Settlement of structures on granular soils subjected to static and earthquake loads.

摘要

An investigation has been conducted with the objective of developing a simple method for estimating settlement of structures on granular soil deposits subjected to earthquake shaking.; A database of cyclic laboratory test results is established to identify the factors that influence cyclic shear-induced compressibility of granular soils under drained, and undrained conditions. The database, together with a critical review of the available methods for estimating earthquake-induced settlement of level granular soil deposits, and some field observations lead to the development of two simple charts for settlement analysis for both drained and undrained responses. A simplified procedure for estimating the influence of drainage on both liquefaction resistance and earthquake-induced settlement of level granular soil deposits is developed. The procedure is extended to be used for analyzing soil deposits improved by gravel drains installation. The procedure, and the two simple charts, are integrated in one proposed method for earthquake-induced settlement analysis of level granular soil deposits.; A database of field earthquake-induced settlement records is developed to evaluate existing and proposed methods for earthquake-induced settlement analyses of granular soil deposits. The evaluation involved 23 sets of calculations to test aspects such as influence of fines content on settlement calculations, method of settlement analysis, type of response, the contribution of silt layers to the observed settlements, the use of pre-earthquake versus post-earthquake in-situ penetration resistance profiles in settlement analysis, and the use of post-improvement time-dependent penetration resistance profile in the analysis.; An updated version of database of static settlement records of footings on granular soils is presented. Records that involve settlement versus pressure relationships are used to develop an empirical method that explicitly consider, beside the other factors, the effect of stress level on settlement. The method is upgraded for estimating earthquake-induced compressibility of granular soil mass influenced by footing loads below bearing capacity level. A database of structure earthquake-induced settlement records is developed. The database is used to evaluate the proposed method for non-failed structures and to provide an empirical tool for estimating the bearing-capacity-failure-induced settlement of structures.