钻孔灌注桩压浆后承载性能的可靠度分析
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摘要
钻孔灌注桩在压浆后的承载特性得到明显改善,离散程度明显降低,但目前对压浆后钻孔灌注桩的可靠度还缺乏系统研究。收集了122根未压浆的钻孔灌注桩和147根压浆后的钻孔灌注桩静载试验资料,结合可靠度分析方法中的确定性和不确定性分析方法,利用近似概率法的基于一次二阶矩法的验算点法(简称JC法)和Monte Carlo法对钻孔灌注桩压浆前和压浆后的可靠度指标进行了对比分析。结果表明:压浆后桩的可靠度指标有很大幅度提高,压浆可减少持力层对可靠度的影响,同时后压浆桩的可靠度有随桩径增大而提高的趋势,且不同荷载效应比值下可靠度随桩径变化的趋势趋于一致。
The bearing capacity of bored piles is significantly improved and the dispersion of bearing capacity is reduced obviously by employing the method of grouting. However, the reliability of post-grouted bored piles is still lack of systematic research yet. In this study, the static load test data of 122 non-grouted bored piles and 147 post-grouted bored piles are collected. Then, combined with the certainty and uncertainty analysis methods in reliability analysis method, the approximate probability method based on the first-order second-moment method(JC method) and Monte Carlo method is employed to analyze the reliability indexes of these forementioned post-grouted bored piles and non-grouted ones.. The results indicate that the reliability index of post-grouting bored piles have been greatly improved compared to the non-grouting ones and the bearing stratum has less influence on the reliability of post-grouted bored piles than the reliability of non-grouted bored piles. Moreover, the reliability of post-grouted bored piles tends to increase with the increase of pile diameter and this trend between reliability and diameter remains consistent even under different load compositions.
The bearing capacity of bored piles is significantly improved and the dispersion of bearing capacity is reduced obviously by employing the method of grouting. However, the reliability of post-grouted bored piles is still lack of systematic research yet. In this study, the static load test data of 122 non-grouted bored piles and 147 post-grouted bored piles are collected. Then, combined with the certainty and uncertainty analysis methods in reliability analysis method, the approximate probability method based on the first-order second-moment method(JC method) and Monte Carlo method is employed to analyze the reliability indexes of these forementioned post-grouted bored piles and non-grouted ones.. The results indicate that the reliability index of post-grouting bored piles have been greatly improved compared to the non-grouting ones and the bearing stratum has less influence on the reliability of post-grouted bored piles than the reliability of non-grouted bored piles. Moreover, the reliability of post-grouted bored piles tends to increase with the increase of pile diameter and this trend between reliability and diameter remains consistent even under different load compositions.
引文
[1]史佩栋.深基础工程特殊技术问题[M].北京:人民交通出版社,2004:35-48.SHI Pei-dong.Special technical problems in deep foundation engineering[M].Beijing:China Communications Press,2004:35-48.
[2]张忠苗,包风,陈云敏.考虑材料应变软化的球(柱)孔扩张理论在桩底注浆中的研究[J].岩土工程学报,2000,22(2):243-246.ZHANG Zhong-miao,BAO Feng,CHEN Yun-min.Research on grouted-in pile bottom with spherical(columnar)hole expansion theory considering material strain-softening[J].Chinese Journal of Geotechnical Engineering,2000,22(2):243-246.
[3]黄生根,龚维明,张晓炜,等.钻孔灌注桩压浆后的承载性能研究[J].岩土力学,2004,25(8):1315-1319.HUANG Sheng-gen,GONG Wei-ming,ZHANG Xiaowei,et al.Study on load bearing behavior of post-grouted bored piles[J].Rock and Soil Mechanics,2004,25(8):1315-1319.
[4]黄生根,龚维明.桩端压浆对超长大直径桩侧阻力的影响研究[J].岩土力学,2006,27(5):711-716.HUANG Sheng-gen,GONG Wei-ming.Study on effect of base grouting on shaft friction of overlength large diameter pile[J].Rock and Soil Mechanics,2006,27(5):711-716.
[5]黄生根,龚维明.超长大直径桩压浆后的承载性能研究[J].岩土工程学报,2006,28(1):113-117.HUANG Sheng-gen,GONG Wei-ming.Study on bearing behavior of super long-large diameter piles after grouting[J].Chinese Journal of Geotechnical Engineering,2006,28(1):113-117.
[6]黄生根.钻孔灌注桩压浆后浆液沿桩侧上升高度及其对桩周土的作用方式研究[J].岩土力学,2006,27(增刊2):779-783.HUANG Sheng-gen.Study on rirsing height of gorut along a pile after grouting and effect of grout on soils[J].Rock and Soil Mechanics,2006,27(Suppl.2):779-783.
[7]戴国亮,万志辉.后压浆桩增强效应作用机制及荷载沉降关系研究[J].岩土工程学报,2017,39(12):2235-2244.DAI Guo-liang,WAN Zhi-hui.Enhanced mechanism and load-settlement relationship of post-grouting piles[J].Chinese Journal of Geotechnical Engineering,2017,39(12):2235-2244.
[8]RUIZ S.Reliability index for offshore piles subjected to bending[J].Structural Safety,1984,2(2):83-90.
[9]邓志勇,陆培毅,王成华.钻孔灌注桩单桩承载力的可靠度研究[J].岩土力学,2003,24(1):83-87.DENG Zhi-yong,LU Pei-hua,WANG Cheng-hua.Reliability research on bearing capacity of single bored pile[J].Rock and Soil Mechanics,2003,24(1):83-87.
[10]边晓亚,郑俊杰,徐志军.考虑桩基设计方法的基桩承载力可靠度分析[J].岩土工程学报,2013,35(增刊2):1099-1102.BIAN Xiao-ya,ZHENG Jun-jie,XU Zhi-jun.Reliability analysis of bearing capacity of foundation piles considering pile foundation design approach[J].Chinese Journal of Geotechnical Engineering,2013,35(Suppl.2):1099-1102.
[11]徐宁,葛忻声,王丽娟,等.区域性场地土中桩基承载力可靠度及抗力分项系数的研究[J].太原理工大学学报,2014,45(6):795-798.XU Ning,GE Xin-sheng,WANG Li-juan,et al.Research of resistant coefficients and reliability of the load-carring capacity of the pile on the regional site soil[J].Journal of Taiyuan University of Technology,2014,45(6):795-798.
[12]王景梅,肖芳,陈家俊,等.基于贝叶斯理论和蒙特卡洛模拟的桩基可靠度分析[J].地下空间与工程学报,2017,13(增刊1):85-90.WANG Jing-mei,XIAO Fang,CHEN Jia-jun,el al.Areliability analysis method for pile foundation based on Bayesian theory and monte carlo simulation[J].Chinese Journal of Underground Space and Engineering,2017,13(Suppl.1):85-90.
[13]傅旭东,周天想.铁路桥梁钻孔桩的可靠度设计研究[J].铁道学报,1999,(3):88-95.FU Xu-dong,ZHOU Tian-xiang.Research on reliabilitybased limit state design theory for railway bridges’bored-piles[J].Journal of the China Railway Society,1999,(3):88-95.
[14]冷伍明.基础工程可靠度分析与设计理论[M].长沙:中南大学出版社,2000.LENG Wu-ming.Reliability analysis and design theory of foundation engineering[M].Changsha:Central South University Press,2000.
[15]中国建筑科学研究院.GB50068-2001建筑结构可靠度设计统一标准[S].北京:中国建筑工业出版社,2001.China Academy of Building Research.GB50068-2001Unified standard for reliability design of building structures[S].Beijing:China Architecture&Building Press,2001.
[16]赵国藩,曹居易,张宽权.工程结构可靠度[M].北京:科学出版社,2011:52-54.ZHAO Guo-fan,CAO Ju-yi,ZHANG Kuan-quan.Reliability of engineering structure[M].Beijing:Science Press,2011:52-54.
[17]何军,赵彤.深层搅拌桩复合地基承载力可靠性研究[J].岩土力学,2000,21(4):401-403.HE Jun,ZHAO Tong.Reliability research on bearing capacity of composite foundation[J].Rock and Soil Mechanics,2000,21(4):401-403.
[2]张忠苗,包风,陈云敏.考虑材料应变软化的球(柱)孔扩张理论在桩底注浆中的研究[J].岩土工程学报,2000,22(2):243-246.ZHANG Zhong-miao,BAO Feng,CHEN Yun-min.Research on grouted-in pile bottom with spherical(columnar)hole expansion theory considering material strain-softening[J].Chinese Journal of Geotechnical Engineering,2000,22(2):243-246.
[3]黄生根,龚维明,张晓炜,等.钻孔灌注桩压浆后的承载性能研究[J].岩土力学,2004,25(8):1315-1319.HUANG Sheng-gen,GONG Wei-ming,ZHANG Xiaowei,et al.Study on load bearing behavior of post-grouted bored piles[J].Rock and Soil Mechanics,2004,25(8):1315-1319.
[4]黄生根,龚维明.桩端压浆对超长大直径桩侧阻力的影响研究[J].岩土力学,2006,27(5):711-716.HUANG Sheng-gen,GONG Wei-ming.Study on effect of base grouting on shaft friction of overlength large diameter pile[J].Rock and Soil Mechanics,2006,27(5):711-716.
[5]黄生根,龚维明.超长大直径桩压浆后的承载性能研究[J].岩土工程学报,2006,28(1):113-117.HUANG Sheng-gen,GONG Wei-ming.Study on bearing behavior of super long-large diameter piles after grouting[J].Chinese Journal of Geotechnical Engineering,2006,28(1):113-117.
[6]黄生根.钻孔灌注桩压浆后浆液沿桩侧上升高度及其对桩周土的作用方式研究[J].岩土力学,2006,27(增刊2):779-783.HUANG Sheng-gen.Study on rirsing height of gorut along a pile after grouting and effect of grout on soils[J].Rock and Soil Mechanics,2006,27(Suppl.2):779-783.
[7]戴国亮,万志辉.后压浆桩增强效应作用机制及荷载沉降关系研究[J].岩土工程学报,2017,39(12):2235-2244.DAI Guo-liang,WAN Zhi-hui.Enhanced mechanism and load-settlement relationship of post-grouting piles[J].Chinese Journal of Geotechnical Engineering,2017,39(12):2235-2244.
[8]RUIZ S.Reliability index for offshore piles subjected to bending[J].Structural Safety,1984,2(2):83-90.
[9]邓志勇,陆培毅,王成华.钻孔灌注桩单桩承载力的可靠度研究[J].岩土力学,2003,24(1):83-87.DENG Zhi-yong,LU Pei-hua,WANG Cheng-hua.Reliability research on bearing capacity of single bored pile[J].Rock and Soil Mechanics,2003,24(1):83-87.
[10]边晓亚,郑俊杰,徐志军.考虑桩基设计方法的基桩承载力可靠度分析[J].岩土工程学报,2013,35(增刊2):1099-1102.BIAN Xiao-ya,ZHENG Jun-jie,XU Zhi-jun.Reliability analysis of bearing capacity of foundation piles considering pile foundation design approach[J].Chinese Journal of Geotechnical Engineering,2013,35(Suppl.2):1099-1102.
[11]徐宁,葛忻声,王丽娟,等.区域性场地土中桩基承载力可靠度及抗力分项系数的研究[J].太原理工大学学报,2014,45(6):795-798.XU Ning,GE Xin-sheng,WANG Li-juan,et al.Research of resistant coefficients and reliability of the load-carring capacity of the pile on the regional site soil[J].Journal of Taiyuan University of Technology,2014,45(6):795-798.
[12]王景梅,肖芳,陈家俊,等.基于贝叶斯理论和蒙特卡洛模拟的桩基可靠度分析[J].地下空间与工程学报,2017,13(增刊1):85-90.WANG Jing-mei,XIAO Fang,CHEN Jia-jun,el al.Areliability analysis method for pile foundation based on Bayesian theory and monte carlo simulation[J].Chinese Journal of Underground Space and Engineering,2017,13(Suppl.1):85-90.
[13]傅旭东,周天想.铁路桥梁钻孔桩的可靠度设计研究[J].铁道学报,1999,(3):88-95.FU Xu-dong,ZHOU Tian-xiang.Research on reliabilitybased limit state design theory for railway bridges’bored-piles[J].Journal of the China Railway Society,1999,(3):88-95.
[14]冷伍明.基础工程可靠度分析与设计理论[M].长沙:中南大学出版社,2000.LENG Wu-ming.Reliability analysis and design theory of foundation engineering[M].Changsha:Central South University Press,2000.
[15]中国建筑科学研究院.GB50068-2001建筑结构可靠度设计统一标准[S].北京:中国建筑工业出版社,2001.China Academy of Building Research.GB50068-2001Unified standard for reliability design of building structures[S].Beijing:China Architecture&Building Press,2001.
[16]赵国藩,曹居易,张宽权.工程结构可靠度[M].北京:科学出版社,2011:52-54.ZHAO Guo-fan,CAO Ju-yi,ZHANG Kuan-quan.Reliability of engineering structure[M].Beijing:Science Press,2011:52-54.
[17]何军,赵彤.深层搅拌桩复合地基承载力可靠性研究[J].岩土力学,2000,21(4):401-403.HE Jun,ZHAO Tong.Reliability research on bearing capacity of composite foundation[J].Rock and Soil Mechanics,2000,21(4):401-403.