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为了研究包裹碎石桩的承载机制,开展了室内模型试验,对不同套筒长度和刚度的包裹碎石桩承载力、端阻力、变形和破坏情况等进行了分析。试验中利用自制的桩体径向变形测量仪监测了桩体的径向变形情况。试验结果表明:当桩体支承在坚硬土层时,全长包裹碎石桩有效提高碎石桩的承载力和刚度,且采用弹性模量较大的土工材料套筒,包裹碎石桩的极限承载力和刚度也较大,部分包裹碎石桩(包裹长度为0.6倍桩长)相对于碎石桩优势不明显。这是因为部分包裹碎石桩和全长包裹的承载特性、变形特点和破坏模式均存在差异。全长包裹碎石桩传递至桩底端的荷载大于部分包裹碎石桩和碎石桩的。与部分包裹碎石桩和碎石桩比较,全长包裹碎石桩桩身变形分布较为均匀,同一应力作用下,桩身最大径向变形量较小。此外,全长包裹碎石桩刺入顶部褥垫层发生破坏,而部分包裹碎石桩发生鼓胀破坏。
In order to study the bearing mechanism of the wrapped gravel pile, an indoor model test was carried out to analyze the bearing capacity, end resistance, deformation and damage of the wrapped gravel pile with different length and stiffness of the sleeve. In the experiment, the self-made pile radial deformation measuring instrument was used to monitor the radial deformation of the pile. The test results show that when the pile is supported on the hard soil, the full length of the crushed stone piles effectively increases the bearing capacity and stiffness of the stone piles, and the geotextile sleeve with larger elastic modulus, the limit of the crushed stone piles Bearing capacity and stiffness are also larger, partial parcel gravel pile (parcel length of 0.6 times the pile length) relative to the gravel pile advantage is not obvious. This is because the bearing characteristics, deformation characteristics and failure modes of some parcels and full-length parcels are different. The length of the full-length gravel pile transferred to the bottom of the pile is larger than that of the partially-covered gravel pile and gravel pile. Compared with partial parcel gravel pile and gravel pile, the deformation distribution of full-length parcel gravel pile is more uniform, and under the same stress, the maximum radial deformation of pile body is smaller. In addition, the full-length parcel pile piercing into the top of the cushion was damaged, and some of the parcel pile gravel damage.