| Due to the influences of geological conditions and the surrounding environment,underground engineering projects(including hydraulic cavern and metro engineering)have high safety risks and many restrictive factors and need dynamic follow-up.To ensure the safety and stability of the structure and surrounding environment during the construction period of underground engineering,it has become a topic of high interest to summarize and put forward reasonable and feasible methods of real-time deformation control and safety risk identification during the construction period of urban underground engineering.Among them,the typical urban subway project covers two important types of underground engineering which are foundation pit and tunnel.In this paper,the main research contents include deformation prediction,real-time deformation control,and safety risk identification method in the process of close connection construction of urban subway station and tunnel engineering.And they were applied and verified by typical practical engineering cases.Suggestions for deformation control and risk identification during the construction of urban underground engineering have been proposed.The specific research contents and results are as follows:(1)The study on deformation prediction and control method of urban underground engineering during the construction period.The common methods of deformation prediction of the existing underground engineering structure and surrounding soil during the construction period were summarized.And the corresponding deformation prediction method was proposed for the urban subway project in the soft soil area near the sea.Meanwhile,the scope of different levels of the affected areas around the project area was divided.The applicability of the method was verified by the measured data.The step-by-step displacement control method and real-time deformation control flow for underground construction were proposed.(2)The study on the real-time deformation control method and the application in subway station construction.The deformation prediction method and empirical formula of a metro station in the construction period suitable for the offshore soft soil area were proposed.The dynamic deformation control method was developed and applied.Combined with refined 3D numerical simulation and actual measurement,the construction process was optimized based on the actual engineering with complex stratum and the surrounding environment.The construction dynamic deformation control method was applied to ensure the safety of the construction itself and the surrounding buildings/structures were not damaged.(3)The study on the real-time deformation control method and the application in subway tunnel construction.A step-by-step displacement control method for tunnel construction was proposed.And the reasonable control standards of corresponding construction stages were formulated.Based on the different construction methods,cross-section forms,and the surrounding environment of the actual subway tunnel project,the construction stages were divided.The construction process was optimized,and the dynamic deformation prediction and control of the whole process of tunnel construction were carried out.During each stage of construction,engineering measures were taken to control the deformation of the structure and surrounding soil through the comparative analysis of deformation predictions,step-by-step displacement control standards,and the on-site monitoring.The step-by-step displacement control standards were evaluated and revised in time by monitored to improve the accuracy of prediction and the control of deformation in the next stage,and ultimately ensure the safety of construction and the controllable impact of the surrounding environment.(4)The study on the real-time safety risk identification for metro construction adjacent to Buildings.The accidents and case statistics of the subway project were summarized,and the potential safety risks of the subway projects were analyzed.Combined with the interval analytic hierarchy process(IAHP)and extended technique for order preference by similarity to ideal solution(TOPSIS),a real-time safety risk identification model for metro subway construction was established.The weights of safety risk criteria were assigned at each stage of construction.Based on the real-time updated construction data,it made multiple-index decisions on the interval number and ranked the relative proximity of safety risk factors,so as to more accurately identify the safety risks of subway projects.According to a typical case of subway tunnel construction adjacent to a complex surrounding environment,the model was used to identify safety risks in real-time.And the results were compared with the actual situation of safety risks in the typical construction stage,which proved the feasibility and effectiveness of the model used for identification.The model can be used to identify the safety risks of similar subway projects and even underground projects in other disciplines. |
