摘要
为研究膨胀土地层中基坑SMW工法桩加支撑围护结构的服役性能,本文以扬州瘦西湖隧道工程为依托,开展现场试验,分析了桩顶水平位移、桩顶沉降、支撑内力、地表沉降、地下水位等关键指标变化规律,论证了膨胀土地层中基坑SMW工法桩加支撑围护结构的可靠性与适应性,得出的主要结论有:SMW工法桩加支撑围护结构在膨胀土地层基坑中能很好地控制基坑围护变形;开挖过程中,桩顶水平位移体现出向基坑内侧位移变化的趋势、桩顶竖向位移体现为整体向上移动的特点;当混凝土支撑、钢支撑等多道支撑组合受力时,支撑的架设与拆除对其他支撑受力将产生明显影响,降雨可导致膨胀土压力增大、支撑轴力出现局部量值波动;基坑附近地表均发生不同程度的沉降,随着距离围护结构距离的增大,呈现出'汤勺'变化;开挖后期地下水位保持稳定,论证了 SMW工法桩加支撑围护结构具有较好的止水效果.研究结果可为膨胀土地层及类似地层中土建施工提供经验参考.
In order to study the service performance of the SMW method pile and support retaining structure in the expansive soil layer foundation pit,based on the project of Yangzhou Slender West Lake Tunnel, the field test was carried out to focus on the change regulations of key indicators, such as the pile top horizontal displacement, pile top settlement,support internal force, surface settlement and the groundwater level etc.,and obtained the reliability and adaptability of the SMW method pile and the support retaining structure in the foundation pit. The main conclusions are as follows: the SMW method and support retaining structure can control the deformation of the foundation pit well. The horizontal displacement of the pile top reflects the change trend of the displacement to the inner side of the foundation pit and the vertical displacement is characterized by the whole upward movement during the excavation process. When the multiple support combinations such as concrete support and steel support are forced,the erecting and dismantling of support will have an obvious effect on other supporting forces. The rainfall can cause the expansion of the expansive soil pressure and the local fluctuation of the support axis force, and there are different degrees of settlement on the ground near the foundation pit. The settlement, with the increase of enclosure structure distance, shows the change of 'soup ladle', and the underground water level is stable in the later period of the excavation. It is demonstrated that the SMW pile and the supporting structure have better water sealing effect. The research results could provide a reference for civil construction in expansive soil layer and similar strata.
作者
孙锋
Sun Feng(China Railway 14th Bureau Group Large Shield Engineering Co.Ltd.,Nanjing Jiangsu 211800,China)
出处
《铁道建筑技术》
2018年第A02期202-206,共5页
Railway Construction Technology
基金
国家自然科学基金项目(51578462).
关键词
SMW工法桩
膨胀土
基坑围护
现场试验
地表沉降
SMW method pile
expansive soil
bracing of foundation pit
field test
surface settlement
