Subsurface ground movements due to circular shaft construction

Abstract

The rapid development of modern metropolises has led to a shortage of surface space and in response engineers have pursued alternatives below ground level. Shafts are commonly used to provide temporary access to the subsurface for tunnelling and, as permanent works, are utilised for lifts or ventilation purposes. The construction sequence of axisymmetric shafts makes them a dramatically simple solution. In addition, circular shafts are inherently stiffer than other plan geometries. Those, perhaps, are reasons why circular shafts are preferred in situations of restricted space or unfavourable ground conditions. However, due to the lack of case histories reporting ground movements induced by shaft construction, no empirical prediction method for subsurface soil displacements exists. The work presented here seeks to provide clearer insights into surface and subsurface soil displacements induced by circular shaft construction by means of analysis on measurements obtained from centrifuge tests and available field data. Novel empirical equations and procedures are suggested for practical use.

Analytical prediction of ground movements due to circular shaft construction in clayey soils

“…(2017); New and Bowers (1994); Newhouse (2017) in case histories using different construction methods in stiff clay, additionally to the high-quality centrifuge test results of Le et al (2019) conducted in clay. Table 1 summarizes final excavation depth (𝐻), the wall length (𝐻 𝑤 ), the diameter of the shaft (𝐷), the construction method, and the ground conditions.…”

“…Current studies on ground movements induced by deep excavations focused on rectangular pits (Hsiung, 2020;Ng et al, 2020Ng et al, , 2012Teng et al, 2018;Yoo and Lee, 2008); for plane-strain excavations and rectangular pits, there have been successful applications of elastic theory to vertical and horizontal displacement prediction (Fan et al, 2021;Lei et al, 2001;Ng and Yan, 1998;Ng and Lei, 2003). However, despite the availability of history case studies of circular shaft construction (Faustin et al, 2017(Faustin et al, , 2018Tan and Wang, 2013;Wong and Kaiser, 1988), that could be used to calibrate similar analytical solutions, practical methods for preliminary prediction of induced soil movements in shafts are limited to empirical methods (Le et al, 2019;New and Bowers, 1994). In particular, New and Bowers (1994) presented an empirical formula to predict the surface settlements by shaft construction calibrated on the monitoring data from one shaft at Heathrow Express Trial tunnel in stiff clay.…”

“…Ground movements arising from the excavation of circular shafts using SBE are smaller compared with the EBS and combined method that may also be characterized by a degree of overexcavation (as for tunnelling). In addition, the estimation of subsurface soil movements is also of interest; Le et al (2019) performed centrifuge tests in kaolin clay to investigate the effects of pre-install shaft construction and suggested two empirical equations to describe the distributions of subsurface soil movements. Alternately, advanced numerical modelling (Lai et al, 2020;Schwamb and Soga, 2015) is an effective tool for the design of shaft.…”

Research on the Stress and Deformation Characteristics of Circular Foundation Pit during Excavation in Sand Soil

“…Existing parameter of the selection methods focusses on probabilistic inverse analysis. Te feld practicability of the research results is poor, and there is a lack of a parameter checking method that can link feld monitoring and numerical simulation [19][20][21]. Terefore, it is of great theoretical and practical signifcance to propose and establish a new method for parameter checking, and to carry out research on the deformation response mechanism of deep soil under circular foundation pit excavation and support.…”

Design and Research of Intelligent Safety Monitoring Robot for Coal Mine Shaft Construction

“…ere are 1367.681 billion tons of coal resources in the buried depth of 1500-2000 m, among which the reliable coal resources are 329.229 billion tons, accounting for 30.1% of the predicted total amount. With the exploitation of deep coal resources, the depth of coal mine shafts [2] is keeping breaking records, and higher requirements are put forward for coal mine construction, especially deep shaft construction [3]. Due to the coupling action of temperature and pressure on deep rocks, coupled with the rock characteristics of strata, complex stratification, and joint structure, the shaft construction is faced with a variety of disasters such as water damage, gas, lifting, transportation, and falling [4,5].…”