The quality of road engineering not only affects the development of urban economy, but also affects people's quality of life. Then, what are the key points of road engineering soft soil subgrade reinforcement technology and construction?
The acceleration of urbanization has promoted more and more road construction, and the most common problem in road construction is that the existence of soft soil subgrade hinders the construction progress. Because the soft soil subgrade does not have strong bearing capacity, it has a great influence on the quality of road construction. Therefore, the reinforcement technology of soft soil subgrade in highway construction has become a topic of concern. In this paper, the reinforcement technology of soft soil subgrade in highway engineering is studied, and the key contents in construction are analyzed in order to improve the quality of highway construction in China.
Road engineering; Soft soil subgrade; Reinforcement technology; Key points of construction
1 Introduction
The quality of road engineering not only affects the development of urban economy, but also affects people's quality of life. Therefore, the construction of road engineering needs to ensure the completion of high quality. The biggest obstacle to road construction is the problem of soft soil subgrade. Soft soil subgrade can not meet the quality standards of road engineering because of its soft soil, low hardness and small bearing capacity. Therefore, the problem of soft soil subgrade in highway engineering construction needs to be solved urgently, and the reinforcement technology of soft soil subgrade is the guarantee to improve the quality of the whole highway engineering.
2 Soft soil subgrade texture and hazard analysis
Generally speaking, the main components of soft soil include soft clay, silt and peat soil, and the saturation of soft soil is relatively high, even reaching more than 95%. The texture characteristics of soft soil are closely related to its firmness, hardness, stability and bearing capacity. If a large external force is applied, the structure will be deformed and damaged. The characteristics of soft soil subgrade are mainly manifested in three aspects.
2. 1 poor bearing capacity
The main characteristics of soft soil are large internal pores, high compression possibility and weak shear strength. When high-strength external force acts, it is easy to cause deformation and structural damage, which is characterized by high fluctuation, potholes and even uneven settlement of the road surface.
2.2 More pores
Soft soil foundation has many pores and high compressibility. With more pores, the water in the soil will be fully retained, and a large amount of water will be lost after consolidation, and the soil will settle and collapse, which is more harmful.
2.3 low strength, easy to be destroyed.
The strength of soft soil is easily influenced by external natural forces, and the soil is also easily lost due to rain erosion, so that the foundation will be destroyed and the stability will be greatly reduced. By analyzing the basic characteristics and performance of soft soil, it can be found that the soft soil subgrade of road engineering needs to be reinforced, the thixotropy and fluidity of soft soil will cause the settlement and collapse of subgrade, the uneven settlement of pavement will cause the damage and destruction of pavement structure, and the imbalance of pavement will also pose a threat to traffic, and may even threaten people's lives and property safety.
3 municipal road construction in the process of soft soil foundation reinforcement technology
The reinforcement technology of soft soil subgrade should first understand the basic geological conditions and complexity of soft soil subgrade, and then take corresponding reinforcement measures according to the specific geological conditions. In the design process, if the survey work of the project is not detailed enough, relevant supplementary survey work can be carried out appropriately to ensure the scientific nature of the project. In the process of subgrade investigation, it is necessary to make clear the influence of hydrogeological factors on it, understand the basic situation of subgrade, and choose the appropriate reinforcement method scientifically and reasonably from the reality.
3. 1 soil replacement method
If the thickness of the naturally formed soft soil subgrade is not very large, you can choose to dig out the soft soil layer in a certain area below the bottom of the subgrade and roll it instead of high-strength and high-performance materials, which can effectively ensure the compactness of the soft soil layer after layered rolling. Generally speaking, the soft soil method is suitable for soft soil with a thickness of 0.5 ~ 3m. If the thickness of soft soil exceeds 3m, the soft soil at a certain depth under the subgrade can be excavated and covered with a layer of gravel, which can strengthen the bearing capacity of the subgrade to a certain extent and increase the service life of the road.
3.2 Riprap and silt squeezing
This is a forced soil replacement method. Putting large stones and fragments in most positions of soft soil subgrade can fill most positions of subgrade and greatly improve the stability of subgrade. This method is mainly used to treat soft soil subgrade with high water content and high compressibility.
3.3 Compaction method
Compaction method is to drive steel pipes through various pile drivers, or to form regular gaps on soft soil subgrade by high-pressure water injection blasting, and then add stones, sand, lime and other materials to form a large pile, so that the gaps in soft soil are greatly reduced and become more dense. This method has the best reinforcement effect on soft soil subgrade with large gap.
3.4 Grouting method
The principles of water pressure, air pressure and electrochemistry tell us that the slurry can be injected into the stratum with the help of the slurry pipe, and the compactness and permeability of the slurry layer can be used to narrow the gap and discharge the moisture in the soft soil foundation, so that the original loose soil particles can be transformed into a structurally stable whole, thus strengthening the subgrade.
3.5 Strengthening Strip Method
If the soft soil subgrade has a large area and the water level is low, all the soil in the soft soil layer can be excavated, and 1 layer of sand and gravel can be added to the surface layer, and the places with less sand and gravel can be reinforced. The ribs are relatively stable and can play a role in compression. This method can greatly reduce capital and investment, and can be advocated in areas with less sand and gravel [1].
3.6 geotextile method
Laying geotextile on soft soil subgrade can not only reduce uneven settlement of subgrade, but also prevent road drainage. If the soft soil subgrade is silt, geotextile can be considered. This method has less investment, and is generally used together with other reinforcement methods, and rarely used alone.
3.7 Drainage consolidation
Foundation drainage can greatly reduce the gap of foundation and accelerate the reinforcement process of soft soil subgrade. Drainage consolidation method mainly includes horizontal drainage sand cushion and vertical drainage body. In the case of thin subgrade and strong permeability, just lay a sand cushion on the ground.
Analysis of soft soil subgrade reinforcement technology in road engineering
When encountering soft soil subgrade in road engineering construction, it is necessary to take certain measures to reinforce it, so that its bearing capacity can meet the normal driving standard of the road and ensure people's travel safety. There are many kinds of reinforcement technologies for soft soil subgrade, and the implementation of each reinforcement technology needs to be operated according to the actual situation.
4. 1 Analysis of integral reinforcement technology of soft soil subgrade
In highway construction, when the soft soil subgrade is sometimes soft inside the whole subgrade, it is most suitable to implement the integral reinforcement technology. Grouting method can be applied to integral reinforcement technology. Prepare slurry with certain strength and hardness, and pour it into soft soil subgrade by machine to fill the gap of soil layer. Due to the strong coagulation ability and good coagulation effect of mud, the strength and hardness of soft soil layer can be improved under the action of mud, thus improving the bearing capacity of soft soil subgrade. The integral reinforcement technology that is also suitable for soft soil subgrade reinforcement is dynamic compaction. The principle of dynamic compaction technology is free falling. A rammer with a certain weight will fall freely to a certain height under the action of gravity. At this time, landing will produce a very large force on the ground and play a role in tamping the soft soil subgrade. Through the gravity action of rammer, the gap between soil layers of soft soil subgrade is narrowed, and soil particles can be more closely combined, thus improving the bearing capacity of soft soil subgrade. Dynamic compaction method is mainly used to strengthen soft soil subgrade, whether it is gravel soil or sandy soil. In order to make the dynamic compaction method achieve good results in practical application, it is necessary to find out the dynamic compaction point and make corresponding marks before construction. In the process of dynamic compaction construction, it is necessary to calculate the construction strength and tamping times scientifically to ensure the smoothness of the whole pavement [2].
4.2 Analysis of Local Reinforcement Technology of Soft Soil Subgrade
In road construction, when only a part of soft soil subgrade is soft, or a part of soil has a lot of water and silt, local reinforcement is generally adopted. Local reinforcement technology is also widely used in soft soil subgrade, and the specific operation methods need to be taken according to the actual situation. The local reinforcement technology of soft soil subgrade is different from the whole reinforcement technology. Among them, soil replacement method is one of the local reinforcement methods of soft soil subgrade. When the local reinforcement method is adopted, the area and thickness of the soft soil layer in the soft soil subgrade are relatively small, and the soil replacement construction can perfectly achieve the purpose of strengthening the soil layer without consuming too much labor. Another local reinforcement technique is drainage consolidation method. Soft soil that needs local reinforcement is generally a road near the river. The water content of soft soil subgrade is relatively large. As long as the water is pumped out, the gaps between soil particles can be narrowed. The operation of drainage consolidation method needs to clean up the silt first, and then fill it with reinforcement material.
5 conclusion
Through the above analysis and discussion, we know that the use of soft soil subgrade reinforcement technology has an important impact on the quality assurance of road engineering. The reinforcement of soft soil subgrade should be considered according to the actual situation, and every key point should be grasped well during the construction. Relevant construction units should pay enough attention to this, realize the serious harm of soft soil subgrade in road construction, actively organize the study of reinforcement technology, make the bearing capacity of soft soil subgrade pavement meet the needs of normal driving, provide guarantee for people's travel safety, and provide technical support for the stable development of road engineering in China.
refer to
1 Liu Jia. Exploration on effective measures of highway soft soil subgrade construction technology [J]. Science and technology communication, 20 13(4):30-3 1.
Liu Feng. Discussion on soft soil subgrade construction technology of highway engineering [J]. Science and technology entrepreneur, 20 13(7):28-34.
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