渗压突变下砂砾层巷道失稳灾变机制及防控原理

The seepage field of high water pressure sandy gravel stratum with high discreteness and nonlinearity is very sensitive to external disturbance, while the failure mechanism of surrounding rock under seepage field mutation is the key to solve the problem of catastrophe control for water-rich sandy gravel roadway. But the current study on abnormal change of mesostructured, evolution of hydro-mechanical coupling damage area and the stability of surrounding rock is quite inadequate. The main research contents of this project are abnormal change of mesostructure, damage and evolution mechanism for surrounding rock instability in water-rich sandy gravel stratum under mutation of seepage pressure. Based on the geomechanics, fluid-solid coupling theory, catastrophe theory, etc., and by the theoretical analysis, mechanical test, numerical calculation method etc., the abnormal change features of mesostructure, damage laws of mesostructure, deterioration laws of mechanical parameters with the nonlinear growth of seepage pressure and influence mechanisms of key disaster-causing factors for hydro-mechanical coupling damage area within water-rich sandy gravel stratum will be studied when mutation of seepage pressure and hydro-mechanical coupling interaction are taken into consideration. Then the catastrophe mechanism of surrounding rock will be revealed under mutation of seepage pressure, and the united instability criterion of displacement modulus-damage zone for water-rich sandy gravel stratum will be established. On this basis the principle and method of graded cooperative control by increasing stability and guiding pressure also will be proposed.

高水压砂砾层具有高度离散性、非线性，其渗流场对外部扰动很敏感，而流场突变及水-力耦合作用下围岩的破坏失稳机制是解决富水砂砾层巷道围岩灾变控制难题的关键，但是目前针对渗压突变下围岩细观结构异变、水-力耦合损伤区演化及围岩稳定性的研究十分不足。本项目以渗压突变下富水砂砾层的细观结构异变、损伤破坏及围岩失稳灾变演化机理为主要研究内容，基于岩土力学、流固耦合理论、突变理论等，采用理论分析、力学试验、数值计算等方法，研究考虑渗压突变与水-力耦合作用的富水砂砾层细观结构异变特征、细观损伤破坏规律、力学参数随渗压非线性增长的劣化规律、致灾关键因子对围岩水-力耦合损伤区的影响机制，揭示渗压突变下围岩失稳灾变的力学机理，建立富水砂砾层巷道的位移模-损伤区联合失稳判据，提出增稳导压分级协同控制原理。

高渗压下中生代砂砾层巷道围岩灾变控制是目前煤矿生产和建设中的难题之一。本项目通过理论分析、实验室试验、数值计算、现场测试等手段，研究了水-力耦合作用下富水砂砾层细观结构异变与破坏特征，揭示了渗压突变下砂砾层巷道失稳灾变机制；基于突变理论建立了位移模极值和损伤区面积突变判据，最后提出了这类巷道的围岩控制方法，取得了以下创新性成果或发现：砂砾试样随含水率的增加表现出显著的剪胀特性。砂砾试样骨架破坏是由于渗压增量过大导致的颗粒粘结破裂数急剧增长。砂砾层巷道围岩存在一个临界渗压，当外扰引起渗压突增而超过该值时，砂砾颗粒粘结破裂数剧增，损伤破裂范围自顶板向帮部、底板迅速扩展，导致巷道围岩丧失承载力，产生失稳灾变。高渗压及其外扰突变是富水砂砾层巷道失稳破坏的主控因素，在寻求提高围岩强度、稳定性的同时，应充分考虑导水降压，防止渗压突变。通过导压扩散与预警技术实现了自动化快速导水卸压与实时监测预警，防止渗压突变，减轻了动水压力对围岩造成的不利影响。提出了增稳导压分级协同控制方法，揭示了该方法的作用机制。通过科学、合理构建超前承载拱、被动承载拱及滞后承载拱，从多级、多层次对巷道进行协同综合控制，强化围岩强度与自承能力，主动降低渗压，保障了围岩稳定，促进了矿山压力与围岩控制理论与技术的发展。