Deformation characteristics of ultra-deep circular shaft in soft soil: A case study

IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL
Yafei Qiao , Feng Xie , Zhanwei Bai , Jiafeng Lu , Wenqi Ding
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Abstract

A circular shaft is often used to access a working well for deep underground space utilization. As the depth of underground space increases, the excavation depth of the shaft increases. In this study, the deformation characteristics of a circular shaft with a depth of 56.3 m were presented and analysed. The main monitoring contents included: (1) wall deflection; (2) vertical wall movement; (3) horizontal soil movement; (4) vertical surface movement; and (5) basal heave. Horizontally, the maximum wall deflection was only 7.7 mm. Compared with the wall deflection data collected for another 29 circular excavations, the ratio of maximum wall deflection to excavation depth of this shaft was smaller due to a smaller ratio of diameter to excavation depth. The wall deflection underwent two stages of deformation: the first stage was mainly circumferential compression caused by the mutual extrusion of joints between walls, and the second stage was typical vertical deflection deformation. The horizontal soil movement outside the shaft was greater than the wall deflection and the deep soil caused great horizontal movement because of dewatering at confined water layers. Vertically, a basal heave of 203.8 mm occurred in the pit centre near the bottom. Meanwhile, the shaft was uplifted over time and showed 3 stages of vertical movement. The surface outside the shaft exhibited settlement and uplift deformation at different locations due to different effects. The basal heave caused by excavation was the dominant factor, driving the vertical movement of the shaft as well as the surrounding surface. The correlation between the wall deflection and the surface settlement outside the shaft was weak.

软土中超深圆形竖井的变形特征:案例研究
圆形竖井通常用于进入工作井,以利用深层地下空间。随着地下空间深度的增加,竖井的挖掘深度也随之增加。本研究介绍并分析了一个深度为 56.3 米的圆形竖井的变形特征。主要监测内容包括(1) 井壁挠度;(2) 井壁垂直移动;(3) 土壤水平移动;(4) 地表垂直移动;以及 (5) 基底隆起。在水平方向上,墙体的最大挠度仅为 7.7 毫米。与其他 29 个圆形挖掘坑的坑壁挠度数据相比,该竖井的最大坑壁挠度与挖掘深度的比率较小,这是因为直径与挖掘深度的比率较小。井壁挠度经历了两个变形阶段:第一阶段主要是井壁之间接缝的相互挤压引起的周向压缩,第二阶段是典型的垂直挠度变形。竖井外的土体水平运动大于井壁挠度,深层土体由于承压水层的脱水而产生了巨大的水平运动。在垂直方向上,基坑中心靠近底部的位置出现了 203.8 毫米的基底隆起。同时,竖井随着时间的推移而隆起,并出现了三个阶段的垂直移动。由于受到不同影响,竖井外表面在不同位置出现了沉降和隆起变形。开挖引起的基底隆起是主要因素,推动了竖井和周围地表的垂直运动。井壁挠度与井筒外表面沉降之间的相关性很弱。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Underground Space
Underground Space ENGINEERING, CIVIL-
CiteScore
10.20
自引率
14.10%
发文量
71
审稿时长
63 days
期刊介绍: Underground Space is an open access international journal without article processing charges (APC) committed to serving as a scientific forum for researchers and practitioners in the field of underground engineering. The journal welcomes manuscripts that deal with original theories, methods, technologies, and important applications throughout the life-cycle of underground projects, including planning, design, operation and maintenance, disaster prevention, and demolition. The journal is particularly interested in manuscripts related to the latest development of smart underground engineering from the perspectives of resilience, resources saving, environmental friendliness, humanity, and artificial intelligence. The manuscripts are expected to have significant innovation and potential impact in the field of underground engineering, and should have clear association with or application in underground projects.
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