为解决西部地区孔隙型含水岩层钻井法凿井壁后充填技术难题，开展了充填层作用机理及材料配制研究。首先，以可可盖煤矿中央回风立井为工程背景，利用Comsol Multiphysics数值计算软件进行了围岩、充填层和钻井井壁流固耦合作用分析。计算结果表明:有效应力和孔隙水压力分布曲线呈现出明显的“压降漏斗”型特征（即越靠近井筒中心，两者降低速率越快），且曲线的陡降段位于充填层区域；由此可见，在西部孔隙型含水岩层中，充填层不但具有固井和封水作用，而且还具有减载功能。然后，基于有效应力原理和达西渗流理论，提出充填层材料应具有低渗透性、较高强度和较大比重、微膨胀、不收缩，同时拌合物的流动性好、满足泵送机械化施工要求。综上，提出采用高性能水泥砂浆作为西部地区孔隙型含水岩层钻井井筒壁后充填材料。最后，通过正交试验测定了充填材料的主要物理力学性能，并采用极差分析法研究了粉煤灰与膨胀剂质量掺量对充填材料各因素指标的影响；同时，将比重、三轴抗压强度、渗透系数3者作为其性能的最终评定指标；基于综合平衡法获得水泥、粉煤灰、膨胀剂、水、砂、〖JP2〗泵送剂等壁后充填材料的最优配合比为1∶0.286∶0.143∶2.144∶〖JP〗0.443∶0.014 3。论文研究结果为西部地区孔隙型含水岩层钻井法凿井的壁后充填提供了工程应用基础。

To solve the problem of the backfill layer of the drilling method in porous water-bearing rock stratum in western China, the mechanism of filling layer and material preparation were studied. Firstly, taking the central air return shaft of Kekegai Coal Mine as the engineering background, the fluid-structure interaction of surrounding rock, filling layer, and drilling shaft lining was analyzed by using Comsol Multiphysics numerical calculation software. The calculated results show that the effective stress and pore water pressure curves show obvious “pressure drop funnel” type characteristics (that is, the decrease rate is faster the closer to the shaft center), and the steep drop section of the curve is located in the backfill layer zone. It can be seen that the backfill layer not only plays the role of cementing and sealing water; but also has the function of load reduction in porous water-bearing rock stratum in western China. Then, based on the effective stress principle and Darcy seepage theory, it is proposed that the backfill material should have low permeability, high strength, large specific gravity, small expansion, unshrinking, and good fluidity of the mixture to meet the requirements of pumping mechanized construction. Therefore, it is proposed that high performance cement mortar should be used as the backfill material of the drilling shaft in the porous water-bearing rock stratum in western region. Finally, the main physical and mechanical properties of backfill material were measured by orthogonal test, and the influence of the mass content of fly ash and expansion agent on the factors of backfill materials was studied by the range analysis method. At the same time, the specific gravity, triaxial compressive strength, and permeability coefficient are taken as the final evaluation indexes of its performance. Moreover, through the orthogonal experiment and the filling material of the main physical and mechanical performance test, and based on the comprehensive balance method to obtain the backfill material of optimal mixing proportion of cement∶fly ash∶expansion agent∶water∶sand∶pumping agent=1∶0.286∶0.143∶2.144∶0.443∶0.014 3. The research results provide a theoretical and practical basis for the backfilling of the porous water-bearing rock stratum in western China.