底基层施工准备及注意事项.docx

1、底基层施工准备及注意事项底基层施工准备及注意事项（Preparation and notice of bottom base construction）Subbase construction preparation and precautions of.TxtThe road in the construction process, affected by many factors, weather, temperature, hydrological and mechanical equipment, construction method, are more or less of thi

2、s or that problem, often appear some quality problems in operation, such as part of the road surface construction is completed, rigid pavement broken slab cracks, flexible pavement, there will be severe in the bag, frothing. Although these problems no longer exist after the rectification of quality

3、defects, but revealed a problem in the construction of the road construction is often attached to the road surface construction quality, but ignore the construction quality of the base. Because the fracture surface layer, the surface layer Bu see enough of a problem, the essence and the construction

4、 quality is closely related to. The road surface construction is completed and base closely together, the load on the surface layer mainly rely on the grassroots to bear, dispersion. The construction quality will directly affect the service life of the road.1 construction preparation1) acceptance of

5、 the roadbed. Soil roadbed surface should be flat, solid, with prescribed surface height, crown, roadbed width, roughness, compactness etc. shall meet the standard requirements, qualified on-site supervision engineer signed the approval process. Where the acceptance of sections, measures must be tak

6、en to reach the standard, before the construction of cement stabilized layer.2) construction machinery and equipment. The construction equipment of cement stabilized soil with grader, roller and water tankers, each working group should be equipped with 1 graders, 1 roller and 3 water tankers, tanker

7、s number according to the size of water quality adjustment. Traders in the project construction, construction machinery is the best combination of two work groups with the homework, namely 2 graders, 2 rollers, 5 water tankers, it saves a water truck, and the construction efficiency is fast and can

8、ensure the quality of construction.3) cement preparation. The cement should be used in the final setting time is longer, the lower grade of Portland cement, Portland cement, slag cement, etc.4) proportion of cement stabilized soil. In the laboratory of soil sampling, cement inspection, test, sample

9、preparation, according to the specimen maintenance 7d unconfined compressive strength test results obtained. Different aggregates for each soil pile, we are sampling to do the test, the cement content is 1%, 2%, 3% different test match, we selected the field soil is sandy soil of different grade, th

10、e highest amount of cement is 3%, the lowest was 2%.5) the calculation of material consumption. According to the roadbed width, thickness and predetermined degree of compaction, calculate the aggregate weight of each stem need, according to the water content of aggregate and material transport vehic

11、le tonnage, per vehicle material stacking distance; according to the cement stabilized layer thickness and the predetermined dry density and the dosage of cement, cement stabilized soil to calculate 1m2 cement weight, and calculate the per bag of cement paving area, calculated per bag of cement vert

12、ical and horizontal spacing.6) test section. The test section is to test the construction scheme, the cement stabilized soil with an important means, determination of thickness and mechanical properties of virtual paving construction. By the contractor with the engineer according to the site visit,

13、a common choice of the road is representative and typical soil as the experimental sections, prepared by the contractor construction plan submitted to the Engineer for approval.In the test section construction, should be targeted to collect the thickness and the degree of compaction and rolling mach

14、inery through the relationship between the number of data, the test section after the preparation of test road construction summary, in order to guide the overall construction.2 processTo transport material, construction lofting paving, paving thickness, check the material manual arrangement for pav

15、ing cement, cement ground, dry mixing, wet mixing, spraying shaping, rolling, seams and the treatment and health.3 technical requirements1) base measurement line. Back on both sides of the subgrade height and direction of the line control survey of piles, each pile with a 20m. Carefully check the el

16、evation of pile height nail. The top is 11.4m wide Pasay highway roadbed, roadbed fill the total height of about 1m 2m, so most of the measuring distance of pile center line 10m. Of course, according to the actual situation is different, can choose different distance.2) transportation and paving. Th

17、e transport material, the predetermined stacking lower in the compost before watering, make it moist. Aggregate loading, should be controlled almost the same amount of material per vehicle, according to the calculated distance materials will be unloaded to the middle of the road, discharge distance

18、should be strictly controlled, too much or too little to avoid, by the person in the field of controlling the discharge. Unload material after the Grader will feed out flat, paving thickness determined by test to determine the coefficient of loose paving, paving after by the foreman responsible for

19、elevation pile check material thickness, if not suitable to adjust.3) paving cement. Good in the aggregate shop stalls, according to the calculation of the per bag of cement and cement well spacing, placing markers per bag of cement in the aggregate layer, and draw the paving cement line. Cement fro

20、m manufacturers when the goods shipped directly to the site, the equipment shipped cement should be rain. The cement with tray scattered on the roadside, the day before the afternoon stable layer construction using artificial per bag of cement shipped to mark the location, check for missing and exce

21、ss. In the stable layer construction on the morning, open the bag of cement in the grader before starting to work, will fall in the cement aggregate layer, then use the grader blade in front of the cement evenly spread out. Each bag of cement paving paving cement equal area, after the surface should

22、 be no blank.4) dry mix. With plough grader behind will be paved cement stirring for two times, the cement distribution to aggregate, but not plough in the end, in order to prevent the cement into the bottom. The first time the road center began, the mixture turned to the middle, and mechanical spee

23、d. Second times instead, from both sides began to mix to rollover.5) wet mix. Dry mix after watering wet mix immediately. In front of the sprinkler sprinkler, sprinkler with grader after mixing, the uniform distribution of water in the mixture, in a relatively large longitudinal slope sections shoul

24、d be closely matched to reduce water outflow. Wet mix should begin in the middle, in front of the grader blade will turn to the material on both sides of the subgrade, and then turn to the two sides of the subgrade material by the middle of the road, and finally the material out flat, wet mix at lea

25、st 3 times; sprinkler watering should be continuous, not interrupted, watering should be long distance some, should the spill at the waterwheel and the other end at 2m or beyond the mixing head. The sprinkler is should not be a U-turn in the mixing and mixing on the road and the plan to stay, to pre

26、vent the local water is too large; and in the process of mixing water, water content of mixture should be timely check,The water content of fast determination of water content of mixture, but also in the field of artificial control, the optimum moisture content of the mixture to squeeze into the gro

27、up in the hand, fell on the ground to spread out; the process of mixing watering, but also with artificial sorting oversize particles, remove the coarse and fine particles and the nest local too wet or too dry place; mark mixing is completed, no ash ash mixture group and flower surface, no particle

28、nest and the water right uniform.6) rolling. After shaping, when the mixture at the optimum moisture content range of 1%, immediately by roller vibration above 12t for compaction in roadbed in full width. Line segments, from both sides of the shoulder into the center of the road roller; flat curve s

29、egments by the medial shoulder to external shoulder rolling. In short, from low to high gradually rolling. When rolling, cross rolling wheel requires half wheel, roller for walking speed1.5kmh 2.0kmh, degree of compaction of subgrade increases, increasing the rolling speed. Round trip is over, the g

30、eneral rolling several times. The first pressing 1 times, then the vibration pressure of 3 to 5 times to reach the required number of rolling after detection by test personnel density, unqualified should continue rolling until qualified; compaction after passing the final pressure again can. The ful

31、l picture of the rolling requirements during the rolling process, no leakage pressure, all parts of the rolling frequency should be the same, the width of the road on both sides should be appropriate to increase the number of rolling; rolling process should be appropriate to the surface of the cemen

32、t stabilized soil watering, keep wet, hot mixture evaporation of surface water is too large, should be timely watering, increasing water sprinkling; rolling process, if there is spring, loose, peeling and other phenomena, should be re opened or replacement of artificial mixing mixture is new, so as

33、to meet the quality requirements. Combined with the construction site, when rolling pressure across the dividing line between about 4m, ensure the compactness of the combination of.7) health. Each section of the cement road roller is completed, shall immediately proceed to health. The ultimate strength of cement soil formed after a long time