弱胶结软岩本构关系及其工程灾害孕育与演化机理研究

Weakly consolidated soft rock which were formed from the period of Triassic, Jurassic, and Cretaceousre respectively are widely distributing in China's western region of Xinjiang,Gansun, Ningxia, and western Inner Mongolia. Due to their poor characteristics of low strength, easy weathering and softening, and rapid disintegration and deterioration under water and excavation, engineering disasters such as foundation pit collapse, slope sliding, and large area roof-fall, deep rib spalling, terrible floor heaving of roadway frequently occurred. Therefore, the control and prevention of engineering disasters in weakly consolidated soft rock are needed urgently in the geotechnical engineering construction in western area. In this study, a number of experiments such as deformation and failure test, and shear-seepage-rheological coupled test in the interface of large scale rock sample under different water contents will be carried out firstly in order to reveal the degradation mechanism of weakly consolidated soft rock under water erosion and excavation, and explore the shear damage mechanism of different rock interfaces under the action of water and rock-soil coupling. Then, the damage criterion, evolution equations of rheological-damage coupling,as well as the shear-seepage-rheological coupling considering multiple interfaces will be established based on the framework of thermodynamics and equivalence principle of deformation energy. Comprehensive analysis will be made on orthogonal numerical simulations and inversion of engineering test information by embedding the constitutive model into common software, and mechanical response law of weakly consolidated soft rock in engineering geological conditions after excavation will be studied in order to reveal the generation and evolution law of engineering disaster. Finally, the judgment criterion and prediction function of engineering disaster will be established.

在我国新疆、甘肃、宁夏、蒙西等西部地区广泛分布着三叠纪、白垩纪、侏罗纪弱胶结软岩。由于其强度低，易风化，开挖、遇水后极易软化、崩解，岩质迅速劣化，致使基坑坍塌、边坡滑落、巷道大冒顶、高片帮、严重底臌等工程灾害频繁发生。所以，弱胶结软岩工程灾害防治问题是西部岩土工程建设中亟待解决的问题。本课题依托煤矿井巷工程，采集多种典型岩样，在不同含水率状态下进行系列岩块变形、破坏试验和大尺度岩样界面剪切渗流流变耦合试验，揭示开挖、水蚀对弱胶结软岩的劣化机理，探索不同岩层界面水岩耦合作用剪切破坏机制；基于热力学框架和形变能等效原则，建立弱胶结软岩损伤准则、流变损伤演化方程及其多界面剪切渗流流变耦合方程；将以上本构关系嵌入通用软件，结合典型工程进行正交数值分析和工程测试信息反演等综合方法，研究弱胶结软岩在工程地质环境下，围岩开挖力学响应规律，揭示工程灾害孕育、发生机理，提出灾害度量参数，建立灾害预测模型。

为了解决我国新疆、甘肃、宁夏、蒙西等西部地区弱胶结软岩工程灾害防治和岩土工程建设中亟待解决的问题。本课题研究了“弱胶结软岩劣化机理及其本构关系研究、弱胶结软岩界面剪切渗流流变耦合损伤演化模型研究、弱胶结软岩工程灾害孕育与演化机理研究”等内容。其研究成果不仅解决了西部地区软岩工程中亟待解决的关键理论问题，为其它地区类似岩体工程建设和灾害防治提供了理论基础，有广泛的应用前景，而且丰富和发展了岩石力学学科理论。. 本课题依托煤矿井巷工程，在不同含水率状态下进行系列岩块变形、破坏试验和岩样界面剪切渗流流变耦合试验，结合数值模拟和理论分析，掌握了典型弱胶结软岩劣化机理及其本构关系；揭示了弱胶结软岩界面的力学特性和几何形态与岩体等效变形模量和有效强度的相关性。提出了弱胶结软岩界面剪切渗流流变耦合模型和单裂隙岩体流固耦合本构关系；在基础上进行了系列数值模拟分析，推出了多界面软岩渗流流变耦合损伤演化方程和给出了强度准则，确定了与岩体基本力学性质和应力状态相关的岩体裂隙水渗透系数计算公式。揭示了开挖、水蚀对弱胶结软岩的劣化和岩体界面水岩耦合作用剪切破坏机制，遵循热力学框架和形变能等效原则，建立了弱胶结软岩损伤准则、流变损伤演化方程及其多界面剪切渗流流变耦合方程。. 基于理论成果，结合典型工程进行正交数值分析和工程测试信息反演，研究弱胶结软岩在工程地质环境下，围岩开挖力学响应规律，揭示工程灾害孕育、发生机理，提出灾害度量参数，建立灾害预测模型。在我国西部弱胶结软岩矿区井巷工程、济南地铁岩土混合地层隧道、青岛地铁土岩胶结地层隧道、郑州软土层下穿黄河调水隧道、长沙市旁穿浏阳河富水砾石软土地层并下穿公路和铁路两用桥隧道等工程中应用。共发表期刊论文40篇，其中SCU收录5篇，EI收录5篇；国家授权发明专利8项。