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基于盾构进洞地基冻结法加固免拔管的需要,选取PVC塑料管作为盐水冻结管,开展了PVC管(接头)在冻结过程中的抗弯强度和挠度、拉伸剪切强度、水密耐压、温度应力试验研究,得出PVC管(接头)抗弯强度随冻结温度降低而增大,挠度随冻结温度降低而减小的结论。-30℃低温冻结比常温下抗弯强度平均增加了9.4%,挠度平均减小了74%;PVC管接头拉伸抗剪强度大于2.48 MPa。运用数值模拟方法,分析得出盾构进洞水平冻结加固工况下PVC冻结管最大弯曲应力、剪应力和位移值,与试验得出的PVC管强度和挠度值进行了安全度校核,现场试验也验证了PVC冻结管的水密性和可切割性。因此,PVC冻结管在盾构进洞盐水水平冻结工程中应用具有可行性。
Based on the need of shield-free hole freezing method to strengthen extubation, PVC plastic pipe was selected as the brine freezing pipe to carry out the flexural strength and deflection, tensile shear strength, watertightness of PVC pipe (joint) during the freezing process The results show that the flexural strength of PVC pipe (joint) increases with decreasing the freezing temperature, and the deflection decreases with decreasing the freezing temperature. The low-temperature freezing at -30 ℃ increased 9.4% on average and the deflection decreased by 74% on average at room temperature. The tensile shear strength of PVC pipe joints was more than 2.48 MPa. Using numerical simulation method, the maximum bending stress, shear stress and displacement value of PVC frozen tube under freezing freezing condition of shield tunnel are analyzed, and the safety of PVC tube strength and deflection obtained by the test is verified. The tests also verified the watertightness and cuttability of PVC freezers. Therefore, it is feasible to use PVC frozen pipe in freezing salt water level shield tunnel project.