The roadbed design elevation is 4m and the pavement is built in two layers. The embankment is full of pavement and the layer spacing is 80cm. The grille should be effectively anchored in the original soil sample. The ground anchor hole is dry-made into holes, and the M30 cement mortar is injected into the grille. The hole is inserted into the steel bar to form the ground anchor. The steel bar is made of Φ25 steel bar and is rust-proofed. The ground anchor is placed at a distance of 50cm along the longitudinal direction of the route.
1 Project Overview Our project undertakes the construction of the Yellow River Wetland Landscape Road Project in Baotou City, with a total length of 9.141 kilometers, a roadbed width of 8 meters, a road width of 6 meters, and a sidewalk of 1 meter on both sides. The pavement structure layer is made of 20cm limestone and gravel as the base layer. A 5 cm medium-sized asphalt concrete (AC-20) was used, and the upper layer was made of 3 cm fine-grained colored asphalt concrete (AC-13). The project is a key project for the comprehensive implementation of wetland protection and utilization planning and improvement functions in Baotou City to create a characteristic landscape and culture of wetlands. 2 Application of steel-plastic geogrid in this project Most of the dams of this project are widened on both sides, the south side is closer to the river channel, and the water is deeper. It is necessary to bury the silt first and then fill it in the dam. To ensure the quality of the project, the design requires two layers of steel-plastic geogrid to be laid in the roadbed, respectively, between the upper and lower roadbeds; the pavement design elevation is 4m and two floors are paved, the embankment is fully covered, the layer spacing is 80cm, the grille It should be effectively anchored in the original soil sample. The ground anchor hole is made into dry hole, and M30 cement mortar is injected into the ground. The steel bar is inserted into the grid hole to form the ground anchor. The steel bar is made of Φ25 steel bar and is rust-proofed. The anchor is placed at a distance of 50 cm in the longitudinal direction of the route.
2.1 Steel Plastic Composite Geogrid is made up of a steel-plastic composite reinforced belt (built-in high-strength carbon spring steel wire <stress material>, coated with polyethylene resin <protective material>) , geosynthetics formed by ultrasonic welding according to the plane latitude and longitude at right angles. It is an existing rigid rib (flat steel strip, ribbed steel strip, galvanized steel strip, stainless steel strip, reinforced concrete belt, etc.) and flexible ribs (polypropylene strip, plastic geogrid, warp woven A comprehensive product such as grids. Due to its high tensile strength, low elongation (≤3%), small creep, and strong interlocking and biting cooperation on the soil, it can effectively treat the soft soil foundation and restrain the side of the soil. Displacement, overcoming the uneven settlement of the soil, greatly enhancing the bearing capacity of the foundation and improving the overall performance of the foundation; it can be widely applied to road engineering, railway engineering, supporting structures and dam engineering, hydraulic engineering, tunnels The reinforcement and reinforcement of the project; it has a significant guarantee effect and good social and economic benefits against rutting and cracking of the road surface.
2.2 Steel Plastic Composite Geogrid construction process 2.2.1 Steel-plastic grid construction process cleaning the lower bearing layer → ground anchor hole drilling → artificial laying geogrid → lap joint, lashing → anchoring → paving the upper roadbed soil and stone. 2.2.2 Steel-plastic grid construction method (1) Lower bearing layer cleaning: Before laying the steel-plastic geogrid, the completed filling layer must be trimmed first. First, leveling and compacting should be carried out. For blocks with protruding surfaces. Crushed stone must be removed to prevent wear of the plastic geogrid and reduce its strength. (2) Ground anchor hole drilling: artificial drilling, the ground anchor hole is made by dry operation, the hole diameter is 10cm, and the drilling hole is 1.5m deep into the original soil. Fill and dig the junction along the route longitudinally every 50cm. 2.2.3 laying of geogrid (1) The geogrid is laid on the flat bottom layer of the roadbed filling area and the full width. (2) The upper and lower layers of the geogrid have no spoilage of the geogrid. When the geogrid is laid, the direction of high strength is arranged perpendicular to the axis of the embankment. (3) The two-way steel-plastic geogrid has the same vertical and horizontal strength. (4) Use bamboo piles (or stakes) to mark the extent of geogrid laying and then lay it. (5) Put an end to all construction vehicles and construction machinery driving or parked on the paved geogrid. Check the quality of the geogrid at any time during construction, and find that it is damaged when damaged, puncture, tear, etc. Or replace it.
2.2.4 Laying requirements Geogrid should be fully tensioned, leveled and straight; the width of both sides is the same as the width of the roadbed. The connection of the geogrid is generally not less than 30cm. In order to meet the design requirements of the lap joint, there should be one lashing point every 10-15cm; there should be at least two lashing points in the direction of the force. When laying in multiple layers, the upper and lower layers should be laid out in a staggered manner. The two adjacent geogrids are stretched and stretched when laying, avoiding wrinkles, twists or potholes. The geogrid is spliced along the longitudinal direction by a lap joint method, the lap width is not less than 20 cm, and is anchored by a "U" shaped ground anchor. After the grid is laid, it should be covered with soil materials in time. Generally, it should not exceed two days. If the ultraviolet radiation is weak, the coverage time can be extended appropriately. 2.2.5 Anchoring and anchoring of steel-plastic geogrid To ensure that the plastic-plastic geogrid is not damaged and anchored, it is anchored in the geogrid, and the anchoring length is greater than or equal to 1.4m to ensure the anchoring of the lower geogrid. The length in the undisturbed soil sample is not less than the design value. The ground anchor hole is made into dry holes, and M30 cement mortar is injected into the ground. The “U” shaped steel bar is inserted into the grid hole to form a ground anchor. The ground anchor is placed at a position of 50 cm along the longitudinal direction of the route. The ground anchor steel bar is made of Φ25 steel bar and is rust-proofed. The two oils are wrapped in two cloths and the plastic hose is wrapped. 2.2.6 After the completion of the laying of the geogrid for the embankment of the upper roadbed, the roadbed is filled. Manually lay the upper layer of filler and complete the rolling in time to avoid long-term exposure. Then use mechanical transportation, leveling, and rolling. The mechanical paving and rolling are pushed from the two sides to the middle, and the rolling is carried out from the two sides to the middle, and the compaction degree is maintained to meet the specification requirements. Filling requirements: The maximum material diameter of embankment mixed with embankment within 8cm from the geogrid layer shall not exceed 6cm. The first layer of geogrid paving with geogrid shall be driven along the axis of the embankment for compaction and filling. The compacted thickness is greater than 60 cm. In order to avoid certain damage to the geogrid when the transport vehicle is crushed or turned, the earthwork can be filled by means of roll-filling, the bulldozer is leveled, the road roller is crushed, and the earth and stone filling and crushing should meet the requirements of the roadbed earthwork compaction. . 2.2.7 After the upper layer of plastic geogrid is laid and the earthwork is filled and crushed, the upper geogrid is laid. The laying requirements and connection methods are the same as those of the bottom geogrid, except that the width should be consistent with the top width of the fill layer. 2.2.8 After the completion of the construction of the upper earthen grille of the earthwork, a layer of soil should be filled on it as soon as possible to prevent damage such as sun exposure. The earth and stone side of this layer is strictly filled according to the filling thickness and rolling requirements of the roadbed earth and stone. The thickness of the loose paving should not exceed 40cm. The construction technology and construction method are constructed according to the roadbed earthwork filling scheme.
2.3 Construction Precautions 2.3.1 The maximum strength direction of the grid should be consistent with the direction of the maximum stress. 2.3.2 Heavy vehicles should be avoided as far as possible on the paved geogrid. 2.3.3 Minimize the amount of cutting and sewing of the geogrid to avoid waste. 2.3.4 The steel-plastic geogrid is hard, easy to cut hands and rub the knees, pay attention to safety. 3 Application Experiences Steel-plastic geogrid is superior to general grid performance, with high strength, high modulus, low creep, corrosion resistance, anti-aging, anti-brittle and pre-design. It is an excellent material used in road engineering. In road engineering, the use of steel-plastic geogrid can effectively control the rut, control the reflection crack, reduce the damage degree of the road surface, improve the service life of the road, and reduce the life expectancy of road construction. 4 Summary Steel-plastic geogrid is superior to general grid performance, with high strength, low creep, low elongation, corrosion resistance, anti-aging, anti-brittle and pre-design. It is used in road engineering. Excellent material. The use of steel-plastic geogrid in road engineering can effectively control rutting, control reflection cracks, slow down road damage, improve road life and reduce project life expectancy. When using the steel-plastic geogrid, construction specifications and standards should be strictly implemented to create high-quality projects and promote the continuous development of urban road construction.
