There are more non-dense areas at this point, there is a small cavity about 150cm deep in mark 1 position, there is also a lack of concrete fragmentation in the upper right crack, there is a lack of compaction in mark 2 position on the right side, the depth is 50cm~150cm, there are other more non-dense places in this section. At this time, two typical points were selected for marking records.
At this point, there are voids intermixed with gravel, and there are voids in the right measurement with a depth of about 84cm, while there are small voids and voids in the data of 6800 channels with a depth of 123cm.