用波速与动静三轴试验评定地基剪切模量的统计分析
A Statistical Study of Shear Modulus Determination by In-situ Shear Wave Velocity and Dynamic/Static Triaxial Tests
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摘要: 本文是对土的剪切模量在很大应变范围内变化规律的统计分析成果,其目的是为在北京地区粘性土与砂卵石交互地层中做沉降分析时提供非线性变形模量的确定依据。为了克服常规三轴试验不能在很小应变时测得可靠的应力—应变数据的困难,这项研究是根据动静统一的观点采用现场剪切波速和动、静三轴平行配套试验资料来进行的。为简便起见,采用了一根双对数拆线近似地模拟剪切模量在很大应变范围内的变化规律,同时采用了另外一个指数关系来反映侧限压力的影响。本文还总结了通过统计分析所找到的几个土的非线性变形的基本情况。Abstract: This paper is a statistical study of the variation of shear modulus over a wide range of strain with the objective of providing a basis of nonlinear modulus estimation for settlement analysis in alternating layers of cohesive and sandy/gravelly soils in Beijing. In order to overcome the difficulty of obtaining reliable stress-strain data from routine triaxial tests when the strains are very small, this study is based upon an unified treatment of dynamic and static stress-strain behavior utilizing the data of in-situ shear wave velocity and dynamic/static triaxial tests conducted in parallel. A broken line relationship on a log-log plot is adopted for simplicity and convenience to approximate shear modulus changes over a wide range of strain and another exponential rule is employed to take account of the effect of the lateral confining pressure. Some basic trends of nonlinear deformation of soils as evidenced by this statistical study have also been summarized.