(1) Preparation work.
During construction, a reliable work platform must be set up to protect belt conveyors, pipelines and other equipment, and create a suitable construction space and work height for the construction personnel. The length of the working platform is 3m (the width of the roadway of the original nose section), the width is 1.5 m, and the height is 1.2 m; the tunnel roof support and cross bars are erected with ∮51 mm steel pipes, and the joints are firmly connected by connectors, matching 3.00 mx0.30 m x0 The .02 m frame board is made into a steel arch support working platform.
(2) Lifting and supporting.
The length of the support arch f is not more than 1.2 m each time. After the support arch is raised, find the roof in time, check the specification and quality of the tunnel roof support, and perform the initial spraying in time (the concrete spraying thickness is 50 mm) after meeting the requirements. Floating gangue, etc. are cleaned up.
After the temporary top support arch is completed, the belt conveyor shall be maintained in time, and the original nose section shall be expanded according to the requirements of the width of the reconstructed nose section.
1) The expansion is carried out on a single side, and the length of each expansion does not exceed 1.2 m. The original head section is masonry made of rough stone. Due to the poor stability of the surrounding rock of the roadway, the rock formation is not hard. Therefore, vibration blasting is not required when expanding the gang. Manually pry off the rough stone, and expand the nose section to the designed section with a hand pick. After the expansion, spray 50 mm thick concrete for temporary support in time.
2)After the roadway is expanded to the Mao section, the U-shaped steel arch support shall be erected in time. In the process of erecting the U-shaped steel support, the metal nets are hung along the top and the top in time.
(4) After all the work such as lifting, expanding and initial spraying of the standby head section is completed, the two ends of the lifting beam and the arch wall of the steel arch support head section shall be leveled and solidified with concrete. Finally, the top and side of the entire nose section are supported by double spraying concrete, and the double spraying is carried out in 2 times until the design thickness is reached.
