我国西部地区深基岩冻结立井井壁受力机理与设计计算方法

Freezing method shaft sinking have the characteristics of large shaft diameter, shallow alluvium weak bedrock deep and aquifer more in Jurassic and cretaceous strata of western region in our country. Due to insufficient understanding of formation characteristics in the region and lack of in-depth study in freezing engineering, wall structure design theory and construction technology, cause often happened in flooding wells or fracture accident. This topic integrated use of frozen soil mechanics, rock mechanics, rock and soil seepage mechanics, mechanics of underground structure theory, and the theoretical analysis, numerical simulation and model test of the combination of comprehensive research method, based on the strata and shaft wall structure interaction mechanism, explore the Jurassic and Cretaceous frozen pressure characteristics and regular; The Jurassic and Cretaceous deep bedrock pore water forms as the research object, by using the theory of liquid-solid coupling seepage, then establishing mechanical calculation model on vertical shaft wall rock pressure and water pressure; The shaft structure form is researched which is suitable in the special strata of the western region and the solid coupling mechanism of borehole wall structure is revealed; Combining with the field monitoring results, the design and calculation method is putted forward on the Jurassic and Cretaceous deep bedrock freezing wall. To perfect and develop the theory of shaft wall structure design, solve the western region of freezing method sinking, key technical problems to provide applied basic theory basis.

我国西部地区白垩系、侏罗系地层冻结法凿井具有井筒直径大、冲积层浅、软弱基岩深、含水层多等特点。因对该地区地层特性认识不足，在冻结工程、井壁结构设计理论以及施工技术等方面缺乏深入研究，导致淹井或井筒破裂事故时有发生。本项目综合运用冻土力学、岩石力学、岩土渗流力学、地下结构力学等理论，采用理论分析、数值模拟、模型试验相结合的综合研究方法，基于岩层与立井井壁结构共同作用原理，探索侏罗系、白垩系冻结压力特征与规律；以侏罗系、白垩系高压孔隙水深基岩为研究对象，运用流固耦合渗流理论，建立作用立井井壁的岩层压力和水压力力学计算模型；研究适合西部地区特殊地层井壁结构形式，揭示在流固耦合作用下井壁结构受力机理；结合现场监测结果，提出侏罗系、白垩系深基岩冻结立井井壁结构设计计算方法。该项目对完善与发展井壁结构设计理论，解决我国西部地区冻结法凿井关键技术难题，具有重要的理论意义和应用价值。

针对因对我国西部地区白垩–侏罗纪煤系地层的工程地质属性和含水基岩段冻结立井井壁承载机理缺乏深入研究，而导致立井设计与施工中遇到的诸多难题，基于围岩与结构共同作用原理，采用室内试验、理论解析、数值模拟、和模型试验相结合的方法，在西部地区典型含水基岩的物理力学试验的基础上，构建了常温和冻结状态下的岩石蠕变本构模型；通过细观冻胀模型和基于RBF模糊神经网络构建的冻结压力预测模型，分别从细观和宏观角度对岩层的冻结压力进行了预测；通过对含水基岩段立井井壁承载状态的分析，构建围岩与井壁共同作用下的井壁外荷载分析模型，并在此基础上提出了井壁外荷载设计取值方法；通过模型试验，进一步阐述了井壁的水压传递特征与渗流机理，为井壁设计优化提供了重要的试验依据；进而揭示了侏罗系、白垩系深基岩冻结立井井壁受力机理与荷载形成机理，提出了侏罗系、白垩系深基岩冻结立井井壁结构设计计算方法。