西部地区深基岩冻结井筒井壁结构设计及其优化研究

发布时间：2018-10-24 13:20

【摘要】：2000年以来,随着我国西部大开发战略的实施,该地区开始了有史以来最大规模的煤炭新井建设。西部地区多为白垩系侏罗系地层,工程与水文地质条件与华北沉积平原东部地区差异很大。我国现行冻结法凿井设计与施工规范(规程)均基于东部地区条件,不能简单套用。西部地区冻结法凿井多为穿越白垩系侏罗系地层深井基岩冻结,冻结压力小,地层以孔隙水渗流场为主,白垩系侏罗系岩遇水砂、泥化是其显著特点。采用单层结构井壁虽可降低成本,但井壁接茬漏水严重。工程实践表明,采用双层井壁结构通过壁间注浆,可有效封堵井筒漏水。但简单采用现行规范,势必造成内层井壁过厚。因此,基于西部地区条件,研究双层井壁结构受力特点,优化内层井壁设计,有效降低其厚度,是西部地区深井冻结急待解决的技术问题。本文基于西部地区特点,揭示深基岩冻结法凿井双层井壁结构受力特性,为优化井壁设计提供依据。首先,将井壁横截面视为平面问题,建立井壁力学模型,给出内壁应力计算公式,分析其受力状态。然后,通过相似模型试验,研究在均布围压作用下井壁结构应力应变关系,得出内壁内、外侧缘最大应力和极限承载力。其后,使用有限元分析软件ABAQUS,建立井壁结构计算模型,数值模拟井壁结构受力状态,比较模拟结果和试验结果,验证了模型试验结果的正确性。最后,根椐理论与试验结果,给出了适应西部地区基岩深井冻结双层井壁结构混凝土强度提高系数,为井壁优化设计提供了重要参数。研究结果表明,由混凝土强度提高系数计算井壁的极限承载力是可行的,同时由混凝土强度提高系数优化井壁厚度符合井壁真实受力状态,所以上述的优化措施能为该类井壁优化设计提供参考。
[Abstract]:Since 2000, with the implementation of the strategy of western development in China, the construction of new coal wells in this area has begun on the largest scale in history. Most of the western areas are Cretaceous Jurassic strata, and the engineering and hydrogeological conditions are quite different from those in the eastern part of North China Sedimentary Plain. The current code for design and construction of freezing shaft sinking in China is based on the conditions of the eastern region and cannot be simply applied. In the west of China, the freezing method is mostly deep well rock freezing through the Cretaceous Jurassic formation, the freezing pressure is small, the formation is dominated by porous water seepage field, the Cretaceous Jurassic rock meets water sand, and mudding is its remarkable feature. Although the cost can be reduced by adopting single-layer structure, the water leakage in the stubble of the shaft lining is serious. The engineering practice shows that the water leakage of wellbore can be effectively sealed by using double-layer shaft lining structure through interwall grouting. But simply adopting the current code will inevitably cause the inner shaft wall to be too thick. Therefore, based on the conditions in the western region, it is an urgent technical problem for freezing deep wells in the western region to study the mechanical characteristics of the double-layer shaft lining structure, optimize the design of the inner shaft wall, and effectively reduce its thickness. Based on the characteristics of the western region, this paper reveals the mechanical characteristics of double-layer shaft lining by freezing deep bedrock method, which provides the basis for optimizing the design of shaft lining. Firstly, the cross-section of the shaft wall is regarded as a plane problem, and the mechanical model of the shaft wall is established, the formula for calculating the stress of the inner wall is given, and the stress state of the shaft wall is analyzed. Then, the stress-strain relationship of shaft wall structure under uniform confining pressure is studied by similar model test, and the maximum stress and ultimate bearing capacity of inner and outer edge of shaft wall are obtained. Then, the finite element analysis software ABAQUS, is used to establish the wellbore structure calculation model. The simulation results and the experimental results are compared to verify the correctness of the model test results. Finally, based on the theoretical and experimental results, the improvement coefficient of concrete strength for frozen double-layer wall structure in deep bedrock wells in western China is given, which provides important parameters for the optimum design of shaft lining. The results show that it is feasible to calculate the ultimate bearing capacity of the shaft wall from the concrete strength enhancement coefficient, and the optimization of the wall thickness by the concrete strength enhancement coefficient is in line with the true stress state of the shaft wall. Therefore, the above optimization measures can provide a reference for the optimization design of this kind of shaft lining.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD262

【参考文献】