Research On Shield Tunnel Underpass Urban Buildings Risk Assessment Method

It is inevitable to cause the disturbance of surrounding soil during shield tunnelling process,which will further cause deformation and damage of superstructure.Therefore,the risk assessment of shield tunnel underpass buildings has been paid more attention and has become an important research topic.Shield tunnelling construction is a complicated process,which involves many influencing factors.Based on the relevant research and expert opinions,the risk factors of shield tunnel underpass building was fully investigated and analyzed,a new risk assessment system was put forward,the improved multi-criteria evaluation method to the risk assessment of shield tunnel underpass building for the first time was applied,and the safety early warning decision of the building was realized in this paper.The main research contents of this paper are as follows:(1)A risk assessment system of shield tunnel underpass buildings was established.There are many influencing factors of shield tunnel underpass building.By investigating relevant literature,consulting experts,and combining with engineering practice,a risk assessment system with 19 influencing factors was determined,mainly including soil properties,building factors,tunnel factors,and shield tunneling parameters.Risk factors were divided into subjective factors and objective factors for risk grading,and specific factor grades were obtained by experts’ scoring and actual measurement.(2)A set of risk pre-assessment method for adjacent shield tunnel buildings was proposed.Based on the experts’ scoring results,the triangular fuzzy number improved analytic hierarchy process was used to calculate the weight of factors,and the building risk grade standard was calculated by the VIKOR method.For the first time,the improved interval number VIKOR method was introduced into the risk assessment of shield tunnel underpass buildings to calculate the risk grade of buildings.The risk assessment method was applied to the buildings along Changsha Metro Line 4 and Shenzhen Chunfeng Tunnel respectively,the assessment results were consistent with the reality,which proved the effectiveness of the assessment method.(3)A set of risk assessment methods for adjacent shield tunnel buildings during tunnel construction was proposed.The PFAHP method was introduced into the tunnel engineering field for the first time,and the weight of factors was calculated by transforming the language description of experts into quantitative numbers.The building risk grade standard in shield tunneling process was calculated by TOPSIS method which was one of the multi-criteria decision-making method.For the first time,the improved interval number TOPSIS method was introduced into the risk assessment of shield tunnel underpass building to determine the risk grade of building.The method was applied to risk assessment of under passing a building of Changsha Metro Line 4,and assessment results were consistent with the actual damage assessment results,which proved the effectiveness of the method.(4)Based on the proposed risk assessment methods,a risk assessment software was developed.The software includes risk factor classification standard,risk assessment before shield tunnel construction,and risk assessment during shield tunnel processing.The software simplifies the calculation process of risk assessment,which has strong practicability and provides strong auxiliary support for the safe construction of shield tunnel and protection of superstructure.