| With the acceleration of urbanization,the scale of deep foundation pit engineering becomes larger and larger,and the depth of excavation becomes larger and larger,coupled with the complex surrounding environment,neighboring buildings and more uncertain factors,leading to the frequent occurrence of deep foundation pit engineering accidents.And once the accident occurs,it will not only cause work stoppage,casualties and economic loss,but also cause certain impact on the society.Therefore,it has certain theoretical and practical significance to identify the risk factors of deep foundation pit engineering scientifically and comprehensively,evaluate the risk accurately and effectively,and adopt appropriate countermeasures for risk prevention and control.This paper carries out risk assessment research on a deep foundation pit project in Jingzhou City,with the following main contents:(1)Introducing several accident causation theories,analyzing the advantages and disadvantages of each accident causation theory,proposing the accident causation mechanism of deep foundation pit engineering,determining four level indicators of survey work,design work,construction work and monitoring and supervision work from the work content of the whole process management of deep foundation pit engineering,and finally determining 21 risk factors according to the analysis of deep foundation pit engineering accident cases.By comparing the advantages and disadvantages of risk analysis methods,the advantages of easy access to data and relatively simple operation of hierarchical analysis are used for weighting analysis,and the advantages of cloud model that can transform each other between qualitative and quantitative are used for risk evaluation.Finally,countermeasures are proposed for the risk factors.(2)The relevant data are obtained through the questionnaire,the weights are determined using the hierarchical analysis method,the cloud numerical characteristics are determined using the inverse cloud generator in the cloud model,and the weights of the first-level indicators are combined with the cloud numerical characteristics to obtain the comprehensive evaluation cloud of risk.The position of the comprehensive evaluation cloud is compared with the position of the standard cloud to see which area of the evaluation cloud is closer to the standard cloud,or the similarity method is used to calculate and determine the risk level range.Finally,we get that the whole deep foundation pit project is in medium risk,the entropy value En of this comprehensive cloud is 5.852,the super entropy He is 1.772,which satisfies 3He < En.The distribution of the cloud drops of the comprehensive cloud map presents the state of pan-normal distribution,which indicates that the cloud drops group shows better cohesion,thus proving that the method has certain feasibility. |
