考虑桩土变形协调的复合地基设计方法  

Design method of composite foundation considering pile-soil deformation coordination

作　　者：彭良泉 PENG Liangquan(Changjiang Survey,Planning,Design and Research Co.,Ltd.,Wuhan 430010,China;National Dam Safety Engineering Technology Research Center,Wuhan 430010,China)

机构地区：[1]长江勘测规划设计研究有限责任公司,湖北武汉430010 [2]国家大坝安全工程技术研究中心,湖北武汉430010

出　　处：《人民长江》2024年第5期157-162,共6页Yangtze River

基　　金：国家大坝中心自主创新项目(CX2022Z01-1)。

摘　　要：目前在复合地基的设计中,由于采用桩体压缩模量计算得到的复合压缩模量偏大,造成复合地基加固区沉降被低估;另外桩和桩间土承载力发挥系数取值主观性较强,导致复合地基承载力计算结果偏大。针对上述两个问题,从复合地基形成机理出发,指出桩及桩间土共同直接承担荷载时必须保证桩土变形协调。桩土变形协调的条件是:(1)桩刺入垫层的深度不能超过垫层厚度;(2)桩宜设置为摩擦桩。在此前提下,分别计算桩及桩间土的沉降,利用桩土变形协调方法得到了桩土应力比和承载力发挥系数理论值,进而得到加固区的沉降计算方法。工程算例证实,从保证复合地基有效设计和工程安全的角度出发,应该根据桩土变形协调来进行复合地基设计计算。The composite compression modulus obtained by using the compression modulus of pile body is usually larger,which leads to the underestimate of the settlement of composite foundation reinforcement area.In addition,the selection of bearing capacity coefficient between piles and soil is subjective,resulting in a larger calculation result of the composite foundation bearing capacity.In view of the above two problems,starting from the formation mechanism of composite foundation,we point out that the pile-soil deformation must be coordinated when the pile and the soil bear capacity together.The conditions for the coordination of pile-soil deformation are as follows:①the depth of pile penetration into the cushion cannot exceed the thickness of the cushion;②piles should be set as friction pile.Under this premise,the settlements of piles and soil between piles were calculated respectively.The theoretical values of pile-soil stress ratio and bearing capacity coefficient were obtained by using pile-soil deformation coordination method.Further the settlement calculation method of reinforcement area was given.The engineering example shows that the design of composite foundation should be carried out according to the deformation coordination of pile-soil from the perspective of ensuring the effective design and engineering safety of composite foundation.

关 键 词：复合地基 桩土变形协调 承载力发挥系数 桩土应力比 沉降 

分 类 号：TU472[建筑科学—结构工程]