基于熵权二维云模型的深基坑施工风险评价

Risk assessment of the deep foundation pit based on the entropy weight and 2-dimensional cloud model

深基坑施工过程中的风险因素具有模糊性与随机性的特点,基于此提出一种熵权二维云模型的风险评价方法。从环境因素、管理因素和施工因素3个方面进行危险源辨识,确定深基坑施工风险评价指标体系,并应用熵权法对评价指标进行加权处理;将风险概率和风险后果作为二维云模型的基础变量,同时提出风险云相近度的计算方法以确定风险等级。应用上述方法对南宁轨道交通3号线青秀山站明挖站厅基坑的施工过程进行了风险评价,得出该施工过程的风险需采取一定控制措施方可接受,与实际情况相符,表明基于熵权二维云模型的风险评价方法合理可行。

The paper is inclined to present a comprehensive risk evaluation method based on the entropy weight method and2-dimensional cloud model for evaluating the risk of the deep foundation pit in the construction of Qingxiushan station of Nanning Metro Line 3. For this purpose,we have,first of all,been trying to identify and determine the risk factors from the 3 closely related factors, that is, the factors in environment,management and construction. In doing so, we have established 12 second level evaluation indicators via refining the first level indicators,and an evaluation index system for the construction risk with the deep foundation pits. Furthermore,we have also built up the effective linkage between the risk grade and the 2-dimensional cloud for evaluating the risk probability and the risk consequence severity through defining the basic variables of the 2-dimensional cloud. The weights of evaluation indexes gained with the entropy weighing method can help to reflect the influential degrees of the respected indexes on the evaluation objectives. Furthermore,the digital features of the risk cloud and the weight cloud gained by the back-sequential cloud generator and the integrated risk cloud matrix derived by the weighing operation can help us to work out the cloud matrix and that of the risk cloud so as to gain a comprehensive risk picture by the normal cloud generator with the aid of the MATLAB software. And,eventually,we have proposed the similarity degree of the risk clouds to determine the risks of the foundation pits. Thus, the aforementioned methods prove to be suitable for assessing the construction risks of the foundation pit of Qingxiushan station of Nanning Metro Line 3,by properly calculating the grades of the entire foundation pit project and evaluation indexes at all levels,which is well in accord with the actual project situation. Hence,the final results show that the risk assessment method based on the entropy weight and the 2-dimension cloud model can effectively solve the fuzziness and randomness of risk evaluation indexs,take into the influence of evaluation index weight on evaluation results,and realize the transformation between qualitative concept and quantitative expression of risk grade,which evaluation result is more intuitive and reliable.