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研究富水砂层斜井冻结壁力学特性及温度场分布规律,可为解决斜井冻结法凿井穿越富水砂层技术难点提供可靠依据。以陕北某斜井冻结法凿井工程为研究背景,通过室内物理力学试验、现场实测及有限元数值模拟相结合的方法,研究了冻结状态下砂土的热物理及力学特性,分析了斜井冻结法凿井期间冻结壁受力机制,深入分析斜井冻融过程中冻结压力变化规律及原因,对测温孔与冻结壁径向温度实测与数值模拟结果进行了对比分析。研究结果表明,随着温度降低,冻结砂土导热系数呈现出先增大后减小的趋势,且冻结温度对冻结砂土的内摩擦角影响较大;冻结温度、井筒埋深和地下水对冻结压力的影响较大;混凝土水化热对冻结壁的影响范围约为460~475 mm。研究结果可为富水砂层地区斜井冻结法凿井的优化设计和安全稳定性研究提供依据。
Studying the mechanical properties and temperature field distribution of the inclined wall of the water-rich sand stratum can provide a reliable basis for solving the technical difficulties of inclined shaft freezing shaft drilling through the water-rich sand layer. Taking a shaft freezing shaft sinking project in northern Shaanxi as a research background, the thermal physical and mechanical properties of the sand under freezing condition were studied by means of in-house physical and mechanical tests, field measurements and finite element numerical simulation. The mechanism of freezing wall stress during shaft freezing and sinking is analyzed. The variation regularity and reason of freezing pressure in inclined shaft during freezing and thawing process are analyzed in depth. The results of actual measurement and numerical simulation of radial temperature of freezing hole and frozen wall are compared and analyzed. The results show that as the temperature decreases, the thermal conductivity of the frozen sand increases first and then decreases, and the freezing temperature greatly affects the internal friction angle of the frozen sand. The freezing temperature, the depth of the wellbore and the influence of the groundwater on the freezing pressure The influence of concrete hydration heat on the frozen wall is about 460 ~ 475 mm. The research results can provide the basis for the optimization design and safety and stability study of inclined shaft freezing shaft drilling in water-rich sand area.