非均布载荷下充填开采岩层连续弯曲移动力学模型

Mechanical model of rock strata continuous bending movement under non-uniform load in backfill mining

为了通过采空区充填控制顶板岩层连续弯曲移动,实现保护矿区生态,提出了充填开采覆岩移动"四带"划分:充填体压缩带、连续弯曲下沉带、关键层承载带和生态保护稳定带。试验研究了不同配比(2∶1、3∶1、4∶1、5∶1、6∶1)矸石和粉煤灰的压缩力学特性,得出充填体的"应力-应变"关系近似呈抛物线关系。充填体压缩初期(0~2 MPa)快速变形,压缩后期(>6 MPa),变形量增长较缓慢,可知充填体初期捣实对岩层变形控制起重要作用。当矸石和粉煤灰配比为4∶1时,充填体抗压变形性能最好。分析了工作面后方应力降低和近似线性恢复的关键层承载保护机制。基于充填体压缩特性和工作面后方应力非均匀分布,建立了非均布载荷作用下充填顶板岩层连续弯曲力学模型,得出了充填开采顶板岩层连续弯曲变形的力学条件,实现对充填开采顶板连续弯曲移动的准确判定。数值模拟分析了不同充填率时上覆岩层移动规律,得知当充填率大于90%时,顶板岩层近似发生连续变形移动,且直接顶和地表最大下沉量的模拟结果与理论预测非常接近。

In order to control the overburden continuous movement through gob backfill and protect the ecosystemin the mining area,the"four zones"of the overburden movement of the backfill mining are proposed:the backfill compression zone,the continuous subsidence zone,the key strata bearing zone and the ecological protection zone.The experiment has studied the compressive mechanical properties of gangue and fly ash with different ratios(2∶1,3∶1,4∶1,5∶1,6∶1),and the"stress-strain"relationship of the backfill body is approximately Parabolic relationship.In the initial stage of compression(0~2 MPa),the backfill deforms rapidly,and in the later stage(>6 MPa),the deformation increases slowly,which indicates the initial compaction of the backfill plays an important role in controlling the deformation of the rock formation.The compression deformation resistance is the best when the proportion of gangue and fly ash is 4∶1.The key layer load-bearing protection mechanism of stress reduction and the linear recovery behind the working face is analyzed.The key layer load-bearing protection mechanism of stress reduction and the linear recovery behind the working face is analyzed.Based on the compression characteristics of the backfill body and the non-uniform distribution of the stress behind the working face,the continuous bending mechanical model of the backfill roof rock under the action of non-uniformly distributed load was established,and the mechanical conditions of the continuous bending deformation of the backfill mining roof rock layer were obtained,andthe accurate judgment of the continuous bending movement of the roof in backfill mining was realized.Numerical simulation analyzes the movement law of the overlying strata at different backfill rates and it is known that when the backfill rate is greater than 90%,the roof strata approximately undergoes continuous deformation and movement,and the simulation results of the direct roof and the maximum surface subsidence are very close to the theoretical predictions.