Based on the analysis method for tailings dam in upstream raising method presently used in metallurgy and nonferrous metals tailings depository in the world, an effective stress analysis method of seismic response for...Based on the analysis method for tailings dam in upstream raising method presently used in metallurgy and nonferrous metals tailings depository in the world, an effective stress analysis method of seismic response for high tailings dam was developed according to the results of engineering geological exploration, static and dynamic test and stability analysis on Baizhishan tailing dam 113.5 m high. The law of generation, diffusion and dissipation of seismic pore water pressure during and after earthquake was investigated, and the results of tailings dam’s acceleration, seismic dynamic stress and pore water pressure were obtained. The results show that the seismic stability and liquefaction resistance of high tailings dam are strengthened remarkably, and the scope and depth of liquefaction area at the top of dam are reduced greatly. The interior stress is compressive stress, the stress level of every element is less than 1.0 and the safety coefficient of every element is greater than 1.0. The safety coefficient against liquefaction of every element of tailing dam is greater than 1.5 according to the effective stress analysis of seismic response by finite element method. The calculated results prove that liquefaction is the main reason of seismic failure of high tailing dams, and the effect of seismic inertia forces on high tailing dams’ stability during earthquake is secondary reason.展开更多
In order to evaluate the seismic stability of reinforced soil walls against bearing capacity failure,the seismic safety factor of reinforced soil walls was determined by using pseudo-dynamic method,and calculated by c...In order to evaluate the seismic stability of reinforced soil walls against bearing capacity failure,the seismic safety factor of reinforced soil walls was determined by using pseudo-dynamic method,and calculated by considering different parameters,such as horizontal and vertical seismic acceleration coefficients,ratio of reinforcement length to wall height,back fill friction angle,foundation soil friction angle,soil reinforcement interface friction angle and surcharge.The parametric study shows that the seismic safety factor increases by 24-fold when the foundation soil friction angle varies from 25°to 45°,and increases by 2-fold when the soil reinforcement interface friction angle varies from 0 to 30°.That is to say,the bigger values the foundation soil and/or soil reinforcement interface friction angles have,the safer the reinforced soil walls become in the seismic design.The results were also compared with those obtained from pseudo-static method.It is found that there is a higher value of the safety factor by the present work.展开更多
A three-dimensional viscoelastic LDDA method is put forward on the basis of the two-dimensional elastic LDDA method and a corresponding computer program is developed. Both the method and the program, verified by a num...A three-dimensional viscoelastic LDDA method is put forward on the basis of the two-dimensional elastic LDDA method and a corresponding computer program is developed. Both the method and the program, verified by a numerical frictional experiment composed of two blocks, are correct and reliable. Simultaneously, using this program, the present velocity field of the eastern Asia area, which is induced by the collision of the Indian shield against the Asian plate, is investigated. The primary result shows that the velocity field in magnitude is largest near the colliding boundary and attenuates fast away from it. The Tibet plateau moves northeast, the North China plain and the southeastern Asia moves eastward and southeastward, respectively. The attenuation of the velocity field across Qilianshan is nonlinear, its direction changes from the northeast nearly to the east, its gradient is 0.05 mma-1km-1 and 0.007 mma-1km-1 to the southwest and the northeast of Qilianshan, respectively. The attenuation of the velocity field is almost linear across the Longmenshan fault, its gradient is 0.01 mma-1km-1 and its direction is toward the southeast. The remarkable deformation caused by collision extends to the east longitude 115 and to the north latitude 45. The velocity field obtained by the method is basically consistent with the data from the Global Positioning System. The relative slip rate along the Bangong-Nujiang-Lancangjiang fault is 0.5 mm/a, the Jinshajiang fault, 0.8 mm/a, while the Tanlu fault hardly moves. It is shown that the method proposed in this paper could be employed to study the geodynamic problems with faults.展开更多
基金Projects(03JJY3078, 04JJ40032) supported by the Natural Science Foundation of Hunan Province, China project(03A006) supported by Scientific Research Fund of Hunan Provincial Education Department, China
文摘Based on the analysis method for tailings dam in upstream raising method presently used in metallurgy and nonferrous metals tailings depository in the world, an effective stress analysis method of seismic response for high tailings dam was developed according to the results of engineering geological exploration, static and dynamic test and stability analysis on Baizhishan tailing dam 113.5 m high. The law of generation, diffusion and dissipation of seismic pore water pressure during and after earthquake was investigated, and the results of tailings dam’s acceleration, seismic dynamic stress and pore water pressure were obtained. The results show that the seismic stability and liquefaction resistance of high tailings dam are strengthened remarkably, and the scope and depth of liquefaction area at the top of dam are reduced greatly. The interior stress is compressive stress, the stress level of every element is less than 1.0 and the safety coefficient of every element is greater than 1.0. The safety coefficient against liquefaction of every element of tailing dam is greater than 1.5 according to the effective stress analysis of seismic response by finite element method. The calculated results prove that liquefaction is the main reason of seismic failure of high tailing dams, and the effect of seismic inertia forces on high tailing dams’ stability during earthquake is secondary reason.
文摘In order to evaluate the seismic stability of reinforced soil walls against bearing capacity failure,the seismic safety factor of reinforced soil walls was determined by using pseudo-dynamic method,and calculated by considering different parameters,such as horizontal and vertical seismic acceleration coefficients,ratio of reinforcement length to wall height,back fill friction angle,foundation soil friction angle,soil reinforcement interface friction angle and surcharge.The parametric study shows that the seismic safety factor increases by 24-fold when the foundation soil friction angle varies from 25°to 45°,and increases by 2-fold when the soil reinforcement interface friction angle varies from 0 to 30°.That is to say,the bigger values the foundation soil and/or soil reinforcement interface friction angles have,the safer the reinforced soil walls become in the seismic design.The results were also compared with those obtained from pseudo-static method.It is found that there is a higher value of the safety factor by the present work.
文摘A three-dimensional viscoelastic LDDA method is put forward on the basis of the two-dimensional elastic LDDA method and a corresponding computer program is developed. Both the method and the program, verified by a numerical frictional experiment composed of two blocks, are correct and reliable. Simultaneously, using this program, the present velocity field of the eastern Asia area, which is induced by the collision of the Indian shield against the Asian plate, is investigated. The primary result shows that the velocity field in magnitude is largest near the colliding boundary and attenuates fast away from it. The Tibet plateau moves northeast, the North China plain and the southeastern Asia moves eastward and southeastward, respectively. The attenuation of the velocity field across Qilianshan is nonlinear, its direction changes from the northeast nearly to the east, its gradient is 0.05 mma-1km-1 and 0.007 mma-1km-1 to the southwest and the northeast of Qilianshan, respectively. The attenuation of the velocity field is almost linear across the Longmenshan fault, its gradient is 0.01 mma-1km-1 and its direction is toward the southeast. The remarkable deformation caused by collision extends to the east longitude 115 and to the north latitude 45. The velocity field obtained by the method is basically consistent with the data from the Global Positioning System. The relative slip rate along the Bangong-Nujiang-Lancangjiang fault is 0.5 mm/a, the Jinshajiang fault, 0.8 mm/a, while the Tanlu fault hardly moves. It is shown that the method proposed in this paper could be employed to study the geodynamic problems with faults.
