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目前关于冻土的室内三轴压缩试验研究多采用恒围压下的轴向加载方法,而实际工程中的受压土体基本处于围压、轴压同时发生变化的情况.以冻结粉质砂土为研究对象,进行了变围压和恒围压下的三轴剪切测试.根据试后试样变形情况,给出了试样面积的统一修正公式,研究结果表明:当含水量较小时,围压路径对应力-应变曲线的初始段和最终段没有显见影响,但在应力-应变曲线中间段,变围压下的应力-应变曲线明显在相应的恒围压曲线之下,且初始围压越小,曲线位置越低.当含水量不低于饱和值时,围压路径和含冰量共同影响着应力-应变曲线的发展趋势,且变围压曲线的最终段基本都在相应的恒围压曲线之上,中间段变化特点与含冰量和初始围压有关.围压路径对强度随围压变化趋势的影响跟含水量大小有关.当含水量较小时,两种围压路径下的强度值比较接近;当含水量不低于饱和值时,恒围压下的强度值低于相应变围压下的强度值.
At present, the research on indoor triaxial compression test of permafrost mostly adopts the axial loading method under constant confining pressure, while the compressive soil in the actual project is basically confined pressure and axial pressure change at the same time.In order to freeze silty sand Soil as the research object, the triaxial shear tests with variable confining pressure and constant confining pressure were carried out.According to the deformation of the specimen after the test, the uniform formula for the area of the specimen was given.The results show that when the water content is small The confining pressure path has no obvious influence on the initial section and the final section of the stress-strain curve. However, in the middle section of the stress-strain curve, the stress-strain curve under the confining pressure is obviously below the corresponding constant confining pressure curve, and the initial The smaller the confining pressure, the lower the position of the curve.When the water content is not less than the saturation value, the confining pressure path and the ice content affect the development trend of the stress-strain curve, and the final sections of the confining pressure curve are basically corresponding , The characteristics of the middle section are related to the ice content and the initial confining pressure.The influence of confining pressure path on the trend of strength with confining pressure is related to the amount of water content.When the water content is small, The intensity of the path is relatively close; when When the amount of water is not less than the saturation value, the intensity value of the constant confining pressure becomes lower than the intensity value of the corresponding confining pressure.