1. The foundation is poured on site and the foundation pit is excavated manually. For the rock parts that cannot be excavated manually, shallow holes are drilled with pneumatic picks or air guns, supplemented by weak blasting, and the upper soil pit wall is excavated obliquely, while the lower rock pit wall is vertical. The slope of foundation pit excavation depends on the ground, and the size of foundation pit should conform to the outline of foundation pit. Before the installation of concrete foundation, check the size, plane position, ground flatness and compactness of foundation pit in time, and then carry out foundation construction.

2. Basic inspection

Before pouring foundation concrete, the foundation pit should be inspected. The contents of the inspection are as follows: ① Whether the plane position and elevation of the foundation meet the requirements of the specification. (2) whether the foundation soil conforms to the specification and whether the bearing capacity meets the specification requirements. (3) Whether the low foundation has accumulated water, sundries and loose soil, and whether it is clean and flat.

Treatment of low foundation: when the low foundation is dry soil, it should be wetted, and a layer of gravel should be rammed at the design elevation of low foundation. When the low foundation is rock, it should be wet and covered with a layer of cement mortar, and the foundation concrete construction should be carried out before the mortar solidifies.

3. Foundation concrete pouring

The foundation shall not be exposed for a long time after excavation, and the concrete foundation shall be poured as soon as possible, and its position, stability and elevation shall be guaranteed when pouring the foundation: the concrete foundation size of the column is 400 mm * 300 mm

Matters needing attention

There should be no obvious distortion, welding and lengthening of the column, and the burr at the end should be removed. Column lofting should be based on the control points on the highway, and the column spacing should be appropriately adjusted according to the distance. The installation of the column shall conform to the design drawings and be in harmony with the road alignment. The column must be firmly buried in the soil, and the buried depth must reach the depth specified in the design and be perpendicular to the ground plane. (2) No matter what method is adopted to install the guardrail, the contractor shall try to avoid damaging the pipeline facilities buried under the pavement. If damage is caused, the contractor shall be responsible for the repair, and the repair cost after damage shall be borne by the contractor. (3) After the guardrail is installed, a smooth linear shape should be formed in the horizontal and vertical directions. Good guidance should be given to the landscape and the driver's sight.

The corrugated beam guardrail installed on the roadside should not make the guardrail surface invade the boundary of highway buildings. Generally, corrugated beams and plates should be formed by continuous rolling. Bolt holes on corrugated beams must be located accurately. All splicing bolts and splicing at each end should not be tightened prematurely. From the installation of the column to the installation of the column cap, sundries should be prevented from falling into the column. Connecting bolts and splicing of corrugated beams should not be tightened prematurely. Before tightening the connecting bolts, adjust the bracket (anti-blocking block) to the exact position.

Importance of installing highway guardrail: installing highway guardrail actually reduces the traffic accident rate and the safety of residents' travel.