西安渭河高漫滩砂土层抗剪强度试验与强度参数对比研究

Comparative Study on Shear Strength Test and Strength Parameters of Sandy Soil Layer in High Floodplain of Weihe River in Xi'an

砂土作为西安地区轨道交通建设中常见土体类型,由于其无黏性散粒结构的特性,工程中对其抗剪强度参数的直接确定较为困难。通过对渭河高漫滩地区不同砂层进行了原状试样和重塑试样的直剪试验、重塑砂试样的三轴压缩试验和休止角试验,探讨轨道交通工程中砂土的抗剪强度参数取值问题。结果表明,各砂层固结排水剪试验的抗剪强度包线均在直剪试验之上;直剪试验得到的粉细砂重塑样抗剪强度参数比原状砂试样大,粗砂和砾砂的结果则相反,中砂的原状试样和重塑试样之间相差不大;内摩擦角介于水上休止角和水下休止角之间。对于轨道交通地下工程,建议砂土的强度参数可不考虑黏聚力,内摩擦角可参考原状砂试样的直剪试验结果给出了研究成果,可为西安地区轨道交通等类似地下工程建设提供参考及借鉴。

Sandy soil is a common soil type in the construction of rail transit in Xi'an.Due to its non-cohesive granular structure,it is difficult to directly determine its shear strength parameters in engineering.Through the direct shear test of the undisturbed sample and the remolded sample,the triaxial compression test and the angle of repose test of the remolded sand sample taken from different sand layers in the high floodplain area of the Weihe River,the parameter value for the shear strength of the sand in the rail transit project is discussed in this paper.The results show that the shear strength envelope of the consolidated drainage shear test of each sand layer is higher than that of the direct shear test;the shear strength parameters of remolded silty fine sand samples are larger than those of undisturbed sand samples obtained by direct shear test.The results of coarse sand and gravel sand are on the contrary,and there is little difference between the undisturbed and remolded samples of medium sand;the internal friction angle is between the water angle of repose and the underwater angle of repose.For underground engineering of rail transit project,it is suggested that the strength parameters of sand soil may not consider cohesion,and the internal friction angle can be determined by referring to the direct shear test results of undisturbed sand samples,the results can provide reference for the construction of similar underground engineering such as rail transit projects in Xi'an.