嵌岩群桩基础间增补非嵌岩短桩的作用机理及荷载分配规律
引用文献：
王明珉 刘攀 王垚 邹金林 钟聪明. 嵌岩群桩基础间增补非嵌岩短桩的作用机理及荷载分配规律[J]. 建筑结构，2022，48（02）：22-27.
WANG Mingmin LIU Pan WANG Yao ZOU Jinlin ZHONG Congming. Action mechanism and loads distribution rule of supplementing non-rock-socketed short piles between rock-socketed piles[J]. Building Structure，2022,48（02）：22-27.
摘要：结合实际工程案例，采用三维有限单元法研究了既有嵌岩长桩基础之间增补非嵌岩短桩的作用机理及荷载分配规律。采用PLAXIS 3D有限元软件，首先分析了单根嵌岩长桩的轴力随深度变化情况，并与试桩静载荷试验结果进行对比。在校验有限元模拟计算参数的合理性与准确性之后，建立长桩基础和长、短桩组合基础有限元模型，分析长桩基础和长、短桩组合基础的轴力变化规律，进一步探讨了嵌岩长桩与非嵌岩短桩之间的荷载分担规律及调控方法。研究表明，桩端嵌入深埋岩层中的钻孔灌注桩在开展单桩静载荷试验时呈现出摩擦桩性状，但在群桩共同作用时则凸显出端承桩性状。在嵌岩长桩之间增补非嵌岩短桩，能够有效减小长桩上部的轴力，但长桩中下部的轴力并未减小。长桩与短桩之间的荷载分配关系取决于二者刚度比值，根据实际需求确定长、短桩刚度比的目标区间并采取适当措施对长、短桩刚度比进行调节是长、短桩组合基础设计的关键。
关键词：嵌岩桩，增补非嵌岩短桩，长、短桩组合，桩刚度
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Action mechanism and loads distribution rule of supplementing non-rock-socketed short piles between rock-socketed piles
Abstract: The action mechanism and load distribution rule of adding non-rock-socketed short piles between existing rock-socketed piles were studied by using three-dimensional finite element method in combination with an actual engineering case. Using PLAXIS 3 D finite element software, the variation of axial force along depth of single long rock-socketed pile was analyzed and compared with static load test results of trial piles. After checking the rationality and accuracy of finite element simulation calculation parameters, the finite element models of long-pile foundation and long-short pile composite foundation were established, and the variation rule of axial force of long-pile foundation and long-short pile composite foundation were analyzed, and the loads distribution rule and control method between rock-socketed long pile and non-rock-socketed short pile were further discussed. The research shows that the bored cast-in-place pile with its toe embedded in deep buried rock presents the behavior of friction pile in the single pile static loading test but shows the behavior of end bearing pile in pile groups. Adding non-rock-socketed short piles between rock-socketed long piles can effectively reduce the axial force on the upper part of long piles, but the axial force on the middle and lower part of long piles is not reduced. The load distribution relationship between long and short piles depends on the ratio of pile stiffness. It is the key for the design of long-short pile composite foundation that the determining the target range of stiffness ratio of long piles to short piles according to actual requirements and taking appropriate measures to adjust the stiffness ratio of long piles to short piles.
Keywords: rock-socketed pile; supplementary non-rock-socketed short pile; combination of long-short composite pile; pile stiffness
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