盾构隧道施工预测与动态调控方法研究
Construction prediction and dynamic control of shield tunnel
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摘要: 隧道近距离穿越已有结构的风险不容忽略,而盾构隧道开挖引起的地层变形主要由地层损失引起,通过对施工过程的调整控制可影响开挖过程中的地层损失率。基于此,提出一种盾构隧道施工预测与动态调控的方法:基于地层损失理论建立地层损失率与地层变形的关系,同时基于经验公式对盾构施工过程进行动态调控,使盾构施工引起的变形满足控制要求。具体而言,通过试算确定满足变形要求的最大地层损失率,并进一步依据已盾构区段的施工情况,通过动态调控使风险区段地层损失率符合要求,从而满足安全施工的要求。相对其他方法,本方法易于操作、具有实用性,同时减少了人为因素,结果较准确。通过苏州轨道交通3号线下穿1号线重叠隧道的工程实例验证,具有可行性,针对该下穿区段,提出地层损失率应控制在0.76%以内,并为3号线下穿1号线给出安全施工建议。Abstract: It can not be ignored that the construction of shield tunnel in the proximity of the existing structures is risky. The stratum loss is the major cause of ground deformation during the construction process of shield tunnel. It is suggested that the stratum loss rate should be controlled by regulating the construction procedure. Therefore, based on these two premises, a method for construction prediction and dynamic control during shield tunneling is proposed: to establish a relationship between the stratum loss rate and the ground deformation based on the stratum loss theory, meanwhile to dynamically regulate the construction procedure to make ground deformation meet the control requirements. To be more specific, firstly through pilot calculation the maximum stratum loss rate is obtained under the control requirements, then, the construction procedure is dynamically regulated based on the data from constructed sections to make sure that the stratum loss rate of risky sections does not exceed the maximum value and thus meets the requirements of construction safety. Compared with other methods, this method is relatively simple and practical, and at the same time less impressionable by human factors, which makes the results more accurate. Through the example of the project case of Suzhou Metro Line 3, the feasibility of the proposed method is illustrated. The results show that the stratum loss rate should be kept within the limit of 0.76% in the overlapped section. Moreover, some construction advices are also put forward regarding the project of Suzhou Metro Line 3 tunneling beneath Line 1 to significantly lower the construction risks.