成层地基中单桩竖向承载力鲁棒性设计  

Robust geotechnical design of a single pile under vertical loads in layered soils

作　　者：张峰 周峰 王旭东 

机构地区：[1]南京工业大学交通运输工程学院,江苏南京210009 [2]中建海峡建设发展有限公司,福建福州350015

出　　处：《岩土力学》2017年第11期3311-3318,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.51278244)~~

摘　　要：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 foundations are widely used in geotechnical engineering. Meanwhile, the calculation method and reliability of the pile vertical bearing capacity attract more attention from geotechnical engineers. The pile capacity is affected by the uncertainty of properties of the layered soil. To solve this problem, we present herein a robust geotechnical design（RGD） as a new geotechnical design concept based on the reliability design（RBD）. The mean and standard deviation of the soil properties are considered as the uncertainty of soil parameters in RGD method. and the scope of the RGD method is expanded in the pile vertical bearing capacity from sand to clay by introducing more soil properties. The pile side friction（Qside）, calculated layer by layer by RGD method, is used as one of the uncertain parameters in the change of applicability of the pile vertical bearing capacity by layered soil. Both of ultimate limit state（ULS） and serviceability limit state（SLS） are used as performance function in pile design. In this paper, as a safety evaluation standard, robustness is used to evaluate the feasibility of the design scheme in pile design with the RGD method. With the RGD approach, the focus is to satisfy two design objectives, namely cost-efficiency and robustness. As with multi-objective engineering optimization, it is possible to provide a best solution set to accomplish the goal both in cost-efficiency and robustness. Meanwhile, the pile vertical bearing capacity of the design is guaranteed.

关 键 词：桩基 成层地基 不确定性 鲁棒性 

分 类 号：TU43[建筑科学—岩土工程]