Identification and Treatment of Collapse and Mud Inrush Caused by Deep Karst Trough in Tunnels

Table 1

Surface detection result of GPR.

Survey line	Location	Depth to tunnel vault/m	Detection results
1	GK0+386.5	14.353	Within the depth of 0~5 m, there may be accumulative layer or Quaternary clay layer, with serious weathering and large pores. Corrosion fissures are developed at the depth of 8~16 m, and small karst caves may exist at about 20 m below.
2	GK0+390	13.968	Corrosion fissures and pores are relatively developed at the depth of 2~12 m, and the rock mass is relatively broken. The corrosion fissures within the depth of 15~22 m are abnormally developed, and there may be small cavities.
3	GK0+398.6	13.981	Within the depth of 8~20 m, corrosion fissures and pores are relatively developed, and the rock mass is relatively broken.