CN114381981A - Construction method of double-layer combined paving test section of guide road - Google Patents

Abstract

The invention provides a construction method for a double-layer combined paving test section of a guide road, which belongs to the field of municipal engineering. It is convenient to cultivate soil on the road shoulder, set reference points on both sides to control the elevation; S3, mixing and transportation of the mixture; S4, the paving of the mixture, using two paver trapezoid operations, during normal paving, continuous and uniform Paving; S5. Rolling of the mixture. The rolling process is initial pressure-re-compression-final pressure. The initial pressure makes the paved mixture into a stable state after initial pressing, and the re-pressing is used to compact the road surface, and the final pressure is used to close the pavement. Surface; S6, joint treatment, avoid longitudinal joints, and manually fill the horizontal construction joints with the mixture with appropriate water content; S7, health care and quality inspection, the quality meets the requirements of design and construction specifications. The invention has stable and reliable construction quality and high efficiency.

Description

Construction method of double-layer combined paving test section of guide road

technical field

The invention belongs to the field of municipal engineering, relates to the cement-stabilized gravel construction of a guide road, and in particular relates to a construction method for a double-layer combined paving test section of a guide road.

Background technique

Municipal road engineering is an important part of urban construction work, and it is a basic project that provides services for the life and production of urban residents, enterprises and institutions. Therefore, the quality of road engineering construction directly affects the economic construction of the city.

In actual work and life, it is often encountered that a certain section of the expressway needs to be closed due to weather, accidents or road construction to interrupt traffic. At this time, it is necessary to build a guide road, and the implementation standard shall be carried out in accordance with the expressway standard to ensure the smoothness of traffic. .

In order to determine the model of the road roller and the use of small rammers and other machinery to best match the economical choice; to determine the thickness of loose paving, compaction thickness and other parameters, it is necessary to set up a test section to ensure the construction quality of the entire subsequent project, so the construction of the test section critical.

SUMMARY OF THE INVENTION

The problem to be solved by the present invention is to provide a construction method for the double-layer joint paving test section of the guide road, which solves the problems existing in the above background technology, and has stable and reliable construction quality and high efficiency.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is: the construction method of the double-layer paving test section of the guide road comprises the following steps:

S1. Preparation of the lower bearing layer. Before the construction of the sub-base, the lower bearing layer is checked and accepted, and the steel formwork is supported on the inner side of the lower bearing layer, and then the lower bearing layer is thoroughly cleaned;

S2. Measure and set out, set out the middle pile and side pile, determine the width of the paving, which is convenient for road shoulder cultivation, and set reference points on both sides to control the elevation;

S3. Mixing and transportation of the mixture; the mixture is mixed evenly, so that the moisture content of the mixture when it is transported to the site for paving is not less than the optimum moisture content. If it is larger than 50cm, when unloading, let the mixed material unload into the paver hopper naturally, and the unloading speed should be coordinated with the paving speed to avoid the transport vehicle hitting the paver and unloading the mixed material outside the paver;

S4. For the paving of the mixed material, two pavers are used for trapezoidal operation. At the starting point of the paving, the paver screed is raised, and the processed sleepers are placed below according to the thickness of the virtual paving. Pave thickness requirements, and then drop the screed, and pave continuously and evenly during normal paving;

S5. For the rolling of the mixture, the driving wheel faces the direction of the paver, from the side of the road to the middle of the road, first light and then heavy, first slow and then fast, and rolling at low speed to avoid the phenomenon of shifting, peeling and leakage. It is strictly forbidden for the road roller to turn around or brake suddenly during the rolling process or the rolling road section; the rolling process is initial pressure-recompression-final pressure. , the final pressure is used to close the surface;

S6. Joint treatment, avoid longitudinal joints, manually fill the horizontal construction joints with the mixture with appropriate water content, place square wood perpendicular to the road centerline, the height of the square wood is equal to the thickness of the compaction layer, and the rolling is compact;

S7. Health preservation and quality inspection. The cement stabilized gravel mixture is rolled and compacted. After the test is passed, the permeable geotextile is covered with water in time for health preservation. The two pieces should overlap each other by more than 20cm to ensure that the surface is moist. The quality meets the design and construction specification requirements.

Further, in step S2, use φ20mm steel drill to set reference points on both sides, the reference point elevation is the design elevation plus 20cm, when the reference point is established, a steel drill is used for every 10 meters in the straight line, and a steel drill is used for every 5 meters in the curved segment. Steel drill, hang the wire rope and tighten it to ensure the level of the reference line. The reference line is fixed on the steel drill with φ5mm steel wire. The length of each section should be less than 200m, and the tension is not less than 1000N.

Further, in step S4, two pavers are used for trapezoidal operation, the outer paver is in front, the inner paver is behind, the outer side of the front paver is controlled by the elevation reference line, and the road is controlled by a 6m long guide beam. ;The outer side of the rear paver is controlled by the elevation reference line; the distance between the front and rear paver is not more than 10m, and the horizontal overlap width is 30cm. When artificially paving the special-shaped road section, use the hanging line to control the elevation, and the paving speed should be uniform and controlled at 1.5m -2.0m/min, no speed change is allowed in the middle, and the paving is not stopped or interrupted.

Further, in step S5, the sand filling method is used to check whether the compaction degree is qualified. If it is unqualified, the number of rolling passes should be increased. The compaction degree detection frequency should be 2 points per 200m per lane. 3m, stop on the road section that has been rolled, and after the recompression is completed, the rolling bulge will be manually processed, and a special person will use a 6m ruler to test the flatness, and each lane will be tested.

Further, before step S1, the raw materials of the mixture are prepared, including cement, coarse aggregate, and fine aggregate, the mixture is designed by the vibration molding method, the gradation of the mineral mixture is prepared, and different cement dosages are prepared. The dose is 4%-6%.

Further, 32.5 ordinary Portland cement is used as the cement, and stone chips with good gradation are selected as the fine aggregate. The methylene blue value is not more than 10g/Kg, and the sand equivalent is not less than 50%.

Further, when the commissioning of the mixing equipment is completed and the design of the material composition is completed, the commissioning of the construction mix ratio is carried out, including the first stage of trial production: according to the set construction parameters, no cement and water are added, and the material is reclaimed and screened on the belt. , verify whether the gradation meets the design requirements, adjust the production parameters if necessary and make relevant records;

The second stage of trial production: first add cement and water according to the design mix ratio, then add cement and water according to ±1% of the standard dose, and take samples for water content determination, cement dose determination, standard density and unconfined The compressive strength test determines the construction mix ratio to guide the construction.

Further, before the formal mixing, do the aggregate screening test to check whether the gradation of the crushed stone mixture meets the requirements. If there is any problem, adjust it in time. When the particle gradation of the material changes, the mixing ratio should be re-adjusted to ensure that the mixture gradation meets the design requirements. When mixing, the cement dosage should be increased by 0.5% compared with the design, and the mixture should be screened every half a day to ensure the mineral material gradation. Accurate, when the gradation changes, the calculation is adjusted, the mixture is mixed evenly, the phenomenon of whitening and segregation is strictly prohibited, and the moisture content is 1.0%-2.0%.

Further, during the mixing process, the segregation of the mixture should be reduced. When the water-stabilized mixture is output in the mixing station, the discharge height should be reduced. The finished product warehouse should be discharged intermittently. m; During the paving process, two-thirds of the auger of the paver is buried in the mixture, so that the auger runs evenly.

Compared with the prior art, the present invention has the following advantages and positive effects.

1. The present invention strictly controls the mixing quality of the mixture, checks the mixing process from time to time, and adjusts the performance of the equipment to ensure the cement dosage. During mixing, the cement dosage should be increased by 0.5% compared with the design, and the mixture is screened every half a day. Ensure that the grading of mineral materials is accurate. When the grading changes, the calculation is adjusted, and prevention and preparation are carried out from the raw materials to ensure the construction quality of the thickness;

2. In the process of transportation and paving, the present invention sets the precautions for loading and unloading, reduces the segregation of the mixture as much as possible, and ensures uniform loading, continuous paving and unloading, and stable speed. A special person should be set up to eliminate the segregation of fine aggregates, and at the same time, the cloth bolts and reverse blades of the paving equipment should be adjusted, and the angle should be adjusted to prevent segregation, which is stable and reliable, and has high efficiency;

3. The invention can ensure the flatness of the water stable layer, and the rolling is completed before the initial setting of the cement and the delay time determined by the test, and reaches the required compaction degree. During the paving process of the paver, the continuous and uniform paving is ensured. Guaranteed compaction.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide further understanding of the present invention, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the attached image:

Fig. 1 is the cross-sectional view of the guide road of the construction method embodiment of the double-layer paving test section of the guide road of the present invention;

Fig. 2 is the flow chart of the construction method of the double-layer paving test section of the guide road of the present invention;

Fig. 3 is a standard table for the detection of cement-stabilized base layers of the present invention.

Detailed ways

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

In the description of the present invention, it should be understood that the terms "center", "portrait", "horizontal", "top", "bottom", "front", "rear", "left", "right", " The orientation or positional relationship indicated by vertical, horizontal, top, bottom, inner, outer, etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and The description is simplified rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. In addition, the terms "first", "second", etc. are used for descriptive purposes only, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first", "second", etc., may expressly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in Fig. 1-Fig. 3, the guide road station number range is DXK0+222.425-DXK1+200.120, the total length is 977.695m, the whole line adopts the standard of two-way four-lane expressway, the design speed adopts 80Km/h, and the standard width of the roadbed is 21.5m. The width of the carriageway is 4*3.75m, the central dividing belt is 1m, the curb belt is 2*1.5m, the hard shoulder is 2*1.5m, and the dirt shoulder is 2*0.75m, as shown in Figure 1, it is a guide road Cross-sectional view.

The test section of the cement-stabilized gravel of the guide road is selected at DXK0+427.591-DXK0+994.954, with a total length of 567.363m and a compaction thickness of 0.18m. The cement-stabilized gravel in the test section is divided into two layers, which are the sub-base 3.0Mpa/7d and the base. 4.0Mpa/7d, the paving method adopts double-layer joint paving, and the strength is implemented according to the base layer 4.0Mpa/7d. This section is used as the test section of cement-stabilized gravel double-layer joint paving.

The area where the project is located has a warm temperate monsoon continental semi-humid arid climate, with little rain in spring, wet and rainy summer, cool and dry autumn, and cold winter with little snow. The annual average temperature is 12.4°C, the extreme maximum temperature is 41.2°C, and the extreme minimum temperature is -22.2°C. The annual average precipitation is 495.1 mm, the extreme maximum annual precipitation is 931.8 mm, and the extreme minimum precipitation is 207.3 mm. The northerly wind is the most throughout the year, with an annual average wind speed of 2.1 m/s. The extreme maximum wind speed in history is 20 m/s.

The foundation of the site where the project is located is basically stable, the groundwater level has little impact on the construction of the project, there are basically no problems such as soft soil and liquefiable soil, and the development of land subsidence is weak. The Quaternary alluvial deposits are distributed within 15 meters of the site, with obvious sedimentary rhythm in the vertical direction, and the distribution thickness in the horizontal direction is relatively stable. The site soil is mainly divided into silty clay, silt, silt, medium sand, etc. The groundwater level of the site is buried at a depth of 12.74-13.41 meters. The thickness of the non-liquefied soil layer and the depth of the groundwater table are in line with dw>d0+db-3. The site may not consider the impact of liquefaction, and the standard freezing depth in this area is 0.6 meters.

The construction method of the double-layer joint paving test section of the guide road includes the following steps.

1. Before construction, follow the steps below to prepare for construction.

1. Station preparation

(1) The cement stabilized crushed stone is transported to the site by the finished material of the commercial mixing station. The commercial mixing station is located in Dahezhuang Village, Bazhou City Development Zone, Langfang City, Hebei Province. The transportation distance is 23.5 kilometers, and it takes 45 minutes to transport to the construction site. , Commodity station adopts WCB-800 (800T/H) stabilized soil mixing equipment, the equipment adopts double mixing cylinder, the length of mixing cylinder is not less than 5m, 5 cold silos, equipped with water flow meter and cement weight meter, and can be used in The operation room displays the amount of water added and the amount of cement. The mixing equipment is accurately measured and qualified by the quality and technical supervision institute. The computer of the mixing building can record the production mix ratio, output and total amount by time period at any time, and can store or export. And the mixing station is installed and monitored.

(2) Add a 10cm×10cm steel grid with a diameter of not less than φ16 above the hopper to screen out the aggregates and sundries that exceed the particle size specification, and set up baffles between the hoppers with a height of not less than 80cm.

(3) Centralized stacking of waste, especially the waste that has not been emptied on the material transporter.

(4) The mixing site should be clean and tidy, there should be no water accumulation under the aggregate pile, and the equipment should be parked in an orderly manner.

(5) After the plan of the test section is approved by the supervision unit, the construction of the test section can be carried out only after the technical and safety disclosures are made to the operation team.

2. Raw material preparation

Since the cement stabilized crushed stone is transported to the construction site by the purchased finished materials, the construction unit shall control the process materials and the mixing ratio.

(1) Cement

According to the design and verification of indoor mix ratio, 32.5 ordinary Portland cement is used, and the cement entering the site is sampled and tested by the laboratory, and various technical indicators must meet the requirements of national technical standards.

Table 1 Mud technical indicators

(2) Coarse aggregate: The gradation of coarse aggregate meets the requirements of the following table.

Table 2 Technical Specifications of Coarse Aggregate

Test items skills requirement experiment method Organic content lighter than standard T0316 Dust content below 0.075mm (%) ≦2 T0316 Needle flake content (%) ≦20 T0316 Sulfate content (%) ≦0.25 T0316 Soft stone content (%) ≦5 T0316 Crushing value (%) ≦26 T0316

(3) Fine aggregates: fine aggregates are selected from stone chips with good gradation. The content of particles smaller than 0.075mm in the fine aggregates should not exceed 15%, the plasticity index should not exceed 8%, and the methylene blue value of the aggregates should not exceed 10%. More than 10g/Kg, the sand equivalent is not less than 50%.

Table 3 Technical Specifications of Fine Aggregate

Test items skills requirement methylene blue value ≦10 Dust content below 0.075mm (%) ≦15 plasticity index ≦8

3. Design of the composition of the mixture

The mixture adopts the vibration molding method to design the mix ratio, mixes the mineral mixture gradation, and prepares different cement dosages. The cement dosage configuration is 2 kinds, respectively 4% and 5%. The actual test results of the 4% cement dosage are 4.1 and 5%. The actual test result of the cement dosage on site is 5.4, and the 5% cement dosage meets the requirements of the design drawing 7d/4.0Mpa. The tested theoretical ratio and other indicators are as follows:

Table 4 Mixture Design

The 7d water immersion compressive strength of cement-stabilized crushed stone should meet the relevant requirements of "Technical Specification for Construction of Highway Pavement Base".

In order to reduce cracks in the sub-base, the cement dosage should be controlled on the basis of satisfying the design strength, and the cement dosage should be controlled at 4%, and the maximum should not exceed 6%. While reducing the amount of cement, limit the amount of fine aggregate and powder; adjust the water consumption according to the construction climatic conditions.

4. Mineral grading

The composition design of cement-stabilized crushed stone includes raw material quality inspection, mineral mixture gradation composition design, determination of necessary cement dosage and optimal water content of mixture, etc. Before the mixing plant starts production, the design mix ratio should be re-examined according to the on-site aggregate, and the re-examined mix ratio will be used as the standard mix ratio to control production.

Table 5 Gradation range of cement stabilized crushed stone

5. Debugging of the production mix ratio of the sub-base

When the mixing equipment is debugged and the material composition design is completed, the construction mix ratio should be debugged.

The first stage of trial production: According to the set construction parameters, without adding cement and water, take and screen the material on the belt to verify whether the gradation meets the design requirements, adjust the production parameters if necessary, and make relevant records.

The second stage of trial production: firstly add cement and water according to the designed mix ratio, and then add cement and water according to ±1% of the standard dosage. Samples were taken for moisture content determination, cement dosage determination, standard density and unconfined compressive strength tests to determine the construction mix ratio to guide construction.

6. Construction site preparation

(1) Subgrade inspection: Subgrade inspection shall be realized jointly by the superintendent's office and the construction unit.

(2) Subgrade quality inspection: The subgrade construction quality (elevation, midline offset, width, transverse slope, flatness, compaction, reflection cracks, deflection, etc.) should be checked.

(3) Before the cement stabilized gravel (4.0Mpa/7d) is applied, there should be no over-dry or over-wet phenomenon, and the surface should be smooth, without water accumulation and looseness.

2. The construction process of the double-layer combined paving test section of the guide road is as follows

Process flow: As shown in Figure 2, lower bearing layer preparation → measurement and lofting → mixture mixing → mixture transportation → mixture paving → mixture rolling → compaction detection → preservation → finished product acceptance → next process.

1. Preparation of the lower bearing layer

(1) The inspection and acceptance of the lower bearing layer before the construction of the sub-base layer is qualified. Including elevation, midline offset, width, cross slope, flatness, reflection crack, deflection, etc. The surface of the lower bearing layer should be flat and solid, with suitable road crowns and cross slopes, without any loose and weak parts, with straight edges and smooth and tidy shoulders.

(2) A steel formwork with a height of 180mm is set up on the inner side of the lower bearing layer, and the firm line of the steel formwork should be straight and straight; on the outside, the road shoulder is first built, and compacted with a small compactor, and the cut edge is perpendicular to the bottom surface after reaching the specified degree of compaction , and then lay plastic film to prevent water loss at the edge of the water stabilized gravel, and the paving width ensures the design width of the upper layer.

(3) Thoroughly clean the lower bearing layer and sprinkle appropriate amount of water. During the construction process, keep the surface of the lower bearing layer moist to ensure the combination between the upper and lower layers.

2. Measure and stake out

(1) After the lower bearing layer is checked and accepted by the supervision engineer, GPS is used to accurately set out the middle piles and side piles, and the width of the paving is determined to facilitate the road shoulder cultivation.

(2) Use φ20mm steel drills to set datum points on both sides to strictly control the elevation. The elevation of the datum point is the design elevation plus 20cm. When the datum point is established, a steel drill is used for every 10 meters in the straight line segment, and every 5 meters in the curved segment. Meter a steel drill, the hanging wire rope should be tightened to ensure the level of the reference line.

(3) The reference line is fixed on the steel wire with φ5mm steel wire, the length of each section should be less than 200m, and the tension is not less than 1000N.

3. Mixing of the mixture

(1) The cement stabilized crushed stone mixture is mixed with WCB800t/h stabilized soil mixing equipment. Before mixing, the mixing equipment is repeatedly inspected and adjusted, so that the mixing equipment is accurately measured and qualified by the Quality and Technical Supervision Institute. .

(2) Three sets of ZL-50 loaders are used to feed the hopper, and the operator is trained before the start of construction. The shovel meets the requirements, and the occurrence of segregation during feeding is reduced. The feeding is uniform and should not be overfilled. The partition is separated to avoid the phenomenon of stringing. Before feeding, the tester should measure the moisture content of the aggregate to avoid frequent changes in the moisture content of the aggregate and affect the moisture content of the mixture.

(3) Before starting the formal mixing, do the aggregate screening test to check whether the gradation of the crushed stone mixture meets the requirements. If there is any problem, adjust it in time, and strictly control the pass rate of the key sieve holes of 19mm, 9.5mm and 4.75mm. When the particle gradation of the aggregate changes, the mix ratio should be readjusted to ensure that the mix gradation meets the design requirements.

(4) The mixture should be evenly mixed, and the phenomenon of whitening and segregation is strictly prohibited. The moisture content should be adjusted in time according to the change of weather and temperature. Generally, the moisture content should be controlled at about 1.0%-2.0% greater than the optimum moisture content, so that the mixture can be transported to the site for paving. The moisture content is not less than the optimum moisture content.

(5) The on-site tester of the mixing station shall detect the cement dosage, moisture content and the mixing ratio of various aggregates of the mixture during mixing, and make a record, and adjust or stop the production in time when any abnormality is found.

(6) Each hopper is equipped with 1-2 staff members to clean the super-sized stones and sundries at the entrance of the hopper in time, and monitor the feeding situation at all times to ensure that there is no jamming phenomenon, and to ensure the normal operation of the mechanical equipment.

4. Transportation of mixed materials

(1) According to the mixing capacity (800t/h), transportation distance (about 23.5Km) and paving speed (1.5m-2.0m/min), 20 large-tonnage dump trucks with a load of more than 50t are planned to be transported. It should be cleaned up and no residual material or water should accumulate on the bottom of the carriage.

(2) When discharging materials from the mixing building to the material transporter, the distance between the discharge port and the highest point of the trough of the carriage shall not be greater than 50cm, and the three-time discharge method shall be adopted to reduce the segregation of coarse and fine aggregates.

(3) After the dump truck is loaded, it is covered with an impermeable tarpaulin. The lower edge of the tarpaulin reaches 2/3 of the groove (calculated from top to bottom) and is tied firmly to avoid water loss and affect the compaction and forming effect.

(4) When the transport vehicle comes out, weigh and issue an out-of-field order, indicating the tonnage, appearance time, and number of vehicles in quadruplicate, and keep the stub in the weighing room. For the mixture that is too long, it will be abolished. After paving, sign and receive the exit list, and indicate the paving time.

(5) The transport vehicle is commanded by a special person, equipped with liaison communication tools and simple maintenance tools. The vehicle can be communicated and dealt with in a timely manner to ensure that after the vehicle fails, it can be repaired in time and can resume operation in the shortest time.

(6) When the transporter is unloading, a special person shall be set up to direct the transporter to stop the transporter about 30cm in front of the paver and put it in neutral gear. The hopper is lifted in three times, so that the mixed material is naturally unloaded into the paver hopper, to avoid the dump truck lifting too fast, and the coarse aggregate rolling down concentratedly causing partial segregation. The transporter driver and the paver operator closely cooperate to move forward Side unloading, the unloading speed is coordinated with the paving speed, to avoid the transporter hitting the paver and unloading the mixture outside the paver.

5. Paving of the mixture

Before paving, the lower bearing layer should be cleaned, free of debris, and sprinkled with water. excess.

(1) Paver model: two XCMG paver models: 903, 953T

Cement-stabilized gravel 4.0Mpa/7d is divided into upper and lower bases. In general, the designed paving width of the lower base is 10.81, and the design paving width of the base is 10.48; the assembly widths of the two paver are 6.5m and 4.50m respectively.

The loose paving coefficient is verified in two stages:

①The loose laying coefficient of DXK0+427.591-DXK0+677.591 section is planned to be 1.25, the loose laying thickness=18cm×1.25=22.5cm, and the loose laying thickness of 22.5cm shall be controlled during construction.

②The loose laying coefficient of DXK0+677.591-DXK0+994.954 section is planned to be 1.30, the loose laying thickness=18cm×1.30=23.4cm, the loose laying thickness of 23.5cm shall be controlled during construction, and the thickness shall be adjusted in time according to the thickness detection after compaction.

(2) Trapezoidal operation with two pavers (outside paver is in front and inner paver is behind). The outer side of the front paver is controlled by the elevation reference line, and the road is controlled by a 6m long guide beam; the outer side of the rear paver is controlled by the elevation reference line; the distance between the front and rear paver is not more than 10m, and the horizontal lap width is 30cm. When artificially paving special-shaped sections, use hanging lines to control the elevation. The specific method of placing the paver in place is as follows: at the starting point of paving, raise the paver screed, place the processed sleepers below according to the thickness of the virtual paving, place it in a balanced manner to meet the requirements of the thickness of the virtual paving, and then lower the screed. , Check the operation of the screw feeder and the sensitivity of the sensor to ensure the normal operation of the machine.

(3) During normal paving, there are 2 to 3 transport vehicles waiting for unloading in front of each paver to ensure continuous and even paving. When unloading, the bucket angle of the transport truck should be as large as possible, so that the mixture will collapse as a whole, so as to avoid segregation during unloading. When paving, the screw feeder should feed at a uniform speed to prevent high-speed operation, and avoid the separation of the bottom mixture caused by the concentrated rolling of the coarse aggregate; the paving speed should be uniform and controlled at 1.5m-2.0m/min. Do not stop or interrupt, and the material transporter should be reversed and unloaded as continuously as possible, so as not to cause the paving to stop and wait for materials; to keep the material level in the storage room stable, and to make the paver auger evenly supply material to both sides, spiral material The material level of the auger is slightly higher than that of the auger, and the auger is fully buried and the material is conveyed at a low speed, so that the mixture before the screed baffle is consistent in the full width, and the segregation of the paving layer is avoided.

(4) When paving, there are special personnel on both sides of the paver to take care of the sensors to ensure that the baseline is not disturbed. At the same time, the pull line is used to detect the lower return height at any time, so as to find the problem and communicate with the paver operator in time to make adjustments to ensure the thickness of the paving and avoid wavy surfaces. The loose thickness is detected in time during the paving process.

(5) Before each paver, two people should clean the pellets before the track. A worker is set behind each paver to check the surface after paving, replace the abnormal mixture in time, and notify the person in charge of the front field, so as to analyze the cause of the abnormal mixture in time, and communicate with the person in charge of the test and the person in charge of mixing. The problem of segregation of coarse and fine aggregates, especially the local coarse aggregate nests, should be eliminated, and the fine mixture should be sieved with a sieve to make up for it manually.

(6) The paver operator should observe the state of the mixture from time to time. If it is found that the water content is too small, the color difference of the mixture is large (small cement content), and the mixing is uneven, etc., they should immediately stop paving and notify the scene. Technicians handle.

(7) The mixture that is scattered on the ground when the transport vehicle leaves should be removed immediately to prevent the paver track from pressing on it and affecting the smoothness of the paving surface. Set up a special person to measure vertically and horizontally with a 6m ruler, and manually remove and level the parts with poor flatness.

6. Rolling of the mixture

(1) After the cement-stabilized gravel mixture is paved with a length of 30-50m, the road roller can be rolled over the full width. When rolling, the driving wheel should face the direction of the paver, from the roadside to the middle of the road. It is strictly forbidden for the roller to make a U-turn or brake suddenly in the rolling or rolling section.

(2) Rolling process:

Rolling machinery: 2 sets of 22t tire vibratory road rollers, 1 set of 30t rubber tire road rollers and 1 set of 13t double drum road rollers. In order to determine the compaction effect of the water-stabilized gravel subbase test section, two rolling methods are proposed (choose an optimal rolling combination):

DXK0+427.591-DXK0+677.591 segment adopts rolling method 1:

Preliminary pressure: (pressure stabilization) A rubber wheel roller is used, leaving 30cm on the outside without rolling (to prevent shoulder slipping), the road roller is rolled once at a walking speed of 2.5km/h, and the stop joint is rolled once in a 45-degree trapezoid to make the paving A good mixture is initially pressed into a stable state.

Re-compression: (compacting) 22-ton vibratory rollers are used to stagger 1/2 round, vibrate once and revive three times, and control the rolling speed at 2.0km/h.

Final pressure: Use a 30t rubber wheel roller to roll twice to close the surface.

DXK0+677.591-DXK0+994.954 segment adopts rolling method 2:

Initial pressure: (pressure stabilization) Drum roller is used, the roller is rolled once at a walking speed of 2.5km/h, and the stop joint forms a 45-degree trapezoidal rolling once, so that the paved mixture is initially pressed into a stable state.

Re-compression: (compacting) 22-ton vibratory rollers are used to stagger 1/2 round, vibrate once, reinvigorate twice, and vibrate once, and control the rolling speed at 2.0km/h.

Final pressing: Roll the surface twice with a rubber wheel roller, and then roll it once with a steel wheel roller to close the surface.

After the single-drum vibratory roller is revitalized twice, use the sand filling method to test whether the compaction degree is qualified. If it is unqualified, the number of times of rolling should be increased. The compaction degree detection frequency is 2 points per 200m per lane (the detection frequency of the test section is doubled) .

(3) The roller should stop naturally when reversing, and no brakes are allowed unless there are special circumstances; the gear shift should be light and smooth, and do not pull the grassroots. During the first preliminary voltage stabilization, return to the original road after reversing, the shifting position should be on the already pressed section, and the shifting and reversing position on the unrolled end should be staggered, and it should be tooth-shaped, and there will be individual pulping, starting When peeling, it should be leveled.

(4) The rollers should be parked in a staggered manner, with an interval of not less than 3m, and should be parked on the road section that has been rolled. It is strictly forbidden for the roller to turn around and brake suddenly on the road that has just been completed or is being rolled. The rolling compaction should be completed before the initial setting of the cement and within the delay time determined by the test to achieve the required degree of compaction without obvious wheel tracks.

(5) The mixture is mixed with water until the time of rolling and molding, which shall not exceed the initial setting time of the cement.

(6) Flatness detection and treatment: After the recompression is completed, the rolling bulge is manually processed, and a special person is assigned to use a 6m ruler to test the flatness, and each lane is tested.

7. Seam processing

(1) Transverse seam

It is not advisable to interrupt the paving of the mixture. If it is interrupted for more than 2 hours or after the construction every day, horizontal construction joints should be set up. Drive the paver away from the end of the mix, and manually make up the mix with the proper moisture content. Place square wood perpendicular to the road centerline, the height of the square wood is equal to the thickness of the compaction layer, and the rolling is dense. Use a 6m ruler to test the flatness, determine the cutting range and draw a line, and remove the mixture with unqualified flatness along the line. Before re-laying the mix, clean the underlayer and apply grout to the joints.

(2) Longitudinal seams

Avoid longitudinal joints. When construction must be divided into two pieces, the longitudinal joints must be vertically equal, and miter joints are not allowed.

8. Health

(1) The cement-stabilized crushed stone mixture is rolled and compacted. After passing the test, it should be covered with permeable geotextiles and sprinkled with water in time. The two sheets should overlap each other by more than 20cm to ensure that the surface is moist.

(2) During the health preservation period, all vehicles except the sprinkler are prohibited from passing through. The sign railings with a height of 1.5m are used for horizontal full-width layout, and a "No Pass" sign is set up, and a special person is assigned to take care of it.

(3) The health preservation period is not less than 7 days, and the number of health care days signs will be set up in the completed section every day. The number of waterings for the first three days should be at least 6 times a day. After that, the surface should be kept moist, and each working surface should be assigned a special person to be responsible for the health preservation work.

9. Quality inspection

(1) The pellets should meet the requirements of design and construction specifications, and the firm and clean pellets should be selected according to the local source.

(2) The amount of cement and mineral grading should be controlled accurately according to the design.

(3) When paving, attention should be paid to eliminate segregation, especially band segregation and nest segregation.

(4) The mixture should be in the best moisture content condition, and it should be rolled with a road roller to the required degree of compaction. The time from mixing with water to the end of rolling should not exceed the initial setting time of cement.

(5) After the rolling inspection is passed, it should be covered or sprinkled with water immediately, and the curing period should meet the requirements of the specification.

(6) The surface is flat and dense, the edges are neat, there is no looseness, potholes, and soft elastic phenomena, and the construction is smooth.

The measured items are shown in Figure 3.

10. Appearance requirements

(1) The surface is smooth and compact, without potholes and obvious segregation.

(2) The construction stubble is smooth and stable.

3. Safeguard measures

1. Mixing quality of the mixture (water content, cement dosage, mineral gradation)

Moisture content is the key to water-stabilized crushed stone rolling. When the actual water content W is close to the optimal water content (W0), the degree of compaction can be guaranteed. And during vibrating rolling, it is easy to accumulate cement slurry on the surface. In this way, when the core is checked, the lower part of the specimen is prone to loosening or insufficient strength. When W<W0, the water stable layer is prone to loosening, and the rolling is not compact, resulting in insufficient strength. In order to ensure that the water content is appropriate, a special person should be set up to detect the water content and adjust the mixing water content in time according to the weather conditions.

The cement dosage is the key to whether the strength of the cement stabilized crushed stone is qualified. During the mixing process, it must be checked from time to time, and the performance of the equipment should be adjusted to ensure the cement dosage. In order to ensure the cement dosage, the cement dosage should be increased by 0.5% compared with the design during mixing. The mixture is screened every half a day to ensure the accurate grading of the ore. When the grading changes, the calculation is adjusted.

2. Segregation of the mixture

In order to minimize the segregation of the mixture, the following requirements are required:

(1) When the water-stabilized mixture is output in the mixing station, the discharge height should be reduced as much as possible, and the finished product warehouse should be discharged intermittently.

(2) The vertical distance between the discharge port of the finished product warehouse and the material transport carriage should not be greater than 0.5m. The material transporter should move the front and rear positions in time to ensure uniform loading and reduce the stack height of each loading.

(3) During the transportation process, the material transport vehicle should drive at a uniform speed, and the starting brake should be stable. When the road conditions are poor, it should drive slowly to avoid strong bumps and vibrations.

(4) When the material transport vehicle is unloading to the paver hopper, it should lift the carriage slowly and evenly, and avoid the speed too fast.

(5) During the paving process, two-thirds of the auger of the paver should be buried in the mixture, and the auger should be run evenly, and should not be fast or slow. A special person should be set up behind the paver to eliminate the segregation of fine aggregates, especially the local "nests" of coarse aggregates should be removed and filled with freshly mixed materials.

(6) When leveling manually, the shovel fabric should be buckled, and the shovel should not be thrown far away. At the same time, the number of scraping and dragging should not be more than 2 times.

(7) Paving equipment cloth bolts and reverse blades, and adjust the angle to prevent segregation.

(8) Appropriately reduce the number of times the paver is retracted, and try not to retract the bucket.

(9) Appropriately reduce the height of the screed.

(10) Add a rubber pad to the rear of the paver auger to prevent the large material from rolling backwards and causing upper and lower segregation.

3. Flatness

The flatness of the water stabilization base is related to the construction quality of the surface layer. If the control is not good, on the one hand, it will affect the flatness of the surface layer, and on the other hand, the thickness of the surface layer will be difficult to control. In order to ensure the smoothness of the water stable layer, do the following:

(1) The lower bearing layer of the water-stabilized base must meet the specified flatness requirements before the water-stabilized base can be paved. If the surface of the lower bearing is wavy with poor flatness, it will inevitably reflect to the surface of the base. As a result, the flatness of the base surface is difficult to control.

(2) The rolling compaction should be completed before the initial setting of the cement and the delay time determined by the test, and the required compaction degree should be achieved, and there is no obvious wheel track. Rolling is carried out in strict accordance with the rolling process of the construction plan to prevent waves and affect the flatness.

(3) For manual leveling, experienced and responsible personnel should be selected to be responsible for leveling, and at the same time, a ruler of about 6m should be equipped to assist in checking the unevenness.

(4) During the paving process of the paver, it should be ensured that the paving is continuous and even, and there should be a transport vehicle in front of the paver waiting to unload, otherwise the frequent stop of the paver will affect the flatness.

(5) Do the compaction test immediately after the rolling is completed. If the test result fails to meet the standard, carry out the rolling again.

(6) Strictly control the water consumption of the mixture to avoid too large or too small moisture content.

4. Rolling quality

In order to ensure the compaction of the cement-stabilized gravel base, compaction machinery is the key, and the capacity of compaction equipment is relatively high. During the construction process, the rolling combination determined in the test section must be strictly followed, and a road roller must be equipped to ensure the degree of compaction. Quality Assurance Measures

5. Establish a quality inspection system of "horizontal to edge, vertical to the end, and effective control". The project management department organizes a well-organized and perfect functional management organization, in accordance with the requirements of the normal operation of the quality assurance system, according to the management principle of division of labor and mutual coordination, and implements functions, responsibilities, risks and interests layer by layer to ensure that in the entire project construction process, quality, quality To ensure the normal operation of the system and play a role in safeguarding.

6. Quality control during construction

6.1. Raw materials

(1) Materials such as cement and crushed stone must be approved by the supervising engineer, and those without approval are not allowed to be used.

(2) Cement: Cement with a longer final setting time (preferably more than 6 hours) should be used, and 32.5 cement should be used. Fast-hardening cement, early-strength cement and cement that has been deteriorated by moisture are strictly prohibited.

(3) Crushed stone: the crushing value is required not to exceed 26%, and the maximum particle size is not greater than 31.5mm; the particle composition of the crushed stone should meet the specification gradation requirements. The content of particles less than 0.075mm should be less than the requirement of 20%.

(4) Water: use drinking water.

6.2. Composition design of mixture

(1) Composition design principle: the powder content should not be too much; on the premise of reaching the strength, the optimal cement dosage should be adopted; the aggregate gradation should be improved and the cement dosage should be reduced.

(2) Continuously optimize the construction mix ratio to optimize its strength and compaction.

6.3. Mixing of cement stabilized base mix

When the mixing station prepares the mixture, the amount of ash, water content and gradation must conform to the design values. Due to the influence of factors such as machine operating error and climate, various indicators of the mixture deviate from the design values. Test personnel should monitor and adjust in time to keep it within the design value.

6.4. Control the water content of the mixture

The moisture content of the mixing station should be about 1% higher than the optimal moisture content from the discharge, and the average moisture loss of the mixture is about 1% before the paving and rolling.

6.5. Transportation of cement stabilized base mix

The truck must be covered with a tarpaulin, which should be covered immediately after loading, and the tarpaulin may not be removed until unloading to prevent water evaporation from affecting the quality of paving and rolling.

6.6. Paving of cement stabilized base mix

From the mixing station to the paving site, the time should be shortened as much as possible, and the mixing, transportation, paving, rolling, etc. should be completed within the initial setting time of the cement.

6.7. Rolling of cement stabilized base mix

When rolling, the rolling principle should be followed, and a special person should be set up to check the flatness.

Strictly follow the above steps, and strictly control from the preparation of raw materials, mixing to transportation, and carry out the following process: preparation of the lower bearing layer → measurement and lofting → mixing of the mixture → transportation of the mixture → paving of the mixture → rolling of the mixture →Compact degree detection →Health care →Finished product acceptance →The next process reduces the rework process and improves the quality and efficiency of the construction of the test section.

An embodiment of the present invention has been described in detail above, but the content is only a preferred embodiment of the present invention, and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention should still belong to the scope of the patent of the present invention.

Claims (9)

1. the construction method of the double-layer joint paving test section of the guide road, is characterized in that: comprise the following steps, S1. Preparation of the lower bearing layer. Before the construction of the sub-base, the lower bearing layer is checked and accepted, and the steel formwork is supported on the inner side of the lower bearing layer, and then the lower bearing layer is thoroughly cleaned; S2. Measure and set out, set out the middle pile and side pile, determine the width of the paving, which is convenient for road shoulder cultivation, and set reference points on both sides to control the elevation; S3. Mixing and transportation of the mixture; the mixture is mixed evenly, so that the moisture content of the mixture when it is transported to the site for paving is not less than the optimum moisture content. If it is larger than 50cm, when unloading, let the mixed material unload into the paver hopper naturally, and the unloading speed should be coordinated with the paving speed to avoid the transport vehicle hitting the paver and unloading the mixed material outside the paver; S4. For the paving of the mixed material, two pavers are used for trapezoidal operation. At the starting point of the paving, the paver screed is raised, and the processed sleepers are placed below according to the thickness of the virtual paving. Pave thickness requirements, and then drop the screed, and pave continuously and evenly during normal paving; S5. For the rolling of the mixture, the driving wheel faces the direction of the paver, from the side of the road to the middle of the road, first light and then heavy, first slow and then fast, and rolling at low speed to avoid the phenomenon of shifting, peeling and leakage. It is strictly forbidden for the road roller to turn around or brake suddenly during the rolling process or the rolling road section; the rolling process is initial pressure-recompression-final pressure. , the final pressure is used to close the surface; S6. Joint treatment, avoid longitudinal joints, manually fill the horizontal construction joints with the mixture with appropriate water content, place square wood perpendicular to the road centerline, the height of the square wood is equal to the thickness of the compaction layer, and the rolling is compact; S7. Health preservation and quality inspection. The cement stabilized gravel mixture is rolled and compacted. After the test is passed, the permeable geotextile is covered with water in time for health preservation. The two pieces should overlap each other by more than 20cm to ensure that the surface is moist. The quality meets the design and construction specification requirements. 2. the construction method of the double-layer joint paving test section of the guide road according to claim 1, is characterized in that: in step S2, set reference points on both sides with the steel drill of φ 20mm, and the reference point elevation is the design elevation plus 20cm , When the reference point is established, a steel drill is used every 10 meters in the straight line segment, and a steel drill is used every 5 meters in the curved segment. The wire rope is tightened to ensure the level of the reference line. The reference line is fixed on the steel drill with φ5mm steel wire. If it is less than 200m, use a tensioner to tighten it, and its pulling force is not less than 1000N. 3. The construction method for the double-layer combined paving test section of the guide road according to claim 1, characterized in that: in step S4, two paver trapezoidal operations are adopted, the outer paver is in front, and the inner paver is in the Afterwards, the outer side of the front paver is controlled by the elevation reference line, and the road is controlled by a 6m long guide beam; the outer side of the rear paver is controlled by the elevation reference line; When laying manually, use the hanging line to control the elevation, and the paving speed should be uniform and controlled at 1.5m-2.0m/min. 4. The construction method for the double-layer combined paving test section of the guide road according to claim 1, is characterized in that: in step S5, check whether the compaction degree is qualified by the sand filling method, if unqualified, the number of times of rolling should be increased, The detection frequency of compaction degree is 2 points per lane every 200m. The parking of road rollers should be staggered, and the distance between them should not be less than 3m. They should be parked on the road section that has been rolled. The ruler is used for flatness detection, and each lane is detected. 5. The construction method of the double-layer joint paving test section of the guide road according to claim 1, is characterized in that: before step S1, the preparation of mixture raw materials is carried out, including cement, coarse aggregate, fine aggregate, and the mixture adopts The mixing ratio is designed by the vibration molding method, the gradation of the mineral mixture is prepared, and different cement dosages are prepared, and the cement dosage is 4%-6%. 6. The construction method of the double-layer paving test section of the guide road according to claim 5, characterized in that: cement adopts 32.5 ordinary Portland cement, fine aggregate selects stone chips with good gradation, and the fine aggregate is less than 0.075 The particle content of mm should not be greater than 15%, the plasticity index should not be greater than 8%, and the methylene blue value of the aggregate should not be greater than 10g/Kg, and the sand equivalent should not be less than 50%. 7. The construction method for the double-layer joint paving test section of the guide road according to claim 5, is characterized in that: when the debugging of the mixing equipment is completed, and after the design of the material composition is completed, the debugging of the construction mix ratio is carried out, including the first-stage trial production: According to the set construction parameters, without adding cement and water, take and screen the material on the belt to verify whether the gradation meets the design requirements, adjust the production parameters if necessary and make relevant records; The second stage of trial production: first add cement and water according to the design mix ratio, then add cement and water according to ±1% of the standard dose, and take samples for water content determination, cement dose determination, standard density and unconfined The compressive strength test determines the construction mix ratio to guide the construction. 8. The construction method for the double-layer paving test section of the guide road according to claim 5, characterized in that: before the formal mixing, an aggregate screening test is performed to check whether the gradation of the crushed stone mixture meets the requirements, if there is any problem Adjust in time and strictly control the pass rate of key sieve holes of 19mm, 9.5mm and 4.75mm. When the particle gradation of the aggregate changes, the mixing ratio should be readjusted to ensure that the mixture gradation meets the design requirements. The dosage is increased by 0.5% compared with the design, and the mixture is screened every half a day to ensure the accurate grading of the mineral material. When the gradation changes, the calculation is adjusted, the mixture is mixed evenly, and the phenomenon of whitening and segregation is strictly prohibited. -2.0%. 9. The construction method of the double-layer combined paving test section of the guide road according to claim 5 is characterized in that: during the stirring process, the segregation of the mixture is reduced, and the water-stabilized mixture is outputted in the mixing station, and the discharge height is reduced, and the finished product is The bin should be discharged intermittently, and the vertical distance between the discharge port of the finished product bin and the transport carriage should not be greater than 0.5m; during the paving process, two-thirds of the auger of the paver is buried in the mixture, so that the auger run evenly.

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