Integrated TEM and GPR data interpretation for high-resolution measurement of urban underground space

Ground penetrating radar (GPR) and transient electromagnetic (TEM) technologies can detect urban underground space efficiently and with good sensitivity. These two technologies have complementary advantages, but they are often used independently in urban underground space detection and are rarely used for the integrated interpretation of urban geology. To realize the high-resolution measurement of urban underground space, we take the shallow structure information of GPR as the input information of TEM inversion and use the transdimensional Bayesian (Trans-Bayes) inversion method to realize an integrated interpretation of TEM and GPR data. The simulation results show that, compared with inversion using only TEM data, an integrated inversion improves the accuracy of the inversion results, retains the lateral smoothness of the 2-D model, and reduces the multiple solutions of the TEM inversion. In addition, the richer the layer interface information provided by GPR, the more significant the improvement in inversion quality. We successfully applied GPR and TEM technologies to the accurate detection of an urban underground air-raid shelter area and verified the superiority of GPR in improving the resolution of TEM shallow geological imaging. The combination of GPR and TEM provides a new idea for the high-resolution measurement of urban underground space geology and has practical application value in the accurate early warning of underground water gushing and road collapse accidents.