With the increasing development of underground spaces adjacent to urban levees, contact seepage frequently occurs at the interface between the soil and underground structures. However, traditional geophysical detection methods are often rendered ineffective in such environments due to spatial restrictions and detection blind spots. To address these challenges, this paper proposes a vertical-array lateral scanning detection method. This approach utilizes electrical resistivity tomography (ERT) with flat-base electrodes and ground-penetrating radar (GPR) to acquire data directly from vertical wall surfaces. The feasibility of this method is validated through numerical simulations and field data. The results indicate that the proposed method effectively overcomes the high-resistance shielding effect of hardened walls and clearly reveals the electrical structure of the soil behind the wall. Specifically, the contact seepage zone manifests as a layered low-resistivity feature immediately adjacent to the wall, while the penetrating leakage channel presents as a continuous low-resistivity anomaly extending from the contact interface deep into the levee body. These findings confirm the applicability of this technology for the qualitative identification and effective detection of hazards in complex, space-restricted urban environments.

Due to human activities, the evolution of the lower reaches of the Yangtze River is complex, and the underwater terrain near the docks is varied. There may be serious erosion and sedimentation of the bank slope, which will affect the stability and cause engineering accidents. To explore the changes in underwater terrain and their impacts, taking a dock in Jiangsu Province in China as an example, a multi-beam bathymetry system is used to conduct full coverage measurement of the underwater terrain at the front of the dock. A comprehensive analysis method for underwater terrain is proposed from the perspectives of contour lines, cross-sections, etc., in order to monitor the changes in erosion and sedimentation in the dock area. Then, the impact of underwater terrain changes on the bank slope stability is explored by simulating the bank slope soil and the concrete pile foundation. Targeted engineering measures to ensure the stability and safety of the dock and bank slope are proposed. The methods and conclusions proposed in this manuscript, including underwater terrain measurement, analysis of the impact of underwater terrain changes on stability, and recommendations for related engineering measures, will help to ensure the long-term safe operation of docks. This research will be of great significance in reducing water conservancy accidents and promoting sustainable and efficient development of water resources.