瓦斯爆炸载荷与深部高应力耦合作用下的巷道损伤失稳机制研究

Emergency rescue channel block caused by roadway collapse under gas explosion is a severe and realistic problem in the current accident rescues. The deformation and destabilizing process of deep roadways during gas explosion disaster is really complex, which revolves a coupling process of explosion pressure, high in-situ stress, and transient stress unloading. Its mechanism, which is still not clear, is the current domestic and foreign research hot spot and difficulty. This project adopts the research method combining theory, numerical simulation and experiment, and aims at structure stability of roadways in high in-situ stress environment under gas explosions. We will study dynamic response characteristics and laws of damage and stability of coal and rock, roadway supporting structure and its constituent materials under coupling of gas explosion pressure and high in-situ stress. The research mainly focuses on the reason and mechanism of large deformation of surrounding rock under original prestressed damage and gas explosion pressure, and disturbance-damage mechanism of surrounding rock in original stress zone caused by roadway deformation induced by transient high stress unloading. The assessment method of dynamic damage criterion and damage range for roadway surrounding rock and its support will be established. Meanwhile, the failure mechanism of roadway structure in high in-situ stress environment under gas explosion pressure and high in-situ stress will be revealed. The research will provide a theoretical basis for anti-explosion design of deep roadway or tunnel engineering under high in-situ stress condition.

瓦斯爆炸诱发巷道失稳垮塌阻碍救援通道是当前事故抢险面临的突出现实问题，其中涉及的爆炸灾变条件下的深部巷道变形失稳过程复杂，受爆炸载荷、高地应力和瞬态卸荷等多种因素综合作用，其机理尚不明确，是当前国内外研究的热点和难点。本项目采用理论、数值模拟和实验相结合的方法，针对高应力环境下巷道在瓦斯爆炸灾变条件下的结构稳定性问题，深入研究煤岩体、巷道支护结构及材料在瓦斯爆炸载荷与高地应力耦合作用下的动态响应特征与损伤失稳机理；重点突破围岩原始预应力损伤与瓦斯爆炸载荷叠加作用下的巷道大变形损伤原因与机制，以及高地应力瞬态卸荷诱发的巷道变形对原始应力区围岩的扰动损伤机制两个关键科学问题；建立巷道围岩及其支护的动态损伤判据与损伤演化范围评估方法，揭示高应力环境下巷道结构在爆炸载荷和高应力耦合作用下的破坏机理，为深部高应力条件下的巷道或隧道工程的抗爆设计提供科学的理论依据。

项目按照预定的研究内容和目标开展了研究工作，先后投入固定研究人员2人，研究生6人。项目完成了煤矿地下巷道围岩常见煤岩体的静态和动态力学性能测试，发现在单轴压缩条件下石灰岩、烟煤均属于脆性破坏，而无烟煤、砂岩、页岩属于脆-延性破坏，且试样的压缩破坏过程分为孔隙压密阶段、弹性形变阶段、塑性变形阶段以及试样破坏阶段四个阶段，试样的动态应力-应变曲线，与静态抗压实验相似，可大致分为四个阶段：线性变化阶段、非线性变化段、卸载阶段和曲线回弹段。研究了复合煤岩体的静态和动态力学性能，发现煤岩厚度比例越高，复合煤岩体的抗压强度和弹性模量越小；随着组合角度的增加，复合煤岩体的弹性模量逐渐增加，弹性模量最大的组合角度为90°，弹性模量最小的角度为0°；抗压强度先减小后增加，组合角度为45°时，抗压强度最小，组合角度为90°时，抗压强度最大。在单轴加载下，复合试样组合角度小于45°时主要以劈裂破坏为主，45°时劈裂破坏和压剪破坏并存，大于45°时为沿交界面的剪切破坏。在动态载荷下，45°角的应力-应变曲线由于煤岩接触面滑移没有出现回弹现象，且此时动态抗压强度最小。研究还发现地应力存在两种作用：在爆炸载荷作用前，地应力的存在造成了巷道围岩的预应力损伤，降低了围岩强度，导致围岩在爆炸载荷作用下发生变形破坏；在瓦斯爆炸载荷作用于巷道围岩后，地应力对应力在围岩内的传播起到抑制作用。巷道围岩在爆炸载荷与地应力耦合作用下的破坏按成因可分为预应力损伤、爆破损伤和卸荷损伤，呈现多米诺式破坏链，危害巨大；根据破坏成因选择多种支护方式进行综合性支护，才能实现巷道维稳。此外，项目研究期间积极参加各类学术交流活动，并在高水平期刊上发表论文9篇，培养研究生3名等。