1, the circular arc template is made. 1.22*2.44*0.0 1m bamboo veneer is selected as the circular arc template. Considering the template thickness is 1cm, the circular arc radius is adjusted according to the diameter of each culvert, with three pieces, the chord height is 30cm, one piece is installed in the middle, and the other two side plates are horizontally spaced by 5.

2. Construction of cement mortar for the lower semicircle: firstly, the bottom of the lower semicircle is constructed, then the two sides are constructed, and then the two sides are constructed after the mortar strength at the bottom meets the requirements. During construction on both sides, circular arc formwork shall be used for symmetrical construction. In order to ensure the mortar thickness and construction quality, 8mm spiral ribs are placed between the formwork and the steel corrugated pipe, with no less than 4 ribs per square, and an expansion joint with a width of 1cm is set in the 6 m construction section. When constructing the next section, pay attention to the joint.

3. Semi-circular construction is carried out in three times, first on both sides and then on the top. A steel bar with a diameter of 16 is arranged at 30 degrees along the horizontal bolts on both sides to increase the rigidity of steel wire mesh and the integrity of composite mortar, and five arcs are arranged. At the same position as the bolt, the bolt is fixed with iron wire, and the middle part of the two bolts is supported by internal and external scaffolding. Pay attention to the loose mortar at the joint before construction on both sides, and apply the cement slurry with the same label before installing the template. The upper and middle parts are supported by spiral ribs with a diameter of 8mm to ensure the thickness of mortar, and the construction is symmetrical on both sides. Template construction is fixed with tic-tac-toe scaffolding, with 15cm space at both ends for adjusting and fixing the jack-up of movable scaffolding. Pour the mortar into the top and vibrate it with a small hammer. During roof construction, pay attention to leave 15* 15cm square holes for mortar pouring, and pay attention to the fullness of mortar. To prevent holes from appearing at the top, the formwork can only be removed when the strength reaches 5Mpa. Pay attention to curing and watering, and pay attention to the joint is not dense, which will affect the service life and quality of steel corrugated pipe.

Second, the artificial plastering construction method

First, install the steel wire mesh. Installation method is the same as above. Install steel wire mesh under artificial pressure, and apply composite mortar for three times. For the first time, paste the gap between the steel wire mesh and the concrete surface of the section to be reinforced. Apply it for a second time immediately after the initial setting, and it is not allowed to exceed 12 hours. After initial setting, apply it for the third time to the design thickness. The thickness of each smear should not exceed half of the total thickness. Try to avoid repeated pressure application.

After the plastering of composite mortar is completed, it should be covered with plastic sheets in time. After the final setting of composite mortar, it should be kept moist for 24 hours, watered in time, kept wet for 7 days and naturally maintained for 28 days.