碎石桩加固深厚湿陷性黄土地基的试验研究

为明确碎石桩加固深厚湿陷性黄土地基的效果,依托某深厚湿陷性黄土地基处理工程,开展了碎石桩加固地基的系列试验研究。通过多种方式检测了加固后地基土体的物理力学参数、承载能力及沉降变形,并分析其变化规律。试验结果表明:采用碎石桩加固深厚湿陷性黄土地基,桩身的密实度在松软土层较低,在坚硬土层较密实,且相同深度的桩身密实度随桩间距的减小而提升;碎石桩对深度1～3 m内的桩间土有较好的挤密效果,对深度3 m以下土层则无显著影响;碎石桩能有效加固湿陷性黄土地基,可消除地基土湿陷性,经加固后的复合地基承载力特征值可提升56.25 %～152.78 %,压缩模量可提升62.90 %～152.78 %,而地基土的干密度和孔隙比与处理前的平均参考值相比则变化较小;桩间距对地基土体的处理效果有较明显的影响,减小桩间距可降低地基土层的后期沉降量;试验区合理的碎石桩置换率为7 %。研究结果可为碎石桩处理深厚湿陷性黄土地基的工程方案及预期目标的设计提供参考。

Application Research on Deep Collapsible Loess Foundation Treatment by Gravel Pile

In order to the strengthen effect of deep collapsible loess foundation treatment by gravel pile, it depend on one deep collapsible loess foundation treatment project as the experiment area, and carried out series of experiments for the foundation treatment by gravel pile. The physical and mechanical parameters, bearing capacity and settlement deformation of the foundation soil after reinforcement tested in various ways, and the change law analyzed. The test results show that: Using gravel pile to reinforce deep collapsible loess foundation, the compactness of pile body is lower in soft soil layer and higher in hard soil layer, and the compactness of pile body at the same depth increases with the decrease of pile spacing; The gravel pile has a good compaction effect on the soil between piles within 1~3 m depth, but has no significant effect on the soil below 3 m depth. The results show that the gravel pile can effectively strengthen the collapsible loess foundation and eliminate the collapsibility of the foundation soil. After reinforcement, the bearing capacity characteristic value of the composite foundation can be increased by 56.25% ~ 152.78%, and the compression modulus can be increased by 62.90% ~ 152.78%, while the dry density and void ratio of the foundation soil change little compared with the average reference value before treatment. The pile spacing has obvious influence on the treatment effect of the foundation soil, and reducing the pile spacing can reduce the later settlement of the foundation soil. The reasonable replacement rate of gravel pile is 7%. The research results can provide a reference for the design of the engineering scheme and the expected goal of the gravel pile treatment of deep collapsible loess foundation.