地铁深基坑支护方案的模糊综合分析与评价

The fuzzy comprehensive analysis and evaluation ofsubway deep foundation pit supporting scheme

由于地铁深基坑支护方案的选择是一种受多因素共同作用影响的复杂项目,需对支护方案进行探讨分析与评价,研究和确定最优支护方案,以期提高支护施工效益并减少支护不当造成的安全风险。依层次分析法构建结构模型,通过综合考虑安全可行、经济成本、环境影响、施工方案4个方面,分析13个影响因素,并利用信息熵综合优化权重,再与模糊综合评价相结合,对支护方案进行综合评价。结合青岛地铁深基坑工程实例,对提出的3种备选方案进行打分、计算处理,并通过对比各因素之间重要程度及总综合评价值,进而得出适合本工程的最优支护方案。研究结果表明,3种支护方案的总综合评价值W′3=3.1433<W′1=3.1486<W′2=3.3140,可知方案2(围护桩+内支撑支护)为最佳支护方案,并通过模拟验算其满足施工要求,且支护效果较好;该评价方法较为准确可行,操作简单,且适用于各种基坑的支护方案选择,可为地铁深基坑支护方案评选提供参考。

As the selection of the support scheme for subway deep foundation pit is a complex project affected by multiple factors,it is necessary to discuss,analyze and evaluate the support scheme,study and determine the optimal support scheme,so as to increase the efficiency of support construction and reduce the safety risk caused by improper support.In this study a structure model is constructed according to analytic hierarchy process,and 13 influencing factors are analyzed from the four aspects of safety and feasibility,economic cost,environmental impact and construction scheme.The weights of the 13 factors are optimized by information entropy,and then combined with fuzzy comprehensive evaluation,the comprehensive evaluation of the support scheme is carried out.Taking Qingdao Metro deep foundation pit engineering as the example,the three alternative schemes are scored and calculated,and the most suitable supporting scheme for this project is obtained by comparing the importance degree and total comprehensive evaluation value of each factor.The research results show that the total comprehensive evaluation value of the three support schemes is W′3=3.1433<W′1=3.1486<W′2=3.3140.We can see that scheme 2(envelope pile+internal support)is the best support scheme,because through calculation and simulation we find that it meets the construction requirements and the support effect is good.This evaluation method is more accurate and feasible,easy to operate,suitable for the selection of various foundation pit support schemes,and can provide a reference for the selection of deep foundation pit support schemes.