Second, the circular pipe culvert has a culvert abutment. Circular tube culvert is the most commonly used culvert structure type in rural highway subgrade drainage. It not only has good mechanical properties, but also has simple structure, convenient construction, short construction period and low cost. Reinforced concrete circular culvert is the most common one.
Circular pipe culvert consists of two parts: the hole body and the mouth of the cave. The tunnel body is the main body of the water passage, which is mainly composed of pipe body, foundation and joint. The entrance of the cave is the connection part of the tunnel body, subgrade and water flow, which mainly has two forms: splayed wall and straight wall.
Extended data:
Construction requirements for culvert abutment:
1, control the packaging quality. Because of the particularity of the filling position, the quality control of the backfill area at the back of abutment should be much higher than that of ordinary subgrade.
The selected filler must first meet the requirements of good water permeability, the particle content of filler below 0.074mm should not exceed 15%, and the maximum material diameter should not exceed 40mm；; The CBR value should not be less than 8. The water content should not be too large, which can effectively control and reduce the compression settlement between subgrade.
2. Before filling, a drainage pipe or blind ditch should be set on the soil arch to make the surface water flow out of the subgrade quickly and smoothly. This is an effective way to reduce the diseases caused by fissure water intrusion and weaken the differential settlement of structures with different stiffness.
3. When filling, both sides of culvert gap shall be backfilled symmetrically and evenly in layers. If mechanical backfill is adopted, the back of culvert abutment and the chest around inspection well should be compacted and filled with small compaction machinery before large-scale backfill can be carried out with machinery.
When the compaction thickness of the culvert top fill must be greater than 50cm, heavy machinery and automobiles can pass, and the bridge structure should also be symmetrically constructed at both ends of the abutment. The filling behind abutment should be carried out at the same time as the filling of cone slope.
4. Carry out construction in strict accordance with relevant construction specifications, and control the layered thickness of backfill layer, which is generally less than 20cm. When using small machines and tools (less than 12T compaction machines and tools), the loose paving thickness of roads above grade one should not exceed 15cm.
The number of rolling passes shall be determined through tests, and the number of rolling passes after acceptance is generally 8~ 10, and the filling quality of each layer shall be tested. The test of permeable materials should control the construction quality through dry bulk density or porosity.
5, if the abutment back must be filled with impermeable materials (such as earthwork, etc.). ), dealing with poor soil quality, high water content of filler for processing, if necessary, can change the soil or mixed with a small amount of lime and cement. At the same time, bridge and culvert construction should be combined with subgrade excavation as far as possible, and the height of fill should be consistent with the construction height of bridge and culvert abutment back, so as to ensure layered compaction and compactness of fill.
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