含水率和含盐量对人工冻土强度特性影响的试验研究

Influence of water and salt contents on strength of artificially frozen soils

冻结法已经广泛应用于建筑基坑加固、地铁隧道开挖等城市地下工程建设,针对人工冻土单轴抗压强度的研究已取得较多成果,但因其强度受温度、含水率、含盐量以及区域水文地质等诸多因素的影响,其研究成果具有典型的区域性,致使研究成果推广受限。选取天津地区粉质黏土和黏土,开展了不同含水率、不同Na Cl含量冻土试样的单轴抗压强度试验,探讨了上述两因素对两种土质人工冻土单轴抗压强度的影响规律,提出了同一温度下人工冻土强度随含水率变化存在一峰值,峰值对应的含水率定义为"冻土最佳含水率",并对其机理进行了揭示。该研究成果可为天津地区冻土工程的设计和施工提供参考。

The artificial freezing method is widely used in the urban construction of underground engineering, such as the foundation reinforcement and excavation of subway tunnels. The strength properties of artificially frozen soils are affected by many factors. Water content, temperature, salt content and other factors affect the strength of artificially frozen soils to a large degree. At present, a lot of researches on uniaxial compressive strength of artificially frozen soils has been made, but they are certainly regional. For the silty clay and clay in Tianjin area, a series of uniaxial compressive strength tests are conducted with different water and salt contents. According to the test results, the effects of water and salt contents on the strength characteristics and the 'optimum water content of the artificially frozen soils' are obtained. The test results show that the dry density of the soils has little effect on the water content corresponding to the peak strength of silty clay and clay. The conclusions can be used to guide the design of engineering in Tianjin area.