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城市建设中桩基应用广泛,单桩竖向承载力的计算方法及可靠性越来越受到设计人员重视。针对桩基设计中岩土参数的不确定性及桩基穿越成层地基对桩身承载力的影响问题,提出基于可靠度理论的鲁棒性设计方法。利用岩土参数变异性的平均值及标准差充分考虑岩土参数的不确定性,并通过扩大考虑地基土的不确定因素将单桩竖向承载力鲁棒性设计由砂土推广到黏土等一般性土壤;提出采用分层计算桩侧摩阻力作为不确定因素考虑地基土成层分布问题,按照承载力极限状态与正常使用极限状态作为目标函数进行桩基竖向承载力设计。单桩承载力鲁棒性设计将鲁棒性作为安全性评价标准,来评估桩基设计方案的可行性,以鲁棒性与经济性为优化目标对桩基设计进行多目标优化,设计方案在满足桩基承载力要求的同时,保证了桩基设计方案的鲁棒性与经济性。
Pile foundation is widely used in urban construction. The calculation method and reliability of vertical bearing capacity of single pile are paid more and more attention by designers. In view of the uncertainty of geotechnical parameters in pile foundation design and the influence of pile foundations on the bearing capacity of piles, a robust design method based on reliability theory is proposed. Taking into account the average and standard deviation of geotechnical parameter variability, the uncertainties of geotechnical parameters are fully taken into account, and the design of robustness of vertical load-bearing capacity of single pile is extended from sand to clay by enlarging the uncertainties of foundation soil General soil. It is proposed that stratified calculation of pile-side frictional resistance as a factor of uncertainty should consider stratified distribution of foundation soil, and design of vertical bearing capacity of pile foundation according to ultimate bearing capacity and normal serviceability limit state. Robustness design of single pile bearing capacity Robustness is taken as the safety evaluation criterion to evaluate the feasibility of pile foundation design scheme. Multi-objective optimization of pile foundation design is carried out with the optimization of robustness and economy. While meeting the requirements of bearing capacity of piles, the robustness and economy of piles design are guaranteed.