To study the influence of the change in soil strength of frozen silty clay on the support design during the foundation pit construction process, a water-rich silt-clay layer railway tunnel foundation pit in Jinan, Shandong Province was taken as the background. Dynamic impact tests on frozen silty clay were conducted using a separated Hopkinson pressure rod test device to analyze the effects of different impact pressures, different moisture contents and different temperatures on frozen silty clay. The test results show that: (1) The dynamic stress-strain curve of frozen silty clay can be divided into three stages: a elastic stage, b plastic stage, and c failure stage. In the plastic stage, a significant strain rate effect is exhibited. (2) As the moisture content continuously increases, the strain continuously decreases. The peak strength first increases and then decreases. At a moisture content of 26% (natural moisture content), the peak strength reaches its maximum. (3) The fracture morphology of the specimen increases with the increase of impact air pressure, moisture content and temperature. The research results can provide experimental basis for winter tunnel construction.
Wan et al. (Wed,) studied this question.