized by relatively high resistivity values ranging from 700 - 6000 ohm-m. The available borehole log data correlated well with the pseudo-sections in relation to the obtained resistivity values and depth. Zones of relatively low resistivity within the bedrock are interpreted to represent potential seepage pathways. Hence, this geophysical method can be successfully used to delineate and map these seepage pathways within the subsurface of the earth dam.展开更多
China has traditional tea and ceramics cultures. They supplement each other. In a certain historical period, tea promoted the development of ceramic. The purple earthenware is a kind of ceramic. The development of thi...China has traditional tea and ceramics cultures. They supplement each other. In a certain historical period, tea promoted the development of ceramic. The purple earthenware is a kind of ceramic. The development of this kind of teapot was closely related with Chinese tea. In ancient China, the tea was boiled instead of being infused, as at present. At that time, most of the tea was in compressed form, not in bulk form, so no particular tea utensil was necessary. Since the Ming dynasty (1368-1644), the展开更多
This paper analyzes the current state of earthen constructions in countries located in the Pacific Ring of Fire.In Latin America,countries such as Colombia,Ecuador,Peru,Bolivia,Chile and Argentina are located in the P...This paper analyzes the current state of earthen constructions in countries located in the Pacific Ring of Fire.In Latin America,countries such as Colombia,Ecuador,Peru,Bolivia,Chile and Argentina are located in the Pacific Ring of Fire and are subject to strong seismic exposure,making earthen constructions more vulnerable.From an analysis of the housing censuses of each country,it was observed that currently,earthen construction continues to be a construction option,that the percentage of earthen constructions varies from country to country,and that they make up a high percentage of dwellings;namely,in Colombia 5.3%(714.478 houses),Ecuador 8%(383.086),Peru 31%(2.390.625),Bolivia 37%(1.037.473),Chile 2%(121.756)and 1.9%in Argentina(230.185 houses).Peru,despite being one of the countries with the highest seismic risk,is the country with the highest number of earthen dwellings.It was concluded that in all the countries analyzed,earthen architecture prevails,employing different construction techniques whose characteristics are deeply rooted in each country’s ancestral culture.This highlights the importance of having regulations in place and skilled workers in order to intervene correctly and repair the structures after a seismic event.展开更多
Earthen sites,which are mainly made of earth,are cultural heritages with historical,artistic and scientific values.Many extremely valuable earthen sites have been preserved in the arid areas in China.The earthen site ...Earthen sites,which are mainly made of earth,are cultural heritages with historical,artistic and scientific values.Many extremely valuable earthen sites have been preserved in the arid areas in China.The earthen site of Jiaohe Ancient City is one of the earliest National Protected Important Cultural Heritage Sites.The Jiaohe Ancient City site exhibits all kinds of deteriorations,which can be found in the earthen sites in arid environments in China.Through a case study of the Jiaohe ancient earthen site,we present in this paper the comprehensive conservation technologies,including the mud bricklaying and reparation,wooden rod anchorage,crack grouting,surface potassium silicate(PS) penetration consolidation,and suspended steel beam ceiling,etc.Results of this case study showed that better conservation effects could be achieved by selecting proper PS penetration and crack grouting processes based on the deterioration characteristics of the earthen sites.The technology of mud bricklaying and reparation was also an effective method for preventing the earthen body from collapsing.Compared with traditional conservation technologies,the suspended steel beam ceiling technology could effectively reduce the negative impacts to the original state of the earthen site.As for unstable cliffs,a new method using composite anchor rod of bamboo and steel with massive loose earth was applied.Deformation monitoring and temporary supports were critical and indispensable measures for the safe of site conservation projects.Through years of monitoring and practical operation at the Jiaohe ancient earthen site,deterioration at the site has been effectively controlled.展开更多
During the process of archaeological excavation in the regions of Southeast China, collapse of test square usually occurs due to poor site-specific conditions. In this paper, the fast Lagrangian analysis of continua i...During the process of archaeological excavation in the regions of Southeast China, collapse of test square usually occurs due to poor site-specific conditions. In this paper, the fast Lagrangian analysis of continua in three dimensions(FLAC3D) is employed to reveal the behaviors of test square. Taking the archaeological works in Liangzhu prehistoric earthen sites as the research background, the paper first introduces the geological setting, excavation procedure and monitoring scheme of the studied test square. Then, the deformation of four sides of the test square is modeled using FLAC3D. By comparison, it shows that the numerical results are consistent with the results from field monitoring. The result suggests that the numerical simulation can be effectively applied to representing the actual behaviors of the test square,which is helpful for determination of excavation scheme and stability evaluation of the test square during archaeological excavation.展开更多
Earthen sites are widely distributed throughout China,and most of them belong to archaeological sites with significant values,which not only directly witness the origin,formation and development of Chinese civilizatio...Earthen sites are widely distributed throughout China,and most of them belong to archaeological sites with significant values,which not only directly witness the origin,formation and development of Chinese civilization,but also possess important values for conservation and exhibition.Many researches and practices on their conservation and consolidation have been carried out:however,the consolidation effect is mainly judged by visual observation and expert evaluation.Scientific assessment of conservation and consolidation effects is a challenging issue.Many instruments in other fields cannot be directly applied to the conservation of cultural relics due to their peculiarity.In order to assess the effects of field conservation experiments,this paper tries to understand the consolidation effects at Liangzhu site using nondestructive or micro-damage methods,including thermo-physical parameters testing,infrared thermal imaging,high-density microelectrode resistivity testing,portable microscope observation,and hydrophilic and hydrophobic testing,and thereby explores the practicable methods for evaluating the properties of consolidation materials for earthen sites treatment.展开更多
Across the American Southwest water development has played a critical role in managing rangelands.Earthen berms have been constructed throughout US rangelands to manage runoff and reduce erosion.The berms altered runo...Across the American Southwest water development has played a critical role in managing rangelands.Earthen berms have been constructed throughout US rangelands to manage runoff and reduce erosion.The berms altered runoff patterns to increase soil moisture with positive local vegetative response.However,altered runoff patterns can be considered a disturbance that affects broader scale vegetation patterns.We hypothesized that the hydrologic impacts of earthen berms in semiarid rangelands will be reflected in contrasting upslope and downslope vegetation patterns.A supervised classification of grass,shrubs,and bare soil was performed using orthographic imagery taken in June 2016 to quantify the effects of 181 earthen berms in the uplands and floodplain of the Altar Valley in Southern Arizona,US.Intact berms blocked runoff,creating downslope runoff"shadows"within which the precipitation is the dominant water input.We documented more bare soil downslope of intact berms in comparison with upslope.Grass and shrub cover affected by berms were related to soil texture.Grass and shrub cover were not different above and below intact berms on fine textured soils,but on sites with coarser textured soil,grass cover was lower downslope of berms.Where breaches occurred on coarser textured soils,the up and downslope differences in grass cover diminished.This study points to the role of conservation structures in adding additional complexity to already heterogeneous landscapes by creating patchwork assemblages of vegetation and bare soil proximal to earthen runoff and erosion control berms.展开更多
The scaling off is among the most pervasive and severe deterioration types.The scaling off developed on earthen sites in Northwest China has a special and complex binary structure composed of crusted and loose layers....The scaling off is among the most pervasive and severe deterioration types.The scaling off developed on earthen sites in Northwest China has a special and complex binary structure composed of crusted and loose layers.Under the synergistic functions of external environmental elements such as rainfall,temperature,and wind,and rammed earth properties,this deterioration has gradually created the crust on the site’s surface,and has then evolved into exfoliation and finally fallen off,leading to the reciprocating progressive destruction of earthen sites.Therefore,determining the development mechanism of scaling off and implementing targeted protection measures for the scientific conservation of earthen sites has become essential.In this review study,the properties of the building material causing the binary structure and the coupling effects of water,temperature,salt,and wind on the development of scaling off were determined,and the quantitative evaluation system for this deterioration development was elaborated.After interpreting the reasons for the development of the scaling off,protective measures including chemical grouting,electro-osmosis grouting,and overlay applications were stated.This study also pointed out the research hotspots and shortage in the study process on the scaling off.The hotspots generally focused on the development mechanism of binary structure,quantitative assessment of the degree of development,and related scientific consolidation measures.The shortcomings around the above directions include less attention to the development characteristics and mechanism of scaling off on earthen sites under special environment types,optimization and applicability of quantitative evaluation models,and the development and feasibility of reinforcement slurries and methods.This study can be beneficial in providing theoretical support for the scientific conservation and engineering practice of the scaling off on the earthen sites.展开更多
Biochemical, chemical, and mechanical, techniques have been employed to enhance soil resilience for decades. While the use of mechanical techniques requires transporting huge amounts of soil materials, the cement used...Biochemical, chemical, and mechanical, techniques have been employed to enhance soil resilience for decades. While the use of mechanical techniques requires transporting huge amounts of soil materials, the cement used in chemical techniques may lead to increase atmospheric carbon dioxide. Numerous studies indicate that biochemical techniques may be less expensive, cost effective, and environmentally friendly. Biopolymers and enzymes derived from microorganisms have been suggested as biological enhancers in strengthening and fortifying soils used for earthen structures. Lime and other treatment techniques used as biobased materials have been shown to be less effective for stabilizing soils. Here, we review biochemical processes and techniques involved in the interactions of soil enzymes, microorganisms, microbial extracellular polymeric substances, and other biopolymers with soil particles, and the challenges and strategies of their use as biobased materials for stabilizing soils. This review provides their impacts on various soil properties and the growth potentials of agricultural crops. .展开更多
文摘The problem with earth constructions is their low resistance to water. Step by step, the water degrades the exterior facings of the structures and ends up creating zones of weakness through the structures, making them collapse and creating enormous socio-economic problems, especially in rural areas. The solutions proposed to date, like the use of straw, cow dung, boiled skins, banana leaves, tar, cement soil, have shown their limits. Generally, the poor adhesion between the protected material and the protective layer means that the latter always ends up peeling off. This work, which is inspired by the traditional practice where plant tannins are used to brush the earthen walls to waterproof them, proposes a tri-layer coating composed of soil, powder and hydrolysable tannins extracted from the stem bark of Bridelia. This work focuses on the geotechnical characterization of the soil, the extraction of hydrolysable tannin, the manufacture of the micro-coating, the resistance tests carried out on the micro-coating, the technique of implementation and the test of evaluation of the performance of the tri-layer coating. The results obtained show that not only does the tri-layer coating adhere perfectly to the layer to protect, but it also waterproofs it and protects it against shocks.
基金The funding was received by Yaser Khaled Al-Sakkaf.
文摘:Earth is the most common and important building material used in the construction industry,since it is found in almost every country in the world.Modern earthen construction is alive and well,and is spread over an enormous geographical area.This technique utilizes various earthen materials and numerous methods,and features many benefits for both construction in general and buildings in particular.Najran,a city located in the south of Saudi Arabia,is distinguished by its heritage of earthen architecture,which displays many advantages and a marvelous variety of types and exterior designs.Many weaknesses of the material,however,along with a lack of knowledge and rapid development have caused the uplifting and destruction of many of Najran’s mud and heritage buildings during the last few generations.Not all soil types are suitable for every building need.Soil specification is thus very important in order to ensure that the materials used in construction meet all requirements.The main goal of this study was to invistegate the suitability of local soils for the earthen building construction.Thus,available local materials of common quality were taken from local sites in Najran.Laboratory experimentation and testing was then performed to determine the properties of those materials.The results showed that local soil properties are suitable for using in the earthen block construction since they satisified the specifications.The results were then recorded for use in further studies,as well as to explore heritage building and rehabilitation,and to improve modern earthen building materials and techniques.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC0404805)the National Natural Science Foundation of China(Grants No.51779153 and 51539006)+1 种基金the Central Public-interest Scientific Institution Basal Research Fund(Grant No.Y717012)the Natural Science Foundation of Jiangsu Province(Grant No.BK20161121)
文摘Based on model tests of earthen dam breach due to piping failure, a numerical model was developed.A key difference from previous research is the assumption that the cross-section of the pipe channel is an arch, with a rectangle at the bottom and a semicircle at the top before the collapse of the pipe roof, rather than a rectangular or circular cross-section.A shear stress-based erosion rate formula was utilized, and the arched pipe tunnel was assumed to enlarge along its length and width until the overlying soil could no longer maintain stability.Orifice flow and open channel flow were adopted to calculate the breach flow discharge for pressure and free surface flows, respectively.The collapse of the pipe roof was determined by comparing the weight of the overlying soil and the cohesion of the soil on the two sidewalls of the pipe.After the collapse, overtopping failure dominated, and the limit equilibrium method was adopted to estimate the stability of the breach slope when the water flow overtopped.In addition, incomplete and base erosion, as well as one-and two-sided breaches were taken into account.The USDAARS-HERU model test P1, with detailed measured data, was used as a case study, and two artificially filled earthen dam failure cases were studied to verify the model.Feedback analysis demonstrates that the proposed model can provide satisfactory results for modeling the breach flow discharge and breach development process.Sensitivity analysis shows that the soil erodibility and initial piping position significantly affect the prediction of the breach flow discharge.Furthermore, a comparison with a well-known numerical model shows that the proposed model performs better than the NWS BREACH model.
基金Projects(2010BAK67B16,2013BAK08B11,2014BAK16B02)supported by the National Science and Technology Support Program of China during the 12th Five-year Plan Period
文摘Salt weathering leads to destruction of many valuable cultural heritage monuments and porous building material. The present study aims at providing more laboratory evidence for evaluating the effects of salt precipitation on the deterioration process. In view of this, the remoulded soil specimens were mixed with three kinds of salts(i.e., NaCl, Na_2SO_4 and their mixture) with different salt concentrations, and the specimens were kept in environment cabinet for undergoing different wet-dry cycles. After each cycle, the ultrasound velocity measurements were employed to monitor the deterioration process. For the specimens that have suffered three wet-dry cycles, the mechanical properties(i.e. shear strength and compression strength) were determined to evaluate the degree of deterioration. Furthermore, considering the realistic conservation environment of earthen sites, mechanical stability of these specimens against sediment-carrying wind erosion was conducted in a wind tunnel. These experiments results indicate that the overall average velocities of the specimens after the third cycle are significantly lower than those subjected to only one cycle. Ultrasound velocity, mechanical strength and wind erosion rate decrease when salt content increases. However, the internal friction angle increases firstly, and then decreases with the increase in salt content added to the specimens. Na_2SO_4 contributes most of the surface deterioration, while NaCl plays little role in the deterioration. The damage potential of the salt mixture is less obvious and largely dependent on the crystallisation location.
文摘In this study, six composite reinforcements such as cement composite made of Abandoned Cell Husks (ASH), Stones, Wood chips, Concrete and Bricks have been used along with control specimen. It is known that the material used in earth reinforcement applications must be safe against tension failure and adhesion failure for its effective utilization in the field and reliable design of earth structures. Single type of material can provide limited reinforcement capability in reinforced earth structures due to its low frictional resistance and poor cohesion. For an optimal response, therefore, composite reinforcement, that fulfils both the requirements such as possess adequate tensile strength and adequate frictional resistance, is getting considerable attention. Slope stability analyses containing six types of reinforcement have been performed. Stability of the slope has been quantified using minimum factor of safety corresponding to critical slip surface. It was observed that the composite reinforcement whose surface treated by brick aggregate enhanced the factor of safety significantly. The paper also depicted the design aids of reinforced slope in terms of embedding lengths and spacing of reinforcements.
文摘The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets were formulated to contain 0% (A0), 10% (A10), 20% (A>sub>20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM), as partial fish meal (FM) substitutes. Diet A0 without AM served as a control. Fish growth decreased as AM level exceeded 20% in diets (P 0.05). Crude lipid was significantly lower in fish fed A50 and significant differences were also found in crude ash (P 20, A30 and A50. High level of the fern reduces growth without negatively affecting fatty acid in fish. Fish PUFA, especially the (n - 3) fatty acids, are affected positively, even when fed 50% AM, which is good for the quality of the fish produced in regard to the benefits for the health of consumers.
基金This project was supported by the National Natural Science Foundation of China(Projects No.51378412)China State Administration of Cultural Heritage(Project No.20110308).
文摘Murals in Mogao Grottoes consist of three parts:support layer,earthen plasters and paint layer.The earthen plasters play a key role in the preservation of murals.It is a mixture of Dengban soil,sand,and plant fiber.Two different natural fibers,hemp fiber and cotton fiber,were reinforced to earthen plasters in the same percentage to evaluate the influence on hygrothermal performance.The two types of earthen plasters were studied:one containing hemp fiber in the fine plaster(HFP)and the other containing cotton fiber in the fine plaster(CFP).Specific heat capacity,dry thermal conductivity,water vapor permeability,and sorption isotherms were investigated.The results showed that the difference between two natural fibers has much more impact on the hygric properties(water vapor permeability and sorption isotherms)of earthen plasters than on their thermal performance(specific heat capacity and dry thermal conductivity).The CFP with higher density has higher thermal conductivity than the HFP with lower density.But no significant differences of specific heat capacity were observed.Compared with HFP,CFP used in murals can reduce the rate of water transfer and prevent salt from transferring water to the mural surface.The overall findings highlight that all these features of CFP are beneficial to the long-term preservation of murals.The study of the earthen plasters in Mogao Grottoes is of general significance,and the measured properties can be used to obtain coupled heat and moisture analysis of the earthen plasters and to dissect the degradation mechanism of murals.
文摘To determine and map the subsurface conditions of a dam, a 2D electrical resistivity tomography study was carried out within the two flanks of Zaria dam at Shika. This was done to ascertain if the variations in the volume of water content in the dam is due to an anomalous seepage beneath the subsurface or seasonal effects. On the basis of the interpretation of the acquired data, various zones of relatively uniform resistivity values were mapped and identified. The first zone is characterized by moderate resistivity values of 150 - 600 ohm-m. It represents unsaturated topsoil with thicknesses varying from 1 - 4.5 m. The second (intermediate depth) resistivity zone, with values ranging from 5 - 100 ohm-m and thickness varying from 3.5 - 10 m, represents a silt clay layer with high moisture content. The third resistivity zone represents fairly weathered granite and is characterized by relatively high resistivity values ranging from 700 - 6000 ohm-m. The available borehole log data correlated well with the pseudo-sections in relation to the obtained resistivity values and depth. Zones of relatively low resistivity within the bedrock are interpreted to represent potential seepage pathways. Hence, this geophysical method can be successfully used to delineate and map these seepage pathways within the subsurface of the earth dam.
文摘China has traditional tea and ceramics cultures. They supplement each other. In a certain historical period, tea promoted the development of ceramic. The purple earthenware is a kind of ceramic. The development of this kind of teapot was closely related with Chinese tea. In ancient China, the tea was boiled instead of being infused, as at present. At that time, most of the tea was in compressed form, not in bulk form, so no particular tea utensil was necessary. Since the Ming dynasty (1368-1644), the
文摘This paper analyzes the current state of earthen constructions in countries located in the Pacific Ring of Fire.In Latin America,countries such as Colombia,Ecuador,Peru,Bolivia,Chile and Argentina are located in the Pacific Ring of Fire and are subject to strong seismic exposure,making earthen constructions more vulnerable.From an analysis of the housing censuses of each country,it was observed that currently,earthen construction continues to be a construction option,that the percentage of earthen constructions varies from country to country,and that they make up a high percentage of dwellings;namely,in Colombia 5.3%(714.478 houses),Ecuador 8%(383.086),Peru 31%(2.390.625),Bolivia 37%(1.037.473),Chile 2%(121.756)and 1.9%in Argentina(230.185 houses).Peru,despite being one of the countries with the highest seismic risk,is the country with the highest number of earthen dwellings.It was concluded that in all the countries analyzed,earthen architecture prevails,employing different construction techniques whose characteristics are deeply rooted in each country’s ancestral culture.This highlights the importance of having regulations in place and skilled workers in order to intervene correctly and repair the structures after a seismic event.
基金Supported by the National Key Technology R and D Program of China (2010BAK67B16)
文摘Earthen sites,which are mainly made of earth,are cultural heritages with historical,artistic and scientific values.Many extremely valuable earthen sites have been preserved in the arid areas in China.The earthen site of Jiaohe Ancient City is one of the earliest National Protected Important Cultural Heritage Sites.The Jiaohe Ancient City site exhibits all kinds of deteriorations,which can be found in the earthen sites in arid environments in China.Through a case study of the Jiaohe ancient earthen site,we present in this paper the comprehensive conservation technologies,including the mud bricklaying and reparation,wooden rod anchorage,crack grouting,surface potassium silicate(PS) penetration consolidation,and suspended steel beam ceiling,etc.Results of this case study showed that better conservation effects could be achieved by selecting proper PS penetration and crack grouting processes based on the deterioration characteristics of the earthen sites.The technology of mud bricklaying and reparation was also an effective method for preventing the earthen body from collapsing.Compared with traditional conservation technologies,the suspended steel beam ceiling technology could effectively reduce the negative impacts to the original state of the earthen site.As for unstable cliffs,a new method using composite anchor rod of bamboo and steel with massive loose earth was applied.Deformation monitoring and temporary supports were critical and indispensable measures for the safe of site conservation projects.Through years of monitoring and practical operation at the Jiaohe ancient earthen site,deterioration at the site has been effectively controlled.
基金financial support provided by the National Natural Science Foundation of China (Grant No. 51578272)the State Administration of Cultural Heritage "Research Program for Outstanding Youth"(Grant No. 2014224)+1 种基金the National Key Technology R&D Program of China during the Twelfth Five-year Plan Period (Grant No. 2013BAK08B11)the Project on Basic Research of Gansu Province's Innovation Group (Grant No. 145RJIF336)
文摘During the process of archaeological excavation in the regions of Southeast China, collapse of test square usually occurs due to poor site-specific conditions. In this paper, the fast Lagrangian analysis of continua in three dimensions(FLAC3D) is employed to reveal the behaviors of test square. Taking the archaeological works in Liangzhu prehistoric earthen sites as the research background, the paper first introduces the geological setting, excavation procedure and monitoring scheme of the studied test square. Then, the deformation of four sides of the test square is modeled using FLAC3D. By comparison, it shows that the numerical results are consistent with the results from field monitoring. The result suggests that the numerical simulation can be effectively applied to representing the actual behaviors of the test square,which is helpful for determination of excavation scheme and stability evaluation of the test square during archaeological excavation.
基金supported by the National"12th Five-Year"Plan for Science and Technology Support(Grant No.2014BAK16B02)the Key Project of the State Administration of Cultural Heritage(Grant No.20120207)the Project on Basic Research of Gansu Province's Innovation Group(Grant No.145RJIF336)
文摘Earthen sites are widely distributed throughout China,and most of them belong to archaeological sites with significant values,which not only directly witness the origin,formation and development of Chinese civilization,but also possess important values for conservation and exhibition.Many researches and practices on their conservation and consolidation have been carried out:however,the consolidation effect is mainly judged by visual observation and expert evaluation.Scientific assessment of conservation and consolidation effects is a challenging issue.Many instruments in other fields cannot be directly applied to the conservation of cultural relics due to their peculiarity.In order to assess the effects of field conservation experiments,this paper tries to understand the consolidation effects at Liangzhu site using nondestructive or micro-damage methods,including thermo-physical parameters testing,infrared thermal imaging,high-density microelectrode resistivity testing,portable microscope observation,and hydrophilic and hydrophobic testing,and thereby explores the practicable methods for evaluating the properties of consolidation materials for earthen sites treatment.
文摘Across the American Southwest water development has played a critical role in managing rangelands.Earthen berms have been constructed throughout US rangelands to manage runoff and reduce erosion.The berms altered runoff patterns to increase soil moisture with positive local vegetative response.However,altered runoff patterns can be considered a disturbance that affects broader scale vegetation patterns.We hypothesized that the hydrologic impacts of earthen berms in semiarid rangelands will be reflected in contrasting upslope and downslope vegetation patterns.A supervised classification of grass,shrubs,and bare soil was performed using orthographic imagery taken in June 2016 to quantify the effects of 181 earthen berms in the uplands and floodplain of the Altar Valley in Southern Arizona,US.Intact berms blocked runoff,creating downslope runoff"shadows"within which the precipitation is the dominant water input.We documented more bare soil downslope of intact berms in comparison with upslope.Grass and shrub cover affected by berms were related to soil texture.Grass and shrub cover were not different above and below intact berms on fine textured soils,but on sites with coarser textured soil,grass cover was lower downslope of berms.Where breaches occurred on coarser textured soils,the up and downslope differences in grass cover diminished.This study points to the role of conservation structures in adding additional complexity to already heterogeneous landscapes by creating patchwork assemblages of vegetation and bare soil proximal to earthen runoff and erosion control berms.
基金supported by the National Natural Science Foundation of China(Grant Nos.42202313 and 41562015)the National Key R&D Program of China(Grant No.2020YFC1521904)+2 种基金the Social Science Fund of Shaanxi Province of China(Grant No.2021G014)the Key Projects of Two Chain Integration of Shaanxi Province of China(Protection and Utilization of Cultural Heritage)(Grant No.2022LL-ZD-01)the High-level Humanities and Social Science Outstanding Achievement Award Cultivation Project of Northwestern Polytechnical University(Grant No.G2022KY0603)。
文摘The scaling off is among the most pervasive and severe deterioration types.The scaling off developed on earthen sites in Northwest China has a special and complex binary structure composed of crusted and loose layers.Under the synergistic functions of external environmental elements such as rainfall,temperature,and wind,and rammed earth properties,this deterioration has gradually created the crust on the site’s surface,and has then evolved into exfoliation and finally fallen off,leading to the reciprocating progressive destruction of earthen sites.Therefore,determining the development mechanism of scaling off and implementing targeted protection measures for the scientific conservation of earthen sites has become essential.In this review study,the properties of the building material causing the binary structure and the coupling effects of water,temperature,salt,and wind on the development of scaling off were determined,and the quantitative evaluation system for this deterioration development was elaborated.After interpreting the reasons for the development of the scaling off,protective measures including chemical grouting,electro-osmosis grouting,and overlay applications were stated.This study also pointed out the research hotspots and shortage in the study process on the scaling off.The hotspots generally focused on the development mechanism of binary structure,quantitative assessment of the degree of development,and related scientific consolidation measures.The shortcomings around the above directions include less attention to the development characteristics and mechanism of scaling off on earthen sites under special environment types,optimization and applicability of quantitative evaluation models,and the development and feasibility of reinforcement slurries and methods.This study can be beneficial in providing theoretical support for the scientific conservation and engineering practice of the scaling off on the earthen sites.
文摘Biochemical, chemical, and mechanical, techniques have been employed to enhance soil resilience for decades. While the use of mechanical techniques requires transporting huge amounts of soil materials, the cement used in chemical techniques may lead to increase atmospheric carbon dioxide. Numerous studies indicate that biochemical techniques may be less expensive, cost effective, and environmentally friendly. Biopolymers and enzymes derived from microorganisms have been suggested as biological enhancers in strengthening and fortifying soils used for earthen structures. Lime and other treatment techniques used as biobased materials have been shown to be less effective for stabilizing soils. Here, we review biochemical processes and techniques involved in the interactions of soil enzymes, microorganisms, microbial extracellular polymeric substances, and other biopolymers with soil particles, and the challenges and strategies of their use as biobased materials for stabilizing soils. This review provides their impacts on various soil properties and the growth potentials of agricultural crops. .
