摘要
采空区CO_(2)矿化充填需完全实现对上覆含水体的渗流隔离。基于FLAC^(3D)-COMSOL有限差分-有限元耦合仿真实验方法,模拟了连采连充CO_(2)矿化充填条件下覆岩渗透性演化规律及展布特征,提出基于渗透率劣化率及渗流速度的覆岩分区阈值确定方法。结果表明:采动覆岩渗透率劣化率呈“蝶形”展布,且在开切眼与停采线呈“类马鞍形”分布。整个开采区域可分为恒定区、恢复区、过渡区、剧增区与紊乱区。基于采动覆岩渗流速度,整个区域可分为:无渗流通道、微渗流通道、弱渗流通道、强渗流通道和渗漏通道。以采-充宽度为30—10 m为例,开采块段回采过程中矿井涌水量分别为280、300、950、1150、1350、1550 m^(3)/d,均小于突水量等级划分标准中规定的最低等级。
[Objective]The exploitation and utilization of coal resources have led to several environmental issues,including CO_(2) emissions,coal-based solid waste discharge,overburden subsidence,and loss of water resources.CO_(2) mineralization backfill in mined-out areas is a common global solution to address these problems.However,the mining-induced deterioration of permeability in the overlying strata can result in water from the overlying aquifer percolating into the permanent CO_(2) storage site,compromising the safety of CO_(2) carbonation sequestration.The primary focus of this paper is to achieve complete blockage of water seepage under continuous extraction and backfill mining using CO_(2) mineralization filling materials(CMFM).[Methods]Thus,the FLAC^(3D)-COMSOL finite difference-finite element coupling simulation method was employed to model the evolution and distribution characteristics of overburden permeability.Initially,the postpeak attenuation behavior of strain-softening parameters for CMFM was analyzed in the protective block.Then,a parameter assignment method for the strain-hardening elastic constitutive model of the caved gangue in the mining block was proposed based on the real-time replacement of the elastic bulk modulus with vertical strain increments.Considering the mechanical properties of CMFM and caved gangue,the collapse of the roof and the overlying layers was simulated using FLAC^(3D) secondary development with the FISH function embedded in the software.Posttreatment of the collapse and accumulation morphology of the roof was next conducted using AutoCAD.The resulting postprocessing images and permeability model were imported into COMSOL software to illustrate the dynamic evolution and distribution characteristics of the permeability deterioration rate and seepage velocity.[Results and Conclusions]Regarding the extracting and backfilling section of 30-10 m,the results show that the permeability degradation rate in the overlying strata follows a butterfly-shaped distribution,with a saddle-shaped distribution at the open-off cut and stopping line.Therefore,a method for determining the zoning threshold of overburden seepage was proposed.The mining area can be divided into the following seepage zones:constant seepage(k_(z)/k_(z0)≈1),seepage recovery(1<k_(z)/k_(z0)≤10),seepage transition(10<k_(z)/k_(z0)≤20),seepage sharply-increased(20<k_(z)/k_(z0)≤55),and seepage disturbance(k_(z)/k_(z0)>>55)zones.In the water inrush zone,the permeability deterioration ratio at the open-off cut is partially higher than that in the protective block.The permeability degradation rate of the strata at the bottom of the water seepage zone follows this order:mining block>open-off cut>protective block.In contrast,the order at the top of the water seepage zone is open-off cut>mining block>protective block.Within the water-seepage-resistance zone,the permeability values of the overlying rock in the open-off cut and mining blocks decreased from 10 to 1 and 8 to 1,respectively,whereas the protective block remained constant at 1.According to the seepage velocity of the overlying strata during coal extraction and CMFM backfill,the entire area can be categorized into the following seepage channels:no(V_(i)≤2×10^(-5) m/s),micro(2<V_(i)≤5×10^(-5) m/s),weak(5×10^(-5) m/s<V_(i)≤10×10^(-5) m/s),strong(10×10^(-5) m/s≤V_(i)<25×10^(-5) m/s),and extremely strong(V_(i)>>25×10^(-5) m/s)seepage channels.Within the water inrush zone,the seepage velocity of the overlying strata above the open-off cut is considerably higher than that of the protective block.The seepage velocity at the bottom of the water seepage zone follows this order:mining block>open-off cut>protective block.The seepage velocity for the other strata within the water seepage zone is as follows:open-off cut>mining block>protective block.Moreover,the water inflow during the extraction of the mining block is 280,300,950,1150,1350,and 1550 m^(3)/day,all of which are lower than the minimum threshold specified in the state water inrush classification standard.
作者
许玉军
马立强
王磊
刘怀谦
李少波
XU Yujun;MA Liqiang;WANG Lei;LIU Huaiqian;LI Shaobo(State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,Anhui University of Science and Technology,Huainan 232001,China;Key Laboratory of Xinjiang Coal Resources Green Mining(Xinjiang Institute of Engineering),Ministry of Education,Urumqi 830023,China;Xinjiang Engineering Research Center of Green Intelligent Coal Mining,Xinjiang Key Laboratory of Coal-bearing Resources Exploration and Exploitation,Xinjiang Institute of Engineering,Urumqi 830023,China)
出处
《实验技术与管理》
北大核心
2025年第1期123-132,共10页
Experimental Technology and Management
基金
安徽理工大学高层次引进人才科研启动基金资助(2023yjrc89)
安徽省教育厅重点项目(2024AH050403)
国家自然科学基金项目(52464015)。
