互层盐岩体的Cosserat介质扩展本构模型

EXPANDED COSSERAT MEDIUM CONSTITUTIVE MODEL FOR LAMINATED SALT ROCK

针对由不同岩层交替而组成的互层盐岩体,如含夹层盐岩体,建立一种新的代表单元,考虑具有不同力学特性相邻岩层之间的细观位移协调,建立了宏观平均意义下考虑细观弯曲效应的Cosserat介质扩展本构模型,并对该模型进行了初步的试验验证。该模型为分析层状盐岩体提供了一条新思路:首先利用该模型求得平均意义下的Cosserat应力,然后再回到某材料点,得到传统意义上的各层岩体的不等梯度的甚至非连续的各层介质的应力应变;结合传统的材料强度理论,可以判断某层盐岩体介质是否开始破坏。该模型可直接推广到三维和非线性问题,将为层状盐岩体内硐室稳定性分析提供关键理论基础。

A new expanded Cosserat medium constitutive model, in which the influence of bending was taken into account, was proposed for bilaminate-layered salt rock. In this model, a new unit cell, namely, the material point containing two alternate layers, was employed to simulate the coordination of the meso-displacement between two layers with mismatch mechanical properties. It was validated primarily by an experiment on laminated salt rock samples under uniaxial compression. This model provides a new way for the analysis of layered salt rock. Having the Cosserat stresses, namely, the macro-average ones, which have been determined, the conventional stresses of the different layers in a unit cell can be obtained in sequence. Then the conventional stresses can be utilized through a routine way for the strength and failure analysis. The proposed model can be expanded to solve three-dimensional and nonlinear problems directly, and is expected to provide a key theoretical frame for the stability analysis of the underground openings in laminated salt rock.