摘要
采用经验方法确定的桩侧极限摩阻力结果存在较大误差。选取广州新电视塔C区的4个挖孔桩底基岩进行混凝土短柱和基岩摩擦试验,对桩在受压、受拉不同应力状态下的摩擦力进行分析,获得桩和岩层摩擦承载力指标。试验研究表明,桩和围岩摩阻力在不同受力状态下表现出不同性质,抗压摩阻力特征值普遍大于抗拔摩阻力特征值。定义了抗拔分项系数γ作为抗拔力计算安全储备,建议γ为1.7～2.0,试验研究成果可为重大工程提供参考。
The estimation of the rock-socketed piles＇ confining bearing capacity by empirical methods always involves large error. So an in-situ method is preferred in important engineering projects. The experimental studies on large rock socketed pile＇s confining bearing capacity properties were carried out in the dug piles＇ bottom at construction zone C of Guangzhou new television station tower site. The short concrete piles were used to simulate the real piles, and the confining friction force between the short pile and the rock mass was determined. The compressive friction tests and the pulling out friction tests were conducted, and the confining friction forces between the short pile and the rock mass were used to determine confining friction parameters. The tests results show that the piles＇ confining friction properties are quite different under the compressive force conditions and under the tensile force conditions, and the compressive friction characteristic value is always larger than that of the pulling out friction. According to the tests analysis, a tensile partial coefficient may be defined for the pile＇s pulling out resistant force computation to achieve a larger safety factor in important buildings. In this new television station tower site project, the tensile partial coefficient is about T in the range of 1.5-2.0, and the tests results provide a useful reference for important building constructions.
出处
《科技导报》
CAS
CSCD
北大核心
2009年第15期59-63,共5页
Science & Technology Review
基金
广州市科技局基金项目(2004B36001028)
关键词
桩基础
嵌岩桩
荷载试验
承载性能
摩擦力特征值
pile foundations
rock-socketed pile
load test
bearing properties
friction eigenvalue
