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针对水下隧道长期赋存于富水环境中,围岩的力学性质较差,地层的成拱能力降低的特点,研究水下盾构隧道的合理覆土厚度,为设计与施工提供参考。在国内外学者研究成果的基础上,依托具体的工程实例,鉴于实际施工中盾尾管片壁后注浆对盾构隧道的动态上浮作用和对地层沉降的影响,进而确定对盾构隧道最小覆土厚度的影响,同时基于水下隧道突水风险研究,综合考虑水、土、注浆浆液的动态影响,通过对颗粒流数值模拟结果进行分析,给出水下盾构隧道合理覆土厚度和最小覆土厚度临界值的判定依据和条件,采取必要的信息化施工和响应联动措施,控制水下盾构隧道浅覆土穿越水体地层变位,保证工程和环境的安全。研究结果表明:双洞隧道的地表沉降曲线基本符合Peck沉降槽理论,随着埋深的增加,地表沉降将由2个独立的沉降槽逐渐发展叠加为1个新的沉降槽;对于依托工程而言,隧道覆土厚度的临界值为1.3D;围岩的竖向位移随距隧道中心线距离的增大而减小,当距离增大到0.5D后位移变化不再显著;隧道开挖后,由于隧道顶部土体拱效应的发挥,不同埋深情况下作用在管片上的土压力将明显小于初始土压力,且压力值与埋深成正比。
In view of the long-term occurrence of underwater tunnels in water-rich environment, the mechanical properties of surrounding rock are poor and the arching ability of formation is reduced, the reasonable casing thickness of underwater shield tunnels is studied, providing reference for design and construction. Based on the research results of scholars at home and abroad, relying on specific engineering examples, in view of the dynamic uplift effect of shield tunneling on the shield tunnel in the actual construction and the influence on the formation settlement, Based on the study of the risk of water inrush from underwater tunnel and considering the dynamic influence of water, soil and grouting slurry, the numerical simulation results of particle flow are given, and the reasonable thickness of overburden shield and minimum overburden Thickness of the critical value to determine the basis and conditions, to take the necessary information technology and response to the linkage measures to control the underwater shield tunnel shallow soil through the water formation deformation, to ensure engineering and environmental safety. The results show that the ground settlement curve of double-hole tunnel basically conforms to the Peck settling tank theory. With the increase of the buried depth, the surface subsidence will be superposed into two new settling tanks by two independent settling tanks. For the relying on the engineering , And the critical value of tunnel covering thickness is 1.3D. The vertical displacement of surrounding rock decreases with the increase of the distance from the tunnel centerline. When the distance increases to 0.5D, the displacement change is no longer significant. After tunnel excavation, The effect of soil arching at the top of the tunnel is exerted. Under different depths, the earth pressure acting on the pipe slice will be obviously smaller than the initial earth pressure, and the pressure value is proportional to the depth of the earth.