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采用一种在无围压条件下的1 g小规模透明土物理模拟试验,观测不同约束形式下完全嵌入模型细长桩的完整屈曲曲线。同时,结合粒子图像测速(PIV)和近景摄影测量技术,非介入地测量细长桩屈曲引起的土体变形。透明土由熔融石英及折射率相匹配的孔隙溶液组成。采用激光面照射透明土模型并拍摄下细长桩屈曲引起变形的数字图像,利用PIV获得所产生的位移场。试验结果分析表明:相对屈曲长度随着桩体强度增加及细长比减小而增加;桩端约束形式对屈曲曲线的影响取决于桩身强度和细长比的变化;土体单元的运动规律与经典朗肯土压力理论相一致。
A physical simulation experiment of 1 g small-scale transparent soil under confining pressure was carried out to observe the complete buckling curve of fully embedded model slender piles with different constraints. At the same time, the soil deformation caused by the buckling of the slender piles is measured non-invasively in combination with PIV and near-field photogrammetry. Transparent soil consists of fused silica and a pore solution that matches the refractive index. The transparent ground model was irradiated with a laser plane and the digital image of the deformation caused by the buckling of the slender piles was taken. The displacement field generated by PIV was obtained. The experimental results show that the relative buckling length increases with the increase of pile strength and the slenderness ratio. The influence of pile-end constraint on buckling curve depends on the change of pile strength and slenderness ratio. It is consistent with the classic Rankun earth pressure theory.