| Loess is widely distributed in China,owing to the structural property and dynamic vulnerability of undisturbed loess is obvious,the question of earthquake disaster in the loess area is serious.Therefore,to solve the problem of actual engineering vibration disaster and provide support for earthquake disaster reduction work in loess area,it has a great theoretical significance to do experimental research on dynamic characteristics of loess under cyclic torsional shear load.In this paper,the dynamic characteristics of Xi’an undisturbed loess under uniform pressure are studied by hollow cylindrical torsionl shears,and two types tests was carried,the one is increase the dynamic shear stress and the another one is single-stage dynamic shear stress loading.The main research results are as follows:(1)The test of increase the dynamic shear stress reveals that the relationship between dynamic shear stress-and dynamic shear strain accords the hyperbolic model well.The failure mode of soil samples under cumulative damage is that the samples generates two sets of relative shear deformation zones.And the test also shows that the discipline of shear modulus and dynamic damping ratio with water content,consolidation confining pressure and dynamic shear strain.(2)Due to the variation law of maximum dynamic shear modulus with consolidation confining pressure and water content under the test of increase the dynamic shear stress,the relationship between maximum dynamic shear modulus and consolidation confining pressure and structural index was established,too.The variation of cyclic torsional shear strength of loess with different water content and different confining pressures was analyzed.(3)The results of dynamic strength curve under torsional shear load can get from the single-stage dynamic shear stress cyclic loading test,and the variation law of dynamic strength index with water content and vibration times was also obtained.The failure mode of loess samples under single-stage cyclic shearing was a spiral crack.(4)The test of single-stage dynamic shear stress cyclic loading also get the variation law of seismic deformation of loess with vibration times under single-stage dynamic torsional shear cycle,and the variation law of seismic subsidence coefficient with water content,consolidation confining pressure,dynamic shear stress and vibration times,the seismic subsidence coefficient and solid The relationship between the confining pressure,water content,dynamic stress amplitude and number of vibrations was established. |
PDF Full Text Request