In the process of road construction, subgrade construction is needed in order to lay the ground because of the uneven ground. Subgrade is generally divided into embankment and cutting. Through the reconstruction of natural landforms, the requirements of engineering design can be met. Road subgrade construction has the characteristics of great difficulty, long time and easy to be influenced by natural geographical environment. Below, the author discusses the matters needing attention and maintenance measures of road subgrade construction technology.
1 road subgrade construction requirements
The strength and stability of subgrade are directly related to the construction quality of road engineering. Therefore, in the process of subgrade construction, we should strictly follow the requirements of construction technology, reasonably control the quality of subgrade construction, choose appropriate construction methods, meet the technical requirements of subgrade construction, and ensure the construction quality of road engineering.
1. 1 subgrade filler
Filler is the raw material of road engineering, and the quality of filler is related to the strength and deformation of subgrade, so subgrade filler has been paid more and more attention in recent years. In order to ensure the strength of subgrade structure, the Highway Subgrade Design Scheme (JTGD30-2004) puts forward clear requirements for subgrade filler, which stipulates that the CBR of the upper subgrade bed (0-30cm) of expressway and first-class highways is ≥ 8%, the CBR of the lower subgrade bed (30-80cm) is ≥ 5%, and the road uplift is (80- 10. Because the strength and stability of subgrade are closely related to the CBR value of subgrade filler, ensuring the CBR value of subgrade filler reaches the standard is the premise to ensure the quality of road construction.
1.2 subgrade compaction
In the current subgrade construction, most construction units use large-tonnage road rollers to compact the subgrade, which greatly improves the rolling effect and effectively improves the subgrade strength. According to the requirements of Highway Subgrade Design Planning (JTGD30-2004), the compactness of the upper subgrade (0-30cm), the lower subgrade (30-80cm) and the upper subgrade (80- 150cm) of expressway and Class I highways should be ≥96% and ≥94%. Compaction degree of subgrade is an important index reflecting the construction quality of subgrade and pavement. The higher the compactness and density, the better the overall performance of the material.
2 road subgrade construction compaction technology
Subgrade construction and compaction are the key links to ensure the quality of road engineering. If the compaction degree of subgrade is lower than the specified standard, pavement settlement and pavement cracking may occur, which will increase the maintenance cost of road in the later period and affect the normal operation of traffic, on the other hand, it will also bring adverse effects to construction enterprises and damage their external image. Therefore, in the process of road subgrade construction and compaction, only by choosing the appropriate construction technology can the project quality be guaranteed and the cost of road construction and maintenance be reduced. Before construction, a suitable roller should be selected according to different soil types and actual conditions. For example, medium-sized steel roller is suitable for compacting cohesionless soil and low cohesive soil, heavy-duty steel roller is suitable for compacting cohesive soil, and vibratory roller is more suitable for compacting crushed stone and gravel. In addition, pay attention to the moisture content of subgrade filler. Only when the road subgrade is compacted under the optimum water content can the construction quality of road engineering be guaranteed.
3 Road subgrade maintenance measures
Road subgrade has changed the stratum structure and broken the original state of natural balance. Some road subgrade is exposed to the external environment and easily eroded by wind, rain and sun, so it is necessary to carry out daily maintenance on road subgrade.
3. 1 shoulder protection
Shoulder is an important part of road subgrade, and it is the extra width on both sides to protect the road surface, ensure the vehicle running and temporary parking. Therefore, granular materials can be used to strengthen the shoulder, and turf can be planted on the slope to ensure the smoothness of the slope, effectively avoid rutting, depression and water accumulation on the ground, and prevent the occurrence of platform dislocation. Specifically, by leveling the road surface, the smooth drainage of subgrade is ensured, and intercepting ditches are set at appropriate positions to avoid subgrade water accumulation, so that ruts and depressions can meet the maintenance standards. For roads with high traffic density, the shoulder can be reinforced with asphalt and stones.
3.2 Slope Plant Protection
Planting plants on the slope can solidify the surface soil, prevent soil erosion caused by rain and avoid cracks. Plant protection includes sowing grass seeds, planting turf, planting shrubs and so on. In the specific implementation process, it is necessary to select suitable plants in combination with local climate and geographical conditions. On the one hand, it is necessary to ensure the survival rate of planted plants, on the other hand, it is necessary to give priority to plants with developed roots, strong adaptability and fast growth.
3.3 scour protection
Scouring protection is a protective measure for building and strengthening slopes, which has the characteristics of not disturbing the original water flow. In the process of building scour prevention facilities, scientific protection measures should be set up according to the characteristics of water flow and the actual situation of river courses. In addition, you can also set up flood control dikes in the river. In the case of water regime, the influence of water flow on subgrade can be alleviated by changing the direction of water flow, which plays a certain protective role on highway subgrade.
3.4 Maintenance of drainage facilities
Water is the main natural factor that causes subgrade and pavement diseases. Too high water content in soil can easily lead to loose soil and reduce subgrade strength. The cracking, settlement and landslide collapse of subgrade in the later stage of highway construction and operation are mostly caused by groundwater erosion, which accelerates the destruction speed of subgrade and pavement. It can be said that the strength and stability of road subgrade are directly related to drainage, so in the actual maintenance process of road subgrade, attention should be paid to drainage facilities. Don't plant crops around the side ditch, keep the slope height, and avoid mud and weeds blocking the side ditch.
4 conclusion
To sum up, with the development of China's economy and the increase of road engineering, people have higher and higher requirements for the quality of road engineering. The quality of road engineering is related to the development of regional economy and the safe and smooth traffic, and subgrade is an important index to measure the overall quality of road engineering. Therefore, the construction unit and the later road operation management unit should fully realize the importance of road subgrade, and do a good job in the compaction process of road subgrade during construction to ensure the quality of road engineering. In the later operation, we should pay attention to all kinds of maintenance work, improve the quality of road engineering by improving the strength and stability of road subgrade, so as to ensure people's traffic safety.
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