高温-高含冰量冻土压缩变形特性研究

高温-高含冰量冻土属于塑性冻土, 荷载作用下具有较强的压缩性.为了研究高温-高含冰量冻土的压缩变形特性, 采用恒温-变载的试验方法得到了不同温度(-0.3、 -0.5、 -0.7、 -1.0、 -1.5℃), 不同含水量(40%、 80%、 120%)条件下冻土试样的体积压缩系数.结果表明: 1)高温-高含冰量冻土具有极大的压缩性, 青藏黏土40%含水量试样在-0.3℃时的体积压缩系数可达0.328 MPa^-1, 属于高压缩性土; 2)高温-高含冰量冻土在压缩过程中存在渗滤变形, 且主要发生于加载的初始阶段; 3)温度与含冰量是影响高温-高含冰量冻土压缩性的主要因素, 它们决定了冻土中体积未冻水的含量, 从而控制了冻土的压缩性; 4)在试验条件下, 高温-高含冰量冻土的压缩性随着温度的升高而增大, 随着含水量的增大而减小.高温时含水量对压缩性的影响比较显著, 低温时影响较小.

Compressibility of Warm and Ice-Rich Frozen Soil

Warm and ice-rich frozen soil belongs to plastic frozen soil, of which the compressibility is remarkable under loading. In order to study the compressive properties of the warm and ice-rich frozen soil, compression tests under constant temperature and stepped load were conducted at temperatures of -0.3, -0.5, -0.7, -1.0, -1.5℃ andwith water contents of 40%, 80%, 120%, respectively. Then the volume compressibility coefficients were obtained. The test results indicate that: The compressibility of the soil is considerable. For example, the volume compressibility coefficient of the clay specimen at -0.3℃ with water content of 40% could reach to 0.328 MPa^-1, which belongs to high compressibility soil. 2) exists in the soil during the process of compression, and mostly occurs in the initial stage of loading. 3) Temperature and water content of the soil, which control the volumetric unfrozen water content, are the most important factors to impact the compressibility. 4) Under the test conditions mentioned above, the compressibility of the soil increases with temperature rising and water content decreasing. When the temperature is higher, the effect of water content on the compressibility is remarkable, but it is not obvious when the temperature is relatively low.