侏罗系煤田弱胶结岩层水砂涌出机制研究与危险性评价

Research on mechanism and risk assessment of water and sand outburst in weakly cemented rock layers of Jurassic coalfields

我国西部侏罗系煤田由于成煤时代相对较晚,岩层特征表现出胶结性差、强度低、遇水易软化崩解的特点,导致工作面回采期间易发生弱胶结岩层水砂涌出事件,因此,查明水砂涌出机制是制定相应防治措施的关键。以新疆某矿为研究对象,通过测试岩石力学强度、软化系数等参数,判定侏罗系砂岩为典型的易软化崩解弱胶结软岩地层;根据该矿首采工作面导水裂隙带发育高度、含水层水位变化、涌水水质分析结果,得出了工作面充水水源,查明水砂涌出形成机制为顶板弱胶结砂岩水沿裂隙带形成的导水通道进行渗流;同时,由于垮落带也贯通了直接顶泥岩发育至砂岩层,以及工作面长期停采导致裂隙进一步扩大,最终水携带崩解的弱胶结砂岩进入采动空间,通过结合弱胶结岩含水层富水性和煤层直接顶泥岩隔水层受垮落带破坏程度,对弱胶结岩层水砂涌出进行危险性分区评价。

Due to the relatively late coal-forming period in the Jurassic coalfields in western China,the rock characteristics often exhibit poor cementation,low strength,and easy softening and collapse in contact with water,which leads to the occurrence of water and sand outburst events in weakly cemented rock layers during mining.Therefore,identifying the mechanism of water and sand outburst is the key to formulating corresponding prevention and control measures.Taking a certain mine in Xinjiang as the research object,by testing parameters such as rock mechanical strength and softening coefficient,it is determined that Jurassic sandstone is a typical weakly cemented soft rock formation that is prone to softening and disintegration;based on the development height of the water conducting fracture zone in the first mining face of the mine,changes in the water level of the aquifer,and analysis of the water quality of the inflow,the water source of the working face has been determined;the mechanism of water and sand outburst is determined to be the seepage of weakly cemented sandstone water along the water conducting channel formed by the fracture zone in the roof.At the same time,due to the collapse zone also connecting the direct development of the top mudstone to the sandstone layer,and the long-term cessation of mining in the working face leading to further expansion of the fractures,water eventually carries the weakly cemented sandstone that has collapsed into the mining space;by combining the water abundance of weakly cemented rock aquifers and the degree of damage to the collapse zone of the coal seam direct roof mudstone aquifer,the hazard zoning evaluation of water and sand outburst in weakly cemented rock layers was carried out.