Risk Evaluation Of The Bias Shallow Buried Tunnel With Small Interval And The Engineering Application

In order to implement the highway tunnel design concept which is safe,perdurable, economic, energy-efficient and beneficial to protect the ecological environment, the bias shallow buried tunnel with small interval become one of the common forms of tunnel structure in the highway of our country. But there are some problems in the excavation process of the bias shallow buried tunnel with small interval, such as unbalanced force caused by bias stress of tunnel, shallow buried surrounding rock of outlet section with poor stability, serious construction interference of small interval between two tunnels and so on. These problems are easy to result in lateral displacement, the roof subsidence and instability of tunnel, leading to casualties and economic losses. In view of this, carrying out a targeted risk assessment research on the tunnel construction, setting up corresponding safety risk assessment system and control measures in advance, can deal with all kinds of risks timely and effectively in the construction process, which ensure the safety of tunnel construction and avoid economic losses.This paper carry out accident risk assessment research about bias shallow buried tunnel with small interval, choosing Malugouling Tunnel project which is part of Hegang to Dalian highway as the background, in order to set up a set of impeccable risk assessment system, assessment method, monitoring measures and control measures in advance which provide guidance for the tunnel construction safety control.Main research content of this paper is as follows:(1) Risk identification and control: summarizing common risk events and influenced factors, elaborating the common risk assessment methods and risk control measures;(2) The typical engineering practice: through participating in typical the bias shallow buried tunnel with small interval-Malugouling Tunnel construction, analyzing the tunnel engineering characteristics, carrying out the construction site investigationand participating in project construction, obtaining risk control factors and dynamic deformation data of surrounding rock in tunnel construction;(3) Risk analysis: using the combination of numerical simulation and field monitoring method for construction risk analysis of the bias shallow buried tunnel with small interval. Setting up Malugouling Tunnel construction mechanics model,analyzing the surrounding rock mechanics and deformation pattern in construction process; Carrying out the field monitoring measurement, actual measuring surrounding rock deformation data and related processing; Using the comprehensive and advanced geological forecast method(combining TSP with GPR) detecting surrounding rock conditions, forecasting construction risk state and risk partition;(4) Risk evaluation: Analyzing roundly the all kinds of factors influenced the stability of the bias shallow buried tunnel with small interval surrounding rock through numerical simulation, monitoring measurement and the comprehensive and advanced geological prediction; Doing risk evaluation about the stability of surrounding rock using expert investigation and Analytic Hierarchy Process(AHP), ultimately determining the probability of occurrence of a risk and calculating the risk acceptable level, which can provide the basis for risk management.(5) Risk control measures in advance: According to the construction characteristics of the bias shallow buried tunnel with small interval, put forward corresponding control measures in advance.