Quality Control of Large Dameter Corrugated Steel Culvert in Rainy Mountain Areas

Our corrugated pipe culverts were used on some mountain rainy area highway. The site construction situation is as bellow: The roadbed wide is 26m, including steel corrugated pipe 43m, the filling height of centre of the culvert is 7.9m, the culvert diameter is 5m,The culvert is located in the gully and is mainly used for drainage in mountainous areas during the rainy season, the horizontal height difference is 10.2m, and the cross slop is 23%.There is obvious uneven settlement in the foundation.

By studying the stress performance of large diameter steel corrugated pipe culvert, and the site situation of obvious uneven settlement foundation, by controlling quality of foundation treatment, pipeline splicing, material quality, abutment compaction, cap beam pouring, and inlet cut-off wall, the project quality of strength design requirement and withstand heavy rain can be ensured , we can get reliable data and experience in quality, cost, schedule, and other aspects.

Quality control point on the site of corrugated pipe culverts.

Foundation

Before excavating , the foundation axis, edge line position, and elevation of each part should be determined on the construction site. The excavation of the foundation should be carried out according to the requirements. When the bearing capacity of the foundation is insufficient, it should be replaced and filled backfill layer by layer. When the back filling is 50cm below the bottom of the culvert, it should be stopped working. Excavation construction shall be carried out on the excavated road section where the culvert is located. If the excavation is on a stone roadbed, in order to ensure that the soil modulus of the culvert base is consistent, blasting treatment shall be carried out on the stone. The excavation depth and filling shall be at the same horizontal position. After the compaction inspection is qualified, a geogrid shall be laid to ensure the stability of the base

Quality control points on site construction

River sand and gravel is adopted on the project for construction replacement and filling treatment. In the construction process, in order to make sure the compactness, manual water pipes can be used to water and compact the backfill.

According to the requirement of the steel corrugated pipe culverts, when back filling with sand and gravel, reserve the pre arch degree of generally 0.3% to 0 5% culvert length, but the center elevation of the culvert should not be higher than the inlet water mouth elevation.

Installation of steel corrugated pipe culverts

The installation of corrugated pipe should be according to the right axis and slop placement on the drawings. The corrugated pipe culverts should be closely attached to grave layer, to make sure the corrugated pipe can be evenly stressed, and installed symmetrically from the center to both ends.

When install the corrugated pipe culvert, the bottom plates should be installed first, then upwards separately, and use a jack to correct the roundness and position of the pipe joints for every 5m distance.

In order to meet the bolt torque requirement, before back filling, every bolts needed to be check,to ensure the torque meet requirement.. After finishing the installation of corrugated pipe culvert, in the process of back filling,the cross section shape and dimensions should be measured, the dimensions should not exceed ±1% the designing size.

Back filling the back abutment

After the assembly and laying of the steel corrugated pipe culvert, the wedge-shaped part of the pipe body, and the top and sides of the diving pipe should be filled with river sand for back filling.and the top and both sides of the pipe in a symmetrical and uniform manner, and sand filling should be adopted, with a layer thickness controlled at around 50cm.Back filling should be carried out towards the center of the structure, and the settlement difference of the river sand at the top of the culvert should be within the specified range within a fixed value, it means overall stability.

The back filling of steel corrugated pipe culvert top

In order to avoid cracking of the mountain foundation area, after back filling 50cm river sand on the top of corrugated pipe culvert, geogrid needed to be laid at the intersection of horizontal and longitudinal direction within rang of 30m.

The minimum filling height of the corrugated pipe culvert top should meet the requirements, otherwise all motor vehicles should be prohibited from passing. When the minimum thickness of the pipe top has been filled, a hand-held vibrating roller can be used for compaction, or static roller compactors should be used for compaction, but large vibrating rollers or heavy hammers should not be allowed to work on, avoiding damaging the corrugated pipes and adjacent fill.

Large diameter Corrugated pipe culvert will be used widely for harsh geological conditions in the future,with the continuous improvement of construction quality.