覆岩隔离注浆充填载荷传递效应及沉陷控制机理

Aiming at the problem that the traditional bedding separation backfilling receives a low injection ratio and the associated both large gob area compression and low subsidence reduction ratio, the idea of overburden isolated grouting backfilling is proposed. This method aims to improve subsidence control effect by using the synergistic effect of the isolated coal pillar and the load transfer effect that is associated with the compaction of gob area in response to the expansion of the bedding separation at the main backfilling horizon. The experiment of overburden isolated grouting backfilling will be conducted by means of the system developed by the proposers. On this basis, the fluid-solid coupling numerical model will be established with the consideration of the grouting and key stratum parameters. The formation condition of main backfilling horizon and the dynamic evolution of filling body characteristic can then obtained. Using this model, we will study the law of overburden load transfer to gob area by the filling body, and then determine the compaction and bearing characters of gob area and the induced supporting zone feature, followed by the controlling effect of grouting backfilling factors on this zone. Finally, the quantitative relation will be given of the combined deformation of supporting zone, filling body and isolated pillars, and the surface subsidence, by which the subsidence control mechanism will be revealed. The results will provide a basis for the optimization of grouting backfilling parameters.

针对传统离层充填沉陷控制方法注采比小导致采空区可压缩量大、减沉率低的问题，提出利用主充填层位扩张离层、压实采空区以形成载荷传递效应，并与隔离煤柱协同作用从而提高减沉率的“覆岩隔离注浆充填”新思路。本项目将利用自行研制的覆岩隔离注浆充填模拟系统开展实验研究，以此为基础考虑注浆充填参数与覆岩关键层特征等因素，建立流固耦合数值模型并进行求解，确定主充填层位形成条件及注浆充填体的动态演化特征；基于主层位内充填体形态模型，研究注浆充填体将上覆载荷向采空区传递的规律，确定采空区压实承载特性及其内部所形成的支撑带范围与变形特征，分析注浆充填参数对其控制作用；建立采空区支撑带、覆岩注浆充填体与隔离煤柱的组合变形特征与地表沉陷的定量关系，揭示覆岩隔离注浆充填地表沉陷控制机理。项目研究将为注浆充填参数优化提供理论依据。

建筑物下压煤开采是我国煤矿面临的重大技术难题。针对传统离层充填减沉方法注采比小、采空区可压缩量大、减沉率低的问题，提出了利用注浆充填载荷传递效应增大可注空间、提高注采比，在采空区内形成压实区承载体，并与隔离煤柱联合作用从而提高减沉率的思路。项目建立了覆岩隔离注浆充填流固耦合模拟模型，得出注浆充填体呈主层位分布规律；提出了注浆充填层位的现场探测方法并进行了试验，验证了注浆充填主层位。得出了注浆压力与时机对充填层位的影响特征，发现主层位主要受注浆时机影响，与注浆压力的关系并不十分显著。建立了多工作面隔离开采条件下的注浆充填体分布模型，各工作面覆岩内的注浆充填体分布相互独立，当注浆层位达到充分下沉时呈梯形模型。建立了覆岩隔离注浆充填压实区力学模型，利用物理模拟实验进行了验证。确定了注浆充填压力传递至采空区后形成的附加应力，导出了采空区压缩量与压实区宽度计算公式，证明了注浆充填压实区承载结构的有效性。研究了不同注浆充填开采参数对压实区特性的影响，注浆压力与采宽的增大有利于压实区形成，而采高与隔离层厚度加大后则不利于压实区形成。注浆充填压实区与隔离煤柱的联合作用是覆岩隔离注浆充填控制地表沉陷的关键。基于岩层运动由下而上的传递规律，建立了覆岩隔离注浆充填开采地表沉陷预计方法，并编制了计算机程序。首先确定注浆层位并计算其下方岩层下沉；利用注浆充填参数确定充填体分布；根据注浆层位下方岩层下沉与充填体分布，得出注浆层位上方岩层的下沉，进而求取注浆充填开采条件下的地表沉陷。该预计方法考虑了注浆充填参数等因素的影响，并得到了实测验证。项目研究为注浆充填参数优化提供了理论依据，指导了淮北临涣煤矿等矿井村庄压煤开采实践。