Application of gravity gradient measurement in the detection of urban underground space

With the continuous progress of urbanization, the safe development and utilization of urban underground space becomes increasingly important. Microgravity measurement technology (including gravity and gravity gradient) has gained widespread use in urban underground space exploration, such as urban ground crack detection and underground cavity detection, due to its advantages of high efficiency, low cost, and broad application. This study describes the composition and working principle of the self-developed quantum gravity gradiometer of Zhejiang University of Technology and analyzes the gravity and gravity gradient anomaly characteristics of subsurface anomalies at different depths through model simulations. The results show that gravity gradient anomalies are more effectively identified than gravity anomalies within a certain depth range at shallow depths. Additionally, this study analyzes the recognition capabilities for anomaly radius, burial depth, and surrounding rock density differences when the gravity gradient accuracy is 1E, providing valuable reference and guidance for practical applications for quantum gravity gradiometer in urban underground space detection. Finally, field measurement data are used to validate the effectiveness, advantages, and challenges of gravity gradient measurement technology in urban underground space detection. This results indicate that gravity gradient measurement technology holds significant potential for urban underground space detection, offering more accurate and reliable data to support the development and utilization of urban underground spaces.