## 3 Results
### Cross-Well Seismic Computed Tomography Results  
The layout diagram of the cross-well seismic computed tomography imaging survey lines is presented in Figure 3. In this study, three representative groups of profiles were selected for detection, which were TMCT 1-TMCT 2, providing the cross-well seismic computed tomography profile in the south of the urban village near the pond to verify the potential water conduction channel at 120 m of the G1-G2 line of the electrical resistivity tomography method; TMCT 3-TMCT 4, providing the cross-well seismic computed tomography profile in the middle of the urban village and verifying the small karst at 135 m and 25 m depth in section G4; and TMCT 5-TMCT 6, providing the profile in the northernmost part of the urban village, verifying the integrity of the limestone in the 0-60 m blind area of the G3-G5 measurement line of the electrical resistivity tomography method. The six boreholes are mainly distributed at the roadside which is convenient for operation and inside the wide alley. The data processing results are shown in Figure 7.  
In the section TMCT 1-TMCT 2, the wave velocity within the soil layer is less than 2000 m/s, while the maximum wave velocity in the bedrock region reaches approximately 4500 m/s. The geotechnical interface is situated at a depth of approximately 27 m. Numerous low-velocity anomalies are observed between the two boreholes. Specifically, low-velocity zones identified during drilling at depths of 29-33 m and 39-45 m in borehole 1, and 37-39 m in borehole 2, were confirmed to be karst cavities. Additionally, two large-scale interconnected anomalous traps were detected in the central section of the profile at depths of 33-39 m, exhibiting a wave velocity of 1800 m/s, which suggests the presence of bead-like karst cavities. The corollary for the G1-G2 profile of the electrical resistivity tomography method is proved.  
In sections TMCT 3 to TMCT 4, the rock-soil interfaces exposed by boreholes exhibit depths of 23 m and 14 m, respectively. The intact bedrock exhibits a wave velocity of up to 5800 m/s. In the middle section and the vicinity of hole 4, a large low-velocity band with a wave velocity between 3200 and 4200 m/s is observed, which could be interpreted as filling caves. This indicates that the region is influenced by the groundwater dissolution process, but is significantly weakened relative to the southern region.  
In sections TMCT 5 to TMCT 6, the majority of the bedrock maintains a wave velocity of approximately 5800 m/s, with only a minor low-velocity zone present near borehole 5, where the wave velocity still reaches 4500 m/s. This indicates that while the area is also affected by groundwater activity, the influence is comparatively weaker.  
Figure 6: Inversion results and geological interpretation maps of resistivity tomography detection data from sections G3–G5.  
Based on the results of cross-well seismic computed tomography imaging interpretation and borehole records, it can be concluded that the rock-soil interface in this region exhibits significant variability, ranging from 14 to 35 m, without a clear pattern. The location of caves, bedrock wave velocity, and the distribution of dissolution zones are strongly correlated with proximity to the pond. From a large number of karst caves in the southernmost part to the TMCT 3-TMCT 4 section in the middle of Tianmeixin village, the karst area and the degree of erosion decreased significantly, and the minor karst of TMCT 5-TMCT 6 was no longer necessary to treat. Therefore, future cross-well seismic computed tomography detection efforts should prioritize the southern section of the network. In the northern region, boreholes may be reduced or eliminated as appropriate to minimize drilling operations. The next cross-well seismic computed tomography detection area is marked by the red box in Figure 3, which is reduced by about two-fifths compared with the original detection area, and the amount of drilling is reduced by nearly 20 holes.