黏性土采动变形-渗透耦合效应研究

The aquifer in the unconsolidated layers is a threat to shallow buried coal seams mining in central and eastern China. The layer of clay, sandy clay and clayey sand, as a auifuge above the weathering zone of bedrock, at the bottom of the unconslidated layers is a common geological structure in this areas. The deformation, failure and infiltration process of the aquifuge caused by mining is a key conditon for safe minging and water conservation..The study will begin after the survey of geological prototype. On considering multiple geological and mining factors, measurement of stress, strain and other informations that can be recorded in the clay layer and weathered zone, pattern recognition of these informations, the tests and analysis of mining stress, strain, pore pressure path and their relationship with mining, obsevation of the structural changes of the deformed clay and capture of the permeability changes and the ultimate bearing head capacity will be completed gradually in order to induce that the coupling effects among soil deformation, seepage, geological and mining factors..The study works would obtain the qualitative and quantitative regulation about the degree of deformation, failure and permeability of the soil for judging the structural stability and watertight stability. This will replace the original decision-making standard that used the thickness of clay as one of the possilble index. A second outcome is to find the macro modes to reveal some deep clayey soil deformation and failure during mining, each has a mechanical mechanism process and a penetration-leakage criterion. This can be summrized as a structural damage - penetration coupling law under the cycle of large deformation of the clay layer. The research can also abstract the key factors of geolgy and mining conditons that influence the deformation and penetration of the clay layer. This can help to establish the geological theory and a systematic approach to exploration, observation, evaluation and certification the feasibility of mining under unconsolidated layers.

)：本项目研究覆盖于基岩风化带之上的黏性土隔水段受开采影响的变形渗透耦合规律，对松散层水害预防和水资源保护有重要意义。研究以地质原型调查为基础，考虑多重地质、开采因素，通过实测黏性土和风化带的应力应变等可测信息和特征识别，试验和分析黏性土采动应力、应变、孔隙压力路径与开采对应关系，测试黏性土变形破坏的结构变化、渗透性变化和极限承载水头能力，归纳黏性土变形破坏和渗流耦合特征以及多重因素影响特征。研究将突破以往仅通过宏观结构、厚度决策松散层底界黏性土防止溃水、溃砂作用的模式，定性和定量揭示出黏性土采动变形破坏的结构稳定性和隔水稳定性；揭示若干深层黏性土变形破坏的宏观模式、力学机制以及渗透渗漏的判别依据，获得周期大变形条件下黏性土结构破坏-渗透耦合的规律；提炼影响黏性土变形破坏的地质开采关键因素，建立探查、观测、评价和论证新生界松散层水体下回收浅部资源的关键地质理论和系统化方法。

本项目以新生界覆盖层下浅层煤炭资源开采造成的深层黏性土变形破坏、变形破坏导致的渗漏和水资源保护为基本背景。课题是在我国中东部地区可采煤炭资源基本消耗殆尽，松散层和水体下压覆的浅部资源开发又面临着地表水体、深层含水层渗漏涌水威胁和水资源流失双重压力条件下提出的。. 研究主要内容包括：新生界黏性土赋存的宏观结构特征及勘探评价方法，近风化带黏性土和低渗透性黏土质砂采动变形破坏的宏观模式和范围，黏性土变形破坏过程结构演化特征和影响因素、力学机制，黏性土变形破坏过程的渗透性及影响因素，典型采区提出防控顶板水砂灾害和水库渗漏的论证应用分析。. 通过研究获得了深层黏性土赋存的宏观结构条件，深层硬黏土在成分、构造、性质上都存在分带性；获得了深层黏性土变形破坏的宏观特征和范围判别依据，深部黏性土变形受岩体变形和上覆土层压力控制，表现为依附变形和土岩分离垮落两种形式。变形范围可用土拱描述，土拱宽度、高度与土的强度、埋深和地应力之间存在定量关系；深层黏性土变形破坏过程是主应力随开采波动、偏转过程，裂隙发育受黏粒含量和含水量的控制；黏性土岩性、变形和裂隙演化对渗透性有控制性作用，黏性土变形渗透表现为三种特征：第一类：随变形增长，渗透性增大，但不显著；第二类：随变形增长，渗透性先增大再下降；第三类：随变形增长，渗透性显著增大，前两类黏性土层变形前后仍具有隔水作用。. 通过研究，形成了新生界覆盖层下浅层煤炭资源开采防水和保水的勘探、评价工作体系，获得了深层黏性土破坏范围与防治水定性分析的几何依据，识别出应力、主应力偏转角、含水量等监测黏性土变形破坏和裂隙演化的具体可测指标，为评价黏土层扰动后的隔水性和主动控制黏土层隔水性提供了理论基础。