用拱梁分载法进行拱坝应力分析时,需要合理确定各计算高程坝基岩体的变形模量和泊松比,但是坝基岩体通常是由各种不同岩性的岩石构成的,用其中任何一种岩性岩体的变形参数来代替或者对所有岩体变形参数进行简单的平均都是不合理的,因而正确评价坝基的综合变形模量对拱坝应力分析具有十分重要的现实意义。给出了在最小二乘意义下,利用三维有限元计算拱坝坝基综合变形模量和泊松比的一种方法。该方法可以求解由多种不同岩性的岩体、断层以及软弱夹层等构成的复杂岩体结构等效的变形模量和泊松比,并与相关的理论解进行了比较。比较结果表明,利用该方法来计算等效变形模量和泊松比是可行的。最后应用该方法对锦屏一级拱坝地基的综合变形模量和泊松比进行了计算,应用结果表明,在充分考虑各种地质构造和地基处理措施后,采用该方法计算的地基综合变形模量是合理的。
A reasonable determination of deformation modulus and Poisson ratio of arch dam foundation rock is very necessary for arch-cantilever method in arch stress analysis. Dam foundation is composed of different lithology rock masses, which shows significant mechanical anisotropy, inhomogeneity and discontinuity. Any rock deformation parameter to replace the whole deformation parameters or a simple averaging of all deformation parameters is unreasonable. In the present paper we present a 3-D finite element method for predicting the synthetic deformation modulus and synthetic Poisson ratio of arch dam foundation based on the least squares method. By comparing with theoretical solution, we found this approach is feasible for predicting the synthetic deformation modulus and synthetic Poisson ratio of complex foundation composed of different lithology rock masses, faults and weak interlayers. As an application of this approach, the synthetic deformation modulus and synthetic Poisson ratio of Jinping arch dam foundation are calculated. Results demonstrate that the deformation modulus calculated by this method is reasonable on the premise of considering geological structures and foundation treatments.
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