静压桩残余应力的长期观测性状

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静压桩施工过程中,可能会沿桩身形成很大的残余应力。通过在砂性土中1根长约26 m静压桩的原位试验,观测了沉桩结束后的残余应力在后续的循环载荷试验、3根邻桩顺次压入、第2次载荷试验以及较长静置期内的长期变化情况,试验历时约212 d。结果显示,循环载荷试验加载水平与循环次数的增加会造成残余应力的进一步累积。邻桩压入使既有桩残余压应力减小,与邻桩即时贯入深度一致的桩身残余应力测点受其影响最明显。桩身残余应力在长时间内会逐步消散至某一稳定值,其时间效应主要与砂性土的蠕变有关,它使得桩周土的土拱效应减弱,并使桩端土的接触压力减小。 Static pressure pile construction process, may form a large residual stress along the pile. Through the in-situ test of a static pile with a length of 26 m in sand soil, the residual stress after the pile sinking was observed in the subsequent cyclic loading test, the three adjacent piles were sequentially pressed in, the second load test As well as long-term changes over longer periods of time, which lasted about 212 days. The results show that the cyclic loading test loading levels and the number of cycles will lead to further accumulation of residual stress. The stress of the residual pile of the existing pile is reduced when the adjacent piles are pressed in and the residual stress of the pile body which is consistent with the instantaneous penetration depth of the adjacent pile is most obvious. The residual stress of pile body will gradually dissipate to a certain stable value in a long time. The time effect is mainly related to the creep of sandy soil. It makes the soil arching effect weakened around the pile and reduces the contact pressure of the pile tip soil small.
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