机场高填方红黏土地基GC-CFG组合桩处理试验研究  

Experimental study on treatment of high fill lateritic clay foundation airport with GC-CFG composite pile

作　　者：刘维正[1,2] 吴民晖 冯瑜 徐阳 LIU Weizheng;WU Minhui;FENG Yu;XU Yang(School of Civil Engineering,Central South University,Changsha 410075,China;National Engineering Research Center of High Speed Railway Construction Technology,Central South University,Changsha 410075,China;Civil Aviation Airport Planning and Design Institute(Group)Co.,Ltd.,Beijing 100002,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中南大学高速铁路建造技术国家工程研究中心,湖南长沙410075 [3]民航机场规划设计研究总院有限公司,北京100002

出　　处：《铁道科学与工程学报》2023年第1期156-168,共13页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(52078500)。

摘　　要：针对在厚层红黏土区域进行高填方机场建设,单一桩型复合地基不能满足工后沉降与稳定性的问题,基于贵阳机场三期扩建项目试验段,采用水泥粉煤灰碎石桩(CFG桩)联合碎石桩(GC桩)法对红黏土地基加固处理。通过重型动力触探、静力触探、标准贯入、静载等现场试验对地基处理的效果进行分析,并监测得到在加荷过程中复合地基桩-土应力比,以及填筑过程中桩土压力、孔隙水压力的变化和地基沉降规律。研究结果表明:1)高填方红黏土地基经过GC-CFG组合桩处理后,承载力约提升2.46倍;2)桩间距为1.0,1.2和1.4 m的复合地基能有效提高红黏土的全深度内标贯击数,最大分别提高59.3%,69.5%和74.2%,优化设计方案的桩间距选为1.4 m;3)复合地基载荷试验中CFG桩、碎石桩与桩间土的应力随着荷载的增大和置换率的提高而增大,桩体刚度越大,应力增加速率越快;加载过程中CFG和碎石桩的桩土应力分别稳定在5.0和2.0左右,相对于载荷试验的结果偏小;4)地基孔隙水压力在道基填筑预压过程中快速消散,沉降和变形速率逐渐收敛,桩间距1.4 m的GC-CFG组合桩能有效减小深厚红黏土地基的工后沉降。研究结果可为高填方红黏土地基处理设计提供参考。This paper aimed at the problem that the construction of high fill airport in lateritic clay area has strict requirements on settlement and single pile no longer meets the requirements. Based on the phase Ⅲ expansion project of Guiyang Airport, cement fly ash gravel pile(CFG pile) combined with gravel pile(GC pile) were used for foundation treatment. Through field tests such as heavy dynamic penetration tests, static penetration tests,standard penetration tests and static loading tests, the effect of foundation treatment was analyzed. The pile-soil stress ratio of composite foundation, the law of foundation settlement, the change law of earth pressure and pore water pressure during filling were monitored. The results are drawn. 1) The bearing capacity of high fill lateritic clay foundation is significantly increased by about 2.46 times after GC-CFG composite pile treatment. 2) The composite foundation with pile spacing of 1.0, 1.2 and 1.4 m can effectively improve the value of SPT blow counts in the full depth of lateritic clay, with the maximum increase of 59.3%, 69.5% and 74.2%, respectively.And the pile spacing should be selected as 1.4 m in the optimal design scheme. 3) The stress of CFG pile, gravel pile and soil between piles increases with the increase of load and replacement rate in the loading test of composite foundation. When the stiffness of pile is greater, the increase rate of stress is faster. The pile-soil stress of CFG and gravel pile is stable at about 5.0 and 2.0 respectively during the loading process, which is smaller than the result of loading test. 4) The pore water pressure of the foundation dissipates rapidly in the process of subgrade filling and preloading, and the settlement and deformation rate gradually converge. The GC-CFG composite pile with pile spacing of 1.4m can effectively reduce the post construction settlement of deep lateritic clay foundation. It can provide some reference for the treatment of lateritic clay foundation.

关 键 词：红黏土 高填方 GC-CFG组合桩 现场试验 承载特性 

分 类 号：TU447[建筑科学—岩土工程]