Next Article in Journal
Fractal Dimension Analysis Applied to Soil CO2 Fluxes in Campotosto’s Seismic Area, Central Italy
Previous Article in Journal
A Computer Aided Approach for River Styles—Inspired Characterization of Large Basins: A Structured Procedure and Support Tools
Previous Article in Special Issue
Three-Dimensional Response of the Supported-Deep Excavation System: Case Study of a Large Scale Underground Metro Station
Open AccessArticle

Investigation of Geological Anomalies at Pile Foundation Location in Urban Karst Areas Using Single Borehole Radar

by Liu Liu 1,2,3, Zhenming Shi 1,2, Ming Peng 1,2,* and Georgios P. Tsoflias 3
Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China
Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai 200092, China
Department of Geology, The University of Kansas, Lawrence, KS 66045, USA
Author to whom correspondence should be addressed.
Geosciences 2020, 10(6), 232;
Received: 20 May 2020 / Revised: 6 June 2020 / Accepted: 9 June 2020 / Published: 16 June 2020
(This article belongs to the Special Issue Urban Geophysics)
Karst geological anomalies at pile locations significantly affect the bearing capacity and construction safety of the piles, posing a significant challenge for urbanization. Borehole geophysical methods are required to extend the detection range and identify karst voids that are at pole locations and near drilled boreholes. In this paper, we developed a near offset and small diameter single borehole ground penetration radar (GPR) prototype. A signal processing method combining complex signal analysis by Hilbert transform (HT) and medium filtering was suggested to differentiate the weak backscattered wave from borehole background noise. A controlled horizontal borehole experiment was used to demonstrate the applicability of the prototype and the advantages of the signal analysis method prior to application in a real project. The controlled test presented three typical wave events corresponding to a soil–rock interface, rock fractures, and karst voids. Field tests were conducted at a freeway bridge extension project in an urban karst area. Multiple karst voids, sinkholes, rock fractures, and integrated bedrock were identified by analysis of four typical detection scenarios. The remediation of the karst voids and a rotary bored piling with real-time steel casing construction strategy were designed based on the investigation results. The construction feedback demonstrates that single borehole radar detection is effective for the investigation of anomalies at pile locations in urban karst areas. View Full-Text
Keywords: karst; single borehole GPR; pile foundation; urban geophysics karst; single borehole GPR; pile foundation; urban geophysics
Show Figures

Figure 1

MDPI and ACS Style

Liu, L.; Shi, Z.; Peng, M.; Tsoflias, G.P. Investigation of Geological Anomalies at Pile Foundation Location in Urban Karst Areas Using Single Borehole Radar. Geosciences 2020, 10, 232.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Search more from Scilit
Back to TopTop