Expressways represent the latest and highest technical level of modern highways and therefore are different from general roads. The construction of subgrade as an important part of high-speed construction is also crucial.
The roadbed is a kind of linear structure built by soil, stone, etc. The formation is relatively simple, but the large amount of works, especially excavation roadbed, is often the key to control the construction progress of the road. Therefore, some preparations must be done well.
Mainly to do the following aspects of the work.
1, familiar with, check the design documents, drawings and related information.
2. Conduct construction surveys to master the following aspects
1 terrain, geology, hydrology, surface drainage and other conditions.
2 Traffic conditions and ground and underground structures and utility pipelines.
3 Water supply, power supply, telecommunications equipment and transportation lines inside and outside the construction site, location of production and living facilities, etc.
4 Places along the line for soil and spoil and related conditions.
5 Drainage and culverts near the line
6 Measurement marks near the construction site.
3, the preparation of the implementation of the construction of the organization, the use of materials and equipment plans, the preparation of the construction budget.
4, site cleanup. The trees and shrubs within the land area shall be cleared before the construction, and the roots shall be completely excavated. The pit shall be filled with soil and the long grass within the land shall be cleaned.
5, do a good job of drainage facilities. The drainage and seepage prevention facilities such as intercepting ditch and drainage ditch should be completed in advance.
6, do relevant tests, such as the maximum dry bulk density, the optimum moisture content, mortar mix ratio.
7. According to the construction procedures one after another, combined with the site transportation routes, engage in field deployment and minimize repeated transportation within the site. At the same time, we must also consider the operational transfer of construction equipment to facilitate construction. Second, we must do a good trial of the road section. According to the construction of the test section, a reasonable number of roller compaction passes and loose paving thicknesses were used to guide the construction.
In the construction, we must rationally arrange the amount of excavation and filling, and fully implement the principle of digging and filling. Before the roadbed construction, pay attention to the drainage in the subgrade construction. Drainage works such as intercepting ditch and drainage ditch should be completed in advance. This is especially true in the southern and rainy seasons.
In the construction, regardless of excavation or filling, there should be a certain cross slope in order to facilitate drainage. There should be no water accumulation on the surface of each construction layer.
Automobile Oxygen Sensor is a key feedback sensor in the control system of electric injection engine. It is also a key part to control automobile exhaust emission, reduce automobile pollution to environment and improve the quality of automobile engine fuel combustion. The oxygen sensor is installed on the engine exhaust pipe.
Q: How do I know the O2 sensor is good or not?
A: The only way to know if the O2 sensor is functioning normally is to check its responsiveness to changes in the air/fuel mixture, by Voltage Measurement or Waveform Simulation.
Use a 10-megaohm digital voltmeter. Hook up the voltmeter's red probe to the sensor's signal wire and the black probe to engine ground. (Use back probe method, DO NOT pierce the wire.) For a good sensor, voltage should fluctuate constantly between 0.1 and 0.9 volts after starting the engine for 2 or 3 minutes.
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