混凝土芯水泥土复合桩混凝土-水泥土界面摩擦特性试验研究  

Experimental study on frictional capacity of concrete-cemented soil interface of concrete-cored cemented soil column

作　　者：俞建霖[1,2] 徐嘉诚 周佳锦 龚晓南 Yu Jianlin;Xu Jiacheng;Zhou Jiajin;Gong Xiaonan(Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China;Zhejiang Urban Underground Space Development Engineering Research Center,Hangz)

机构地区：[1]浙江大学滨海与城市岩土工程研究中心,浙江杭州310058 [2]浙江省城市地下空间开发工程技术研究中心,浙江杭州310058

出　　处：《土木工程学报》2022年第8期93-104,117,共13页China Civil Engineering Journal

基　　金：国家自然科学基金(51978610);浙江省重点研发计划项目(2019C03103);中央高校基本业务费(2021QNA402,2021FZZX001-14)。

摘　　要：混凝土芯水泥土复合桩是由高强度混凝土芯桩和水泥土组成的新型复合桩。芯桩-水泥土以及水泥土-桩周土之间的界面摩擦特性是影响复合桩荷载传递规律的关键因素,目前对芯桩-水泥土界面摩擦特性的研究还较少,而且常规的二维平面剪切试验也无法研究芯桩的直径和截面形状等因素对界面特性的影响。文章采用自主研发的三维桩土接触面剪切试验装置,模拟工程实际情况,对预制混凝土芯桩-水泥土界面摩擦特性进行研究。剪切试验结果表明:混凝土-水泥土界面在剪切试验过程中经历了弹性阶段、脆性破坏阶段和剪切滑移三个阶段,采用三折线模型可以较好地描述其本构关系;界面极限侧摩阻力与芯桩含芯率(或直径)密切相关,随含芯率增加表现为先大幅减小而后逐步趋于稳定;界面极限侧摩阻力与水泥土无侧限抗压强度存在近似线性关系,其值约为水泥土无侧限抗压强度的0.064~0.259倍,而界面残余侧摩阻力受含芯率和水泥土养护龄期的影响相对小;在芯桩侧表面积相同的情况下,圆芯复合桩界面极限侧摩阻力约为方芯复合桩的1.329倍;界面极限相对位移受含芯率、水泥土龄期及芯桩截面形状影响较小,基本在1.23~2.40mm。The concrete-cored cemented soil column is a type of composite column composed of a high strength concrete core pile and the surrounding cemented soil column around the core pile.The shaft capacity of concrete-cored cemented soil column is controlled by the frictional capacity of core pile-cemented soil interface and cemented soil-soil interface.The research on the frictional capacity of core pile-cemented soil interface is very limited,and the conventional direct shear test can not reflect the influence of diameter and shape of core pile on the frictional capacity of core pile-cemented soil interface.This paper conducted a series of core concrete pile-cemented soil interface shear tests in a special 3 D pile-soil interface shear test apparatus to investigate the frictional capacity of concrete pile-cemented soil interface.The form of the core concrete pile-cemented soil interface and boundary condition of the interface were all identical to that of core pile-cemented soil interface of concrete-cored cemented soil column in practical projects.The shear test results showed that the skin friction-relative displacement response of concrete pile-cemented soil interface had three stages in the loading process,i.e.,elastic stage,brittle failure stage and shear slip stage.A trilinear model was proposed to describe the skin friction-relative displacement response of concrete pile-cemented soil interface.The relationship between the ultimate lateral friction and the unconfined compressive strength of cemented soil was approximately linear,and its value was about 0.064-0.259 times of the unconfined compressive strength of cemented soil.The residualskin friction was less affected by the core content and the curing time of cemented soil.In the case of the same surface area,the ultimate skin friction of the pipe pile-cemented soil interface was about 1.329 times that of the square pile-cemented soil interface.The ultimate relative displacement was not affected by the core content,the curing time of cemented soil and the shape

关 键 词：混凝土芯水泥土复合桩 三维界面剪切试验 极限侧摩阻力 界面本构关系 

分 类 号：TU472[建筑科学—结构工程]