嵌岩段桩极限侧阻和端阻力系数影响因素和取值  

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

作　　者：鲁先龙 乾增珍[2] 杨文智 LU Xianlong;QIAN Zengzhen;YANG Wenzhi(China Electric Power Research Institute,Beijing 100192,China;China University of Geosciences,Beijing 100083,China)

机构地区：[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

出　　处：《工业建筑》2024年第7期181-187,共7页Industrial Construction

基　　金：国家电网公司科学技术项目(GCB17201600230)。

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。The assumed composition of the ultimate compression and uplift bearing capacity of rock-socke-ted piles is essentially the same in current Chinese codes.In addition,the same method is adopted to cal-culate the ultimate shaft resistance and tip resistance of piles for rock-socketed sections by using the ulti-mate 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 di-ameters and ultimate shaft resistance coefficients as well as ultimate tip resistance coefficients of rock-socke-ted 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 opti-mum 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 re-sistance 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).

关 键 词：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 

分 类 号：TU473.1[建筑科学—结构工程]