摘要
针对《建筑物、水体、铁路及主要井巷煤柱留设与压煤开采规范》中安全煤(岩)柱设计以及水压对顶板突水控制作用等问题进行探讨。首先分析了规范的附表4-3表头文字,指出保护层厚度的有关规定仅适用于松散含水层(含地表水体),至于基岩含水层下采煤应如何确定保护层厚度则未明确;进而以泥岩与黏性土层均具有阻水功能为桥梁,推导出基岩含水层下采煤可参照“松散层下黏性土层累计厚度大于采厚”条件执行,遵照“就高不就低原则”,基岩含水层下保护层厚度统一取采厚的4倍为宜;既然规范适用条件为单层采厚不大于3.0 m,则附表4-3中“松散层厚度小于采厚”的规定难以理解,建议删除。其次,基于“保护”一词的科学内涵对“保护层”重新定义,即导水裂缝带顶界面到含水层底界面之间的隔水岩层均具有“保护”功能,应统称为保护层H_(b);进而提出了保护系数B_(s)概念,即保护层厚度与单层采厚的比值;松散含水层下保护系数分区阈值(B_(i)=2、3、4、5、6、7),基岩含层下保护系数分区阈值B_(i)=4,据此对顶板水害风险进行等级划分:突水区(B_(s)≤0)、危险区(0<B_(s)<B_(i))、安全区(B_(s)≥B_(i))。此外,借鉴底板突水系数概念,将单位厚度保护层承受的水头压力称为保护层承压系数(T=P/H_(b)),通过对3种煤水结构条件下承压系数的分析,得出第4系松散含水层、非煤系基岩含水层下采煤可以不考虑水压,煤系基岩含水层下采煤随着开采深度增加、水压随之增大而带来突(涌)水风险。最后,分析了底板含水层顶部存在被泥质物充填隔水带时,《“三下”开采规范》给出的底板防水安全煤(岩)柱表达式(h_(a)≥h_(1)+h_(2)+h_(4))与附图相矛盾,正确的表达式应为h_(a)≥h_(1)+h_(2)-h_(4)。
This paper explores the design of safe coal(rock)pillars and the control effect of water pressure on roof water inrush in the“Code for Coal Pillar Retention and Coal Mining in Buildings,Water Bodies,Railways,and Main Tunnels”.Firstly,by analyzing the header text of Appendix 4–3 of the standard,it is pointed out that the relevant regulations on the thickness of the protective layer only apply to loose aquifers(including surface water bodies),and it is not clear how to determine the thickness of the protective layer for coal mining under bedrock aquifers;Furthermore,taking both mudstone and cohesive soil layers as bridges with water blocking function,it is inferred that coal mining under the bedrock aquifer can be carried out according to the condition that the cumulative thickness of cohesive soil layer under the loose layer is greater than the mining thickness.Following the principle of“high not low”,it is advisable to uniformly take four times the mining thickness as the protective layer under the bedrock aquifer;Since the applicable conditions of the specification are that the thickness of a single layer should not exceed 3.0 m,it is difficult to understand the provision in Appendix 4-3 that“the thickness of the loose layer is less than the thickness of the mining”,and it is recommended to delete it.Secondly,based on the scientific connotation of the term“protection”,the“protective layer”is redefined,which means that the waterproof rock layers between the top interface of the water conducting fracture zone and the bottom interface of the aquifer all have a“protection”function and should be collectively referred to as the protective layer(H_(b));Furthermore,the concept of protection factor(B_(s))was proposed,which refers to the ratio of the thickness of the protective layer to the thickness of a single layer of mining;The threshold for dividing the protection coefficient under the loose aquifer is B_(i)=(2,3,4,5,6,7),and the threshold for dividing the protection coefficient under the bedrock aquifer is B_(i)=4.Based on this,the risk of roof water damage is classified into three levels:water inrush zone(B_(s)≤0),hazardous zone(0<B_(s)<B_(i)),and safe zone(B_(s)≥B_(i)).In addition,drawing on the concept of water inrush coefficient of the bottom plate,the head pressure borne by the unit thickness of the protective layer is called the pressure coefficient of the protective layer(T=P/H_(b)).Through the analysis of the pressure coefficients under three types of coal water structure conditions,it is concluded that coal mining under the loose aquifer of the Quaternary system and the non coal bearing bedrock aquifer can not consider water pressure.The risk of water inrush caused by the increase of mining depth and water pressure under the coal bearing bedrock aquifer increases.Finally,it was analyzed that when there is a mud filled water barrier at the top of the bottom aquifer,the expression for the bottom waterproof safety coal(rock)column(h_(a)≥h_(1)+h_(2)+h_(4))given in the“Three Down Mining Specification”is contradictory to the attached figure.The correct expression should be h_(a)≥h_(1)+h_(2)-h_(4).
作者
吕玉广
孙国
吴宝峰
李硕
LYU Yuguang;SUN Guo;WU Baofeng;LI Shuo(Anhui University of Science and Technology,Huainan 232000,China;Inner Mongolia Shanghai Temple Mining Co.Ltd.,Erdos 016299,China;Xinkuang Inner Mongolia Energy Co.,Ltd.,Erdos 016299,China)
出处
《煤炭科学技术》
EI
CAS
CSCD
北大核心
2024年第8期139-145,共7页
Coal Science and Technology
基金
国家自然科学基金资助项目(51574250)
内蒙古自治区科技计划资助项目(2020GG0291)。
关键词
保护层
保护系数
分区阈值
“三区”划分
承压系数
安全煤(岩)柱
protective layer
protection coefficient
partition threshold
division of the“three zones”
pressure bearing coefficient
safe coal(rock)pillar
