粗粒土K_(0)固结与等压固结三轴试验比较

Comparison of K_(0) Consolidation and Isobaric Consolidation Triaxial Test of Coarse Grained Soil

对茨哈峡坝覆盖层砂卵石料进行了同一密度试样中型三轴试验,试验包括常规各向等压固结的三轴排水剪切试验(CID试验)和各向不等压固结的三轴排水剪切试验(CK_(0)D试验),探讨了两种三轴试验在强度特性以及应力应变特性中的差异.结果表明,两种三轴试验得到的应力应变曲线总体上规律比较相似;与CID试验相比,CK_(0)D试验得到的偏应力峰值更大,CK_(0)D试验的偏应力峰值平均比CID试验的偏应力峰值大5.4%;CK_(0)D试验的剪胀性比CID试验的剪胀性更加明显,CK_(0)D试验的内摩擦角值平均比CID试验的内摩擦角值大0.48°;CK_(0)D试验的初始切线模量Ei与切线体积模量Bt均比CID试验的大;同时总结出了破坏摩擦角与相变摩擦角的差值与围压关系的公式,也通过相关文献验证了此公式的合理性,这对研究反映剪胀性的本构模型具有一定的参考价值.总的来说,对于本文所用的试验材料而言,两种三轴试验的试验结果差异较小.

Using middle-scale shearing device,isotropically consolidated-drained triaxial test(CID test)and K_(0) consolidated-drained triaxial test(CK_(0)D test)under different confining pressures are performed with the same density overburden materials of sand and gravel in overburden layer of Cihaxia Dam,the differences of strength and stress-strain characteristics between the two triaxial tests are discussed.The results show that the stress-strain curves obtained by the two triaxial tests are generally similar.Compared with CID test,the deviatoric stress peak obtained by CK_(0)D test is larger,and the deviatoric stress peak of CK_(0)D test is 5.4%larger than that of CID test on average.The dilatancy of CK_(0)D test is more obvious than that of CID test,and the internal friction angle in CK_(0)D test is 0.48°larger than that in CID test on average.Initial tangent modulus Eiand tangent bulk modulus Btof CK_(0)D test are both larger than those of CID test.At the same time,the formula of the relationship between the difference of failure friction angle and phase change friction angle and confining pressure is summarized,and the rationality of the formula is verified by the relevant literature,which has certain reference value for the study of constitutive model reflecting dilatancy.In general,for the test materials used in this paper,the difference between the test results of the two triaxial tests is small.