钙质砂后压浆桩水平承载性状模型试验研究

Experimental study on lateral bearing behavior of post-grouted piles in calcareous sand

后压浆技术已应用于珊瑚岛礁基础设施建设中,但有关钙质砂后压浆桩水平承载性状的研究较少。针对钙质砂地基中后压浆桩的水平承载问题,通过室内模型试验手段对钙质砂未压浆桩与后压浆桩的水平承载规律进行了研究,探究了后压浆对钙质砂桩基水平承载性状的影响,并通过开挖后压浆单桩,分析了注入的水泥浆液在钙质砂中的渗扩情况。结果表明,钙质砂后压浆桩的水平临界荷载和水平极限荷载较同条件下未压浆桩均有显著的提高,且变形控制能力优于同条件下未压浆桩;未压浆桩与后压浆桩的桩侧地基土水平抗力系数的比例系数m值随桩顶侧向位移的增加逐渐趋于一致,且桩身弯矩和桩侧土压力都主要集中在上部桩身和土层中;桩基水平承载力受上部土体的影响较大,桩侧压浆通过改善上部土层的物理力学性质能有效提高桩基抵抗水平荷载的能力。此外,通过开挖分析得出桩侧注入的水泥浆液沿着桩身上返、下渗并横向扩散与钙质砂颗粒形成了水泥土加固体的稳定结构,进而提升了钙质砂桩基水平承载性能。

Post-grouting technique has been applied to the infrastructure construction of coral reefs,but there has been little research about the horizontal bearing behavior of post-grouted piles in calcareous sand.Based on the case of post-grouted piles in calcareous sand under horizontal load,the horizontal bearing rule of ungrouted and post-grouted piles in calcareous sand was studied comprehensively by laboratory model tests,and the influence of post-grouting on the horizontal bearing behavior of pile in calcareous sand was investigated.The infiltration and diffusion of injected cement grout in calcareous sand were analyzed through soil excavation of post-grouted piles.The results show that the lateral critical load and the lateral ultimate load of post-grouted piles in calcareous sand are significantly improved compared with those of ungrouted piles under the same condition.Besides,the ability to control lateral deformation under grouting is better than that of piles without grouting.The proportional coefficient m of the lateral soil resistance coefficient of ungrouted and post-grouted piles gradually tends to be consistent with the increase of the lateral displacement of the pile head,and the bending moment of pile shaft and the soil pressure around piles are mainly concentrated in the upper part of the pile and soil.The lateral bearing capacity of piles is greatly affected by the upper level of soil,and grouting at the pile side can effectively increase lateral bearing capacity by improving the upper soil physico-mechanical properties.In addition,according to the soil excavation analysis,the cement grout injected at the pile side is mixed with calcareous sand to form a stable structure of cement stabilized soil.This provides the improved lateral bearing capacity of the pile in calcareous sand.