This is the second paper of two, which describe the results of an integrated research effort to develop a four-step simplified approach for design of raft foundations against dip-slip （normal and thrust） fault ruptu...This is the second paper of two, which describe the results of an integrated research effort to develop a four-step simplified approach for design of raft foundations against dip-slip （normal and thrust） fault rupture. The first two steps dealing with fault rupture propagation in the free-field were presented in the companion paper. This paper develops an approximate analytical method to analyze soil-foundation-structure interaction （SFSI）, involving two additional phenomena： （i） fault rupture diversion （Step 3）; and （ii） modification of the vertical displacement profile （Step 4）. For the first phenomenon （Step 3）, an approximate energy-based approach is developed to estimate the diversion of a fault rupture due to presence of a raft foundation. The normalized critical load for complete diversion is shown to be a function of soil strength, coefficient of earth pressure at rest, bedrock depth, and the horizontal position of the foundation relative to the outcropping fault rupture. For the second phenomenon （Step 4）, a heuristic approach is proposed, which ＂scans＂ through possible equilibrium positions to detect the one that best satisfies force and moment equilibrium. Thus, we account for the strong geometric nonlinearities that govern this interaction, such as uplifting and second order （P-△） effects. Comparisons with centrifuge-validated finite element analyses demonstrate the efficacy of the method. Its simplicity makes possible its utilization for preliminary design.展开更多
Foundation pit excavation engineering is an old subject full of decision making. Yet, it still deserves further research due to the associated high failure cost and the complexity of the geological conditions and/or t...Foundation pit excavation engineering is an old subject full of decision making. Yet, it still deserves further research due to the associated high failure cost and the complexity of the geological conditions and/or the surrounding existing infrastructure around it. This article overviews the risk control practice of foundation pit excavation projects in close proximity to <span style="font-family:Verdana;">existing</span><span style="font-family:Verdana;"> disconnected piled raft. More focus is given to geotechnical aspects. The review begins with achievements to ensure excavation performance </span><span style="font-family:Verdana;">requirements,</span><span style="font-family:Verdana;"> and follows to discuss the complex </span><span style="font-family:Verdana;">soil structure</span><span style="font-family:Verdana;"> interaction involved among the fundamental components</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">: </span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">the retaining wall, mat, piles, cushion, and the soil. After bringing consensus points to practicing engineers and </span><span style="font-family:Verdana;">decision makers</span><span style="font-family:Verdana;">, it then suggests possible future research directions.</span></span></span></span>展开更多
基金OSE (the Greek Railway Organization)the EU Fifth Framework Programme Under Grant No. EVG1-CT-2002-00064
文摘This is the second paper of two, which describe the results of an integrated research effort to develop a four-step simplified approach for design of raft foundations against dip-slip （normal and thrust） fault rupture. The first two steps dealing with fault rupture propagation in the free-field were presented in the companion paper. This paper develops an approximate analytical method to analyze soil-foundation-structure interaction （SFSI）, involving two additional phenomena： （i） fault rupture diversion （Step 3）; and （ii） modification of the vertical displacement profile （Step 4）. For the first phenomenon （Step 3）, an approximate energy-based approach is developed to estimate the diversion of a fault rupture due to presence of a raft foundation. The normalized critical load for complete diversion is shown to be a function of soil strength, coefficient of earth pressure at rest, bedrock depth, and the horizontal position of the foundation relative to the outcropping fault rupture. For the second phenomenon （Step 4）, a heuristic approach is proposed, which ＂scans＂ through possible equilibrium positions to detect the one that best satisfies force and moment equilibrium. Thus, we account for the strong geometric nonlinearities that govern this interaction, such as uplifting and second order （P-△） effects. Comparisons with centrifuge-validated finite element analyses demonstrate the efficacy of the method. Its simplicity makes possible its utilization for preliminary design.
文摘Foundation pit excavation engineering is an old subject full of decision making. Yet, it still deserves further research due to the associated high failure cost and the complexity of the geological conditions and/or the surrounding existing infrastructure around it. This article overviews the risk control practice of foundation pit excavation projects in close proximity to <span style="font-family:Verdana;">existing</span><span style="font-family:Verdana;"> disconnected piled raft. More focus is given to geotechnical aspects. The review begins with achievements to ensure excavation performance </span><span style="font-family:Verdana;">requirements,</span><span style="font-family:Verdana;"> and follows to discuss the complex </span><span style="font-family:Verdana;">soil structure</span><span style="font-family:Verdana;"> interaction involved among the fundamental components</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">: </span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">the retaining wall, mat, piles, cushion, and the soil. After bringing consensus points to practicing engineers and </span><span style="font-family:Verdana;">decision makers</span><span style="font-family:Verdana;">, it then suggests possible future research directions.</span></span></span></span>
