挤密效应对砂土中水平受荷桩承载特性的影响
Influences of compaction effect on bearing capacity of laterally loaded piles in sand
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摘要: 砂土中的挤土桩在实际工程中广泛应用,部分挤土桩长期遭受风荷载、波浪荷载等水平循环荷载的作用,而挤土桩对桩周土体的挤密效应会对桩身水平承载力产生较大影响。通过开、闭口桩的室内模型试验,研究分析了砂土初始相对密度、桩径、长径比等因素对挤土桩单调和循环承载特性的影响。结果表明,在不同密实度砂土中,开口桩水平承载力总体上弱于闭口桩。桩径、长径比和土体相对密度都会对开口桩、闭口桩之间承载力的差值造成较大的影响。循环荷载作用下,松砂中不同桩径和埋深的开口桩、闭口桩的水平承载力都随着加载周期的增加而增大,而在中密砂中,随着循环次数的增加,循环加载后承载力增加的幅度较松砂中的减少,甚至出现下降。Abstract: Displacement piles are widely adopted in practical engineering. Some of the piles are used to resist the horizontal cyclic loadings induced by wind or wave. Based on the model tests conducted on open-end and closed-end piles, the effects of the initial relative density of sand, pile diameter and length-diameter ratio on the static and cyclic bearing capacities are investigated. The results indicate that the bearing capacity of the open-end piles is generally weaker than that of closed-end piles in both loose and medium-dense sands. Difference in the pile diameter, length-diameter ratio, and relative density of sand will result into significant difference in the bearing capacities of the open-end and closed-end piles. Under cyclic loading, the bearing capacity of the piles in loose sand always increases with the number of loading cycles. In the medium dense sand, the increment in the loading capacity as caused by the cyclic loading is smaller than that in the loose sand, and becomes negative in some cases.