With the rapid development of geosynthetics and its application technology, the research on “reinforced soil” in civil engineering field is more in-depth and detailed.
When geogrid is added to backfill soil, it can bear tensile, compressive and shear effects, and can significantly improve the strength of backfill, so as to ensure the stability of backfill;
Through the soil reinforcement material to maintain stability, the backfill slope can be built very steep, even vertical, and can bear larger settlement deformation;
By making full use of the joint action of soil and reinforcement, the requirements of retaining wall for foundation bearing capacity are relatively low, adaptability, integrity and seismic performance are better.
1.Type of geogrid selected:
Unidirectional tensile plastic geogrid is a kind of high-strength geosynthetic material, which is made of high-density polyethylene (HDPE) as raw material, extruded and pressed into thin plate, then punched into regular hole net, and then stretched longitudinally. It is widely used in the fields of dams, tunnels, docks, highways, railways, buildings, etc.
2.Greogrid Installation Guide:
2.1. The foundation shall be set and constructed according to the designed wall system. When the prefabricated reinforced concrete panel is selected, it is generally 12-15cm thick and supported on the prefabricated concrete foundation. Its width is not more than 30cm, its thickness is not less than 20cm, and its buried depth is not less than 60cm to prevent the influence of foundation frost heave;
2.2. The wall foundation shall be leveled, excavated and leveled according to the design requirements. The soft soil needs to be compacted or replaced. When it is compacted to the required density, it should be slightly beyond the scope of the wall;
2.3. The main strength direction of the reinforcement shall be perpendicular to the wall surface and fixed with pins;
2.4 For wall filling, mechanical filling shall be adopted, and the distance between wheel and reinforcement shall be kept at least 15cm, and the thickness of the compacted layer shall be about 15-20cm;
2.5 During wall construction, the wall shall be wrapped with geotextile to prevent leakage of fill.
3.Precautions for Geogrid Installation in Geogrid Retaining Wall Systems:
3.1 The laying method of geogrid is very simple, but the requirements are very strict. The geogrid must be laid horizontally and perpendicular to the wall, without curling and folding.
3.2 Fix one end of geogrid, and apply tension with tensioning beam at the other end until the geogrid is tensioned, and fix this end.
Only in this way, geogrid can play the largest role in the soil. When the geogrid is laid in the curve and corner section, the adjacent geogrid will have gaps or overlaps.
3.3 When the geogrid is laid outwards, there will be a gap at the corner. To ensure the continuity of reinforced soil, small pieces of Geogrid of the same type will be laid in the gap and cover all reinforced areas.
3.4 When the geogrid is laid inwards, some geogrids will overlap at the corner, and the friction coefficient of the overlapped geogrid will be reduced. A layer of coarse sand with the thickness of 10-20 mm must be laid to separate the two layers of geogrid, so as to ensure the exertion of friction resistance.
3.5 The quality, paving thickness and rolling of reinforced earth filler and rolling earth fill are closely related to the engineering quality of geogrid reinforced earth retaining wall.
The filling quality shall strictly meet the design requirements. Mechanical equipment such as excavator can be used to fill the reinforced earth filler. The filler shall be unloaded from the end of the geogrid to the geogrid in a waterfall manner. When unloading, the mechanical equipment shall stop moving. The filler to be unloaded has been compressed and has good social benefits.