宁东侏罗系煤层顶板粗粒含水砂岩特性研究

相似模拟实验研究一直是保水开采的主要实验手段之一,其中相似材料与岩石之间力学参数的相似度尤为关键。宁东煤田属于我国典型的生态脆弱矿区,该区域主采煤层为侏罗系煤层,其顶底板广泛分布着成岩程度低且富含黏土矿物的一类特殊砂岩,该层砂岩在采动、吸水-失水动态循环作用下呈现软岩力学特征。选取其中的一类含水砂岩为研究对象,通过分析该含水砂岩岩石成分和结构特征确定其为粗粒泥质长石砂岩,并分析认为其形成于快速堆积的沉积环境;利用X衍射仪定量分析其矿物组分,发现该含水砂岩主要由黏土矿物、石英和长石组成,其中黏土矿物富含蒙脱石、伊蒙混层及绿泥石等吸水易膨胀组分;利用MTS伺服控制试验机研究了该类砂岩三轴抗压强度及渗透特性,发现其具有明显的塑性破坏特征;且饱水含水砂岩渗透率有突变点存在,突变点后渗透率大致恒定直至试件破坏时渗透率增至最大值;进一步研究了含水率对该含水砂岩单轴压缩变形特征的影响规律,发现含水砂岩单轴抗压强度、弹性模量与含水率负线性相关。

Experimental study on coarsely water-bearing sandstone in roof of Jurassic coal seam

The similar simulation experiment has always been an essential method to study water-preserved mining,during which the similarity between simulation materials and rock properties is the most significant issue.Ningdong coalfield is a typically ecological-fragile mining area where a special sandstone contains a large amount of low maturity and clay minerals.This sort of sandstone represents the soft-rock properties under mining influence and water absorb-drying process.It was confirmed that this is coarsely argillaceous arkose which is formed in quickly emerging sedimentary environment in accordance with its composition and structure.The sandstone is comprised of clay,quartz and feldspar by the quantified analysis of X-ray diffraction.The clay incorporates enormous mont-morillonite,illite smectite mixed layer and chlorite and all of these materials are water swelling.The study of triaxial compressive strength and permeability of the sandstone by MTS Servo demonstrates that the sandstone samples have plastic-failure characteristics.The permeability of water-saturated sandstone has mutational points,after which it is approximately constant before increasing to the maximum at failure.In addition,the uniaxial compressive strength and elastic modulus have a negative relation with moisture content.