茅口灰岩隐伏承压溶洞围岩时效破断—滞后突水机理研究

South China coalfields is Moukou limestone karst deposits mainly composed of water filling cave. Many accidents of water bursting form confined karst cave occurred in south China coalfields.Tremendous economic loss and social harm were generated, because of water bursting form confined karst ,thereby, It is an important problem demanding prompt solution for south China coalfields mining. According to problems on lagging water bursting form concealed confined karst cave in Maokou limestone in south China coalfields,In this research project, by experimental study means, rheological fracture and seepage mechanical properties of Maokou limestone were revealed. By adopting percolation theory of overburden rock stratum and rock fracture damage mechanics ,Law of rheological damage of mining induced surrounding rock and delay instability of water flowing fractured under the action of fluid-solid coupling was investigated. The aging rupture theory of mining induced surrounding rock under fluid-solid coupling was constructed. Through studying the flow state conversion of accumulating phase ,initiation phase and outbreak phase of karst water bursting, the flow state conversion critical condition of lagging water bursting was analyzed. The nonlinear seepage model for karst water bursting was established.In terms of the academic thought about muti-field coupling, the mathematical model for mining induced surrounding rock aging rupture-lagging water bursting coupling was built. The analyzing coupling program was developed under COMSOL Multiphysics platforms, the aging stability of waterproof pillar, catastrophe condition causing lagging water bursting, forecasting lagging time of water inrush were studied. This paper provides theoretical basis for controlling karst water bursting in south coalfields, It is of great theoretical importance for South China coalfields mining method improvement.

我国南方煤田大多是以充水溶洞为主的茅口灰岩岩溶矿床，承压溶洞突水事故在南方煤矿已发生多起，造成了严重的经济损失和社会危害，是我国南方煤矿开采亟待解决的重大课题。本项目针对南方煤矿茅口灰岩隐伏承压溶洞滞后突水问题展开研究，通过试验研究手段揭示茅口灰岩的流变断裂、渗流力学特性；应用采动岩体渗流理论、岩石断裂损伤力学，研究流固耦合作用下采动围岩流变损伤、导水裂隙时滞失稳规律，构建采动围岩时效破断理论；通过研究岩溶突水蓄势段、萌生段、爆发段的流态特性，分析滞后突水流态转换临界条件，构建岩溶突水非线性渗流模型；依据多场耦合学术思想，建立采动围岩时效破断-滞后突水耦合数学模型，在 COMSOL Multiphysics平台下开发耦合分析程序，分析防水煤岩柱时效稳定特性，滞后突水形成的灾变条件、预测突水滞后时间。该研究为南方煤矿岩溶突水的防治供理论依据，对于南方煤矿开采方法改进具有重大理论意义。

项目围绕茅口灰岩隐伏承压溶洞突水灾变机理相关科学问题，在茅口灰岩的流变-断裂力学与渗流试验研究、采动应力-岩溶水压下围岩流变断裂时效破断理论与数值研究及防突水技术方面取得了一些重要进展。（1）完成了分级加卸载下裂隙灰岩的流变试验，建立了基于塑性扩张的岩石变参数蠕变损伤模型；完成了岩石双扭试件的亚临界裂纹扩展试验，建立了岩石裂纹的压剪流变断裂模型；为探讨裂隙灰岩强度特性与破裂模式，进行了双裂隙类岩石材料的裂纹发展和应力-应变行为研究；完成了全应力-应变过程中裂隙灰岩的水-力耦合特性试验研究，研究水-力耦合作用下裂隙灰岩的强度和变形特性；完成了茅口灰岩裂隙渗流-应力耦合试验，获得了茅口灰岩裂隙渗流的非线性规律及与表面形貌的相关性；研制了承压溶洞泥水突出的试验装置，完成了承压溶洞泥水时滞突出的试验研究。（2）研究了裂隙岩体剪胀-渗流耦合效应，建立岩体节理的非线性剪胀-渗流模型和节理剪胀耦合的裂隙岩体等效渗透系数经验公式；研究了高水压作用下岩体裂隙的变形和翼形裂纹的萌生、扩展、贯通的渗流-断裂耦合作用机制，建立了高水压作用下岩体裂隙的渗流-流变-断裂耦合数学模型；采用岩石断裂力学和流变力学，研究了采动卸荷岩体裂纹扩展的时效特性，建立了采动卸荷岩体裂纹流变断裂模型及数值方法，并提出了卸荷岩体裂纹止裂判据。（3）为研究溶洞突水的渗水-涌水-突水全过程，引入承压溶洞突水的管道流折算渗透系数，将溶洞突水全过程用统一的高度非线性的渗流方程来近似表达，从而构建耦合非线性渗流-管道流于一体的承压溶洞突水全过程分析模型，在此基础上建立了承压溶洞突水过程的流固耦合–强度折减法联动分析和滞后突水流态转换临界判剧，研究了承压溶洞突水全过程的流态转换机理；引入防突岩柱安全系数的概念，将安全系数为1.5 的岩柱厚度作为防水岩柱的计算安全厚度，提出防水岩柱工程留设厚度等于炮眼深度、爆破扰动深度和防水岩柱计算安全厚度之和的计方法。（4）针对南方煤矿茅口灰岩底板具有复式向斜的地质构造，提出井下对深部茅口灰岩复式向斜隆起部分进行注浆，将茅口灰岩裂隙体变成隔水带，阻止浅部岩溶水向深部渗透，提升矿井水位，减少矿井深部水平的涌水量的防突水关键技术，找到了解决茅口灰岩矿井突水频繁、排水费用高等难题的有效途径。项目出版学术专项1部，发表学术论文44篇，获得授权发明专利6项，研究成果获湖南省科技进步奖和自然科学奖三项。