Non-destructive Detection of the Anomalies and Thickness of a Shaft Using GPR
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ORIGINAL PAPER
Non-destructive Detection of the Anomalies and Thickness of a Shaft Using GPR Jiaqi Guo
. Binzhong Zhu . Yuan Qian . Guangjun Liu
Received: 4 March 2020 / Accepted: 1 April 2020 Ó Springer Nature Switzerland AG 2020
Abstract Ground penetrating radar (GPR) has been proven to be one of the most promising non-destructive methods that has been widely used in engineering quality inspections and condition assessments of underground structures. This paper reports an application study of GPR that presents a comprehensive survey of the auxiliary shaft of the Anli coal mine in China. During shaft installation, water gushing with a maximum inflow rate of approximately 16.0 m3/h occurred, and thus, it was urgent to determine the distribution range of anomalies and evaluate the lining thickness of the shaft to provide precise technical guidance for later treatments. A GPR grid scan was carried out by towing the antenna along 6 vertical measuring lines and 11 orthogonal circular measuring lines on the shaft surface. The GPR results show that the anomalies experienced by the shaft are voids, uncompacted areas and water bodies. Most anomalies were located in the outer shaft lining and surrounding soil. A vast majority of the shaft lining thickness reach its designed value, with a qualified rate of 91.2% for the inner shaft lining and 89.9% for the outer shaft lining, and the outer shaft lining exhibited inferior J. Guo (&) B. Zhu Y. Qian School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454003, Henan, China e-mail: [email protected] G. Liu CCCC-SHEC Fourth Highway Engineering Co., Ltd, Luoyang 471013, Henan, China
smoothness and uniformity. Under the guidance of the GPR results, a grouting treatment was carried out to water seal and strengthen the shaft lining, which, consequently, reduced the water inflow rate by 90%. The favourable grouting effect demonstrates that the GPR method can feasibly and successfully reflect the shaft lining and anomalies in shaft assessments. This engineering practice could serve as a case study reference for investigating any similar underground structure in the future. Keywords Ground penetrating radar Nondestructive detection Anomaly Auxiliary shaft Thickness
1 Introduction Underground construction is in great demand in many civil facilities and infrastructure projects worldwide (Qian and Lin 2016; Gamayunova and Gumerova 2016; Nelson 2016), such as highway and railway tunnels, urban metros, utility tunnels, energy underground engineering (e.g., coal mines, hydropower projects and underground petroleum storage caverns) and other underground facilities. Unfavourable geological conditions, material weathering due to harsh environmental conditions, deficient structural performance, poor construction quality, etc. may cause
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Geotech Geol Eng
damage to the underground structural integrity during the construction period or its service stage (Zhang et al. 2018; Inokuma and Inano 1996). In comparison to the
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