富水砂层斜井冻结壁力学特性及温度场研究

Mechanical properties and temperature field of inclined frozen wall in water-rich sand stratum

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。

Mechanical properties and temperature field of inclined frozen wall provide reliable basis for solving technical difficulties of inclined frozen mine construction in the water-rich sand stratum. Taken the inclined frozen engineering in northern Shaanxi as an example, thermo-physical and mechanical properties of frozen sand were studied by the combination of laboratory tests, field measurement and the finite element simulation. The variation and causes of freezing pressure in inclined frozen sand well were analyzed and the measured temperatures were compared with numerical results obtained in thermometer holes. It is found that the thermal conductivity of frozen sand initially increases and then decreases with the decrease of temperature, and the internal friction angle of frozen sand was greatly influenced by freezing temperature. The freezing pressure was significantly affected by the freezing temperature, shaft depth and groundwater. The effect of the concrete hydration heating on the frozen wall was in the range of 460 and475 mm. The results provide evidence for the optimization design and stability of inclined mine construction by frozen in the water-rich sand stratum.