采矿疏干漏斗区岩溶土洞发育及塌陷机理研究

Covered karst region possesses rich mineral resources in our country. In recent ten years, mine drainage causes a lot of karst ground subside,which is a serious threat to ecological environment and people's lives and property around the mine. The third-largest iron ore Chengchao Iron mine will be chosen as the support engineering for the project. A variety of typical geological structure model in the covered karst area will be built based on the investigation and analysis of domestic and international mine karst disaster. Flow field change characteristics of mining precipitation funnel of different karst geological structure model is to be studied through laboratory test and field monitoring with the application of rock mechanics，seepage mechanics and nonlinear mathematical theory. The distribution and process of karst soil cavity extending to destruction under the hydraulic action of precipitation funnel is to be revealed and the collapse mechanism of karst soil cavity in mine will be clarified.Besides, the main control factors lead to karst soil cavity collapse in covered karst mineral region will be determined. On the basis of the above research,the quantitative prediction model of karst soil cavity collapse is to be established from the energy point. Besides help make forecast and early warning of karst disaster in covered karst mineral region a reality,the proposed model will provide theoretical reference for the prevention and control of karst disaster triggered by mining and similar large drainage engineering.

我国覆盖型岩溶区域富存大量矿产资源，近十多年，采矿疏干降水引发的岩溶地面塌陷急剧增加，严重威胁到周边的生态环境及人民生产生活安全。本项目拟以我国第三大铁矿程潮铁矿开采为工程依托，基于对国内外采矿引起岩溶土洞塌陷的资料调研，构建覆盖型岩溶矿区的多种典型地质结构模型；应用岩土力学、渗流力学和非线性数学等理论，采用理论研究、室内试验和现场监测方法，研究不同岩溶地质结构模型中采矿降水漏斗的流场变化特征，揭示降水漏斗水力作用下的岩溶土洞发育、扩展及分布规律，阐明采矿疏干降水导致岩溶土洞发育至塌陷的机理，确定覆盖型岩溶矿区的土洞塌陷主控因素，并以此从系统能量角度建立岩溶土洞塌陷的量化预测模型，实现对覆盖型岩溶矿区及依托工程的岩溶土洞塌陷预测预警，为采矿及类似大型疏排地下水工程引发的岩溶灾害防控提供理论参考。

针对大规模采矿疏干地下水导致的地面岩溶塌陷问题，本项目通过现场水文地质勘测调查、模型实验、理论分析和现场监测等综合研究手段，深入开展基础研究，取得了以下重要结论和创新点：在大量调研国内外矿区岩溶塌陷资料的基础上，通过依托工程现场高密度电法岩溶勘测、钻孔岩心质量分析、岩溶覆盖层土体物理力学特性测试等研究手段，概化出了采矿区典型岩溶地质结构模型；通过矿区水文工程地质研究，掌握了采矿降水漏斗分布特征；在此基础上，研发了可模拟多种水力作用条件及地质结构的岩溶土洞塌陷模型实验装置；通过室内试验，开展了降水漏斗水力作用下岩溶土洞的塌陷机理研究，定量研究了土盖层粘粒含量、渗透系数、水力梯度等影响岩溶土洞稳定性的多项主控因素及其关联特性；针对采矿降水预先疏干期和平行疏干期矿降水漏斗区不同的水力作用条件，分析研究了降雨入渗和深部采矿动力扰动对岩溶发育及塌陷的影响，阐明了采矿疏干漏斗区岩溶土洞发育及塌陷机理。本项目研究成果可为为岩溶矿区的地面塌陷灾害防控提供理论支持，也可为其它覆盖型岩溶区地下水疏干引起的地面塌陷减灾防灾提供参考。