洛川Q_2黄土残余强度影响因素试验研究

Factors residual strength of Luochuan loess

自然界存在许多天然黄土边坡,当它们发生滑动时,发现这些滑坡的滑动面上的平均剪应力,比它们的抗剪强度小得多,发生上述现象的一个重要因素就是土的残余强度问题,因此研究黄土的残余强度具有深刻意义。试验结果表明:环剪仪是目前测量土残余强度最符合实际的仪器,单级剪切是作为测量土残余强度的首选剪切方式;洛川Q_2黄土的初始结构对其残余强度几乎无影响;洛川Q_2重塑黄土的残余强度参数c_r、φ_r随着初始含水率的增大而减小;洛川Q_2重塑黄土的残余强度参数cr、φr随干密度的增大而增大;洛川Q_2重塑黄土的残余黏聚力cr随着剪切速率的增大而减小,残余内摩擦角φ_r随着剪切速率的增大呈先增大后减小的趋势。

In the loess regions loess landslide is one of the major geological disasters. Every year it results in a large number of casualties and destructions. It is found that the average shear stress on the sliding surface of these landslides is much smaller than their shear strength when the natural loess slope is slidded. One of the most important factors in the occurrence of these phenomena is the residual strength of soil. So the study on the residual strength of loess is of great significance. The test results show that the ring shear apparatus is the most realistic instrument to measure the residual strength of the soil, and the best way of measuring the residual strength of loess is single-stage shear. The ring shear test residual strength of Luochuan Q_2 loess is more realistic than the repeated shear. The initial structure of Luochuan Q_2 loess has few influences on the residual strength. The residual strength parameters(c_r, φ_r) of Luochuan Q_2 loess decrease with the increasing moisture content. The increase in the initial dry density causes the increase of the residual strength parameters of Luochuan Q_2 remolded loess. Luochuan remolded Q_2 residual remolded cohesion cr decreases with the increasing shear rate, and the residual friction angle φ_r increases firstly and then decreases with the increasing shear rate.