Finite element simulation of simple shear tests considering inherent anisotropy
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摘要: 在单剪条件下,由于侧边界上不存在互补的剪切应力会导致应力不均匀,使得室内单剪试验研究变得复杂。提出一个考虑砂土初始各向异性的单剪试验数值分析方法。主要是通过引入初始各向异性修正的临界状态本构模型,并将模型编入有限元大变形计算平台。利用三维有限元分析实际的GDS型单剪试验条件,以分析在剪切过程中试样的不均匀特征。此项研究可以提高对单剪试验过程中边界效应的理解和认识,并且提供一种分析试样的不均匀性的计算方法。Abstract: The absence of complementary shear stress on the side boundary of a specimen in the simple shear tests will cause stress inhomogeneity. An enhanced critical state-based constitutive model is proposed by incorporating the inherent anisotropy fabric, and also implemented into the finite element code for the numerical simulation. In addition, a three-dimensional finite element analysis with the same size as the GDS-type simple shear apparatus is performed to illustrate the inhomogeneous features of the specimen. Above all, this study can improve the understanding and knowledge of boundary effects for the simple shear tests, and provide a calculation method for analyzing the inhomogeneous ness of the specimen.
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Keywords:
- simple shear test /
- constitutive model /
- inherent anisotropy /
- critical state /
- finite element method /
- sand
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表 1 SIMSAND模型的基本本构方程
Table 1 Basic constitutive equations of SIMSAND
组成部分 本构方程 弹性准则 ˙εeij=1+υ3K(1−2υ)σ′ij−υ3K(1−2υ)σ′kkδij K=K0⋅pat(2.97−e)2(1+e)(p′pat)n 屈服面 f=qp′−H 塑性势面 ∂g∂p′=Ad(Mpt−qp′), ∂g∂q=1 硬化参数 H=Mpεpdkp+εpd 临界状态参数 ec=eref−λ(p′pat)ξ tanϕp=(ece)nptanϕμ tanϕpt=(ece)−ndtanϕμ 三维强度标准 Mp=6sinϕp3−sinϕp[2c411+c41+(1−c41)sin3θ]14,其中 c1=3−sinϕp3+sinϕpMpt=6sinϕpt3−sinϕpt[2c421+c24+(1−c42)sin3θ]14 ,其中 c2=3−sinϕpt3+sinϕpt 表 2 枫丹白露砂单调加载的单剪试验列表
Table 2 Summary of monotonic simple shear tests on fontainebleau sand
编号 加载方式 e0(初始) e′(K0固结后) σ′n0 /kPaS-1 法向应力恒定 0.70 0.691 104 S-2 法向应力恒定 0.70 0.688 208 S-3 法向应力恒定 0.70 0.678 416 S-4 法向高度恒定 0.68 0.666 208 S-5 法向高度恒定 0.68 0.654 416 -
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