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大量的软岩三轴剪切试验表明,不同的围压下,软岩力学特性变化非常大。随着围压的增加,软岩的应变软化和剪胀性变弱;当围压足够大时,甚至表现为应变硬化和剪缩。已有软岩热弹黏塑性本构模型针对不同的围压大小,需要设定不一样的参数,使其应用到数值分析上带来一定困难。为了能用统一参数来描述软岩受围压影响的力学性质,对已有的软岩热黏弹塑性本构模型进行修正。修正模型中所有参数都具有明确的物理意义且都可通过常规三轴试验确定。通过实验数据与计算结果对比,验证了修正本构模型的正确性。
A large number of soft-rock triaxial shear tests show that the mechanical properties of soft rocks vary greatly under different confining pressures. As the confining pressure increases, the strain softening and dilatancy of soft rock become weaker; even when the confining pressure is large enough, it even shows strain hardening and shear shrinkage. The visco-plastic viscoelastic constitutive model of soft rock has been developed for different confining pressures. Different parameters need to be set, which makes it difficult to apply numerical analysis. In order to describe the mechanical properties of soft rock affected by confining pressure with uniform parameters, the existing soft-rock thermo-viscoelasto-plastic constitutive model is modified. All the parameters in the revised model have a clear physical meaning and can be determined by conventional triaxial tests. The correctness of the revised constitutive model is verified by comparing the experimental data with the calculated results.