盾构隧道内机械法施工竖井泵房封底试验与数值模拟研究

为验证在盾构隧道内机械化施工废水泵房施工工艺的可行性以及泵房封底混凝土的可靠性，首先设计室内试验，模拟验证封底混凝土板在高水压深层地层环境中施工的安全性，然后采用三维有限差分软件FLAC3D建立三维数值模型，模拟其封底情况，用FLAC3D内置接触面单元模拟封底混凝土与外盾体之间的接触面，探究考虑接触对模型计算结果的影响。结果表明： 1）仿真地层模拟系统设计合理，盾构主隧道内机械化施工泵房封底各试验结果均能符合预期要求，机械化封底注浆能够达到设计要求，能足以抵抗施工中的水压而不发生破坏，工艺具有可行性； 2）考虑接触面的影响后，对模型计算结果影响较大，能更准确地预测接触面的受力情况； 3）实际工程中的地下水压远低于试验设定水压，室内试验、数值模拟结果具有一定的安全储备，机械化施工泵房封底工艺应用于实际工程具有可行性。

Experimental Study and Numerical Simulation of Bottom Sealing of Shaft Pump Room in Shield Tunnel Constructed by Mechanical Method

To validate the feasibility of the construction technology of mechanized construction for wastewater pump room in shield tunnel and the reliability of the bottom sealing concrete of the pump room, an indoor test is designed to simulate and validate the safety of the bottom sealing concrete slab in the high water pressure deep stratum environment. Then, three dimensional(3D) finite difference software FLAC3D is employed to build a 3D numerical model to simulate the bottom sealing situation. The FLAC3D internal contact element is used to simulate the contact surface between the bottom sealing concrete and the outer shield body, and further examine the influence of considering the contact on the calculation results of the model. The results show the following: (1) The design of simulation system is reasonable, the test results of mechanized construction of pump room bottom sealing test in main shield tunnel can meet the expected requirements, and the mechanized bottom sealing grouting can meet the design requirements, indicating the feasibility of the technology. (2) The contact surface has a great influence on the calculation results of the model, resulting in a better prediction of the force of the contact surface. (3) Generally, the underground water pressure in the actual project is far lower than the test one, the results of the indoor test and numerical simulation have a certain safety reserve, and the sealing technology of the mechanized construction of pump room is feasible in the actual project.