嵌岩段桩极限侧阻和端阻力系数影响因素和取值

鲁先龙; 乾增珍; 杨文智

doi:10.3724/j.gyjzG22091705

嵌岩段桩极限侧阻和端阻力系数影响因素和取值

doi: 10.3724/j.gyjzG22091705

1. 中国电力科学研究院有限公司, 北京 100192;
2. 中国地质大学(北京), 北京 100083

基金项目:

国家电网公司科学技术项目(GCB17201600230)。

详细信息

作者简介:
鲁先龙,博士,教授级高级工程师,主要从事电力工程地基基础与防灾减灾研究。电子信箱:luxianlong@163.com

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出版历程
- 收稿日期: 2022-09-17
- 网络出版日期: 2024-08-16

Influencing Factors and Corresponding Values of Ultimate Shaft Resistance and Tip Resistance Coefficients for Piles of Rock-Socketed Sections

1. China Electric Power Research Institute, Beijing 100192, China;
2. China University of Geosciences, Beijing 100083, China

摘要

摘要: 我国各行业技术标准对嵌岩桩抗压和抗拔极限承载力组成假设基本相同,采用极限侧阻力系数ξ_s和端阻力系ξ_b乘以岩石单轴抗压强度f_ucs计算嵌岩段桩极限侧阻力和端阻力的方法也相同。但各标准关于ξ_s和ξ_b确定的原则不同,取值大小也存在一定差异。基于已有试验成果分析了桩端嵌岩条件(桩径、嵌岩深度和嵌岩深径比)和岩石单轴抗压强度对嵌岩段桩极限侧阻力和侧阻力系数、极限端阻力和端阻力系数的影响规律。结果表明:桩径与嵌岩段桩极限侧阻和端阻力系数间无显著统计相关性。随嵌岩深度和嵌岩深径比增大,嵌岩段桩极限侧阻和端阻力系数总体呈下降趋势,且存在最佳嵌岩深度和嵌岩深径比使嵌岩段桩极限侧阻端阻力同时得到最大程度的发挥。嵌岩段桩极限侧阻和端阻力随岩石单轴抗压强度的增大而增大,但极限侧阻和端阻力系数则随岩石单轴抗压强度增大而减小。岩石强度是极限侧阻和端阻力系数最主要影响因素,且两者间具有较好统计相关性,并可分别采用ξ_s=0.436f_ucs^-0.68和ξ_b=4.183f_ucs^-0.79拟合计算。
- 嵌岩桩 /
- 极限侧阻力系数 /
- 极限端阻系数 /
- 嵌岩深径比 /
- 岩石单轴抗压强度
Abstract: The assumed composition of the ultimate compression and uplift bearing capacity of rock-socketed piles is essentially the same in current Chinese codes. In addition, the same method is adopted to calculate the ultimate shaft resistance and tip resistance of piles for rock-socketed sections by using the ultimate shaft resistance coefficient ξ_s and tip resistance coefficient ξ_b to multiply uniaxial compressive strength f_ucs of rock. However, the values of the aforementioned ξ_s and ξ_b in the criteria are quite different. Based on test data of rock-socketed piles under compression loads, influence laws of pile diameters, rock-socketed depths, ratios of rocketed depths to diameters, and uniaxial strength of rock on ultimate shaft resistance and shaft resistance coefficients as well as ultimate tip resistance and ultimate tip resistance coefficients of rock-socketed sections were analyzed. It was indicated that there was no significant correlation between pile diameters and ultimate shaft resistance coefficients as well as ultimate tip resistance coefficients of rock-socketed piles. With increase in rock-socketed depths and ratios of rocketed depths to diameters, the ultimate shaft resistance and ultimate tip resistance of rock-socketed piles generally decreased. There was an optimum rock-socketed depths and a ratio of rocketed depths to diameters, which could make the ultimate shaft resistance and tip resistance of rock-socketed sections played their roles most fully and coordinately. The ultimate shaft resistance and tip resistance increased but the ultimate shaft resistance coefficients and tip resistance coefficients decreased with increase in the uniaxial compressive strength of rock. The strength of rock was a significant factor to determine the coefficients of shaft resistance and tip resistance. There was a good statistical correlation between them, which could be respectively fitted as ξ_s=0.436 f_ucs^-0.68 and ξ_b=4.183 f_ucs^-0.79.
- rock-socketed pile /
- ultimate shaft resistance coefficient /
- tip resistance coefficient /
- ratio of rocketed depths to diameters /
- unconfined compressive strength of rock

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