岛状冻土区应用生石灰桩复合地基效果评价  

Effect of quicklime pile composite foundation on patchy permafrost

作　　者：杨晓明 程佳 蔡汉成 YANG Xiaoming;CHENG Jia;CAI Hancheng(Northwest Research Institute Co.,Ltd of C.R.E.C,Lanzhou 730000,China;Qinghai Province Key Laboratory of Permafrost and Environmental Engineering,Golmud 816000,China)

机构地区：[1]中铁西北科学研究院有限公司,甘肃兰州730000 [2]青海省冻土与环境工程重点实验室,青海格尔木816000

出　　处：《铁道科学与工程学报》2022年第4期941-948,共8页Journal of Railway Science and Engineering

基　　金：中国中铁股份有限公司科技开发计划项目(2017-引导-39);中铁科研院科技开发计划项目(2017-KJ007-Z007-XB);中国中铁新疆区域工程建设指挥部科技研发项目(2019002)。

摘　　要：生石灰桩预融处理岛状冻土是一种新的地基处理技术,目前国内外相关研究极少。为明确生石灰桩复合地基在岛状冻土区的实际效果,依托漠河机场改扩建工程地基处理项目开展生石灰桩预融技术研究。通过对现场生石灰桩开展地温及变形监测、挖探及室内外试验,经过近1 a的观测和试验,对生石灰桩复合地基的地温、桩径、干密度、含水率等关键参数的变化特征进行深入分析,明确生石灰桩处理岛状冻土地基能达到预融并加固融土地基的工程效果。研究结果表明:生石灰桩能完全融化桩间冻土,且预融处理后的复合地基在3个月内即已基本稳定。处理后的复合地基变形量小(竖向膨胀2.4~3.0 mm),稳定快(施工完成后3个月达到稳定),承载力满足设计要求。生石灰桩预融冻土后桩体发生膨胀,膨胀率受深度影响较小,与土体粒径成分关系较大,砂类土膨胀率低于黏性土。生石灰桩膨胀对桩周土体的挤密作用随范围扩大而减小,最大影响范围为1.25倍桩径。生石灰桩完工近1 a后,桩体完全熟化,桩体含水率明显高于桩周地基土体,桩周地基土体含水率平均降低了约8%,且距离桩体越近含水率越低。Using quicklime pile to pre-melting permafrost is a new foundation treatment technology to treat patchy permafrost,but this technology is rarely studied around the global.Based on the Mohe Airport reconstruction and expansion project,where a large area of patchy permafrost exists,a lime pile test project wascarried out in order to studythe effect of quicklime pile composite foundation on patchy permafrost.By means of nearly one year’s ground temperature and deformation monitoring,geological prospecting,indoor and outdoor test,the variation characteristics of key parameters such as ground temperature,pile diameter,dry density and water content were analyzed about quicklime pile composite foundation,and the results proved that using quicklime pile can melt permafrost and reinforce the foundation.The main conclusions are as follows:The frozen soil is melted completely and the foundation becomes stable within 3 months.After treatment,the vertical deformation of composite foundation is small,only increased 2.4~3.0 mm,and the bearing capacity meets the design requirements.The expansion rate of quicklime pile after thawing frozen soil is less affected by depth,but a greater relationship with particle size composition of soil.The expansion rate of quicklime pile in clay is large than in sand.The compacting effects decrease with the expansion of the soil boundaries,and the maximum influence range is 1.25 times of pile diameter.Nearly one year afterthe completion of quicklime pile,the chemical reactions about quicklime piles are finished fully,and the water content in piles is higher than that of soil.The average water content of soil is reduced by 8%approximately and the closer it is to the pile body,the lower the water content.

关 键 词：石灰桩复合地基 岛状冻土 地温 含水率 

分 类 号：U213.14[交通运输工程—道路与铁道工程]