A study was conducted by collecting eight seepage water samples that drain through the sedimentary rocks, mainly sandstone and shale, to evaluate the hydro- geochemical characteristics. The collected samples were anal...A study was conducted by collecting eight seepage water samples that drain through the sedimentary rocks, mainly sandstone and shale, to evaluate the hydro- geochemical characteristics. The collected samples were analyzed for physico-chemical parameters using standard procedures. Three water types were identified in the Piper plot and the hydrogeochemical evolution starts from a Ca- C1 facies （type 1） via mixed Ca-Mg-C1 and Ca-Na-HCO3 facies （type 2） to Na-C1 facies （type 3）. Increasing trend of electrical conductivity （EC） values were observed from type 1 water to type 3 water. Lower ionic concentrations with an average EC value of 35.7 kts/cm in Ca-C1 facies indicate the recharge water by monsoonal rainfall, and ion exchange/weathering process is reflected in the mixing zone. Higher ionic concentration with an average EC value of 399 kts/cm is noted in Na-C1 facies, which indicates the ion exchange during water-rock interaction. Higher log pCO2 values are also found in this facies, revealing the longer residence time of seepage water in the rock matrix, which release more ions into the water. The relative mobility of elements during weathering suggest that the order of mobility in both sandstone and shale is Na 〉 Ca 〉 Mg 〉 K. It was observed that thehydrogeochemistry of seepage water is mainly controlled by the bedrock geology.展开更多
To solve the problem of water seepage of vertical feeding borehole for solid materials,we established the fluid-solid coupling dynamic model of groundwater flowing in rock mass adjacent to the vertical feeding borehol...To solve the problem of water seepage of vertical feeding borehole for solid materials,we established the fluid-solid coupling dynamic model of groundwater flowing in rock mass adjacent to the vertical feeding borehole.Combining with the engineering geological conditions,we built a numeral model to study the influence rule of the aquifer hydraulic pressure and seepage location of feeding borehole on the amount of seepage with fnite element numerical method.The results show that the nonlinear relationship is presented among the amount of seepage,the seepage location and aquifer hydraulic pressure.The higher the aquifer hydraulic pressure is,the closer the distance between seepage location and aquifer is,and the faster the harmful levels of aquifer will grow.In practice,we calculated the allowable seepage of feeding borehole by the optimum moisture content and natural moisture content of backflling materials,and then determined the protection zone of feeding borehole,so the moisture content of backflling materials can be controlled within the scope of optimum moisture content.展开更多
Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underg...Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underground water seepage flow was taken into account or not. The distribution of displacement field around the multi-arch tunnel, which is influenced by the seepage field, was gained. The result indicates that the settlement values of the vault derived from coupling analysis are bigger when considering the seepage flow effect than that not considering. Through the contrast of arch subsidence quantities calculated by two kinds of computation situations, and the comparison between the calculated and measured value of tunnel vault settlement, it is found that the calculated value(5.7-6.0 mm) derived from considering the seepage effect is more close to the measured value(5.8-6.8 mm). Therefore, it is quite necessary to consider the seepage flow effect of the underground water in aquiferous stratum for multi-arch tunnel design.展开更多
Based on the characteristics of surrounding rocks for deeply inclined roadway affected by argillation and water seepage, a structure model of layer crack plate was established to analyze the shear sliding instability ...Based on the characteristics of surrounding rocks for deeply inclined roadway affected by argillation and water seepage, a structure model of layer crack plate was established to analyze the shear sliding instability mechanism. Through solid mechanics analysis of anchored surrounding rock with defect from water seepage, combined with numerical analysis for instability mechanism under water seepage in deeply inclined roadway, key factors were proposed. Results show that with increasing height of layer crack plate, lateral buckling critical load value for high wall of the roadway decreases; there is a multistage distribution for tensile stress along the anchor bolt with defect under pulling state condition;groundwater seepage seriously affects the strength of surrounding rock of the roadway, to some extent the plastic zone of the high side rises up to 8 m. Finally some support strategies were proposed for the inclined roadway and successfully applied to Haoyuan coal mine in Tiela mining area,western China.展开更多
Tight sandstone gas(hereafter"tight gas")has become a subject of unconventional gas exploration globally.The large-scale development and use of tight gas resources in the USA,in particular,facilitated the ra...Tight sandstone gas(hereafter"tight gas")has become a subject of unconventional gas exploration globally.The large-scale development and use of tight gas resources in the USA,in particular,facilitated the rapid rebound of natural gas production in the USA,in addition to driving the rapid development of tight gas worldwide.In the eastern Ordos Basin,the Upper Paleozoic feature includes multiple layers of gas,a shallow depth,and notable potential for exploration and development.However,the reservoirs in the area are relatively tight,exhibit strong heterogeneity,and possess a complex micropore structure,thus restricting the eff ective economic development of oil and gas.Thus,research on the primary parameters controlling pore throat structure and the seepage capability of low-permeability reservoirs will be beneficial for the effcient exploration and development of natural gas in the eastern Ordos Basin.The parameters of reservoir porosity and percolation ability,as well as permeability,were analyzed using systematic sampling of the of the Upper Paleozoic Benxi,Taiyuan,and Shanxi Formations in the eastern Ordos Basin,constant-rate mercury injection experiments,nuclear magnetic resonance analysis,and gas–water-phase experimental studies.The results indicate that reservoir porosity is controlled by the effective pore volume and number,whereas permeability is controlled by the largest throat radius,rather than the average.The effective pore volume controls the movable fluid saturation,while reservoir percolation capability is controlled by the effective pore volume,irreducible water saturation,and size of the gas–water two-phase seepage zone.展开更多
hi this paper. the author uses the theory of fluid mechanics. dynamics of fluids in Porous media. gas seepage flow in coal seams and combines the tests in the laboratory with the actual coal infusion to have an inves...hi this paper. the author uses the theory of fluid mechanics. dynamics of fluids in Porous media. gas seepage flow in coal seams and combines the tests in the laboratory with the actual coal infusion to have an investigating and study from the theory to the mechanism of coal infusion to wet coal seams. through the analysis to the process of coal infusion the author builds up the mathematical models and has a detailed discussion to the boundary conditions of coal infusion. Because the equation sets to describe coal infusion are non-linear. we have made a simplification to them to use the dimension analysis theory by leading into the non-dimensions of water pressure of coal infusion, seepage flow rate. increment of coal seam moisture and so on Besides the analytic and approximate solutions have also been discussed. At last. we use the scientific research item of the actual coal infusion to illustrate the effects and importance of the theory to direct actual coal infusion and its designs.展开更多
Soil water content is a key controlling factor for vegetation restoration in sand dunes.The deep seepage and lateral migration of water in dunes affect the recharge process of deep soil water and groundwater in sand d...Soil water content is a key controlling factor for vegetation restoration in sand dunes.The deep seepage and lateral migration of water in dunes affect the recharge process of deep soil water and groundwater in sand dune ecosystems.To determine the influence of vegetation on the hydrological regulation function of sand dunes,we examined the deep seepage and lateral migration of dune water with different vegetation coverages during the growing season in the Horqin Sandy Land,China.The results showed that the deep seepage and lateral migration of water decreased with the increase in vegetation coverage on the dunes.The accumulated deep seepage water of mobile dunes(vegetation coverage<5%)and dunes with vegetation coverage of 18.03%,27.12%,and 50.65%accounted for 56.53%,51.82%,18.98%,and 0.26%,respectively,of the rainfall in the same period.The accumulated lateral migration of water in these dunes accounted for 12.39%,6.33%,2.23%,and 7.61%of the rainfall in the same period.The direction and position of the dune slope affected the soil water deep seepage and lateral migration process.The amounts of deep seepage and lateral migration of water on the windward slope were lower than those on the leeward slope.The amounts of deep seepage and lateral migration of water showed a decreasing trend from the bottom to the middle and to the top of the dune slope.According to the above results,during the construction of sand-control projects in sandy regions,we suggest that a certain area of mobile dunes(>13.75%)should be retained as a water resource reservoir to maintain the water balance of artificial fixed dune ecosystems.These findings provide reliable evidence for the accurate assessment of water resources within the sand dune ecosystem and guide the construction of desertification control projects.展开更多
Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process ca...Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process can release significant amount of heat to raise the temperature of CTB and in turn increase the rate of cement hydration. Meanwhile, the progress of cement hydration consumes water and produces hydration products to change the pore structures within CTB, which further influences the hydraulic behavior of CTB. In order to understand the hydraulic behavior of CTB, a numerical model was developed by coupling the hydraulic,thermal and hydration equations. This model was then implemented into COMSOL Multiphysics to simulate the evolutions of temperature and water seepage flow within CTB versus curing time. The predicted outcomes were compared with correspondent experimental results, proving the validity and availability of this model. By taking advantage of the validated model, effects of various initial CTB and curing temperatures, cement content, and CTB's geometric shapes on the hydraulic behavior of CTB were demonstrated numerically. The presented conclusions can contribute to preparing more environmentally friendly CTB structures.展开更多
Data related to the pre-grouting work of a large underground project are systematically analyzed to reveal the mechanism behind,to shed some light on the execution of practical grouting,and to enrich the theory of eng...Data related to the pre-grouting work of a large underground project are systematically analyzed to reveal the mechanism behind,to shed some light on the execution of practical grouting,and to enrich the theory of engineering geology.Grouting is generally taken as an effective way for controlling nonignorable water seepage during underground rock excavation.Though various models have been developed to guide grouting design or to specify criteria for grouting stop,it does not change the fact that grouting is still highly experience-based.Therefore,explanation of the current situation due to grouting complexity is given through step-by-step data analysis,where the impact on grouting parameters from the geological and hydrogeological conditions is investigated,and the grouting features of two tunnels located at the same depth below the sea surface are compared and discussed.Then,the data from individual grout hole are used to construct the regional geological conditions via inverse analysis.It is found that grouting of fractured rock masses is accompanied with great uncertainty,and field grouting data can contribute significantly to a better understanding of the regional geological conditions around an underground tunnel or rock cavern.展开更多
Loess tunnels are widely used in transportation engineering and are irreplaceable parts of transportation infrastructure. In this paper, a dynamic finite element method is used to analyze the coupled effects of a trai...Loess tunnels are widely used in transportation engineering and are irreplaceable parts of transportation infrastructure. In this paper, a dynamic finite element method is used to analyze the coupled effects of a train vibration load and rainfall seepage. By calculating the variation in the safety factor of a loess tunnel because of the effects of various factors, such as different rainfall intensities and soil thicknesses, the dynamic stability of the loess tunnel is studied under the condition of a near-field pulse-like earthquake. The results show that the security and stability of the tunnel decrease gradually with decreasing burial depth. In addition, the plastic strain of the tunnel is mainly distributed on both sides of the vault and the feet, and the maximum value of the critical strain occurs on both sides of the arch feet. Because of the effects of the train vibration load and rainfall seepage, the safety factor of the loess tunnel structure decreases to a certain degree. Moreover, the range and maximum value of the plastic strain increase to various degrees.展开更多
基金University of Malaya for the rock analysis by payment basis through RPI fund
文摘A study was conducted by collecting eight seepage water samples that drain through the sedimentary rocks, mainly sandstone and shale, to evaluate the hydro- geochemical characteristics. The collected samples were analyzed for physico-chemical parameters using standard procedures. Three water types were identified in the Piper plot and the hydrogeochemical evolution starts from a Ca- C1 facies （type 1） via mixed Ca-Mg-C1 and Ca-Na-HCO3 facies （type 2） to Na-C1 facies （type 3）. Increasing trend of electrical conductivity （EC） values were observed from type 1 water to type 3 water. Lower ionic concentrations with an average EC value of 35.7 kts/cm in Ca-C1 facies indicate the recharge water by monsoonal rainfall, and ion exchange/weathering process is reflected in the mixing zone. Higher ionic concentration with an average EC value of 399 kts/cm is noted in Na-C1 facies, which indicates the ion exchange during water-rock interaction. Higher log pCO2 values are also found in this facies, revealing the longer residence time of seepage water in the rock matrix, which release more ions into the water. The relative mobility of elements during weathering suggest that the order of mobility in both sandstone and shale is Na 〉 Ca 〉 Mg 〉 K. It was observed that thehydrogeochemistry of seepage water is mainly controlled by the bedrock geology.
基金funded by the State Key Development Program for Basic Research of China(No.2013CB227900)the National High Technology Joint Research Program of China(No.2012BAB13B00)
文摘To solve the problem of water seepage of vertical feeding borehole for solid materials,we established the fluid-solid coupling dynamic model of groundwater flowing in rock mass adjacent to the vertical feeding borehole.Combining with the engineering geological conditions,we built a numeral model to study the influence rule of the aquifer hydraulic pressure and seepage location of feeding borehole on the amount of seepage with fnite element numerical method.The results show that the nonlinear relationship is presented among the amount of seepage,the seepage location and aquifer hydraulic pressure.The higher the aquifer hydraulic pressure is,the closer the distance between seepage location and aquifer is,and the faster the harmful levels of aquifer will grow.In practice,we calculated the allowable seepage of feeding borehole by the optimum moisture content and natural moisture content of backflling materials,and then determined the protection zone of feeding borehole,so the moisture content of backflling materials can be controlled within the scope of optimum moisture content.
基金Project(50490274) supported by the National Natural Science Foundation of ChinaProject(200516) supported by Hunan Transportation Science and Technology
文摘Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underground water seepage flow was taken into account or not. The distribution of displacement field around the multi-arch tunnel, which is influenced by the seepage field, was gained. The result indicates that the settlement values of the vault derived from coupling analysis are bigger when considering the seepage flow effect than that not considering. Through the contrast of arch subsidence quantities calculated by two kinds of computation situations, and the comparison between the calculated and measured value of tunnel vault settlement, it is found that the calculated value(5.7-6.0 mm) derived from considering the seepage effect is more close to the measured value(5.8-6.8 mm). Therefore, it is quite necessary to consider the seepage flow effect of the underground water in aquiferous stratum for multi-arch tunnel design.
基金provided by the Natural Science Foundation of Jiangsu Province(No.BK20141130)the Fundamental Research Funds for the Central Universities(Nos.2014QNB27 and 2010QNB22)
文摘Based on the characteristics of surrounding rocks for deeply inclined roadway affected by argillation and water seepage, a structure model of layer crack plate was established to analyze the shear sliding instability mechanism. Through solid mechanics analysis of anchored surrounding rock with defect from water seepage, combined with numerical analysis for instability mechanism under water seepage in deeply inclined roadway, key factors were proposed. Results show that with increasing height of layer crack plate, lateral buckling critical load value for high wall of the roadway decreases; there is a multistage distribution for tensile stress along the anchor bolt with defect under pulling state condition;groundwater seepage seriously affects the strength of surrounding rock of the roadway, to some extent the plastic zone of the high side rises up to 8 m. Finally some support strategies were proposed for the inclined roadway and successfully applied to Haoyuan coal mine in Tiela mining area,western China.
基金supported by the National Natural Science Foundation of China(Grants Nos.41390451 and 41172101)the National Key Research Project of China(No.2016YFC0601003)
文摘Tight sandstone gas(hereafter"tight gas")has become a subject of unconventional gas exploration globally.The large-scale development and use of tight gas resources in the USA,in particular,facilitated the rapid rebound of natural gas production in the USA,in addition to driving the rapid development of tight gas worldwide.In the eastern Ordos Basin,the Upper Paleozoic feature includes multiple layers of gas,a shallow depth,and notable potential for exploration and development.However,the reservoirs in the area are relatively tight,exhibit strong heterogeneity,and possess a complex micropore structure,thus restricting the eff ective economic development of oil and gas.Thus,research on the primary parameters controlling pore throat structure and the seepage capability of low-permeability reservoirs will be beneficial for the effcient exploration and development of natural gas in the eastern Ordos Basin.The parameters of reservoir porosity and percolation ability,as well as permeability,were analyzed using systematic sampling of the of the Upper Paleozoic Benxi,Taiyuan,and Shanxi Formations in the eastern Ordos Basin,constant-rate mercury injection experiments,nuclear magnetic resonance analysis,and gas–water-phase experimental studies.The results indicate that reservoir porosity is controlled by the effective pore volume and number,whereas permeability is controlled by the largest throat radius,rather than the average.The effective pore volume controls the movable fluid saturation,while reservoir percolation capability is controlled by the effective pore volume,irreducible water saturation,and size of the gas–water two-phase seepage zone.
文摘hi this paper. the author uses the theory of fluid mechanics. dynamics of fluids in Porous media. gas seepage flow in coal seams and combines the tests in the laboratory with the actual coal infusion to have an investigating and study from the theory to the mechanism of coal infusion to wet coal seams. through the analysis to the process of coal infusion the author builds up the mathematical models and has a detailed discussion to the boundary conditions of coal infusion. Because the equation sets to describe coal infusion are non-linear. we have made a simplification to them to use the dimension analysis theory by leading into the non-dimensions of water pressure of coal infusion, seepage flow rate. increment of coal seam moisture and so on Besides the analytic and approximate solutions have also been discussed. At last. we use the scientific research item of the actual coal infusion to illustrate the effects and importance of the theory to direct actual coal infusion and its designs.
基金This study was funded by the National Natural Science Foundation of China(31670712)the Strategic Priority Research Program of Chinese Academy of Sciences(XDA26020104).
文摘Soil water content is a key controlling factor for vegetation restoration in sand dunes.The deep seepage and lateral migration of water in dunes affect the recharge process of deep soil water and groundwater in sand dune ecosystems.To determine the influence of vegetation on the hydrological regulation function of sand dunes,we examined the deep seepage and lateral migration of dune water with different vegetation coverages during the growing season in the Horqin Sandy Land,China.The results showed that the deep seepage and lateral migration of water decreased with the increase in vegetation coverage on the dunes.The accumulated deep seepage water of mobile dunes(vegetation coverage<5%)and dunes with vegetation coverage of 18.03%,27.12%,and 50.65%accounted for 56.53%,51.82%,18.98%,and 0.26%,respectively,of the rainfall in the same period.The accumulated lateral migration of water in these dunes accounted for 12.39%,6.33%,2.23%,and 7.61%of the rainfall in the same period.The direction and position of the dune slope affected the soil water deep seepage and lateral migration process.The amounts of deep seepage and lateral migration of water on the windward slope were lower than those on the leeward slope.The amounts of deep seepage and lateral migration of water showed a decreasing trend from the bottom to the middle and to the top of the dune slope.According to the above results,during the construction of sand-control projects in sandy regions,we suggest that a certain area of mobile dunes(>13.75%)should be retained as a water resource reservoir to maintain the water balance of artificial fixed dune ecosystems.These findings provide reliable evidence for the accurate assessment of water resources within the sand dune ecosystem and guide the construction of desertification control projects.
基金Project(SKLCRSM13KFB05)supported by State Key Laboratory for Coal Resources and Safe Mining(China University of Mining&Technology)
文摘Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process can release significant amount of heat to raise the temperature of CTB and in turn increase the rate of cement hydration. Meanwhile, the progress of cement hydration consumes water and produces hydration products to change the pore structures within CTB, which further influences the hydraulic behavior of CTB. In order to understand the hydraulic behavior of CTB, a numerical model was developed by coupling the hydraulic,thermal and hydration equations. This model was then implemented into COMSOL Multiphysics to simulate the evolutions of temperature and water seepage flow within CTB versus curing time. The predicted outcomes were compared with correspondent experimental results, proving the validity and availability of this model. By taking advantage of the validated model, effects of various initial CTB and curing temperatures, cement content, and CTB's geometric shapes on the hydraulic behavior of CTB were demonstrated numerically. The presented conclusions can contribute to preparing more environmentally friendly CTB structures.
基金the“Start-up Funding for New Faculty”provided by the Nanjing University of Aeronautics and Astronautics。
文摘Data related to the pre-grouting work of a large underground project are systematically analyzed to reveal the mechanism behind,to shed some light on the execution of practical grouting,and to enrich the theory of engineering geology.Grouting is generally taken as an effective way for controlling nonignorable water seepage during underground rock excavation.Though various models have been developed to guide grouting design or to specify criteria for grouting stop,it does not change the fact that grouting is still highly experience-based.Therefore,explanation of the current situation due to grouting complexity is given through step-by-step data analysis,where the impact on grouting parameters from the geological and hydrogeological conditions is investigated,and the grouting features of two tunnels located at the same depth below the sea surface are compared and discussed.Then,the data from individual grout hole are used to construct the regional geological conditions via inverse analysis.It is found that grouting of fractured rock masses is accompanied with great uncertainty,and field grouting data can contribute significantly to a better understanding of the regional geological conditions around an underground tunnel or rock cavern.
基金supported in part by the National Natural Science Foundation of China(Grant No.51478212)the Education Ministry Doctoral Tutor Foundation of China(Grant No.20136201110003)
文摘Loess tunnels are widely used in transportation engineering and are irreplaceable parts of transportation infrastructure. In this paper, a dynamic finite element method is used to analyze the coupled effects of a train vibration load and rainfall seepage. By calculating the variation in the safety factor of a loess tunnel because of the effects of various factors, such as different rainfall intensities and soil thicknesses, the dynamic stability of the loess tunnel is studied under the condition of a near-field pulse-like earthquake. The results show that the security and stability of the tunnel decrease gradually with decreasing burial depth. In addition, the plastic strain of the tunnel is mainly distributed on both sides of the vault and the feet, and the maximum value of the critical strain occurs on both sides of the arch feet. Because of the effects of the train vibration load and rainfall seepage, the safety factor of the loess tunnel structure decreases to a certain degree. Moreover, the range and maximum value of the plastic strain increase to various degrees.
