After installation of tunnel roof support, due to poor soil since the stability of surrounding rock and a certain distance between each excavation tunnel roof support in a short period of time did not close whole section, possible arch steel sinks and result in instability of surrounding rock or invade the lining boundaries, so need to strengthen in the process of construction of the tunnel roof support after installation of monitoring, when necessary, take effective measures to reinforce, in order to prevent the tunnel roof support sinking.
To strengthen the tunnel roof support locking foot fixation measures
Due to the partial excavation method, the arch of steel after installation, steel temporarily can't closed loop, the whole section at the same time, the soil arch tunnel of steel could not be located in solid rock, therefore, the arch of steel lock foot measures must be taken, the steel frame two foot firmly locked, to prevent steel sink or two foot recycling, steel lock foot using two L = 4.0 m Φ 42 anchor pipe lock lock foot, anchor pipe using spray of molten steel tube, pressure cementing slurry in anchorage, such as poor geologic, USES the extended length of anchor pipe and lock foot again add a lock foot anchor tube to strengthen the stability of the structure.
The tunnel roof support foundation is added to connect the longitudinal beam to expand the bottom foot of excavation to prevent the steel frame from hanging
In order to prevent the steel frame from sinking, depending on the geological conditions, when necessary, additional connection rail should be added at the bottom foot of the arch steel frame.
