为分析复杂环境条件下装配式悬吊下沉竖井工法周边地层变形规律以及各施工参数变化对地层变形的影响,依托竹园白龙港污水连通管工程建立三维有限元模型,对其开挖下沉全过程进行数值模拟,系统分析该工法施工过程中对地层变形的影响,并基于参数敏感性分析理论,得到土体最大变形对各施工参数的敏感度。分析结果表明: 1)装配式悬吊下沉竖井工法的地表最大沉降远小于软土地区传统压入式沉井工法的地表最大沉降,也小于上海一级基坑环境保护等级规定的地表最大沉降控制指标,适用于软土地区对地层变形控制要求较高的竖井工程。2)装配式悬吊下沉竖井工法的地表沉降形态随着开挖深度的增加,逐渐由三角形转变为凹槽形; 而土体深层最大水平位移始终发生在软弱土层处。3)在竹园白龙港工程17#井直径条件下,地表沉降影响范围为1.0H~1.4H(H为开挖深度),远小于软土地区基坑工程地表沉降影响范围。4)在竖井直径及一些主要施工参数中,泥浆液面高度和泥浆重度对土体变形的影响相较于其他施工参数更为显著,尤其是对于大直径竖井,对泥浆重度的控制应更为严格,并同时提高泥浆液面高度以减小对周边地层变形的影响。
The authors conduct a case
study on the Zhuyuan Bailonggang sewage connecting pipe project in Shanghai,
China, to examine the deformation patterns of the surrounding strata induced by
the construction of a prefabricated suspended sinking shaft under complex
environmental conditions. They also examine how varying construction parameters
influence strata deformation. Additionally, a three-dimensional finite element model is established to simulate the
shaft sinking process, enabling a systematic analysis of its effects on strata
deformation. Furthermore, parameter sensitivity analysis is employed to
determine the sensitivity of maximum soil deformation to various construction
parameters. The results reveal the following: (1) The maximum surface
settlement in soft soils induced by the construction of prefabricated suspended
sinking shafts in soft soils is significantly smaller than that associated with
the traditional press-in caisson method. The settlement
remains well within the allowable limits for foundation pits under Shanghai′s first-class environmental protection
standard. This demonstrates the suitability of this method for shaft
engineering in soft soil areas with stringent requirements for stratum
deformation control. (2) The surface settlement pattern transitions from a
triangle to a groove shape with increasing sinking depth. The maximum
horizontal displacement in the deep soil primarily occurs within weak soil
layers. (3) Under the shaft diameter conditions of this project, the influence
range of surface settlement is approximately 1.0H-1.4H (H refers
to excavation depth). This range is considerably smaller than that typically
observed in foundation pit projects in soft soil areas. (4) Among the
construction parameters, the slurry level and slurry unit weight exert the most
significant influence on soil deformation. For large-diameter
shafts, the slurry unit weight should be rigidly controlled. Meanwhile, the
slurry level can be raised to minimize the influence on the deformation of the
surrounding strata.