Zhu Xiaojing, Qi Qingxin, Xiao Yonghui, Li Haitao
Chinese Institute of Coal Science, Beijing, P.R. China.
School of Physics, Liaoning University, Shenyang, P.R. China.
Sci Prog. 2024 Oct-Dec;107(4):368504241291395. doi: 10.1177/00368504241291395.
Due to the discrete and non-homogeneous of similar materials and the inability to realize large-size and original scale modeling, it is difficult to restore the structure and stress state of underground coal and rock mass in similar simulation tests. To solve this problem, a lightweight and suitable for large-scale modeling similar material, rock-like porous material has been developed. The quasi-static uniaxial compression experiment was carried out by using the large tonnage multi-module electronic control test system. And the influencing factors of controllable mechanical behavior of rock-like porous materials were studied. The results showed that, under uniaxial compression conditions, the material stress-strain curve exhibits three phases: elastic stage, failure stage, and platform stage. The uniaxial compressive strength, elasticity modulus, stress drop, and softening modulus of rock-like porous materials basically increase with the increase of density. The stress after peak strength changes from a slow decrease to a "stepped" or even "cliff like" downward trend. Polypropylene fibers have the effect of enhancing the uniaxial compressive strength, elasticity modulus, stress drop, softening modulus, shear deformation, and residual strength stability of rock-like porous materials. The rock-like porous material has a critical loading velocity, and it increases with density. At the critical loading velocity, the material shows obvious shear failure, and the shear inclination angle is the largest, and so is the uniaxial compressive strength. Through the experimental research, the influence laws of density, polypropylene fiber, and loading velocity on the failure mode, mechanical parameters, and mechanical behavior of the material are clarified, and the quantitative relationship between density and each mechanical parameter is obtained. The research is helpful to realize the accurate control of mechanical behavior of rock-like porous materials and further inverts the deformation and failure mechanism of underground coal and rock structures through indoor similar simulation tests.
由于相似材料的离散性和非均匀性，以及无法实现大尺寸和原尺寸建模，在相似模拟试验中难以恢复地下煤岩体的结构和应力状态。为解决这一问题，研发了一种轻质且适用于大规模建模的相似材料——类岩石多孔材料。利用大吨位多模块电控试验系统进行了准静态单轴压缩试验，研究了类岩石多孔材料可控力学行为的影响因素。结果表明，在单轴压缩条件下，材料应力 - 应变曲线呈现弹性阶段、破坏阶段和平台阶段三个阶段。类岩石多孔材料的单轴抗压强度、弹性模量、应力降和软化模量基本随密度的增加而增大。峰值强度后的应力从缓慢下降变为“阶梯状”甚至“悬崖状”下降趋势。聚丙烯纤维具有提高类岩石多孔材料单轴抗压强度、弹性模量、应力降、软化模量、剪切变形和残余强度稳定性的作用。类岩石多孔材料存在临界加载速度，且随密度增加而增大。在临界加载速度下，材料呈现明显的剪切破坏，剪切倾角最大，单轴抗压强度也最大。通过试验研究，明确了密度、聚丙烯纤维和加载速度对材料破坏模式、力学参数和力学行为的影响规律，得到了密度与各力学参数之间的定量关系。该研究有助于实现对类岩石多孔材料力学行为的精确控制，并通过室内相似模拟试验进一步反演地下煤岩结构的变形破坏机制。
