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为了考察桩端持力层强度对桩帽网结构路基(地基)承载特性的影响,设计了4组不同桩端持力层状态的离心模型试验,测试了地基变形、加筋垫层拉力和路堤基底压力等数据。测试数据表明:①桩端持力层强度降低,地基由稳定向出现桩底明显刺入再到出现桩端持力层局部剪切破坏方面转化;②桩端持力层强度提高,地基变形减小,路基中心桩底刺入及地表沉降、坡脚地基水平变形均值与持力层承载力的关系曲线可用幂函数描述;③桩端持力层强度越高,桩体承载集中效应与桩间土承载减载效应越明显;④路基中心附近地表沉降与路基面覆盖范围筋带拉力均值间的关系曲线可用二次多项式描述,考虑了路堤横向滑移因素的筋带拉力计算值与实测较接近;⑤端承摩擦桩型的桩端持力层强度提高,筋带所受拉力减小;⑥布设袋装砂井,能加快地基的排水固结,提高桩端持力层承载力,增强地基稳定性。
In order to investigate the influence of the strength of pile-end supporting layer on the bearing capacity of subgrade with pile-cap net, four sets of centrifugal model tests with different pile-end bearing conditions were designed. The deformation of foundation, the tensile force of reinforced cushion and embankment Base pressure and other data. The test data show that: ①The strength of the bearing stratum at the pile tip decreases, the foundation stably penetrates into the pile bottom, and then the local shear failure of the stubble bearing layer at the pile end changes. ② The strength of the pile bearing stratum increases, The curve of the mean horizontal deformation at the foot of slope foundation and the bearing capacity of the bearing layer can be described by power function. The higher the strength of the bearing layer at the pile end, ④The curve of the relationship between the surface settlement near the embankment center and the mean value of the tensile force of the strip in the coverage area of the embankment can be described by the second order polynomial. The calculated value of the tensile force of the strip with the lateral slip factor of the embankment is closer to the measured value ; ⑤ end bearing friction pile-type pile end strength of the pile to enhance the tendons to reduce the tension; ⑥ cloth bagged sand wells, can speed up the foundation of the drainage consolidation, improve the bearing capacity of the pile bearing layer, and enhance the foundation stability.