Non-probabilistic Reliability Reaserch Of System With Foundation Pit Based On Interval Theory

As the rapid development of economic construction and the urban modernization, the excavation engineering has been growing in number day by day. And the engineering accidents related with the excavation's collapse are common occurrence. Therefore, it is one of the crucial research issues of the present excavation engineering for the stability of exterior-protected construction in foundation pit. However, the high-degree uncertainty and the variability of the soil medium, the different undefined factors of the computational model, and the geological conditions,the classification of the rock groups and the sampling methods limit the access to the large amount of the sample data of the geotechnical mechanics parameters. So as to the obtained parameter has an interval range, while lacking the entire information. And on the basis of the assumption of the subjective distribution, the traditional reliability calculations are usually varied with the actual situations. Thus, it is necessary to carry on the further research and discussion.The interval theory and the non-probabilistic reliability were adopted in this thesis. First of all, the exterior-protected construction of foundation pit and the destructive model of the system were analyzed. Considering the geotechnical mechanics parameters'interval of exterior-protected construction in foundation pit, the analysis model of the corresponding non-probabilistic reliability was built. And the non-probabilistic reliability indexes of the anti-sliding and overturning stability which were associated with the project example of gravity retaining system were calculated. And the results met the design requirement. Secondly, through the typical contractual system to analyze the basic theory of the point reliability, the interval non-probabilistic reliability method for exterior-protected construction of the foundation pit was employed. The project example also was combined to calculate the non-probabilistic reliability. And according to the calculation result, the usefulness of non-probabilistic reliability analysis for exterior-protected construction of the foundation pit was further proved. Finally, based on the engineering project of the soil-nail retaining for the foundation pit, the exterior-protected construction unit of the foundation pit and the sensitivity of the system design parameters were analyzed. Analysis founded: With the variability of gravityγ,cohesion and the inner friction angleψ, the variation rules of the exterior-protected construction unit of the foundation pit and interval non-probability reliability indexβwere as following: The variabilityψgreatly influenced the reliability,γwas in the second and was the smallest one, which could almost be neglected. The above study gave a certain significant guidance on the safety evaluation of exterior-protected construction for the foundation pit and the optimal design of the reliability.