Study On The Risk Assessment Of The Impact Of Metro Shield Construction On Neighboring Buildings

Nowadays,metro projects are under rapid construction.In 2021,it will start 48 rail transit lines in 26 cities,with a total investment of 776.481 billion yuan.However,the subway construction environment is complex,there are many risk factors,and the accidents caused by subway construction do great harm,in which the compensation amount of the third party building caused by subway construction is up to 1/4 of the total indemnity of subway construction insurance.The proportion of accidents in subway shield construction is also increasing.How to avoid the damage to adjacent buildings caused by subway shield construction.It is very necessary to evaluate the impact of shield construction on the safety of adjacent buildings.This paper takes the influence of subway shield construction on adjacent buildings in Guangzhou as the research theme,and takes the east extension project of Guangzhou Metro Line 3 as an example,combined with cloud model and evidence theory to set up an evaluation model of the impact of subway shield construction on adjacent buildings,to do effective risk assessment.This paper first discusses the mechanism of building damage caused by subway shield construction.In the investigation on the effects of adjacent buildings caused by subway shield construction,this paper summarizes the characteristics of 27 complaints about building damage caused by subway construction,the proportion of compensation paid by the third party of subway insurance,and the law of collapse accidents caused by subway construction from 2001 to 2019.The necessity of research on risk management of damage this paper pointed to adjacent buildings caused by subway shield construction.Based on study of the failure mechanism and investigation the current situation,combined with the accident cases caused by subway shield construction in Guangzhou,this paper summarizes the risk characteristics of shield construction accidents in Guangzhou,identifies the risk factors,and establishes the risk list.This paper constructs four first-class indexes,including tunnel factors,geological and hydrological factors,building factors and design and construction management factors.Risk Assessment Index system of Shield Construction impact on adjacent buildings with 14 second-level Indexes.Through the analytic hierarchy process and expert scoring method,this paper compared the importance of each index of the risk assessment index system,and got the weight of each index.In order to realize the qualitative evaluation of risk,this paper constructs the impact risk assessment model of adjacent buildings in subway shield construction based on cloud D-S evidence theory.Based on relevant norms and research results,this paper divides the risk into five grades,and determines the value range of each evaluation index under the five safety levels.This paper calculates the membership degree of the index under each risk grade by the cloud model method,and normalize the evidence theory to get the evidence theory BPA,changes the expert evidence BPA according to the support between the expert evidence and the expert reliability.The improved D-S evidence theory is used to weight the index BPA,and this paper carries out the decision-making information fusion through the D-S fusion rule.According to the last fusion result,evaluate the risk grade of the building in the subway shield construction environment.The fifth chapter of this paper makes an empirical analysis combined with the eastern extension project of Guangzhou Metro Line 3,verifies the effectiveness of the model,and finally gives the opinions and suggestions of risk management according to the risk situation of the building.