(1) To ensure the width of the roadbed, the roadbed should be widened by 0.5m on each side. After leveling the basement soil, it should be pressed twice by 25T vibratory roller, and then four times by 50T earthquake. The uneven areas should be leveled manually.

(2) Paving 0.3m thick medium (coarse) sand, manual leveling with mechanical, 25T vibratory roller static pressure twice.

(3) When laying geogrid, the bottom surface should be flat and compact. Generally, the geogrid should be laid flat, straightened, not overlapping, not curling and twisting. The adjacent two geogrids need to be overlapped by 0.2m, and the overlapping part of geogrid should be connected by 8 wires every 1m along the subgrade transversely, and fixed to the ground with U-nails every 1.5-2m.

(4) After the first layer of geogrid is laid, the second layer of 0.2m thick medium (coarse) sand is filled. The method is that the car carries sand to the construction site and unloads it on one side of the roadbed, and then pushes it forward with a bulldozer. After filling 0.1M on both sides of the roadbed, the first layer of geogrid is folded up and then filled with 0.1M medium (coarse) sand. It is forbidden to fill and advance in the middle of both sides, and all kinds of machines are forbidden. The machine works on the geogrids without filling medium (coarse) sand, so that the geogrids can be smooth, not bulging, not wrinkling. After the second layer of medium (coarse) sand is leveled, horizontal measurement should be carried out to prevent uneven filling thickness, and static pressing with 25T vibratory roller twice after placing the grids correctly.

(5) The construction method of the second layer geogrid is the same as that of the first layer. Finally, 0.3 m of medium (coarse) sand is filled. The filling method is the same as that of the first layer. After two times of static pressing with a 25T roller, the subgrade foundation is strengthened.

(6) After the third layer of medium (coarse) sand is rolled and compacted, two geogrids are laid vertically along the line on both sides of the slope, overlapped with 0.16m, and connected by the same method. Then the earthwork construction is started and the geogrids are laid for slope protection. The laying boundary must be measured at each layer, and the geogrids should be buried in the slope after the slope is renovated at 0.10m on each side.

(7) When the slope geogrid is filled with two layers of soil, i.e. 0.8m thick, it is necessary to lay a layer of Geogrid on both sides at the same time, and so on, until it is laid under the surface soil of the shoulder.

(8) After filling the roadbed, the slope should be repaired in time, and the dry masonry stone at the foot of the slope should be protected. Besides widening each side of the roadbed by 0.3 m, 1.5% of the settlement should be reserved.