The length of Qingdao subsea tunnel is 7 120 m, whose tunnel length is 6 170 m (undersea segment about 3 950m). The tunnel is divided into four sections, the hidden digging section of the third construction contract section is 3 214 m. Different from the traditional method of tunnel construction, Qingdao subsea tunnel uses steel grid arch sprayed concrete and anchor bolt supporting, thus ensures the stability of surrounding rock. Its geological structure is mainly volcanic and intrusive rocks, high-angle faults, northeast and northwest trend and mostly crushed breccia rubble in the fault .
It adopts the three-arm hydraulic drilling rig to drill hole and install anchor bolt in Qingdao subsea tunnel construction. The diameter of drill bit is 50 mm. The multiple corrosion anchor bolt is long 3.5 m, an outer diameter of 22 mm, elongation ≥10%, tensile strength of 3210 kN, made of HRB400 grade 45. D. When the 95% of anchor bolt is into the hole during drilling, adjust the position of the plate firmly against the concrete surface.