The generalized Hock-Brown failure criterion was proved to account for the low tension strength as well as high compression strength under different stress states for the rock salt, through the comparison of four failure criteria with experimental data. An elasto-plastic model suitable for rock salt was presented by combining the Hock-Brown cri- terion with stress dependent plastic flow rules. Furthermore, based on the Lemaitre equivalent strain theory, the creep damage component was introduced to establish a new elasto-viscoplastic damage model for the rock salt, which takes into account the transient phase, the steady state phase and the accelerated phase of creep. The constitutive model was validated on the laboratory test and implemented into a three dimensional finite difference software FLAC3D by its sec- ondary development interface. The various rapid withdrawal simulations were conducted to analyze the damage and fail- ure zone evolution around the Jintan salt cavern with the new model. The initial minimum cavern pressure was 7 MPa according to the calculated results. The study indicates that the new damage model agrees well with the rock salt test results and gives a faithful representation of the rock salt elasto-viscoplastic damage behavior. In addition, the presen- ted constitutive law has a good numerical stability during the calculation period.%通过4种屈服准则对盐岩适用性的对比分析,表明广义Hoek-Brown准则能够准确预测盐岩从拉伸到压缩应力区的强度值,结合不同应力状态下的塑性流动法则建立完整的盐岩弹塑性模型。进一步考虑盐岩的黏性损伤,基于Lemaitre等效应变原理,引入损伤蠕变分量建立了一种能够反映盐岩初始蠕变、稳态蠕变和加速蠕变全过程的黏弹塑性损伤模型,并进行试验验证。利用FLAC3D的二次开发接口,实现了新模型的软件嵌入。对金坛盐岩储气库工程进行卸压模拟,分析储库围岩损伤和破坏演化规律,得到了储库初步最小运营内压为7 MPa。研究表明,新模型能够较好地匹配盐岩试验数据,描述盐岩黏弹塑性损伤行为,且数值稳定性良好。
展开▼
