软土基床系数三轴试验法测定及分析

Experiment and Analysis on Subgrade Coefficient of Soft Soil Using Triaxial Test Method

针对宁波轨道交通软土地层,采用三轴试验法得到各土层的基床系数,并对水平基床系数和垂直基床系数进行相关性分析,最后对试验结果进行尺寸效应修正.结果表明:各土层基床系数差异较大,淤泥质土的水平基床系数K_h较小,黏性土水平基床系数K_h较大;水平与垂直基床系数较为接近,且相关性较好;土层基床系数的修正值与经验值吻合较好,从而验证了适用于宁波软土基床系数试验值修正系数的合理性,为轨道交通工程设计和施工提供了理论依据.

Coefficient of subgrade reaction is an important parameter in rail transportation design. Experiment to determine the coefficient of subgrade reaction of soft soil stratum in Ningbo urban rail transit is carried out using triaxial method（CD）, then the correlation analysis is conducted on the horizontal and vertical directions of coefficient of subgrade reaction. Finally, the size effect of the test result is corrected. The results show that coefficient of subgrade reaction on Ningbo soft soil varies significantly. The horizontal direction of coefficient of subgrade reaction of silty clay is small, while it is relatively large for the cohesive soil. The horizontal direction of coefficient of subgrade reaction is close to the vertical direction, and they have a certain correlation, that is, to a certain extent, the vertical direction can be converted to the horizontal direction of coefficient of subgrade reaction. The correction value of coefficient of subgrade reaction of soil is in good agreement with the empirical value, verifying the correction coefficient of test value. The coefficient of subgrade reaction proves to be reasonable in Ningbo area. The analysis provides a theoretical basis for engineering design and construction of rail transit.