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剪切试验中,试样的形变特征决定了剪切强度特征,而干密度,含水率和围压都会影响试样的形变特征。因此通过开展不固结不排水三轴剪切试验,用实测的办法在不同轴向应变时对试样直径的增量进行量测。试验结果表明,剪切过程主要由体压缩阶段、鼓状变形阶段和剪切破坏面发展阶段组成,其中鼓状变形阶段是试验剪切过程的主要变形阶段、干密度的增加表现出试样的鼓状变形与剪切破坏阶段较为明显;含水率的增加提高了试样的塑性,增加了实测直径增量值;围压与端部效应共同作用,围压越大,鼓状变形越明显,实测直径增量就越大。通过形变特征计算剪切强度,分别以试样直径最大增量值和中部1/3部分平均直径值计算剪切强度,结果表明两者应力应变特征基本一致,但最大直径所得剪切强度值相对较小。
Shear test, the deformation characteristics of the specimen determines the shear strength characteristics, and dry density, moisture content and confining pressure will affect the deformation characteristics of the specimen. Therefore, by carrying out unconsolidated undrained triaxial shear test, the increment of the diameter of the sample is measured at different axial strains by the measured method. The experimental results show that the shear process is mainly composed of the body compression stage, the drum-shaped deformation stage and the shear failure surface development stage. The drum-shaped deformation stage is the major deformation stage of the test shear process. The increase of dry density shows that Drum deformation and shear failure stage is more obvious; the increase of water content increases the plasticity of the specimen and increases the value of measured diameter increment; confining pressure and end effect together, the larger the confining pressure, the more obvious the drum-shaped deformation, The larger the measured diameter increase. The shear strength was calculated by the deformation characteristics. The shear strength was calculated by the maximum increment of the diameter of the specimen and the average diameter of 1/3 part of the middle part respectively. The results showed that the stress-strain characteristics of the two parts were basically the same, Smaller.