Double-layer continuous paving construction method for cement-stabilized base layer

Abstract

The invention relates to a double-layer continuous paving construction method for a cement-stabilized base layer. The construction method comprises the following steps: completing construction of a subbase layer, an earth shoulder edge strip and a median strip guardrail foundation strip; elevation control; producing and transporting the mixture; paving a lower base layer, and rolling the lower base layer; after the lower base layer is constructed for a certain distance, laterally distributing materials, paving the upper base layer, and rolling the upper base layer; synchronously constructing the upper base layer and the lower base layer; in the geotechnical cloth curing step, the upper base layer rolling and the lower base layer rolling are performed by adopting an eight-time rolling mode of initial rolling, re-rolling and final rolling, and the initial rolling adopts double-steel-wheel static pressure for one time and single-steel-wheel small vibration for one time; a single steel wheel is adopted for large vibration twice for re-pressing; a single steel wheel slightly vibrates for one time; the final pressing adopts a rubber wheel to stabilize the pressure twice; and double-steel-wheel smooth surface static pressure is performed once. By adopting the double-layer continuous paving construction process, the construction efficiency of the base layer can be improved, and the curing time of the lower base layer is saved;

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, and in particular to a double-layer continuous paving construction method for a water-stable base. Background Art

[0002] The traditional base construction sequence is to complete the lower base first, and then proceed to the upper base construction after the curing period of the lower base. This process is more suitable for working surfaces with long and continuous construction sections, but it will bring problems such as frequent traffic changes and large amount of curing operations. Summary of the invention

[0003] The purpose of the present invention is to provide a double-layer continuous paving construction method for a water-stable base layer to solve the problems raised in the above-mentioned background technology.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solution: a double-layer continuous paving construction method for a water-stable base, the method comprising the following steps:

[0005] Step 1: Complete the construction of the subbase, earth shoulder edge strips, and center divider guardrail foundation strips;

[0006] Step 2: Elevation control;

[0007] Step 3: Mixture production and transportation;

[0008] Step 4: Paving and rolling the lower base;

[0009] Step 5: After a certain distance in step 4, spread the material sideways, spread the upper base, and roll the upper base;

[0010] Step 6: The upper and lower bases are constructed simultaneously;

[0011] Step 7: Geotextile curing;

[0012] Among them, the upper base layer rolling and the lower base layer rolling are carried out by initial rolling, repeated rolling and final rolling, a total of 8 rolling times. The initial rolling adopts double steel wheel static pressing for 1 time and single steel wheel small vibration for 1 time; the repeated rolling adopts single steel wheel large vibration for 2 times; single steel wheel small vibration for 1 time; the final rolling adopts rubber wheel steady pressure for 2 times; and double steel wheel smooth static pressing for 1 time.

[0013] Preferably, the traveling speed of the upper and lower base pavers is controlled at 1.6 m / min as the optimal paving speed, the traveling speed of the side feeder is kept consistent with that of the upper base paving machine at 1.6 m / min, the finished product conveying speed is matched with the traveling speed and maintained at 8 t / min, and the distance between the upper and lower bases is controlled according to two rolling sections, i.e. 80 m to 100 m.

[0014] Preferably, the initial pressing adopts 13t double steel wheel static pressing for 1 time and 26t single steel wheel small vibration for 1 time; the repeated pressing adopts 26t single steel wheel large vibration for 2 times; 26t single steel wheel small vibration for 1 time; the final pressing adopts 30t rubber wheel steady pressure for 2 times; and 13t double steel wheel smooth static pressing for 1 time.

[0015] Preferably, the wheel tracks should overlap by 1 / 2 of the wheel width during rolling, the rear wheel must exceed the joint between the front and rear sections, and the rear wheel should roll the entire width of the road surface once; the overlap width of the rubber wheel should be no less than the width of two wheels and no less than 60cm.

[0016] Preferably, the driving speed of the roller during rolling should be 1.5-1.7 km / h for the first and second passes, and 1.8-2.2 km / h for subsequent passes.

[0017] Preferably, the elevation control of the lower base layer adopts hanging wire construction, and the hanging wire construction is based on the strip, and the elevation control of the upper base layer adopts balance beam construction.

[0018] Preferably, the mixture comprises the following components: 25% 19-31.5 mm crushed stone, 30% 9.5-19 mm crushed stone, 10% 4.75-9.5 mm crushed stone, 35% 0-4.75 mm stone chips, and 5.5% cement.

[0019] Preferably, the crushing value of the crushed stone is not greater than 26%, the maximum nominal particle size is not greater than 31.5 mm, the needle-like content is less than 18%, the plasticity index of the stone chips is ≤17, and the dust content below 0.075 mm is ≤15%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The double-layer continuous paving construction method of the water-stable base provided by the present invention is that when the base construction is carried out after the subbase construction is completed, the upper base covering construction is carried out after the lower base is paved and rolled and before the cement is initially set. The double-layer continuous paving construction process can improve the efficiency of the base construction and save the curing time of the lower base; on the other hand, it is of great help to improve the overall bonding performance between the water-stable bases. In addition, the components of the raw materials provided by the present invention and the paving and rolling methods can ensure the compaction and flatness requirements of the road surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a construction flow chart of the present invention;

[0023] Figure 2 A schematic diagram of elevation control provided by the present invention; DETAILED DESCRIPTION

[0024] The technical solution in one embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0025] See also Figure 1-2 :

[0026] A double-layer continuous paving construction method for a water-stable base layer, the method comprising the following steps:

[0027] Step 1: Complete the construction of the subbase, earth shoulder edge strips, center divider guardrail foundation strips, and lower bearing layer treatment

[0028] Step 2: Elevation control;

[0029] Step 3: Mixture production and transportation;

[0030] Step 4: Paving and rolling the lower base;

[0031] Step 5: After 80m of construction in step 4, spread the material sideways, spread the upper base, and roll the upper base;

[0032] Step 6: The upper and lower bases are constructed simultaneously;

[0033] Step 7: Geotextile curing;

[0034] Taking the double-layer continuous paving construction method of a certain road surface as an example, a specific description is given. The designed thickness of the road surface base is 36cm (18cm for the upper base and 18cm for the lower base):

[0035] 1. Raw material preparation

[0036] The raw materials used for cement stabilized crushed stone base include: 0-5mm stone chips: 5-10mm crushed stone: 10-20mm crushed stone: 20-30mm crushed stone. The crushing value of the crushed stone is not more than 26%, the maximum nominal particle size is not more than 31.5mm, and the needle-like content of the base crushed stone is less than 18%. The plasticity index of the stone chips is ≤17, and the dust content below 0.075mm is ≤15%.

[0037] Its components: 25% 19-31.5mm crushed stone, 30% 9.5-19mm crushed stone, 10% 4.75-9.5mm crushed stone, 35% 0-4.75mm stone chips, and 5.5% cement.

[0038] 2. Work surface preparation

[0039] Before construction, the strip foundation construction of the center guardrail base and the earth shoulder strip construction of the fill section shall be completed, and the longitudinal ditch construction of the super-elevation section shall be completed. The slipform strip foundation can be used as a base template to reduce the mold erection process and achieve the goal of reducing the number of workers in the process.

[0040] 3. Measurement preparation (elevation control): the lower base layer is constructed by hanging wire, and the upper base layer is constructed by balancing beam.

[0041] Before construction, the top elevation of the slipform construction strip and longitudinal ditch was measured and checked, and the points were arranged every 10m. According to the construction design, the top surface of the earth shoulder strip of the fill section is flush with the top surface of the base layer, the top surface elevation of the center strip foundation is 8cm higher than the top surface of the base layer, the top surface elevation of the longitudinal ditch is 3cm higher than the top surface of the base layer, and the roadbed ditch is 18cm higher than the top surface of the base layer.

[0042] ① The construction team will mark the total compacted thickness of the base layer and the compacted thickness of the lower base layer on the strip / base / ditch wall at the corresponding pile number according to the elevation table given by the measurement one day before construction. Make a mark point every 10m and use ink line to pop out the designed top surface height of the lower base layer and upper base layer.

[0043] ② The construction of the lower base line is carried out according to the general steps. Because the construction of the strip / base / longitudinal groove is completed before the base construction, and the structures of the slipform construction are all above 36cm, the iron piles are required to be set up on the top of the slipform structure. Use an electric drill to drill holes and then insert the iron piles, and the insertion depth is controlled at 10cm; an iron pile is erected every 20m in the normal section and one every 10m in the super-high section.

[0044] ③ After the lower base is compacted, check the lower base top elevation marked on the corresponding slipform structure / excavation ditch, mark the sections with a difference of more than 1 cm with spray paint and spray out the difference height together.

[0045] ④ The upper base layer is constructed with a balance beam. Before construction, a mark is made on an iron rod according to the standard thickness multiplied by the loose laying coefficient. During the construction of the upper base layer, fine-tuning is performed on sections where the elevation difference of the lower base layer is more than 1 cm after compaction. At other times, the loose laying thickness is checked every 20 meters.

[0046] ⑤ When constructing the upper base, because a balance beam is used for construction, an iron stake for testing the thickness of the loose paving should be prepared. After the upper base is compacted, it needs to be compared with the elastic line.

[0047] The lower base layer is constructed by hanging wires, which has better effects on layer thickness and flatness control. At the same time, the upper base layer is constructed by balancing beams to achieve automatic leveling without manual hanging wires, thus reducing labor input.

[0048] 4. Mixture production and transportation;

[0049] 5. Paving

[0050] (1) Before paving the lower base, use a cement slurry spreader to spread cement slurry. The amount of cement slurry spread is controlled according to the ratio of water to cement = 0.5:1.

[0051] (2) During the double-layer continuous paving construction, the lateral feeder is used to transport clinker from the upper base paver to the upper base paver on the other side. The lateral feeder is synchronized with the upper base paver. The travel speed of the upper and lower base pavers is controlled in the range of 1.5m / min to 1.8m / min. The travel speed of the lateral feeder is consistent with that of the upper base paver. The finished product conveying speed is matched with the travel speed and maintained between 7.5t / min and 9t / min. The distance between the upper and lower bases is controlled according to two rolling sections, i.e. 80m to 100m, to ensure the rolling quality and the actual measurement index detection space of the lower base.

[0052] 6. Rolling

[0053] When rolling, each layer is rolled using 2 single steel wheel rollers, 1 double steel wheel roller and 1 rubber wheel roller.

[0054] The rolling section of the lower base is 50m, and the rolling section of the upper base is between 50m and 80m. The rolling section should not be too short, otherwise it will form indentation waves between sections, resulting in poor flatness; the rolling section of the lower base should not be too long, otherwise it will affect the paving speed of the upper base, and thus miss the time to complete the rolling of the upper base before the initial setting time of the lower base.

[0055] The base layer and the lower base layer are rolled by initial rolling, repeated rolling and final rolling for a total of 8 times.

[0056] The initial pressure is carried out by using 13t double steel wheel static pressure once and 26t single steel wheel small vibration once; the secondary pressure is carried out by using 26t single steel wheel large vibration twice and 26t single steel wheel small vibration once; the final pressure is carried out by using 30t rubber wheel steady pressure twice and 13t double steel wheel smooth static pressure once.

[0057] When rolling, the wheel tracks should overlap by 1 / 2 of the wheel width, the rear wheel must exceed the joint between the front and rear sections, and the rear wheel should roll the entire width of the road surface once; the overlap width of the rubber wheel should be no less than the width of two wheels and no less than 60cm.

[0058] The driving speed of the roller during rolling should be 1.5-1.7 km / h for the first and second times, and 1.8-2.2 km / h for subsequent times.

[0059] 7. Detection

[0060] By using the construction method provided by the present invention, sampling K40+000~K40+820 of the constructed road surface is tested, and the test results are as follows:

[0061] a) Loose laying coefficient

[0062] 1. The design thickness of the left base of K40+000~K40+820 is 36cm (18cm for the upper base and 18cm for the lower base). Conclusion: The design compaction thickness of the left base of K40+000~K40+820 is 36cm, the loose laying coefficient of the lower base is 1.320, and the loose laying coefficient of the upper base is 1.26.

[0063] B) Thickness and compaction

[0064] The thickness and compaction degree are tested by sand filling method.

[0065] (1) The left base layer from K40+000 to K40+820 was tested for 12 points using 8 rolling passes (the initial rolling was performed using a double steel wheel roller, with 1 static rolling pass and 1 small vibration pass using a single steel wheel roller. The secondary rolling was performed using a single steel wheel roller, with 2 large vibration passes and 1 small vibration pass. The final rolling was performed using a rubber wheel roller, with 2 rolling passes and 1 smooth pass using a double steel wheel roller). A total of 8 passes.

[0066] The single point qualified rate is 100%, and the average compaction degree is 99.4%. See Table 1 and Table 2:

[0067]

[0068]

[0069] Conclusion: The thickness test results all meet the design and specification requirements; the compaction test results are all ≥98%, indicating that the rolling sequence, number of passes, paving speed and roller speed can ensure the base thickness and compaction. Therefore, the subsequent construction base rolling plan recommends the use of an 8-pass rolling process.

[0070] C) Flatness

[0071] 1. The flatness test results of the left base layer of K40+000~K40+820 are as follows, see Table 3 and Table 4:

[0072]

[0073]

[0074] Conclusion: The base was tested at 8 locations with a surface area of ​​10 feet each. The average flatness was 2.0 mm, and the qualified rate was 100%. All of them met the standard requirement of not more than 8 mm. The flatness test results show that the base paving and compacting process can ensure that the flatness meets the requirements.

[0075] Conclusion: The particle gradation of the base mixture meets the requirements of the graded crushed stone base aggregate gradation composition in the design documents.

Claims

1. A double-layer continuous paving construction method for a water-stable base layer, the method comprising the following steps: Step 1: Complete the construction of the subbase, earth shoulder edge strips, and center divider guardrail foundation strips; Step 2: Elevation control; Step 3: Mixture production and transportation; Step 4: Paving and rolling the lower base; Step 5: After a certain distance in step 4, spread the material sideways, spread the upper base, and roll the upper base; Step 6: The upper and lower bases are constructed simultaneously; Step 7: Geotextile curing; in, The upper and lower base layers are compacted using an initial compaction, secondary compaction, and final compaction method for a total of 8 times. The initial compaction uses double steel wheel static compaction for 1 time and single steel wheel small vibration for 1 time; the secondary compaction uses single steel wheel large vibration for 2 times and single steel wheel small vibration for 1 time; the final compaction uses rubber wheel steady pressure for 2 times and double steel wheel smooth static compaction for 1 time.

2. A double-layer continuous paving construction method for a water-stable base according to claim 1, characterized in that: The travel speed of the upper and lower base pavers is controlled at a paving speed of 1.6m / min, the travel speed of the side spreading machine is consistent with that of the upper base paving machine at 1.6m / min, the finished product conveying speed is matched with the travel speed and maintained at 8t / min, and the distance between the upper and lower bases is controlled according to two rolling sections, i.e. 80m~100m.

3. A double-layer continuous paving construction method for a water-stable base according to claim 1, characterized in that: The initial pressing uses 13t double steel wheel static pressing for 1 time and 26t single steel wheel small vibration for 1 time; the repeated pressing uses 26t single steel wheel large vibration for 2 times and 26t single steel wheel small vibration for 1 time; the final pressing uses 30t rubber wheel steady pressure for 2 times and 13t double steel wheel smooth static pressing for 1 time.

4. A double-layer continuous paving construction method for a water-stable base according to claim 1, characterized in that: When rolling, the wheel tracks should overlap by 1 / 2 of the wheel width, the rear wheel must exceed the joint between the front and rear sections, and the rear wheel should roll the entire width of the road surface once; the overlap width of the rubber wheel should be no less than the width of two wheels and no less than 60cm.

5. The double-layer continuous paving construction method of a water-stable base according to claim 1 is characterized by: The driving speed of the roller during rolling should be 1.5-1.7 km / h for the first and second times, and 1.8-2.2 km / h for subsequent times.

6. A double-layer continuous paving construction method for a water-stable base according to claim 1, characterized in that: The elevation control of the lower base layer adopts hanging wire construction, and the hanging wire construction is based on the strip, and the elevation control of the upper base layer adopts balance beam construction.

7. A double-layer continuous paving construction method for a water-stable base according to claim 1, characterized in that: The mixture comprises the following components: 25% of 19-31.5 mm crushed stone, 30% of 9.5-19 mm crushed stone, 10% of 4.75-9.5 mm crushed stone, 35% of 0-4.75 mm stone chips and 5.5% of cement.

8. A double-layer continuous paving construction method for a water-stable base according to claim 7, characterized in that: The crushing value of crushed stone is not more than 26%, the maximum nominal particle size is not more than 31.5mm, and the needle-like content is less than 18%; the plasticity index of stone chips is ≤17, and the dust content below 0.075mm is ≤15%.

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