管桩水泥土复合基桩极限承载力的设计计算  

Research on design calculations of ultimate bearing capacity of composite pile made up of Jet-mixing cement and PHC pile with core concrete

作　　者：宦雯 李俊才 袁孝蓓 戴屹立 Huan Wen;Li Juncai;Yuan Xiaobei;Dai Yili(College of Transportation Science ＆ Engineering, Nanjing Tech University, Nanjing 210009, China)

机构地区：[1]南京工业大学交通运输工程学院,江苏南京210009

出　　处：《建筑科学》2018年第5期23-30,共8页Building Science

基　　金：江苏省科技计划项目:产学研联合创新资金--前瞻性联合研究项目(BY2014005-08)

摘　　要：管桩水泥土复合基桩是在水泥土搅拌桩中即时插入预应力高强混凝土管桩(PHC桩)而形成的一种新型复合基桩。为研究该复合基桩在粉土粉砂地层中的极限承载力,结合江苏如东的一个工程实例,进行了现场单桩静载荷试验和管桩-水泥土粘结强度试验,分析了管桩水泥土复合基桩的破坏模式和管桩水泥土协调变形机理,结果表明管桩-水泥土界面的粘结强度为水泥土无侧限抗压强度的0.197倍。在此基础上提出了适合南通地区管桩水泥土复合基桩承载力计算公式,并将计算结果与现场实测值进行了对比分析,发现公式的计算结果相比于规范公式更接近现场实测值。工程实例表明改进的公式在粉土粉砂地层中具有较高的可靠性,为其在南通地区的适用提供了一定的实测资料和理论基础,为该桩型进一步推广提供依据。The composite pile is a new kind of composite pile,which is formed by inserting prestressed highstrength concrete pipe pile（PHC pile） into the cement soil mixing pile immediately. Combined with the engineering project in Rudong,Jiangsu Province,the site of single pile static load test and pile cement-soil bond strength test are carried out to study the ultimate bearing capacity of the composite pile in silt layers by analysising of failure modes of the CPCP and the coordinate deformation mechanism between pile and cement-soil. The results show that the bond strength between pipe pile and cement soil is 0. 197 times of unconfined compressive strength of cement soil. On this basis,the formula for calculating ultimate bearing capacity of composite pile foundation is improved. Comparing calculated values with field measurement values,the results are closer to field measurement values than the standard formula. It is verified that the improved formula has higher reliability and more important engineering application and theoretical research significance in silt layers,providing a certain basis and reference for this category pile＇s design calculation.

关 键 词：复合基桩 静载荷试验 粘结强度 极限承载力 

分 类 号：TU443[建筑科学—岩土工程]