Stability condition and quality evaluation formula of layerlike backfilling roof,Q≥C,where Q denotes is quality index depending on allowable compressive or tensile strength and integrity of backfilling,and C is the t...Stability condition and quality evaluation formula of layerlike backfilling roof,Q≥C,where Q denotes is quality index depending on allowable compressive or tensile strength and integrity of backfilling,and C is the technical index depending on mining method and backfilling technology,were inferred according to simply supported beam theorem.Technical treatment measures for instable backfilling roof,including optimum of appropriate filling materials and dosage for excellent flow property and reduction of backfill cost.It is proved that slope equation of backfill slurry in a stope to be filled is y=hexp[x2/(2σ)2)],where h is height of cone and σ2 is mean square,and that optimum drainage point of backfill slurry can be determined by the equation and sizes of stope.Case study indicates that the results can give a theoretical support for quality evaluation and control of layerlike backfilling.展开更多
The resilient modulus(MR)of subgrade soils is usually used to characterize the stiffness of subgrade and is a crucial parameter in pavement design.In order to determine the resilient modulus of compacted subgrade soil...The resilient modulus(MR)of subgrade soils is usually used to characterize the stiffness of subgrade and is a crucial parameter in pavement design.In order to determine the resilient modulus of compacted subgrade soils quickly and accurately,an optimized artificial neural network(ANN)approach based on the multi-population genetic algorithm(MPGA)was proposed in this study.The MPGA overcomes the problems of the traditional ANN such as low efficiency,local optimum and over-fitting.The developed optimized ANN method consists of ten input variables,twenty-one hidden neurons,and one output variable.The physical properties(liquid limit,plastic limit,plasticity index,0.075 mm passing percentage,maximum dry density,optimum moisture content),state variables(degree of compaction,moisture content)and stress variables(confining pressure,deviatoric stress)of subgrade soils were selected as input variables.The MR was directly used as the output variable.Then,adopting a large amount of experimental data from existing literature,the developed optimized ANN method was compared with the existing representative estimation methods.The results show that the developed optimized ANN method has the advantages of fast speed,strong generalization ability and good accuracy in MR estimation.展开更多
Soil-bentonite （SB） vertical slurry cutoff wall is a useful treatment for urban industrial contaminated sites. Due to the clay-heavy metal interaction, significant changes would occur in the engineering behavior of ...Soil-bentonite （SB） vertical slurry cutoff wall is a useful treatment for urban industrial contaminated sites. Due to the clay-heavy metal interaction, significant changes would occur in the engineering behavior of SB cutoff walls. However, previous study is limited to kaolinitic soils or montmorillonitic soils along using solidum chloride and/or calcium chloride as target contaminant. In this work, a series of oedometer tests were conducted to investigate the effects of lead （Pb） on the compressibility and the permeability of kaolin-bentonite （KB） mixtures, a simplified model of in-situ SB cutoff wall backfills. In addition, sedimentation tests were conducted to interpret the mechanism controlling the change of compressibility and permeability from the perspective of soil fabric. The Pb-contaminated KB mixtures for oedometer tests and sedimentation tests were prepared with bentonite contents of 0, 5%, 10%, and 15% by dry mass, and they were mixed with pre-determined volume of lead nitrate solution based on designed Pb concentration and solid-to-solution ratio. The Pb concentration was controlled as 0, 0.1, 0.5, 1.0, 5.0, 10, and 50 mg/g with a solid-to-solution ratio of approximate 0.5. The prepared KB mixtures with bentonite contents of 0, 5%, and 10% were chosen for the sedimentation tests. They were freeze-dried and mixed with DDI with a solid-to-solution ratio of 10 g/100 mL. The results indicate that pH, compressibility, and permeability of KB mixture changed considerably with respect to Pb concentration. It is concluded that the fabric of KB mixture, depending on the particle-particle interaction subjected to different ranges of pH and Pb concentration, governs the sedimentation behavior and permeability. The results of liquid limit （WE） cannot be explained in terms of the sedimentation behavior since it is only ionic-dependent.展开更多
A formula was derived for the computation of seismic active earth pressure behind retaining wall using pseudo-dynamic method.This formula considered the actual dynamic effect with variation of time and propagation of ...A formula was derived for the computation of seismic active earth pressure behind retaining wall using pseudo-dynamic method.This formula considered the actual dynamic effect with variation of time and propagation of shear and primary wave velocities through the soil backfills.The influence of tension crack in the top portion of the backfill under seismic loading was investigated.The effects of wall friction angle,soil friction angle,horizontal and vertical seismic coefficients on the seismic active force were also explored.The parametric study shows that the total seismic active force increases as horizontal seismic coefficient increases,while it decreases with the increase in vertical seismic coefficient,internal friction angle and unit cohesion.The seismic active force calculated by the proposed method is larger than that calculated by previous theory.展开更多
The adaptive neuro-fuzzy inference systems(ANFIS)are widely used in the concrete technology.In this research,the compressive strength of light weight concrete was determined.To this end,the scoria percentage and curin...The adaptive neuro-fuzzy inference systems(ANFIS)are widely used in the concrete technology.In this research,the compressive strength of light weight concrete was determined.To this end,the scoria percentage and curing day variables were used as the input parameters,and compressive strength and tensile strength were used as the output parameters.In addition,100 patterns were used,70%of which were used for training and 30%were used for testing.To assess the precision of the neuro-fuzzy system,it was compared using two linear regression models.The comparisons were carried out in the training and testing phases.Research results revealed that the neuro-fuzzy systems model offers more potential,flexibility,and precision than the statistical models.展开更多
To investigate the seismic passive earth thrust with two-dimensional steady seepage, a general pseudo-dynamic solution was established based on the limit equilibrium analysis. This solution was purposefully applied to...To investigate the seismic passive earth thrust with two-dimensional steady seepage, a general pseudo-dynamic solution was established based on the limit equilibrium analysis. This solution was purposefully applied to a waterfront gravity wall, which retains a submerged backfill with a drainage system along the backfill-structure interface. The wall was assumed to move towards the backfill to the passive failure state. And the theoretical derivation considered the pore pressures induced by the seepage, the excess pore pressures generated by the earthquake and the seismic inertial forces. Thereinto, the hydrostatic and hydrodynamic pressures were calculated by the analytical formulas, while the seismic forces were obtained by the pseudo-dynamic method. In the parametric study, the results indicate that the velocity of shear wave has a more prominent impact on the seismic passive earth thrust than that of primary wave. Both the horizontal and vertical seismic actions decrease the passive earth pressure, but the horizontal one affects the amplitude of the earth pressure coefficient more significantly. Moreover, the soil friction and the wall friction distinctly increase the seismic passive earth pressure just like the static situation. The comparison shows that the results are consistent with the previous work, which verifies its validity.展开更多
基金Project(50490270) supported by the National Natural Science Foundation of China
文摘Stability condition and quality evaluation formula of layerlike backfilling roof,Q≥C,where Q denotes is quality index depending on allowable compressive or tensile strength and integrity of backfilling,and C is the technical index depending on mining method and backfilling technology,were inferred according to simply supported beam theorem.Technical treatment measures for instable backfilling roof,including optimum of appropriate filling materials and dosage for excellent flow property and reduction of backfill cost.It is proved that slope equation of backfill slurry in a stope to be filled is y=hexp[x2/(2σ)2)],where h is height of cone and σ2 is mean square,and that optimum drainage point of backfill slurry can be determined by the equation and sizes of stope.Case study indicates that the results can give a theoretical support for quality evaluation and control of layerlike backfilling.
基金Project(51878078)supported by the National Natural Science Foundation of ChinaProject(2018-025)supported by the Training Program for High-level Technical Personnel in Transportation Industry,ChinaProject(CTKY-PTRC-2018-003)supported by the Design Theory,Method and Demonstration of Durability Asphalt Pavement Based on Heavy-duty Traffic Conditions in Shanghai Area,China。
文摘The resilient modulus(MR)of subgrade soils is usually used to characterize the stiffness of subgrade and is a crucial parameter in pavement design.In order to determine the resilient modulus of compacted subgrade soils quickly and accurately,an optimized artificial neural network(ANN)approach based on the multi-population genetic algorithm(MPGA)was proposed in this study.The MPGA overcomes the problems of the traditional ANN such as low efficiency,local optimum and over-fitting.The developed optimized ANN method consists of ten input variables,twenty-one hidden neurons,and one output variable.The physical properties(liquid limit,plastic limit,plasticity index,0.075 mm passing percentage,maximum dry density,optimum moisture content),state variables(degree of compaction,moisture content)and stress variables(confining pressure,deviatoric stress)of subgrade soils were selected as input variables.The MR was directly used as the output variable.Then,adopting a large amount of experimental data from existing literature,the developed optimized ANN method was compared with the existing representative estimation methods.The results show that the developed optimized ANN method has the advantages of fast speed,strong generalization ability and good accuracy in MR estimation.
基金Project(51278100) supported by the National Natural Science Foundation of ChinaProjects(BK2010060, BK2012022) supported by the Natural Science Foundation of Jiangsu Province, ChinaProject(103) supported by the Scientific Innovation Research of University Graduate Students of Jiangsu Province, China
文摘Soil-bentonite （SB） vertical slurry cutoff wall is a useful treatment for urban industrial contaminated sites. Due to the clay-heavy metal interaction, significant changes would occur in the engineering behavior of SB cutoff walls. However, previous study is limited to kaolinitic soils or montmorillonitic soils along using solidum chloride and/or calcium chloride as target contaminant. In this work, a series of oedometer tests were conducted to investigate the effects of lead （Pb） on the compressibility and the permeability of kaolin-bentonite （KB） mixtures, a simplified model of in-situ SB cutoff wall backfills. In addition, sedimentation tests were conducted to interpret the mechanism controlling the change of compressibility and permeability from the perspective of soil fabric. The Pb-contaminated KB mixtures for oedometer tests and sedimentation tests were prepared with bentonite contents of 0, 5%, 10%, and 15% by dry mass, and they were mixed with pre-determined volume of lead nitrate solution based on designed Pb concentration and solid-to-solution ratio. The Pb concentration was controlled as 0, 0.1, 0.5, 1.0, 5.0, 10, and 50 mg/g with a solid-to-solution ratio of approximate 0.5. The prepared KB mixtures with bentonite contents of 0, 5%, and 10% were chosen for the sedimentation tests. They were freeze-dried and mixed with DDI with a solid-to-solution ratio of 10 g/100 mL. The results indicate that pH, compressibility, and permeability of KB mixture changed considerably with respect to Pb concentration. It is concluded that the fabric of KB mixture, depending on the particle-particle interaction subjected to different ranges of pH and Pb concentration, governs the sedimentation behavior and permeability. The results of liquid limit （WE） cannot be explained in terms of the sedimentation behavior since it is only ionic-dependent.
基金Project(50879077)supported by the National Natural Science Foundation of China
文摘A formula was derived for the computation of seismic active earth pressure behind retaining wall using pseudo-dynamic method.This formula considered the actual dynamic effect with variation of time and propagation of shear and primary wave velocities through the soil backfills.The influence of tension crack in the top portion of the backfill under seismic loading was investigated.The effects of wall friction angle,soil friction angle,horizontal and vertical seismic coefficients on the seismic active force were also explored.The parametric study shows that the total seismic active force increases as horizontal seismic coefficient increases,while it decreases with the increase in vertical seismic coefficient,internal friction angle and unit cohesion.The seismic active force calculated by the proposed method is larger than that calculated by previous theory.
文摘The adaptive neuro-fuzzy inference systems(ANFIS)are widely used in the concrete technology.In this research,the compressive strength of light weight concrete was determined.To this end,the scoria percentage and curing day variables were used as the input parameters,and compressive strength and tensile strength were used as the output parameters.In addition,100 patterns were used,70%of which were used for training and 30%were used for testing.To assess the precision of the neuro-fuzzy system,it was compared using two linear regression models.The comparisons were carried out in the training and testing phases.Research results revealed that the neuro-fuzzy systems model offers more potential,flexibility,and precision than the statistical models.
基金Projects(U1234204,51378463) supported by the National Natural Science Foundation of China
文摘To investigate the seismic passive earth thrust with two-dimensional steady seepage, a general pseudo-dynamic solution was established based on the limit equilibrium analysis. This solution was purposefully applied to a waterfront gravity wall, which retains a submerged backfill with a drainage system along the backfill-structure interface. The wall was assumed to move towards the backfill to the passive failure state. And the theoretical derivation considered the pore pressures induced by the seepage, the excess pore pressures generated by the earthquake and the seismic inertial forces. Thereinto, the hydrostatic and hydrodynamic pressures were calculated by the analytical formulas, while the seismic forces were obtained by the pseudo-dynamic method. In the parametric study, the results indicate that the velocity of shear wave has a more prominent impact on the seismic passive earth thrust than that of primary wave. Both the horizontal and vertical seismic actions decrease the passive earth pressure, but the horizontal one affects the amplitude of the earth pressure coefficient more significantly. Moreover, the soil friction and the wall friction distinctly increase the seismic passive earth pressure just like the static situation. The comparison shows that the results are consistent with the previous work, which verifies its validity.
