Construction prediction and dynamic control of shield tunnel

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.