The Research Based On The Synthesis Weights For The Excavation Evaluation Model

Foundation pit supporting scheme design and evaluation is a very complex, comprehensive strong systems engineering. In recent years, the national economy and the rapid development of city construction, making the city land resources is becoming more and more scarce, so people use the space in underground more and more, so the requirement of foundation pit supporting scheme design will be much higher. The stand or fall of foundation pit supporting scheme will directly or indirectly affect the whole excavation engineering safety, quality, progress, investment and the surrounding environment. In practical projects, there are many alternatives in a foundation pit engineering, these schemes have their own advantages and disadvantages, how to select the optimal scheme from alternatives is very important. The evaluation of foundation excavation scheme is evaluation and selection to many schemes, based on multiple targets and a variety of factors, these factors tend to be complex,indefinite and vague etc.According to the characteristics of foundation pit supporting scheme optimization, This thesis comprehensively considered the quantitative and the non-quantitative index,selected five primary indexes and 14 secondary indexes,based on five criteria:engineering quality, investment, progress, safety, and environmental impact. In the schematic evaluation model, first of all, According to the applicable scope of the various solution and the index reference factors, we can preliminary sift the alternatives,to avoid not feasible scheme, which makes the model is more reasonable. This paper used fuzzy mathematical theory, hierarchical analysis theory and the information entropy theory to construct a foundation pit supporting scheme of the evaluation model based on a comprehensive weights. In the process of determining weight, synthesis weights composed of subjective weight and entropy weight, fully exploited the natural information of the evaluation scheme, also retained expert experience, maked the optimization process easier, high resolution. Based on the engineering example, the specific application of this method was verified in foundation pit supporting the feasibility and effectiveness of the scheme evaluation.