|Title:||Study of slope stability analysis based on discontinuity layout optimization and strength reduction method|
|Subject:||Hong Kong Polytechnic University -- Dissertations|
Slopes (Soil mechanics) -- Stability
|Department:||Faculty of Construction and Environment|
|Pages:||158 pages : color illustrations|
|Abstract:||Recent years, a novel slope stability analysis method termed discontinuity layout optimization (DLO) has been developed, and the only related commercial software named LimitState GEO is popularly applied in European countries. However, because of its novelty, more researches should be constructed to check its performance and the suitability in Hong Kong engineering practice. The strength reduction method (SRM) which is regarded as an advanced numerical slope analysis method has been adopted over some time with wide experience, and DLO deserve to be addressed to provide a proper guideline of engineering application. The study of SRM in this dissertation is based on use of FLAC2D 7.0, which is the newest version of FLAC. Based on previous study about the applicability of FLAC2D, many doubts about the implementation of FLAC2D 7.0 need to be addressed. In this study, both homogeneous slope and heterogeneous slope were systematically researched. Soil parameters effect and geometry factors effect to slope stability are considered in the study of homogeneous slope. Whereas, in the study of non-homogeneous slope, scenarios of slopes within a thin soft layer and slopes with a weak foundation layer were introduced. For comparison of the performance between SRM and DLO, other traditional commonly used slope stability analysis methods were adopted as reference standards, which include limit equilibrium method (LEM), analytical method and stability chart. Values of the factor of safety (FOS) were computed by these different slope stability analysis methods and some interesting rules were found by comparing the results. Accuracy of DLO and SRM were also checked through comparison process.|
The results have shown acceptable agreements between these slope stability analysis methods in some common and simple cases. However, for some special cases, the performance of DLO and SRM have some limitations which should be noticed in engineering practices. In homogeneous slope studies, results of DLO and SRM show that in normal situations, both methods are satisfactory for application. However, it still should be noted that FOS by DLO is largest among all the studied slope stability analysis methods. The potential unsafety should be carefully considered when applying DLO in the practice and other methods need tobe used as references. Besides, in this study, DLO analysis performed unsatisfactorily for slope with very small cohesion. As for SRM, impact of dilation angle and slope angle cannot be ignored when using the FLAC2D 7.0. As far as the heterogeneous slope is concerned, results by DLO are coarse and sensitive to small nodal density in the situation of the slope with thin weak inside layer. Whereas, in slope with a soft bottom layer, performance of DLO is great and not sensitive to the nodal density. However, when constructing the research of the relation between the ratio of soft layer cohesion divided surrounding soil cohesion and the calculated factor of safety, good agreements between SRM and DLO were obtained in both soft band and soft foundation situation. Simultaneously, some different disciplines were observed in heterogeneous slope study against in homogeneous slope study through comparing the results by DLO with results by SRM.
|Rights:||All rights reserved|
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