重力式劲性复合吸力式沉箱基础竖向抗拔承载特性试验研究  

Model tests on uplift bearing capacity of gravitational reinforced composite suction caisson foundation

作　　者：戴国亮[1,2] 朱文波[1,2] 龚维明[1,2] 竺明星[1,2] 万志辉 DAI Guo-liang;ZHU Wen-bo;GONG Wei-ming;ZHU Ming-xing;WAN Zhi-hui(Key Laboratory of Concrete and Prestressed Concrete Structure of Ministry of Education,Southeast University,Nanjing 211189,China;School of Civil Engineering,Southeast University,Nanjing 211189,China)

机构地区：[1]东南大学混凝土及预应力混凝土结构教育重点实验室,江苏南京211189 [2]东南大学土木工程学院,江苏南京211189

出　　处：《岩土工程学报》2020年第9期1612-1621,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家重点研发计划专项项目(2017YFC0703408);国家自然科学基金项目(51878160,51678145)。

摘　　要：吸力式沉箱基础作为张力腿平台(TLP)的锚固基础,主要承受上拔荷载作用,然而软黏土中沉箱侧壁摩擦系数较小,排水条件下其抗拔承载力仅靠沉箱内外摩擦力与其自重组成,因此吸力式沉箱基础抗拔承载力较低。针对上述问题,提出一种重力式劲性复合吸力式沉箱基础,通过模型试验、推出试验以及大型直剪试验,研究了软黏土中新型吸力式沉箱基础抗拔承载特性以及沉箱–水泥土界面剪切特性。试验结果表明:新型吸力式沉箱基础抗拔承载力远高于传统吸力式沉箱基础抗拔承载力,且随附加荷载以及加固范围增加而增大;法向应力越大、水泥掺入比越高,水泥土抗剪强度以及沉箱–水泥土界面剪切强度越高;环肋沉箱中肋宽越宽,环肋上方剪切带面积越大,且水泥土剪切面与整体破坏面比值越高,沉箱–水泥土整体界面剪切强度越大;结合推出试验,提出了带肋沉箱模型界面破坏模式,建立了考虑法向应力作用下带肋沉箱–水泥土界面整体剪切强度计算公式,并进行相关参数分析与验证;最后结合等芯沉箱基础抗拔破坏模式,给出了新型吸力式沉箱基础抗拔承载力计算方法,揭示了软黏土中新型吸力式沉箱基础抗拔承载机理,为重力式劲性复合吸力式沉箱基础抗拔承载力分析以及工程设计提供参考。As the anchoring foundation of the tension leg platform(TLP), the suction caisson foundation is mainly subjected to the vertical pullout loads. The uplift bearing capacity of caisson is only composed of the internal and external frictions and caisson weight under the drainage condition, so the uplift bearing capacity is very small. Therefore, the gravitational reinforced composite suction caisson foundation is proposed to solve this problem. The uplift bearing capacity of the new suction caisson foundation and the shearing characteristics of caisson-cement soil interface are studied through the model tests, large-scale shear tests and push out tests. The test results show that the uplift bearing capacity of the new suction caisson foundation is much higher than that of the traditional suction caisson foundation. It increases gradually with the increase of the additional load and reinforcement range. The interface shear strength of caisson-cement soil increases with the increase of normal stress and cement ratio. When the rib width is wider, the area of the shear zone above the ring rib is larger and the ratio of the relative area is larger, the shear strength of the whole interface between the caisson and cement soil is higher. Based on the uplift bearing characteristics of new caisson by model tests and push out tests, the interface failure mode, the overall shear strength, the bearing capacity composition and the relevant method are proposed for analyzing the uplift bearing capacity of suction caisson foundations. It can provide a reference for the engineering design of the new suction caisson foundation under vertical loads.

关 键 词：吸力式沉箱基础 抗拔承载力 破坏模式 界面剪切强度 软黏土 水泥土 

分 类 号：TU473[建筑科学—结构工程]