Risk Analysis And Strategy During Construction Of Chengdu Metro Shield Section Tunnel

The Ground Breaking Ceremony of the Phase 1 Project of Chengdu Metro Line 1 was held on December 28^th, 2005, and it lifted the curtain of the construction of Chengdu Metro. Chengdu locates at the plain of Western Sichuan Province, and the places that the metro lines go through are mainly sandy gravel stratum with water. Comparing with the metro projects of other cities, the geological conditions of Chengdu metro could be summarized as "Three High", which means high groundwater level, high density of pebbles, and high intensity of the stratum. Therefore Chengdu shield construction of the tunnel has encountered technical problems in the world.Because of the special geological conditions and surrounding environment, the cutter of the shield will be worn seriously during the boring. There are also risks that the ground subsidence, mud and sand flow, the damage to the underground cables and pipelines,and building damage on the ground would occur. The main subject of this article is how to identify, analyze and control these risks, set up the contingency plan system, and thus provide reference for the construction of Chengdu Metro Project. For this purpose, basing on the successful experience of the tunnel construction of the Phase 1 Project of Chengdu Metro Line 1, this article studies some part of the risk management of the construction, including the follows:Combined with Chengdu Metro Line 1 construction project characteristics, pointed out that Chengdu Metro shield tunnel construction technical issues raised for the construction of the Chengdu Metro tunnel shield the need for risk management.According to the Chengdu Metro shield tunnel construction characteristics, using static and dynamic analysis of the combination of a shield tunnel construction risks arising from the pregnancy and the risk caused by environmental risk factors, which have a risk-based mechanism of Chengdu Metro Shield Tunnel construction carried out to identify risk and, ultimately, ade Chengdu Metro shield tunnel construction of the 10 existing technical risk.Risk identification on the basis of the use of R = P×C model, fuzzy comprehensive evaluation method, considering the probability of the occurrence of risk factors and loss severity of the risk level, risk indicators to determine the region in order to determine the main construction Risk factors of risk level.According to the risks arising from the mechanism, all the MTR Chengdu, the current bid shield project of the Ministry of the successful experience of Chengdu Metro introduced in the construction of risk control shield specific measures focused on risk factor-induced risk area ( Cutter and the tool selection, construction control parameters in order to ensure the stability of the excavation face, the shield machine equipment failure, operator error and other emergencies, etc.) to take effective control measures.Under the "safe production" and other related laws and regulations require, in order to minimize the risks during the construction project at the time of the accident damage and human casualties, the Chengdu Metro shield tunnel project combined with the Department of the actual construction tenders are Set up a contingency plan for the construction risk system was introduced in the final of this article.