超深地连墙槽壁侧压力演变模式及其施工扰动分析

Evolution mode of lateral pressure on the trench wall and disturbance analysis during construction of super-deep diaphragm wall

地连墙施工扰动的精细分析对预测基坑开挖的环境影响十分重要,尤其是超深基坑。因此,收集分析了某102 m超深地连墙施工过程中的泥浆压力和混凝土压力现场实测数据,总结了槽壁侧压力的演变规律和竖向分布模式,提出了混凝土浇筑过程中槽壁侧压力的三折线模型并验证。三折线模型可以再现槽壁侧压力先增大后减小的趋势,并可退化为双折线模型。最后采用三折线模型建立了精细化数值模型,模拟了百米地连墙的成槽开挖及混凝土浇筑过程,分析了连续墙施工对槽段周围土体应力与变形的影响,并将计算结果与双折线模型结果进行了对比。结果表明:超深地下连续墙施工会引起周围土体的应力重分布,其影响范围在沿槽段方向为1.6倍槽段长度,在垂直槽段方向为4.3倍槽段长度;土体应力重分布有沿竖向和水平向传递两种机制,且以水平向传递为主。在上海软土地区,地下连续墙混凝土的浇筑会对槽壁产生挤压作用,引起槽段体积增大,进而导致混凝土浇筑量的增大。

The detailed analysis of disturbance induced by diaphragm wall construction plays an important role in predicting the environmental influence of deep excavations,especially the super-deep excavation.Therefore,this paper collected and analyzed the field data of slurry pressure and concrete pressure during the construction of a 102 m super-deep diaphragm wall.The evolution law and vertical distribution mode of the lateral pressure on the trench wall during the construction were summarized,followed by a new proposed tri-line model of lateral pressure on the trench wall and its validation.The proposed tri-line model can well capture the first increase and then decrease trend of the lateral pressure on the trench,and it can return to the classic bi-line model.Finally,the fine numerical simulation of the construction process of a 102 m diaphragm wall,including the trenching and concreting,was performed adopting both the tri-line model and bi-line model.The stress state and deformation of soils around the trench were analyzed and compared.The results revealed that the construction of super-deep diaphragm walls can lead to the stress redistribution of adjacent soil.The effect zone is about 1.6D(D is the panel length)along the panel direction and about 4.3D perpendicular to the panel.The stress redistribution is controlled by vertical and horizontal transfer mechanisms,and the horizontal transfer mechanism dominates.In Shanghai soft soil area,the concreting would compress the trench wall and increase the trench volume,causing the increase of concrete volume.