深部软岩流变大变形特性及本构模型研究

Soft rock engineering is an important part of deep resources mining engineering, deep deep soft rock rheological deformation characteristics is an important engineering problem faced in the soft rock engineering.Project soft rock rheological meter with high precision, whole stress strain curves measured soft rock, based on the theory of plastic strain space, build considering changes of moisture content and confining pressure of deep soft rock strain softening model;Determination of moisture content of different soft one peak value before and after creep curves under different deviatoric stress level and lag elasticity recovery curve, the long-term strength of soft rock;Sticky elastic-plastic strain separation methods, the research of soft one value before and after the peak strength parameters with sticky plastic strain nonlinear attenuation law;Determine the soft one peak value before and after the sticky plastic accelerate the start of large rheological deformation conditions;Based on finite deformation theory, build different moisture content of soft rock before the long-term strength viscoelasticity, peak before and after the peak sticky plastic strain softening constitutive model for large rheological deformation;As a function of the rheological model parameters, the analysis of moisture content on large rheological deformation constitutive model parameters are fixed.Large project aims to put forward the deep soft rock rheological deformation constitutive model, revealing the deep soft rock viscoelasticity, peak before the long term strength and large sticky plastic flow deformation law after peak, for the deep soft rock rheological theory of large deformation and disaster prevention and control research foundation.

软岩工程是深地资源开采工程中的重要组成部分，深部软岩流变大变形特性是深部软岩工程中面临的重要工程问题。项目采用高精度软岩流变仪，实测软岩全应力应变曲线，基于塑性应变空间理论，构建考虑含水率及围压变化的深部软岩应变软化数学模型；测定不同含水率软岩峰值前及峰值后各偏应力水平下的蠕变曲线及滞后弹性恢复曲线，确定软岩长期强度；采用黏弹塑性应变分离方法，研究软岩峰值前及峰值后强度参数随黏塑性应变非线性衰减的规律；确定软岩峰值前及峰值后黏塑性加速流变大变形的启动条件；基于有限变形理论，分别构建不同含水率软岩长期强度前黏弹性、峰值前及峰值后黏塑性应变软化流变大变形本构模型；分析含水率与流变模型参数的函数关系，对流变大变形本构模型参数进行修正。项目旨在提出深部软岩流变大变形本构模型，揭示深部软岩长期强度前黏弹性、峰值前及峰值后黏塑性流变大变形规律，为深部软岩流变大变形理论及灾害防治研究奠定基础。

软岩工程是深地资源开采工程中的重要组成部分，深部软岩流变大变形是深部软岩工程中面临的重要工程问题。由于煤系地层复杂地质环境和开采规模的扩大，深部软岩巷道围岩流变大变形问题十分严峻，特别是湿度环境变化时，软岩强度弱化及流变大变形现象更加突出。. 项目采用高精度软岩流变仪，实测软岩全应力应变曲线，基于塑性应变空间理论，构建考虑围压变化的深部软岩应变软化数学模型；测定不同围压条件下软岩峰值前及峰值后各偏应力水平的蠕变曲线，确定软岩长期强度，研究软岩峰值前及峰值后强度参数随黏塑性应变非线性衰减的规律；确定软岩峰值前及峰值后黏塑性加速流变大变形的启动条件；构建软岩流变大变形本构模型。. 通过本项目的研究，获得了典型泥岩峰值前及峰值后的蠕变曲线，采用非线性拟合方法获得蠕变参数随围压变化的规律，基于弹粘塑性理论，提出了一种非线性弹粘性模型与粘塑性应变软化模型耦合的NBSS流变大变形损伤本构模型，采用非线性弹粘性模型模拟泥岩的稳态蠕变行为，采用非线性粘塑性应变软化模型模拟泥岩的加速蠕变行为和峰值后强度衰减行为。基于有限差分方法，提出了隧道软岩蠕变与应变软化耦合作用数值计算方法，对流变大变形本构模型参数进行修正，通过数值计算得到泥岩加速蠕变曲线与试验曲线吻合，验证了模型的可靠性。分别采用NBMC模型和NBSS模型计算深部巷道围岩塑性区分布特征及变形规律，NBMC模型计算得到的塑性区分布均匀，采用NBSS模型计算得到的塑性区范围更大，且具有明显的流变大变形特征。该文提出的NBSS蠕变损伤模型适用于研究复杂围岩应力场及位移场的演化规律。. 通过研究深部软岩流变大变形特性，提出深部软岩流变大变形损伤本构模型，在丰富传统岩石流变力学知识内容，积极推动矿山岩体力学、岩石流变力学等学科的发展，揭示深部软岩流变大变形破坏实质等方面具有重要的科学意义，对深部巷道软岩工程支护设计及稳定性分析具有重要的理论支撑。