Roast clothes
1, when the ground slope is steeper than 1: 5, it is necessary to build steps. The height of each step should not be greater than 300mm, and the width should not be less than1.0m..
2, according to the survey center line pile and downhill foot pile, layered fill and compaction.
3, rolling should be light before heavy, and finally adopt a roller not less than 12t.
4. Only when the top surface of pipe culvert within the filling height exceeds 500mm, can it be rolled by roller.
5, excavation according to the survey center line and side pile excavation.
6. Quality inspection and acceptance: the main control items are compaction degree and deflection value, and the general items include allowable deviation of subgrade, subgrade, embankment slope and other requirements.
7. The minimum strength of subgrade filler CBR subgrade is 8%.
8, fill should be layered, subgrade fill width should be 500mm wider than the design width.
9. The test of subgrade includes: determining the pre-inspection value of subgrade, reasonably selecting compaction machinery, determining the compaction times according to the compaction requirements, and determining the virtual paving thickness of each layer within the width of subgrade.
10. Compaction principle of soil subgrade: light before heavy, static before vibration, low before high, slow before fast, wheel tracks overlap, and the fastest speed of roller shall not exceed 4 km/h. ..
Bake some
1, the compaction quality inspection of soil subgrade mainly checks the compaction degree and deflection value of each layer.
2. Subgrade with poor soil quality can be divided into improved soil, soil replacement and reinforced soil according to the action mechanism.
3. Common base materials: lime stabilized soil base, which is forbidden to be used as the base of high-grade pavement, can only be used as the subbase of high-grade pavement; Cement stabilized soil base has good plate performance and is only used as subbase of high-grade pavement; Lime tool waste residue stabilizes soil foundation and can only be used as subbase (poor subbase); Lime-fly ash stabilized granular materials can be used for the base and subbase of high-grade pavement.
4. The compaction thickness of each layer of urban road base mixture is 200mm, and should not be less than100mm; When pressing, light roller should be used first, and then heavy roller should be used for rolling; It is forbidden to use the method of thin-layer patch for leveling; The curing period of the mixture is 7~ 14d.
5. Geosynthetics have the functions of reinforcement, protection, filtration, drainage and isolation.
6. The asphalt mixture surface shall not be constructed in rainy and snowy weather and when the ambient temperature is lower than 5 degrees.
7, paver must be slow, uniform, continuous uninterrupted spread shop; Strictly control the initial pressure, secondary pressure and final pressure.
8. When rolling, the driving wheel of the roller should be rolled towards the paver from the outside to the center, and it should be rolled from low to high on ultra-high sections and ramps; Heavy-duty tire roller should be used to compact dense graded asphalt mixture first.
9. In order to prevent the asphalt mixture from sticking to the wheel, it is forbidden to brush diesel oil, and a small amount of atomized water of surfactant can also be added to the grinding wheel.
10, the hot mix asphalt pavement can only be opened to traffic when the temperature is below 50 degrees.
Kaodiansan
1. Ordinary asphalt mixture, namely AC asphalt mixture, is suitable for urban secondary roads, auxiliary roads or sidewalks.
2. The modified asphalt mixture surface is suitable for urban expressways and main roads.
3. The width of cement concrete pavement base should be at least 300mm (small machinery), 500mm (crawler paver construction) and 650mm (sliding paver construction) on each side.
4. Cement concrete pavement surface slabs are divided into ordinary concrete slabs, roller compacted concrete slabs, continuous reinforced concrete slabs, prestressed concrete slabs and reinforced concrete slabs, and ordinary concrete slabs are commonly used.
5. Flexural and tensile strength of cement concrete pavement The flexural and tensile strength of cement concrete at 28d age controls the strength of surface concrete.
6. The longitudinal joints of cement concrete pavement shall be provided with tie rods, and the transverse joints shall be provided with dowel rods. Expansion joints should be set in the vicinity of bridges or other fixed structures, where the plate thickness changes, and at small radius horizontal curves.
7. Gravity retaining wall relies on the self-weight of the wall to resist the earth pressure, while counterweight retaining wall uses the downward pressure of the filled soil on the counterweight platform and the backward movement of the center of gravity of the whole wall to increase the stability of the wall.
8. Among the three kinds of earth pressures, the active earth pressure is the smallest, followed by the static earth pressure, and so are the passive earth pressure and displacement.
9. New underground pipelines must follow the following principles: first underground, then above ground, first deep and then shallow.
10, humus soil, domestic garbage soil, silt, frozen soil or saline soil are not allowed to be used for subgrade filling.
The above is Bian Xiao's Collection of Required Test Points for the Course of Municipal Engineering for Secondary Builders. If you want to know other relevant information about the necessary test sites for the second-level constructor exam. Pay attention to Bian Xiao's timely push.