Testing and Analysis on the Quality Problems of CFG Pile Composite Foundation
-
摘要: 某工程场区地层以粉土、黏性土及砂性土为主,地下水位较高,设计采用CFG桩复合地基。CFG桩复合地基检测结果显示,单桩及复合地基承载力均达不到设计要求,针对出现的质量问题采用低应变法和钻芯法检测对比查找并分析出现质量问题的原因。采用高压旋喷桩对地基进行补强加固处理,并对补强加固后的复合地基进行检测,检测结果显示复合地基承载力满足设计要求,建筑物沉降观测结果表明,建筑最大沉降量与整体倾斜值均满足设计与相关规范要求。可为解决同类工程质量问题提供参考。Abstract: The stratum of a project site is mainly composed of silt, cohesive soil, and sandy soil, and the groundwater level is high. CFG pile composite foundation is designed. The test results of CFG pile composite foundation show that the bearing capacity of both single pile and composite foundation cannot meet the design requirements. The low strain method and core drilling method were used to detect and compare the quality problems, and the reasons for the quality problems were analyzed. High pressure jet grouting piles were used to reinforce the foundation, and the reinforced composite foundation was tested. The test results show that the bearing capacity of the composite foundation meets the design requirements. The observation results of building settlement indicate that the maximum settlement and overall inclination of the building meet the design and relevant specifications. It can provide reference for solving similar engineering quality problems.
-
Key words:
- CFG pile composite foundation /
- bearing capacity /
- testing /
- low strain testing /
- core drilling method
-
表 1 地基各土层参数表
土层号 土层名称 层厚/m 承载力特征值/kPa 压缩模量/MPa 桩侧阻力特征值qsi/kPa 桩端阻力特征值qp/kPa ① 粉土夹薄层粉质黏土 3.3~4.9 120 10.5 21 ② 粉质黏土夹薄层粉土 1.4~3.6 105 4.2 25 ③ 粉土 0.7~2.7 125 11.2 22 ④ 粉质黏土夹薄层粉土 3.3~5.7 115 4.5 26 ⑤ 粉质黏土 0.5~2.0 140 5.2 30 ⑥ 细砂 14.3~17.3 240 18.7 33 1000 表 2 增强体竖向抗压静载荷试验成果表
桩号 最大加
载量/kN最大沉
降量/mm最大回
弹量/mm极限承
载力/kN平均极限
承载力/kN承载力
特征值/kN624# 1085 41.52 4.68 930 955.8 477 528# 1085 42.93 3.41 930 593# 1240 42.63 5.75 1085 587# 1085 45.09 4.31 930 535# 1085 43.66 6.78 930 539# 1085 56.22 4.88 930 表 3 复合地基静载荷试验成果表
桩号 最大加
载量/kPa最大沉
降量/mm最大回
弹量/mm极限承
载力/kPa平均极限
承载力/kPa承载力
特征值/kPa626# 966 83.85 8.01 828 782 391 530# 828 84.47 9.94 690 599# 966 85.38 11.89 828 595# 966 86.46 9.88 828 534# 966 86.42 7.38 828 540# 828 79.23 7.51 690 -
[1] 曹江涛. 某工程CFG桩复合地基质量问题分析[J]. 工程勘察,2013,41(11):32-35. [2] 付 宏. 某工程CFG桩复合地基承载力不足原因分析及检测[J]. 山西建筑,2016,42(29):61-62. [3] 葛 岩,潘卫东,冯远景. CFG桩复合地基承载力的试验研究[J]. 路基工程,2008,(5):105-107. [4] 石少敏,刘军林. 载荷试验计算两层土复合地基变形模量[J]. 岩土工程技术,2008,22(6):304-307. [5] 林道俊,刘济鹏,韩彦芳. 初探低应变反射波法在桩基检测中的实践[J]. 岩土工程技术,2013,27(6):288-291. [6] 张金铃. 基桩低应变检测缺陷程度的定量分析方法[J]. 西部探矿工程,2006,(1):22-25. [7] JGJ 340—2015 建筑地基检测技术规范[S]. 北京: 中国建筑工业出版社, 2015. [8] JGJ 106—2014 建筑基桩检测技术规范[S]. 北京: 中国建筑工业出版社, 2014. [9] 王 勃,行小盈. 高压旋喷桩单桩承载力分析[J]. 岩土工程技术,2020,34(1):48-52. [10] JGJ 8—2016 建筑变形测量规范[S]. 北京: 中国建筑工业出版社, 2016.