The construction of a high-speed railway(HSR) in Southwest China is being hindered by a severe shortage of high-quality subgrade materials. However, red mudstone is widely distributed in the Sichuan Basin of China. Th...The construction of a high-speed railway(HSR) in Southwest China is being hindered by a severe shortage of high-quality subgrade materials. However, red mudstone is widely distributed in the Sichuan Basin of China. The ability to use weathered red mudstone(WRM) to fill subgrade beds by controlling its critical stress and cumulative strain would enable substantial savings in project investments and mitigate damage to the ecological environment. To better understand the dynamic behaviour of WRM, both monotonic and cyclic triaxial tests were performed. The evolution of the cumulative strain vs. increased loading cycles was measured. The influences of confining pressure and loading cycles on the dynamic modulus, damping ratio, critical cyclic stress ratio(CSR), and dynamic stress level(DSL) were investigated. The relationship between the CSR and loading cycles under different failure strain criteria(0.1%-1.0%) was analysed. The prediction model of cumulative strain was also evaluated. The results indicated that the shear strength of WRM sufficiently meets the static strength requirements of subgrade. The critical dynamic stress of WRM can thus satisfy the dynamic stress-bearing requirement of the HSR subgrade. The critical CSR decreases and displays a power function with increasing confining pressure. As the confining pressure increases, the DSL remains relatively stable, ranging between 0.153 and 0.163. Furthermore, the relationship between the dynamic strength and loading cycles required to cause failure was established. Finally, a newly developed model for determining cumulative strain was established. A prediction exercise showed that the model is in good agreement with the experimental data.展开更多
Wind load is one of the main lateral control loads that need to be considered in the design of high-rise building structures. It is also of great engineering significance to study the influence of static wind load or ...Wind load is one of the main lateral control loads that need to be considered in the design of high-rise building structures. It is also of great engineering significance to study the influence of static wind load or time-varying wind load on the dynamic response of structures. In this paper, a high-rise building with a rectangular section (46.8 m × 27 m × 33 m) is simulated based on Ansys18.0 APDL software. The real situation of its response under no lateral wind load and different fluctuating wind load conditions is simulated and the stress and strain response of the building under steady-state and time-varying wind load is given. The results show that the upper strain of the structure under wind load is about 1/1000 of the bottom strain, and the strain of the structure shows obvious accumulation from the top to the bottom, that is, the bottom strain of the building will be higher than the top strain. The influence of time-varying wind load on building structure is related to the loading position of wind load on the structure. The results provide a basis for the structural wind resistance design of this type of building.展开更多
基金financially supported by the CAS“Light of West China”Program(Grant No.Y6R2240240)the National Natural Science Foundation of China(Grant No.41761144077)the Sichuan science and technology plan project(Grant No.2017JY0251)
文摘The construction of a high-speed railway(HSR) in Southwest China is being hindered by a severe shortage of high-quality subgrade materials. However, red mudstone is widely distributed in the Sichuan Basin of China. The ability to use weathered red mudstone(WRM) to fill subgrade beds by controlling its critical stress and cumulative strain would enable substantial savings in project investments and mitigate damage to the ecological environment. To better understand the dynamic behaviour of WRM, both monotonic and cyclic triaxial tests were performed. The evolution of the cumulative strain vs. increased loading cycles was measured. The influences of confining pressure and loading cycles on the dynamic modulus, damping ratio, critical cyclic stress ratio(CSR), and dynamic stress level(DSL) were investigated. The relationship between the CSR and loading cycles under different failure strain criteria(0.1%-1.0%) was analysed. The prediction model of cumulative strain was also evaluated. The results indicated that the shear strength of WRM sufficiently meets the static strength requirements of subgrade. The critical dynamic stress of WRM can thus satisfy the dynamic stress-bearing requirement of the HSR subgrade. The critical CSR decreases and displays a power function with increasing confining pressure. As the confining pressure increases, the DSL remains relatively stable, ranging between 0.153 and 0.163. Furthermore, the relationship between the dynamic strength and loading cycles required to cause failure was established. Finally, a newly developed model for determining cumulative strain was established. A prediction exercise showed that the model is in good agreement with the experimental data.
文摘Wind load is one of the main lateral control loads that need to be considered in the design of high-rise building structures. It is also of great engineering significance to study the influence of static wind load or time-varying wind load on the dynamic response of structures. In this paper, a high-rise building with a rectangular section (46.8 m × 27 m × 33 m) is simulated based on Ansys18.0 APDL software. The real situation of its response under no lateral wind load and different fluctuating wind load conditions is simulated and the stress and strain response of the building under steady-state and time-varying wind load is given. The results show that the upper strain of the structure under wind load is about 1/1000 of the bottom strain, and the strain of the structure shows obvious accumulation from the top to the bottom, that is, the bottom strain of the building will be higher than the top strain. The influence of time-varying wind load on building structure is related to the loading position of wind load on the structure. The results provide a basis for the structural wind resistance design of this type of building.
