基于扭剪试验的细砂区域长距离流滑机制分析

大量灾害现场发现，即使地面倾角极其平缓（1°~5°），地表也可能因地震荷载而发生长距离的横向变形。为了解此类砂土变形特性，在改良的空心圆柱扭转剪切仪中采用涌水量概念进行试验，随后采用恒定剪应力静态液化试验，确定排水条件以及小初始静力剪切条件下试样流动的可能性。为突出对比，相同试样被用以进行不排水循环加载试验，观察其行为特征。研究发现：（1）在小初始静态剪应力下可以观察到丰浦砂连续流动的特性；（2）砂土的连续流动特性由初始密实度决定，初始密实度也影响砂土的体积膨胀特性；（3）静态液化试验显示流动砂土试样在涌水机制下可产生流动，而即使样本发生了液化，其在典型的不排水试验中却表现出非流动特性。

Mechanism Analysis of Long-distance Flow Slip in Fine Sand Area Based on Torsional Shear Test

At a large number of disaster sites, it has been found that even if the ground inclination is extremely flat (1°~5°), the ground surface may undergo long-distance lateral deformation due to earthquake loads. In order to understand the deformation characteristics of this kind of sand, the research used the concept of water inflow in an improved hollow cylindrical torsion shear tester. Subsequently, a constant shear stress static liquefaction test was used to determine the possibility of sample flow under drainage conditions and small initial static shear conditions.In order to highlight the comparison, the same sample was used for the undrained cyclic loading test to observe its behavior characteristics. The research found that:(1) The continuous flow characteristics of Toyoura sand can be observed under small initial static shear stress; (2) The continuous flow characteristics of sand are determined by the initial density, which also affects the volume expansion characteristics of sand; (3) The static liquefaction test shows that the flowing sand sample can flow under the water gushing mechanism, and even if the sample is liquefied, it shows non-flowing characteristics in a typical undrained test. This study enriches the related research on the fine sand area, and can provide a certain reference for sand liquefaction analysis.