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挤扩支盘桩以其良好的承载性能及经济效益逐渐在房建及桥梁工程中得到使用,但是支盘桩施工后不同阶段及长期运营作用下的内力变化规律还不够明确。宁波绕城高速公路东段采用了部分支盘桩作为桥梁基础,首先采用静载荷试验确定了3根挤扩支盘桩的承载力,并采用振弦式钢筋计对这3根支盘桩在不同施工阶段及运营状态进行了长达2年的内力监测。结果表明:支盘桩中的支盘承担了相当部分的荷载,不同阶段下支盘分担的总荷载占桩顶荷载的30%~48%;桩顶荷载低于30%极限荷载时,最下层支盘基本没有发挥作用;在长期作用下,随着荷载的增加,桩身下部的承载能力逐渐发挥,支盘承担的荷载比例也有所增加。
With its good bearing capacity and economic benefits, the squeezed branch pile is gradually used in the construction and bridge engineering. However, the variation of the internal forces under different stages and long-term operation after the construction of the branch pile is not clear enough. In the eastern section of Ningbo Ring Expressway, some branch-supported piles are used as the bridge foundation. First, the static load test is used to determine the bearing capacity of the three extruded-expanded branch piles, and the vibration of the three branch piles Different construction stages and operating status for up to 2 years of internal force monitoring. The results show that the support plate in the branch pile takes a considerable part of the load. The total load shared by the branch plates accounts for 30% -48% of the pile top load at different stages. When the pile top load is lower than the 30% limit load, In the long term, with the increase of load, the bearing capacity of the lower part of the pile gradually shows up, and the proportion of the load carried by the branch plate also increases.