This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods.The first configuration involved conducting artificial weather...This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods.The first configuration involved conducting artificial weathering on limestone using the freezing and thawing(F-T)for 40 cycles.The mechanical parameters of the samples were measured at the end of the 40th cycle.In the second configuration,a series of specimens underwent salt crystallization(S-C)tests for 20 cycles.Experimental results were validated using discrete element method(DEM).Next,the weathered limestone model with dimensions of 108 mm54 mm were prepared.The weathering layers were tested at four different thicknesses(i.e.2.5 mm,5 mm,7.5 mm,and 10 mm)and three different positions(at the surface,5 mm under the rock surface,and 10 mm under the rock surface).According to the results,weathering depth and thickness have a considerable effect on the failure process.The results also showed a correlation between the values of compressive strength and failure mechanisms associated with the weathering layer.The numerical results revealed that the tension crack was the dominant factor.Additionally,with increasing weathering thickness,Young's modulus,crack initiation stress,and final strength decreased in constant weathering depth.The results also demonstrated that the failure progress of the numerical models was similar to that observed in the laboratory.展开更多
A two-dimensionM discrete element code, particle flow code （PFC2D）, is employed to investigate foundations reinforced with horizontal-vertical （H-V） inclusions. The initial states and loading processes of both unr...A two-dimensionM discrete element code, particle flow code （PFC2D）, is employed to investigate foundations reinforced with horizontal-vertical （H-V） inclusions. The initial states and loading processes of both unreinforced and H-V reinforced foundations are simulated by PFC2D method. The interface between particles and reinforcements, and the reinforcement mechanism of the H-V reinforced foundations are studied through stress distribution graphs, displacement vector graphs and contact force graphs. The simulation results demonstrate that the vertical elements of the H-V reinforcement keep the particles from being displaced under the applied load. The H-V reinforcement can distribute the load uniformly over a wider area, thereby improving the bearing capacity of soil foundation.展开更多
Although there are many studies involving influence of runaway truck entry speed and longitudinal grade on stopping distance,focusing on aggregate properties is scarce.This paper investigates the influence of the aggr...Although there are many studies involving influence of runaway truck entry speed and longitudinal grade on stopping distance,focusing on aggregate properties is scarce.This paper investigates the influence of the aggregate properties such as types of aggregate and river gravel radius on stopping distance through numerical analysis of particle flow code in two dimensions(PFC2D).The software is used to generate stopping distance data for two aggregate types and four group gravel radii under various approaching speeds and grades.The generated data are compared with the testing results of full-scale arrester bed.The simulated finding of this paper implies that types of aggregates and river gravel radii have a significant impact on the stopping distance for runaway truck on escape ramps.展开更多
文摘This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods.The first configuration involved conducting artificial weathering on limestone using the freezing and thawing(F-T)for 40 cycles.The mechanical parameters of the samples were measured at the end of the 40th cycle.In the second configuration,a series of specimens underwent salt crystallization(S-C)tests for 20 cycles.Experimental results were validated using discrete element method(DEM).Next,the weathered limestone model with dimensions of 108 mm54 mm were prepared.The weathering layers were tested at four different thicknesses(i.e.2.5 mm,5 mm,7.5 mm,and 10 mm)and three different positions(at the surface,5 mm under the rock surface,and 10 mm under the rock surface).According to the results,weathering depth and thickness have a considerable effect on the failure process.The results also showed a correlation between the values of compressive strength and failure mechanisms associated with the weathering layer.The numerical results revealed that the tension crack was the dominant factor.Additionally,with increasing weathering thickness,Young's modulus,crack initiation stress,and final strength decreased in constant weathering depth.The results also demonstrated that the failure progress of the numerical models was similar to that observed in the laboratory.
基金the National Natural Science Foundation of China (Nos. 41202215 and 40972192)the Innovation Program of Shanghai Municipal Education Commission (No. 11ZZ88)the Innovation Foundation of Shanghai University
文摘A two-dimensionM discrete element code, particle flow code （PFC2D）, is employed to investigate foundations reinforced with horizontal-vertical （H-V） inclusions. The initial states and loading processes of both unreinforced and H-V reinforced foundations are simulated by PFC2D method. The interface between particles and reinforcements, and the reinforcement mechanism of the H-V reinforced foundations are studied through stress distribution graphs, displacement vector graphs and contact force graphs. The simulation results demonstrate that the vertical elements of the H-V reinforcement keep the particles from being displaced under the applied load. The H-V reinforcement can distribute the load uniformly over a wider area, thereby improving the bearing capacity of soil foundation.
文摘Although there are many studies involving influence of runaway truck entry speed and longitudinal grade on stopping distance,focusing on aggregate properties is scarce.This paper investigates the influence of the aggregate properties such as types of aggregate and river gravel radius on stopping distance through numerical analysis of particle flow code in two dimensions(PFC2D).The software is used to generate stopping distance data for two aggregate types and four group gravel radii under various approaching speeds and grades.The generated data are compared with the testing results of full-scale arrester bed.The simulated finding of this paper implies that types of aggregates and river gravel radii have a significant impact on the stopping distance for runaway truck on escape ramps.
