重塑黄土的加载速率效应研究

A study of the loading rate effect on disturbed loess

为了揭示不同加载速率条件下重塑土的变形与强度特性对工程实践的影响,通过不同围压、含水率条件下重塑土样在4种加载速率条件下的三轴CU试验,对重塑土在不同状态下的加载速率效应进行分析,并从土的结构性入手对其与原状土加载速率效应的差异进行讨论。基于重塑土样的三轴试验成果,得到了加载速率对重塑土变形与力学特性的影响规律:重塑土的应力-应变曲线在不同加载速率条件下均表现出应变硬化特性;破坏强度随着加载速率的增大而表现出先增大后减小的特性,存在临界加载速率;随着加载速率的增大,黏聚力c先增大后减小,也存在临界加载速率,而内摩擦角φ则保持了小幅减小的趋势。

In order to reveal the impact of deformation and mechanical characteristics of disturbed loess at different loading rates on engineering practice,the loading rate effect of disturbed loess under different conditions are analyzed in this paper by conducting triaxial shear tests of four loading rates under different confining pressures and water content. The difference between the results for disturbed loess and undisturbed loess is discussed based on soil structure. The rule of influence of loading rates on the deformation and mechanical characteristics is obtained.The stress-strain curves show the strain hardening at all the loading rates. There is a critical loading rate in the influence of loading rate on the fracture strength. The fracture strength increases with the increasing loading rate when the loading rate is less than the critical value,but decreases with the increasing loading rate when it exceeds the critical value. With the increasing loading rate,the cohesion c and shear strength have the same rule and critical loading rate,but the friction angle φ decreases slightly.