Safety Risk Assessment Of Subway TBM Construction

Due to the rapid development of China's economy and the accelerated pace of life as well as the increasing volume of traffic,urban rail transit construction has developed rapidly.Due to its many advantages,such as high automation and super formation adaptability,TBM has been applied in subway construction under many hard rock conditions.However,TBM is still in the practice or initial stage of urban subway construction in China.In the construction process,various construction safety risks are often encountered,which directly affect the construction schedule and quality,and sometimes even cause major engineering accidents.Therefore,many factors of construction safety risks of subway TBM should be comprehensively analyzed and evaluated,so that construction safety risks of TBM can be effectively predicted and prevented,which is of great significance to whether the subway project can be completed as scheduled.First,work breakdown structure-risk breakdown structure method(WBS-RBS)was used to identify the construction safety risk factors of subway TBM(rock tunnel boring machine).The subway TBM construction work decomposition structure is obtained by using the work decomposition structure method,which is decomposed according to the construction preparation,shaft construction,TBM starting,TBM heading and TBM arrival in the TBM construction process.The risk decomposition structure of subway TBM construction is obtained by using the risk decomposition structure method,which is further decomposed by the factors of construction personnel,TBM equipment,construction materials,TBM heading technology and surrounding environment,including "personnel","machine","material","method" and "ring".The risk identification matrix of subway TBM construction consists of the work package at the bottom of the work decomposition structure and the risk factors at the bottom of the risk decomposition structure.Finally,the risk identification matrix scoring table is scored by the expert scoring method,and the existence of risk factors is judged,so that the risk identification list is finally formed.Secondly,the weight of each risk factor index is calculated according to the improved optimal and worst method.The traditional expert scoring method is improved to use the average influence value algorithm to calculate the best and worst value in the secondary index,which makes the results more objective and accurate.By comparing the optimal evaluation index with other evaluation indexes,the judgment matrix of the optimal index was obtained,and the judgment matrix of the worst index was obtained by comparing the other evaluation indexes with the worst evaluation indexes.Then,the geometric average value of the judgment matrix of the optimal and the worst indexes was taken to obtain the final judgment matrix of the index weight.The maximum characteristic root is calculated again and the consistencytest is carried out.If the test is qualified,the weight of the final risk factor index can be obtained.Then,the multilevel extension evaluation model of subway TBM construction safety risk is constructed.First through the design principle of evaluation index system of subway TBM construction safety risk evaluation index system,by the average impact value algorithm impact value analysis for each evaluation index to get the optimal worst indicators,the weight of each evaluation index is obtained,also determine the classical domain,joint domain and for evaluation of matter-element,calculation of the secondary evaluation index correlation evaluation index correlation extremely belongs to get secondary risk grade,calculating the comprehensive relational primary extension synthetic evaluation results are obtained,then the secondary extension evaluation,finally it is concluded that the project comprehensive security risk level.Finally,in this paper,the Qingdao metro line 1 table between mooring station ~ sea bridge station TBM construction are analyzed,using the multi-level extension evaluation model to the area between the TBM subway construction safety risk evaluation,the final evaluation results for ? level,in the "safer" state.