What are the steel reinforcement installation requirements of the tunnel lining trolley?
Tunnel trolley is a relatively common product on highways. The installation of tunnel lining trolleys is relatively complicated. First, choose the installation location, and then install the walking wheel frame assembly, various accessories, accessories and systems. And so on, but the installation of steel bars is more important in the entire installation and use process, because it is related to the subsequent use. Then, what are the installation requirements of the lining trolley, let’s take a closer look!
1) Each node of the transverse reinforcement and the longitudinal reinforcement should be tied or welded;
2) The welded lap length of the steel bar shall meet the design and specification requirements, the lap joint of the stressed main bar shall be welded, and the welded lap length and weld shall meet the requirements of the specification;
3) The overlapping positions of adjacent main bars should be staggered, and the staggered distance should not be less than 1000mm;
4) The two overlapping distances of the same stressed steel bar should not be less than 1500mm;
5) The connection point of the stirrup should be at the cross connection of the longitudinal and longitudinal ribs, and should be tied or welded;
6) Other connection methods of steel bars should comply with relevant specifications;
7) When installing steel bars, the length, spacing, position and thickness of the protective layer of the steel bars should meet the design requirements.
Reinforcing steel bars should be positioned according to the design outline. In order to ensure that the positioning of the secondary lining steel bars is accurate and the thickness of the steel protection layer meets the requirements, the following measures should be taken:
(1) First, the surveyor uses coordinates to set out the center points of the front and rear two steel bars within the scope of the self-made trolley on the leveling layer and the vault waterproof layer, and determine the normal direction to ensure the verticality and verticality of the positioning steel bars. The accuracy of the arch reserved steel connection. The verticality of steel tying is determined by the method of three-point hanging ball.
(2) Use a level to measure the elevation of the center point of the positioning steel bar on the leveling layer, calculate the height difference between the center of the mileage and the center point on the leveling layer, and use a self-made tripod to determine the center of the circle.
(3) After the center of the circle is determined, use the ruler method to check whether the size of the positioning steel bar meets the design requirements, re-adjust the positions that do not meet the requirements, and fix the steel bars after all meet the requirements. The steel bar is fixed by the adjustable support rod welded by steel pipe on the self-made trolley.
(4) After the positioning steel bars are fixed, use chalk to mark the location of the circumferential main reinforcing bars on the support rods according to the design steel bar spacing, mark the installation positions of the longitudinally distributed ribs on the positioning steel bars, and then start binding the steel bars within this section. The intersection of steel bars should be tied.
In short, the tunnel lining trolley manufacturer specially reminded that the steel protection layer should be controlled by high-strength mortar pads, and plastic pads should not be used. It is required that the longitudinal spacing of the main ribs, the circumferential spacing of the distributed ribs, the horizontal spacing of the inner and outer layers, and the thickness of the protective layer meet the design requirements.