During the construction of subgrade and pavement in the settlement section of road and bridge, uneven settlement is easy to occur, which affects traffic safety. At present, uneven settlement is widespread, which greatly reduces the construction life of roads and bridges. In order to effectively avoid uneven settlement of subgrade and pavement in the settlement section of road and bridge, this paper first analyzes the causes of uneven settlement based on my many years of experience in road and bridge construction, and then puts forward some effective construction technologies for subgrade and pavement in the settlement section of road and bridge, which can provide reference for preventing vehicle jumping in the settlement section of road and bridge.

Keywords: roads and bridges; Subgrade of settlement section; Pavement construction technology

Cause analysis of road and bridge settlement caused by 1

1. 1 lacks reasonable structural design.

In the construction of the settlement section of the approach road at the bridge head, some projects adopt the methods of coarse aggregate filling, reinforced concrete slab and reinforcement, but these methods are difficult to effectively avoid the impact of vehicle bumps. Through the analysis, it is found that the number of drilling holes is small and the depth of drilling holes is lacking, which makes the geological data used in the specific design inaccurate and leads to the unreasonable structural design. In the design of soft soil foundation, designers have no reasonable and scientific calculation method, which leads to unreasonable structural design. The unreasonable structural design of the settlement section of the bridge head leads to uneven settlement of the settlement section of the bridge and bridge.

1.2 influence of backfill in settlement section of road and bridge

In the process of backfilling the settlement section of roads and bridges, ordinary cohesive soil is used as the filler, which is affected by many factors. Because there are many differences in different areas, different construction site environments, geological conditions, and earthwork compactness of abutment backs of various projects, the fillers will be different. In road and bridge construction, ordinary cohesive soil materials are easily subjected to self-weight and long-term load, which makes the settlement section of road and bridge uneven. That is to say, the unreasonable choice of filler in the backfilling operation of road and bridge settlement section will lead to uneven settlement of road and bridge settlement section.

1.3 The setting of bridge end transition slab leads to uneven settlement.

In bridge construction projects, enterprises choose to set up bridge end transition slab to avoid settlement caused by poor bridge head connection, but bridge end transition slab is easily influenced by other external factors, which leads to uneven settlement of subgrade and pavement in the settlement section of road and bridge. Specific factors include: in the road and bridge construction, bridge end transition slab is mainly located below the asphalt concrete surface and on the top of the flat pavement base, which will lead to the direct transmission of traffic load and subgrade. At the joint, due to long-term rainwater infiltration, the filler will be lost, resulting in the void at the bottom of the slab, resulting in uneven settlement of subgrade and pavement in the settlement section of road and bridge.

2 Road and Bridge Settlement Section Subgrade Pavement Construction Technology

In view of the uneven settlement of subgrade and pavement in the settlement section of road and bridge, we have improved it from the following aspects:

2. 1 scientifically design the structural form of the settlement section

Based on the settlement section of bridgehead approach, the structure lacks reasonable design, which leads to settlement, and corresponding measures can be taken to solve it. Through years of experience in road and bridge construction, we mainly start from two aspects: First, improve the length and strength design of road and bridge settlement slab. At present, there are still many deficiencies in this aspect in China, especially the lack of corresponding design standards. Therefore, in order to ensure the design quality, the design unit must design according to the actual situation of road and bridge engineering and based on its previous design practice. Secondly, in the case of verifying the rationality of the design scheme, from the construction point of view, such as fully combining the actual situation of road and bridge settlement and slab length, we adopt civil grid technology in the subgrade construction process, which greatly reduces the settlement of road and bridge under the premise of stability.

2.2 strap settings

In the construction of subgrade and pavement in the settlement section of road and bridge, in order to prevent the slab from slipping in the vertical direction and causing the bridge head to sag, it is necessary to set pull rods between the transverse directions; Anchor bolts will be fixed vertically, and the appropriate distance between controllers will be ensured by selecting appropriate steel bars, thus ensuring the safety in specific construction. The anchor bolt is fixed vertically, so it is always in a vertical state. However, this state will cause the strap to be easily damaged. Therefore, in the concrete construction, it is necessary to ensure the position of the anchor bolt and the position of the transverse tie rod to ensure the safety of the construction effect. In the choice of bearing, first of all, a cushion should be laid, and the laying position should be close to the abutment plate; The spacing of rubber bearings should be less than 80cm, and the spacing of rubber bearings should be strictly controlled, so its stability can meet the requirements. When the chamfer of the slab turns, it will affect the pavement structure. Therefore, it is necessary to ensure that the upper positions of brackets and abutments are set to chamfer mode. By changing the upper positioning mode of bracket and abutment, the stability of road pavement structure is ensured and the damage of highway subgrade is reduced. When there is a gap between the bridge head and the slab, the construction quality can be ensured by filling materials in the gap, thus effectively preventing the infiltration of rainwater. The filling material can be oil-soaked sugarcane board, asphalt and fiber bit. In addition, it is necessary to pour a certain concentration of asphalt into the filler position to reduce the gap, ensure its waterproof, achieve the sealing effect, improve the construction efficiency and quality, and be beneficial to the maintenance and service life of subgrade and pavement in the settlement section of road and bridge in the later period.

2.3 abutment soft foundation construction

In the process of soft foundation construction of abutment, the main construction techniques include cement powder jet grouting pile foundation method, dynamic compaction method and plastic drainage plate method. In the construction process, the cement powder jet grouting pile has a good foundation reinforcement effect and can effectively shorten the construction period. However, this technical means has high engineering cost and poor economic benefit in the application process. In the process of dynamic compaction construction, the construction technology is more complicated, but it can deal with the soft soil foundation problem well. Therefore, in the process of construction, it is necessary to consider and analyze the engineering situation and choose an effective construction method, which can effectively eliminate the problem of uneven settlement.

2.4 Selection of fillers in backfilling operation of settlement section of road and bridge

Because of the unreasonable choice of filler, uneven settlement occurs in the settlement section of the road and bridge. Therefore, in the backfilling operation of the settlement section of the road and bridge, we should start to choose the appropriate filler from the following aspects: First, the geological requirements of the settlement section are quite different from those of other sections of the project, so we should choose reinforced materials in the selection of fillers. Secondly, the enterprise determines several fillers on the basis of following the above principles, and finally determines the selection of fillers with the help of geotechnical tests. In addition, the geotechnical test results of the enterprise should be based on the water permeability and dry bulk density, and then select the appropriate filler to backfill the settlement section of the road and bridge.

3 Conclusion

In recent years, with the rapid development of road and bridge construction projects, people attach great importance to the construction technology of subgrade and pavement in the settlement section of road and bridge, but there are still many defects in the construction technology of subgrade and pavement in the settlement section of road and bridge, and the phenomenon of vehicle bumping occurs from time to time. Therefore, the causes of uneven settlement in the construction technology of subgrade and pavement in the settlement section of road and bridge are analyzed, and the structural design and pavement construction technology of the settlement section of road and bridge are studied on this basis. It is hoped that through the discussion on the construction technology of subgrade and pavement in the settlement section of road and bridge, it can provide reference for preventing the occurrence of vehicle bumping in the settlement section of road and bridge.

refer to

[1] Han Lujun. On the Construction Technology of Subgrade and Pavement in Settlement Section of Road and Bridge [J]. Architectural Engineering Technology and Design, 20 15(22).

[2] Chen Yong, Zhou Boyang. Technical analysis of subgrade and pavement construction in settlement section of road and bridge [J]. Cited Edition: Engineering Technology, 20 15 (45): 29-29.

[3]-Qin. On the construction technology of subgrade and pavement in settlement section of highway bridge [J]. Sichuan Cement, 2014 (11): 29-29.

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