袋装组合微型石灰桩纠偏加固技术研究

Building Tilting Retrofit and Reinforcement by Combination of Bagged Lime Column and Micro Piles

湿陷性黄土地区,受地下水的影响容易出现地基不均匀沉降,对建筑物的长期使用产生影响。生石灰桩是黄土地区地基纠偏加固的常用方法,针对传统生石灰桩的不足,提出了袋装组合微型桩,并在陕西地区黄土地层开展了现场应用。通过膨胀试验确定了袋装组合微型桩的填充料的配比为生石灰:干素土:中粗砂:水泥体积百分比为75∶15∶7∶3,极限注水量为填料质量的0.834倍。数值仿真和现场监测表明,袋装组合微型桩纠偏加固效果显著,在微型桩施工100d后,地基沉降已进入稳定阶段,地基的最大沉降量仅为24.0mm。

The differential foundation settlements often occur in collapsible loess area due to the fluctuations of the groundwater,which will affect the long-term use of buildings.Quick lime columns are a common method for the retrofitting and strengthening foundations in these areas.Combination of bagged quick lime column and micro-pile are proposed to solve the shortcomings of traditional quick lime piles.The concept was applied in Shanxi Province.According to the expansion tests,the volume ratio of filling material of the column was set quick lime:dry plain soil:medium-coarse sand:cement 75:15:7:3;the maximum water injection amount was set 0.834times of the mass of filling materials.Numerical simulation and field monitoring showed that the proposed micro-pile is feasible for the retrofit and reinforcement of building foundations.The settlements of the foundation tended to stabilize in 100days from construction of the columns,and maximum settlement of the building foundation was less than 24.0mm.