嵌岩桩嵌岩段的岩石极限侧阻力系数

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摘 要：嵌岩桩在岩土工程中已得到广泛应用，但如何准确计算嵌岩段桩的极限侧阻力仍是工程设计人员面临的重要课题。收集整理了不同时期、不同地区、不同岩石强度和不同嵌岩条件下开展的145个嵌岩桩竖向下压承载力试验成果，主要包括嵌岩段岩石类型及其单轴抗压强度、嵌岩桩的直径与嵌岩深度、嵌岩段桩的极限侧阻力等。定义嵌岩段桩的极限侧阻力和岩石单轴抗压强度的比值为嵌岩桩嵌岩段岩石极限侧阻力系数，分析了桩径、嵌岩深度、嵌岩深径比和岩石强度对嵌岩段极限侧阻力和岩石极限侧阻力系数的影响规律，建立了嵌岩段岩石极限侧阻力系数与岩石单轴抗压强度之间的拟合关系式，给出了不同可靠度水平下岩石侧极限阻力系数取值。

关键词： 嵌岩桩;极限侧阻力系数;嵌岩深径比;抗压强度

中图分类号：TU411

 文献标志码：A  文章编号：1674-4764（2018）06-0029-10

Analysis on ultimate side shear resistance factor of

piles socketed into rocks

Lu Xianlong1，Qian Zengzhen2，Yang Wenzhi1，Zheng Weifeng1

（1.China Electric Power Research Institute， Beijing 100192， P. R. China;

2.School of Engineering and Technology， China University of Geosciences， Beijing 100083， P. R. China）

Abstract：Rock-socket pile foundations have been widely used in engineering practices. It is important to determine the ultimate side shear resistance of the piles socketed into rock for designers. In this study， the results of 145 compression load tests were collected to examine several issues related to the bearing capacity behavior of rock-socket piles. All these load test results were representative since they were carried out worldwide， on different rock types and rock-socket conditions， for a long time period. Using these available load test case history data， the socketed rock type of piles， diameter and embedment depth of socketed piles， uniaxial compressive strength of rock in nature， and the ultimate bearing side resistances were collected. The ratio of ultimate side shear resistance to unconfined compressive strength of the rock was denoted as the ultimate side shear resistance factor of the piles socketed into rocks. Effects of pile diameter， rocked depth， ratio of rock rocketed depth to diameter， and the unconfined compressive strength of the rock on ultimate side shear resistance and the influential factors were evaluated. Empirical relationships between the ultimate side shear resistance factor and the unconfined compressive strength are suggested， and based on the statistical results， the specific design recommendations for the ultimate side shear resistance factor are provided.

Keywords：rock-socket pile; ultimate side shear resistance factor; ratio of pile rocketed depth to diameter;  compressive strength

嵌巖桩是大型建（构）筑物的主要基础型式，已在工程中得到了广泛应用，主要用于承受上部结构的下压或上拔荷载。对抗压和抗拔嵌岩桩，嵌岩段桩的侧阻力通常都占总承载力较大比例。嵌岩桩荷载传递是桩 土 岩相互作用的复杂过程。目前，学术界和工程界普遍认为，嵌岩桩抗压承载力主要由基岩上覆土层的桩侧阻力、嵌岩段桩侧阻力和桩端阻力3部分组成。这在中国相关规范[1-4] 给出的嵌岩桩承载力设计计算方法中均得到体现。嵌 岩桩抗拔承载力主要由基岩上覆土层桩侧阻力和嵌岩段桩侧阻力2部分组成。通常采用折减系数，对土层和岩层抗压极限侧阻力进行折减。如文献[5]建议该折减系数为0.7。因此，研究嵌岩桩嵌岩段桩测极限侧阻力及岩石极限侧阻力系数对嵌岩桩的抗压和抗拔承载性能都具有重要的理论和工程意义。

推荐访问:阻力 岩石 系数 极限 嵌岩桩嵌岩段