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

Abstract

The invention provides a construction method of a double-layer combined paving test section of a guide road, belonging to the field of municipal engineering and comprising the following steps of S1 and preparation of a lower bearing layer; s2, measuring and lofting, lofting out middle piles and side piles, determining the width of paving, facilitating hilling of road shoulders, setting reference points on two sides, and controlling elevation; s3, mixing and transporting the mixture; s4, paving the mixture, wherein two pavers are adopted for trapezoidal operation, and the mixture is continuously and uniformly paved when being normally paved; s5, rolling the mixture, wherein the rolling process comprises initial pressing, re-pressing and final pressing, the initial pressing enables the paved mixture to be in a stable state through initial pressing, the re-pressing carries out pavement compaction, and the final pressing carries out surface folding; s6, performing seam treatment to avoid longitudinal seams, and manually filling the mixture with proper water content in transverse construction seams; and S7, performing health preservation and quality inspection, wherein the quality meets the requirements of design and construction specifications. The invention has stable and reliable construction quality and high efficiency.

Description

Construction method for double-layer combined paving test section of guide way

Technical Field

The invention belongs to the field of municipal engineering, relates to construction of guide way cement stabilized macadam, and particularly relates to a construction method of a guide way double-layer combined paving test section.

Background

The municipal road engineering is an important component of urban construction work and is a basic engineering for providing service for life and production of urban residents, enterprises and public institutions, so that the construction quality of the road engineering directly influences various economic constructions of cities.

In actual working life, the condition that traffic is interrupted on a certain section of an expressway due to weather, accidents or the fact that road construction needs to be closed is often met, at the moment, a guide road needs to be built, execution standards are carried out according to the standard of the expressway, and the smoothness of passing is guaranteed.

The optimal matching economy is selected for determining the model number of a road roller and the use of machinery such as a small-sized rammer; determining the loose paving thickness, the compaction thickness and other parameters, and setting a test section to ensure the construction quality of the subsequent whole project, so that the construction of the test section is very important.

Disclosure of Invention

The invention aims to solve the problems in the background technology, and the method for constructing the double-layer combined paving test section of the guide way is stable and reliable in construction quality and high in efficiency.

In order to solve the technical problems, the invention adopts the technical scheme that: the construction method of the double-layer combined paving test section of the guide way comprises the following steps,

s1, preparing a lower bearing layer, checking and accepting the lower bearing layer to be qualified before constructing the subbase layer, erecting a steel template on the inner side of the lower bearing layer, and then thoroughly cleaning the lower bearing layer;

s2, measuring and lofting, lofting out middle piles and side piles, determining the width of paving, facilitating hilling of road shoulders, setting reference points on two sides, and controlling elevation;

s3, mixing and transporting the mixture; the mixture is uniformly mixed, so that the water content of the mixture is not less than the optimal water content when the mixture is conveyed to a site for paving, the distance between a discharge port and the highest point of a carriage ledge is not more than 50cm when the mixture is conveyed and loaded, the mixture is naturally discharged into a hopper of a paver when the mixture is discharged, the discharging speed is coordinated with the paving speed, and the condition that a transport vehicle impacts the paver and discharges the mixture outside the paver is avoided;

s4, paving the mixture, namely, performing trapezoidal operation by adopting two pavers, lifting a screed plate of the paver at the paving starting point, putting the processed sleepers below according to the virtual paving thickness, placing the sleepers in balance to meet the virtual paving thickness requirement, then dropping the screed plate, and continuously and uniformly paving the sleepers during normal paving;

s5, rolling the mixture, wherein the driving wheel faces the direction of the paver, and the road is driven to roll by the road side, the road is light firstly and then heavy, slow firstly and then fast and low-speed, so that the phenomena of pushing, peeling and pressure leakage are avoided, and the road roller is strictly forbidden to roll or turn around or brake suddenly on the road section being rolled; the rolling process comprises initial pressing, re-pressing and final pressing, wherein the initial pressing enables the paved mixture to be in a stable state through initial pressing, the re-pressing carries out pavement compaction, and the final pressing carries out surface compacting;

s6, performing seam treatment to avoid longitudinal seams, manually filling a mixture with appropriate water content in transverse construction seams, placing square timbers perpendicular to the central line of the road, wherein the height of the square timbers is equal to the thickness of a compaction layer, and rolling and compacting;

s7, health preserving and quality inspection, finishing rolling of the cement stabilized macadam mixture, covering water-permeable geotextile for spraying water for health preserving after the cement stabilized macadam mixture is detected to be qualified, overlapping two geotextile layers by more than 20cm, ensuring the surface to be moist, wherein the health preserving period is not less than 7 days, and the quality meets the requirements of design and construction specifications.

Further, in step S2, a reference point is set on both sides with 20mm steel rods, the height of the reference point is 20cm added to the design height, when the reference point is set, one steel rod is set every 10m for a straight line section, one steel rod is set every 5m for a curved line section, a steel wire rope is hung and tensioned to ensure the level of the reference line, the reference line is fixed on the steel rods with 5mm steel wires, the length of each section is less than 200m, and the tension is not less than 1000N by a tightener.

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 an elevation reference line, and a 6m long guide beam is used for control in the road; the outer side of the rear paver is controlled by adopting an elevation datum line; the distance between the front and the rear pavers is not more than 10m, the transverse lap joint width is 30cm, when the special-shaped road sections are paved manually, the elevation is controlled by adopting a hanging wire, the paving speed is uniform and is controlled to be 1.5m-2.0m/min, the speed is not changed in the midway, and the paving is not stopped or interrupted.

Further, in step S5, a sand filling method is used to detect whether the compaction degree is qualified, if not, the rolling times are increased, the compaction degree detection frequency is 2 per lane every 200m, the road roller is stopped at staggered intervals of not less than 3m and stopped on the rolled road section, the rolling bump is manually processed after the re-rolling is completed, and a special person is set to use a 6m ruler to detect the flatness and detect each lane.

Further, before step S1, raw materials of a mixture are prepared, including cement, coarse aggregates and fine aggregates, the mixture is designed according to a mixing ratio by a vibration forming method, gradation of a mineral mixture is prepared, and different cement doses are prepared, wherein the cement dose is 4% -6%.

Furthermore, the cement is 32.5 ordinary portland cement, the fine aggregate is stone chips with good gradation, the content of particles smaller than 0.075mm in the fine aggregate is not more than 15%, the plasticity index is not more than 8%, the methylene blue value of the aggregate is not more than 10g/Kg, and the sand equivalent is not less than 50%.

Further, when the mixing equipment debugging finishes, the material composition design is accomplished the back, carries out the debugging of construction mix proportion, including first stage trial production: taking materials and screening on a belt according to set construction parameters without adding cement and water, verifying whether grading meets design requirements, adjusting production parameters and making related records if necessary;

second-stage trial production: firstly, cement and water are added according to the designed mixing proportion, then the dosage of the cement and the water is adjusted according to +/-1% of the standard dosage, and the samples are respectively taken to carry out water content determination, cement dosage determination, standard density and unconfined compressive strength tests to determine the construction mixing proportion to guide construction.

Furthermore, before formal mixing, an aggregate screening test is carried out, whether the gradation of the crushed stone mixture meets the requirements is checked, if a problem exists, adjustment is carried out in time, the passing rate of key sieve pores of 19mm, 9.5mm and 4.75mm is strictly controlled, when the particle gradation of the aggregate changes, the mixing ratio is adjusted again, the gradation of the mixture is ensured to meet the design requirements, the cement dosage ratio is increased by 0.5% during mixing, the mixture is screened once every half day, the gradation of mineral aggregate is ensured to be accurate, when the gradation changes, calculation is adjusted, the mixture is uniformly mixed, the phenomena of white aggregate and segregation are strictly prohibited, and the water content is 1.0% -2.0%.

Furthermore, in the stirring process, the segregation of the mixture is reduced, the discharging height is reduced when the water-stable mixture is output from the stirring station, the finished product bin is required to intermittently discharge materials, and the vertical distance between the discharging port of the finished product bin and the material conveying carriage is not more than 0.5 m; in the spreading process, two thirds of the spiral material distributor of the spreading machine is embedded into the mixture, so that the spiral material distributor operates uniformly.

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

1. The mixing quality of the mixture is strictly controlled, the detection is carried out in real time during the mixing process, the performance of equipment is adjusted, the cement dosage is ensured, the cement dosage is increased by 0.5% compared with the design during mixing, the mixture is sieved once every half day, the gradation of mineral aggregate is ensured to be accurate, when the gradation changes, calculation is carried out for adjustment, prevention and preparation are carried out on raw materials, and the construction quality of the thickness is ensured;

2. in the process of transportation and paving, the invention sets the attention items of feeding and discharging, reduces the segregation of the mixture as much as possible, ensures uniform charging, continuous paving and discharging, has stable speed, needs a specially-assigned person to eliminate the segregation phenomenon of fine aggregate behind the paver, simultaneously adds a reverse blade on a material distributing bolt of the paving equipment, adjusts the angle, prevents segregation, is stable and reliable, and has high efficiency;

3. the invention can ensure the flatness of the water stabilization layer, complete the rolling before the initial setting of the cement and within the delay time determined by the test, and reach the required compaction degree, and ensure continuous and uniform paving and the compaction degree in the paving process of the paver.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a cross-sectional view of a guideway according to an embodiment of a construction method for a double-layer combined-laying test section of the guideway according to the present invention;

FIG. 2 is a flow chart of a construction method of a double-layer combined paving test section of the guide way of the invention;

FIG. 3 is a table of the test standards for cement stabilized substrates according to the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.

The following detailed description of specific embodiments of the invention refers to the accompanying drawings.

As shown in fig. 1-3, the number range of the guidepost is DXK0+222.425-DXK1+200.120, the total length is 977.695m, the full line adopts a bidirectional four-lane highway standard, the design speed adopts 80Km/h, the standard width of the roadbed is 21.5m, the width of the traffic lane adopts 4 x 3.75m, the central separation zone is 1m, the curb zone is 2 x 1.5m, the hard road shoulder is 2 x 1.5m, and the road shoulder is 2 x 0.75m, as shown in fig. 1, the crosssectional view of the guidepost is shown.

The test section of the guide road cement stabilized macadam is selected from DXK0+427.591-DXK0+994.954, the total length is 567.363m, the compaction thickness is 0.18m, the test section cement stabilized macadam is divided into two layers, namely a subbase layer 3.0Mpa/7d and a base layer 4.0Mpa/7d, the paving mode adopts double-layer combined paving, the strength is executed according to the base layer 4.0Mpa/7d, and the section is used as a cement stabilized macadam double-layer combined paving test section.

The area where the engineering is located belongs to warm temperate zone seasonal style continental semi-humid arid climate, less rain in spring drought, more rain in summer, dry in autumn, less snow in winter. The average temperature of the air is 12.4 ℃, the extreme highest temperature is 41.2 ℃, and the extreme lowest temperature is-22.2 ℃ for many years. Average precipitation for many years is 495.1 mm, maximum precipitation for extreme years is 931.8 mm, and minimum precipitation for extreme years is 207.3 mm. The north wind is the most in the whole year, and the annual average wind speed is 2.1 m/s. The historical extreme maximum wind speed is 20 m/s.

The foundation of the site where the project is located is basically stable, the influence of the groundwater level on engineering construction is small, the problems of weak soil, liquefiable soil and the like do not exist basically, and the development degree of the ground settlement problem is weak. The fourth system of flood-flushing accumulation is distributed in the 15-meter depth range of the field, obvious deposition rhythm is realized in the vertical direction, and the distribution thickness in the horizontal direction is stable. The field soil is mainly divided into silty clay, silt, medium sand and the like. The ground underground water level buried depth is 12.74-13.41 meters, the ground non-liquefaction soil layer thickness and the underground water level depth accord with dw > d0+ db-3, the ground can not consider liquefaction influence, and the standard freezing depth of the local area is 0.6 meters.

The construction method of the double-layer combined paving test section of the guide way comprises the following steps.

Firstly, before construction, construction preparation is carried out according to the following steps.

1. Station preparation

(1) The cement stabilized macadam is conveyed to the site by adopting a finished product material of a commodity mixing station, the commodity mixing station is positioned in the large and villous village of a development area of Bazhou city in corridor, Hebei province, the transport distance is 23.5 kilometers, the finished product material needs 45 minutes to be conveyed to a construction site, the commodity station adopts WCB-800 type (800T/H) stabilized soil mixing equipment, the equipment adopts double mixing cylinders, the length of each mixing cylinder is not less than 5m, 5 cold material bins are provided, a water flow meter and a cement weight meter are provided, the water adding amount and the cement verification amount can be displayed in an operation room, the mixing equipment is accurately metered and qualified through quality technology supervision, a computer of a mixing plant can record the production matching ratio, the yield and the total amount in different time periods at any time, can be stored or exported, and the mixing station is installed and monitored.

(2) A reinforcing steel bar square grid with the diameter not less than phi 16 and the diameter of 10cm multiplied by 10cm is additionally arranged above the hoppers, aggregate and sundries exceeding the particle size specification are screened out, and baffles are arranged among the hoppers and have the height not less than 80 cm.

(3) The waste materials are intensively stacked, particularly the waste materials which are not emptied on the material transporting vehicle.

(4) The mixing site is clean and tidy, no water is accumulated under the aggregate pile, and the equipment is parked orderly.

(5) And after the scheme of the test section is approved by a supervision unit, carrying out technical and safety trade-off on an operation team and then carrying out test section construction.

2. Preparation of raw materials

As the cement stabilized macadam is transported to a construction site by adopting outsourcing finished product materials, the construction unit carries out the control work of the process material and the mixing ratio.

(1) Cement

According to the design verification of indoor mixing proportion, 32.5 common Portland cement is adopted, and various technical indexes of the entering cement meet the requirements of national technical standards through laboratory sampling detection.

TABLE 1 technical indices of mud

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

TABLE 2 technical indices of coarse aggregates

Detecting items	Technical requirements	Test method
			Organic matter content	Lighter than standard color	T0316
Dust content of 0.075mm or less (%)	≦2	T0316
			Needle sheet content (%)	≦20	T0316
Sulfate content (%)	≦0.25	T0316
			Soft stone content (%)	≦5	T0316
Crush value (%)	≦26	T0316

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

TABLE 3 Fine aggregate specifications

Detecting items	Technical requirements
		Methylene blue value	≦10
Dust content of 0.075mm or less (%)	≦15
		Index of plasticity	≦8

3. Mix composition design

The mixture is designed according to the mixing proportion by adopting a vibration forming method, mineral mixture gradation is prepared, different cement doses are prepared, 2 cement doses are prepared, the cement doses are respectively 4% and 5%, the field actual detection result of the 4% cement dose is 4.1, the field actual detection result of the 5% cement dose is 5.4, the 5% cement dose meets the requirement of 7d/4.0Mpa of a design drawing, and the theoretical proportion and other indexes after tests are as follows:

TABLE 4 mix design

The 7d submerged compressive strength of the cement stabilized macadam is in accordance with the relevant requirements of the technical Specification for highway pavement base course construction.

In order to reduce the cracks of the subbase layer, the dosage of the cement is controlled on the basis of meeting the design strength, the dosage of the cement is controlled to be 4 percent, and the maximum dosage is not more than 6 percent. While the cement amount is reduced, the use amount of fine aggregate and powder is limited; the water consumption is adjusted according to the construction climate conditions.

4. Gradation of mineral aggregates

The composition design of the cement stabilized macadam comprises raw material quality inspection, mineral mixture gradation composition design, determination of necessary cement dosage, determination of optimal water content of a mixture and the like. Before the mixing plant starts to produce, the design mixing ratio is tested again according to the on-site aggregate, and the qualified mixing ratio is used as the standard mixing ratio to control production.

TABLE 5 grading Range of Cement stabilized macadam

5. Production mix proportion debugging of subbase layer

And when the mixing equipment is debugged and the material composition design is finished, debugging the construction mix proportion.

Trial production in the first stage: according to the set construction parameters, cement and water are not added, materials are taken from the belt and sieved, whether the gradation meets the design requirements is verified, and production parameters are adjusted and relevant records are made if necessary.

Second-stage trial production: firstly, cement and water are added according to the designed mixing proportion, and then the cement and the water are added according to the dosage of +/-1% of the standard dosage. And respectively sampling to determine the water content, the cement dosage, the standard density and the unconfined compressive strength, and determining the construction mixing ratio to guide construction.

6. Preparation of construction site

(1) Roadbed inspection: the roadbed check is realized by the joint participation of the headquarter and the construction unit.

(2) And (3) roadbed quality inspection: the quality of the subgrade construction (elevation, centerline deviation, width, transverse slope, flatness, compaction, reflection cracks, deflection, etc.) should be checked.

(3) Before the cement stabilized macadam (4.0Mpa/7d) is constructed, the phenomena of over-drying and over-wetting are avoided, and the surface is smooth without water accumulation and loosening.

Second, the construction process flow of the double-layer combined paving test section of the guide road is as follows

The process flow comprises the following steps: as shown in fig. 2, the preparation of the lower bearing layer → the measurement lofting → the mixture blending → the mixture transportation → the mixture paving → the mixture rolling → the compaction degree detection → the curing → the acceptance of the finished product → the next process.

1. Preparation of lower bearing layer

(1) And (4) checking and acceptance of the lower bearing layer before the construction of the subbase layer. Including elevation, centerline offset, width, transverse slope, flatness, reflection cracks, deflection, etc. The surface of the lower bearing layer is flat and solid, has proper road arches and transverse slopes, does not have any loose and weak parts, and has smooth and neat edges and shoulders.

(2) A steel template with the height of 180mm is erected on the inner side of the lower bearing layer, and the steel template is erected firmly, so that the line is straight; the road shoulder is firstly earthed on the outer side, compacted by a small compactor, the edge is cut to be vertical to the bottom surface after the specified compaction degree is reached, then a plastic film is paved to prevent the water loss of the edges of the water-stable macadam, and the paving width ensures the design width requirement of the upper layer.

(3) Thoroughly cleaning the lower bearing layer, spraying water in a proper amount, and keeping the surface of the lower bearing layer moist in the construction process so as to ensure the combination of the upper layer and the lower layer.

2. Survey lofting

(1) And after the lower bearing layer is checked and accepted by a supervision engineer, the GPS is adopted to accurately loft the middle piles and the side piles, determine the paving width and facilitate the hilling of the road shoulder.

(2) And (3) drilling reference points on two sides by using steel rods with the diameter of 20mm to strictly control the elevation, wherein the elevation of the reference points is the designed elevation plus 20cm, when the reference points are set, one steel rod is arranged at each 10 meters of a straight line section, one steel rod is arranged at each 5 meters of a curve section, and the steel wire rope needs to be tensioned to ensure the level of the reference line.

(3) The datum line is fixed on a steel chisel by steel wires with the diameter of 5mm, the length of each segment is less than 200m, and the datum line is tensioned by a wire tightener, and the tension of the datum line is not less than 1000N.

3. Mixing of the mixtures

(1) The cement stabilized macadam mixture is mixed by adopting a stabilized soil mixing device with WCB800t/h, and the mixing device is repeatedly checked and adjusted before mixing, so that the metering of the mixing device is accurate, and the cement stabilized macadam mixture is qualified after quality technical supervision.

(2) The feeding hopper of the 3 ZL-50 loaders is adopted for feeding, a manipulator is trained before starting, the shoveling material meets the requirement, the occurrence of segregation phenomenon during feeding is reduced, the feeding is uniform, the situation that the feeding is too full is avoided, and the hoppers are separated by the partition plates, so that the phenomenon of material mixing is avoided. Before feeding, a tester needs to determine the moisture content of the aggregate, and the moisture content of the aggregate is prevented from being frequently changed to influence the moisture content of the mixture.

(3) And (3) before formal mixing, carrying out an aggregate screening test, checking whether the gradation of the crushed stone mixture meets the requirements, adjusting in time if a problem exists, and strictly controlling the passing rate of key sieve pores of 19mm, 9.5mm and 4.75 mm. When the particle composition of the aggregate changes, the mixing proportion should be readjusted to ensure that the mixture composition meets the design requirements.

(4) The mixture is uniformly mixed, the phenomena of white materials and segregation are strictly forbidden, the water content is timely adjusted according to the change of weather temperature and is generally controlled to be 1.0-2.0% higher than the optimal water content, and the water content of the mixture when the mixture is conveyed to a site for paving is not lower than the optimal water content.

(5) And a mixing station field tester detects the cement dosage, the water content and the mixing ratio of various aggregates of the mixture during mixing, records the cement dosage, the water content and the mixing ratio, and timely adjusts or stops production when abnormality is found.

(6) 1-2 workers are equipped in each hopper to clean the stone blocks and sundries with the excessive grain diameter at the opening of the hopper in time, the blanking condition is monitored constantly, the blockage phenomenon is avoided, and the normal operation of mechanical equipment is ensured.

4. Transport of mix

(1) According to the mixing capacity (800t/h), the transport distance (about 23.5Km) and the paving speed (1.5m-2.0m/min), 20 dumper trucks with the load of more than 50t are supposed to be adopted for transportation, and the carriages of the dumper trucks are required to be cleaned up, so that no residual materials or water is required to be accumulated at the bottoms of the carriages.

(2) When the materials are discharged from the mixing plant to the material transporting vehicle, the distance between the discharge port and the highest point of the compartment ledge is not more than 50cm, and a three-time discharging method is adopted to reduce the segregation phenomenon of coarse and fine aggregates.

(3) After the dump truck is loaded, the dump truck is covered by waterproof tarpaulin, and the lower edge of the tarpaulin reaches 2/3 (calculated from top to bottom) of the ledge and is firmly bound, so that the moisture loss is avoided, and the compaction and forming effects are not influenced.

(4) When the transport vehicle is delivered, weighing, opening a delivery order, marking tonnage, delivery time and vehicle number in quadruplicate, reserving the stub weight house, checking the delivery order and visually observing the quality of the mixture after the mixture is delivered to the site, discarding the mixture with overlong time, signing and receiving the delivery order after the mixture is paved, and writing the paving time.

(5) The transport vechicle is responsible for the commander by the special messenger, is equipped with contact communication tool, and simple repair tools, and the vehicle goes wrong can in time communicate the processing, guarantees after the vehicle breaks down, can in time salvage, can resume the operation in the shortest time.

(6) When the transport vehicle unloads, establish the special messenger and instruct, make the transport vehicle stop about 30cm in paver the place ahead, hang the neutral gear, the paver advances and touches the transport vehicle, knock off the rear fender keeper of transport vehicle by the workman, the transport vehicle hopper rises to divide the cubic to rise, let the mixture unload to the paver hopper naturally, it is too fast to avoid the tipper to rise, coarse aggregate rolls and falls to concentrate on causing local segregation, the transport vehicle driver closely cooperates with paver manipulator, the while is advancing the unloading, the speed of unloading is harmonious with the speed of paving, avoid the transport vehicle to strike the paver and unload the mixture outside the paver.

5. Spreading of mixed materials

The lower bearing layer is cleaned up before spreading, no sundries exist, and the water is sprayed to be wet, the water spraying amount is not too large or too small, so that the water does not flow; when in paving, the lower bearing layer is kept in a wet state, and the water is sprayed along with the paving, so that the water is not excessively sprayed.

(1) The model of the paver: the two creep paving machines are respectively provided with the following models: 903. 953T

The cement stabilized macadam is divided into an upper base course and a lower base course by 4.0Mpa/7d, the paving width of the lower base course in a common road section is 10.81, and the paving width of the base course is 10.48; the assembly widths of the two spreading machines are respectively 6.5m and 4.50 m.

The loose coefficient is verified in two sections and respectively:

the paving coefficient of DXK0+427.591-DXK0+677.591 sections is 1.25, the paving thickness is 18cm multiplied by 1.25 to 22.5cm, and the paving thickness is controlled according to 22.5cm during construction.

The paving coefficient of DXK0+677.591-DXK0+994.954 sections is 1.30, the paving thickness is 18cm multiplied by 1.30 to 23.4cm, the paving thickness is controlled according to 23.5cm during construction, and the paving coefficient is timely adjusted according to the detection of the compacted thickness.

(2) Two pavers are used for trapezoidal operation (outer side paver is in front and inner side paver is behind). The outer side of the front paver is controlled by adopting an elevation datum line, and a 6m long guide beam is adopted in a road for control; the outer side of the rear paver is controlled by adopting an elevation datum line; the distance between the front paver and the rear paver is not more than 10m, and the transverse lap joint width is 30 cm. When the special-shaped road section is manually paved, the elevation is controlled by adopting a hanging wire. The concrete method for positioning the paver is as follows: at the starting point of paving, the screed of the paver is lifted, the processed sleepers are placed below according to the virtual paving thickness, the placement is balanced, the requirement of the virtual paving thickness is met, then the screed is dropped, the operation condition of the spiral feeder and the sensitivity of the sensor are checked, and the normal operation of the machine is ensured.

(3) When the paving machine is normally paved, 2-3 transport vehicles are arranged in front of each paving machine to wait for unloading, so that continuous and uniform paving is guaranteed. The bucket lifting angle of the transport vehicle during unloading is required to be large as much as possible, so that the mixture is integrally collapsed, and segregation is avoided during unloading. When the coarse aggregate is paved, the spiral feeder feeds materials at a constant speed, high-speed operation is avoided, and the separation of a mixture at the bottom caused by the concentrated rolling of the coarse aggregate is avoided; the spreading speed is uniform and controlled to be 1.5m-2.0m/min, the speed cannot be changed in the midway, the spreading is not stopped or interrupted, a material conveying vehicle backs and unloads materials continuously as much as possible, and the spreading machine cannot be stopped for waiting materials; the material level in the material storage chamber is kept stable, the spiral material distributor of the paver is enabled to feed materials to two sides in a balanced mode, the material level of the spiral material distributor is slightly higher than that of the spiral material distributor, spiral low-speed material conveying is fully buried, the mixture in front of the screed baffle is kept consistent in the full-width range, and the phenomenon of segregation of a spreading layer is avoided.

(4) When paving, the two sides of the paver are provided with the special person watching sensors to ensure that the datum line is not disturbed. Meanwhile, the stay wire is adopted to detect the downward returning height at any time, so that problems can be found and communicated with an operator of the paver in time, the adjustment is carried out, the paving thickness is ensured, and the wavy surface is avoided. And detecting the loose paving thickness in time in the paving process.

(5) 2 people need to clean the aggregate in front of the caterpillar in front of each paver. 1 worker behind each paver inspects the paved surface, replaces and fills the abnormal mixture in time, informs a front-end responsible person, is convenient to analyze the reason of the abnormal mixture in time, and communicates with a test responsible person and a mixing responsible person to solve the problem; the segregation phenomenon of coarse and fine aggregates, particularly local coarse aggregate pits, needs to be eradicated, and the mixed materials are screened by a sieve and manually supplemented.

(6) The operator of the paver should observe the state of the mixture at any time, and if the conditions of too low water content, large color difference of the mixture (low cement content), uneven mixing and the like are found, the paver should stop paving immediately and notify field technicians to process the mixture.

(7) When the transport vehicle leaves, the mixture scattered on the ground is immediately removed, and the influence on the flatness of the spreading surface caused by the fact that the crawler of the spreading machine presses on the mixture is avoided. A specially-assigned person is arranged to measure longitudinally and transversely by using a 6m ruler, and the part with poor flatness is shoveled and leveled manually.

6. Rolling of mixes

(1) After the cement stabilized macadam mixture is paved for 30-50 m in length, the road roller can roll within the full width range. When rolling, the driving wheel faces the direction of the paver, and the phenomena of pushing, peeling and pressure leakage are avoided according to the principle that the road side drives to the middle of the road and rolls at light speed, heavy speed, slow speed, fast speed and low speed. The road roller is strictly prohibited from turning around or suddenly braking on a rolling forming or rolling road section.

(2) The rolling process comprises the following steps:

and (3) rolling machine: 222 t tyre type vibratory rollers, 1 30t rubber-tyred roller and 1 13t double steel-tyred roller. In order to determine the compaction effect of the water-stable macadam subbase test section, two rolling modes (selecting an optimal rolling combination) are adopted:

segments DXK0+427.591-DXK0+677.591 adopt a first rolling mode:

initial pressing: and (pressure stabilization) adopting a rubber wheel road roller, keeping 30cm of the outer side without rolling (preventing shoulder slipping), rolling once by the road roller at the walking speed of 2.5km/h, and rolling once by a shutdown connector in a 45-degree trapezoid manner, so that the paved mixture is initially pressed into a stable state.

Repressing: and (compacting) adopting a 22-ton vibratory roller to stagger 1/2 wheels, lightly vibrating once and heavily vibrating for three times, and controlling the rolling speed at 2.0 km/h.

Final pressure: and rolling the surface twice by using a 30t rubber-tyred road roller.

Sections DXK0+677.591-DXK0+994.954 adopt a rolling mode II:

initial pressing: and (pressure stabilization) adopts a steel wheel road roller, the road roller rolls once at the walking speed of 2.5km/h, and the machine-halt joint rolls once in a 45-degree trapezoid manner, so that the paved mixture is initially pressed into a stable state.

Repressing: and (compacting) adopting a 22-ton vibratory roller to stagger 1/2 wheels, lightly vibrating once, heavily vibrating twice and lightly vibrating once, and controlling the rolling speed at 2.0 km/h.

Final pressure: the rolling is carried out twice by adopting a rubber-wheel road roller, and the rolling is carried out once by using a steel-wheel road roller.

After the single-steel-wheel vibratory roller is vibrated twice, a sand filling method is used for detecting whether the compaction degree is qualified or not, if the compaction degree is not qualified, the rolling times are increased, and the compaction degree detection frequency is doubled at every 2 places of each lane at every 200 m.

(3) The road roller should be parked naturally without special conditions and braking; the shift is light and smooth without pulling the substrate. During primary pressure stabilization for the first time, the original path returns after reversing, the gear shifting position is on the pressed section, the gear shifting and reversing position at the non-rolled end is staggered and needs to be toothed, and leveling treatment is needed when individual slurry turning and peeling occur.

(4) The road roller should be stopped on the rolled road section by staggering the parking, wherein the spacing is not less than 3 m. Road rollers are strictly prohibited from turning around and hard braking on sections that are just completed or rolling. The rolling is preferably completed before the initial setting of the cement and within a delay time determined by tests, so that the required compactness is achieved, and meanwhile, no obvious wheel trace exists.

(5) The mixture is mixed with water until the rolling and forming time is not longer than the initial setting time of cement.

(6) Flatness detection and processing: and after the repressing is finished, manually processing the rolling and bulging parts, and arranging a 6m ruler for special use to carry out flatness detection and detecting each lane.

7. Seam treatment

(1) Transverse joint

The mixture should not be broken when being paved, for example, the breaking is more than 2 hours for reasons or a transverse construction joint should be arranged after the construction is finished every day. The paver is driven away from the end of the mixture, and the mixture with proper water content is filled up manually. And square timbers are arranged perpendicular to the central line of the road, the height of the square timbers is equal to the thickness of the compacted layer, and the square timbers are compacted by rolling. And detecting the flatness by using a 6m ruler, determining the cutting range, marking, and removing the mixture with unqualified flatness along the line. And cleaning the lower bearing layer before the mixture is paved again, and brushing cement paste on the joint.

(2) Longitudinal seam

And longitudinal joints are avoided, and when two-frame construction is required, the longitudinal joints are required to be vertically equal, and the oblique joint is not allowed.

8. Health preserving

(1) The cement stabilized macadam mixture is rolled, after the cement stabilized macadam mixture is detected to be qualified, the cement stabilized macadam mixture is covered with water permeable geotextile for sprinkling and preserving health, and the two geotextile materials are overlapped by more than 20cm to ensure that the surface is moist.

(2) In the health preserving period, any vehicle except the sprinkler is prohibited to pass, a marking rail with the height of 1.5m is transversely and fully arranged, a 'no-pass' marking board is arranged, and a specially-assigned person is arranged for watching.

(3) The health preserving period is not less than 7 days, the health preserving day number signboard is arranged at the completion section every day, the watering times of the first three days are at least more than 6 times per day, then the surface is kept wet, and a specially-assigned person is arranged on each working face to be responsible for health preserving work.

9. Quality inspection

(1) The granules should meet the requirements of design and construction specifications and should be selected to be firm and clean according to local material sources.

(2) The cement dosage and the mineral aggregate gradation should be accurately controlled according to the design.

(3) Care should be taken to eliminate segregation, particularly banding and nesting.

(4) And (3) rolling the mixture to the required compaction degree by a road roller under the condition of the optimal water content. The time from adding water for mixing to the end of rolling should not exceed the initial setting time of cement.

(5) And covering or watering for curing immediately after the rolling inspection is qualified, wherein the curing period is in accordance with the standard requirement.

(6) The surface is flat and compact, the side lines are neat, the phenomena of looseness, hollowness and soft elasticity are avoided, and the construction is smooth and continuous.

The measured items are shown in fig. 3.

10. Appearance requirements

(1) The surface is flat and compact, no depression exists, and no obvious segregation exists.

(2) The construction is smooth and stable.

Third, safeguard measure

1. Quality of mix (water content, cement dosage, mineral composition)

The water content is the key to water-stable macadam rolling, when the actual water content W is close to the optimal water content (W0), the degree of compaction can be guaranteed, when W > W0, the water content is easy to 'spring' when rolling excessively, and when the vibration is rolled, the cement paste is easy to gather on the surface. Therefore, during core checking, the lower part of the test piece is easy to loose or insufficient in strength, and when W is less than W0, the water-stable layer is easy to loose and not compact, so that the strength is insufficient. In order to ensure that the water content is proper, a specially-assigned person is required to detect the water content and adjust the mixing water content in time according to the climate condition.

The cement dosage is the key to whether the strength of the cement stabilized macadam is qualified, and the cement dosage is ensured by detecting the cement stabilized macadam constantly in the mixing process and adjusting the performance of equipment. In order to ensure the cement dosage, the cement dosage is preferably increased by 0.5 percent compared with the design during mixing. The mixture is screened once every half day, so that the accuracy of the gradation of the mineral aggregate is ensured, and when the gradation changes, the calculation is carried out for adjustment.

2. Segregation of the mix

In order to reduce the segregation of the mixture as much as possible, the following requirements are required to be met:

(1) when the water-stable mixture is output from the mixing station, the discharging height should be reduced as much as possible, and the finished product bin should discharge materials intermittently.

(2) The vertical distance between the discharge port of the finished product bin and the material conveying carriage is not more than 0.5m, and the material conveying vehicle should move forward and backward in time to ensure uniform material loading so as to reduce the height of a pile body loaded at each time.

(3) During transportation, the material transporting vehicle should run at a constant speed, start and brake stably, and run slowly when the road condition is poor, so that strong jolt vibration is avoided.

(4) When the material transporting vehicle unloads materials to the receiving hopper of the paver, the carriage is slowly and uniformly lifted, and the speed is not too high.

(5) In the spreading process, two thirds of the spiral material distributor of the spreading machine should be embedded into the mixture, and the spiral material distributor should be operated uniformly, so that the speed is forbidden or slow. Specially-assigned people are arranged behind the paver to eliminate the segregation phenomenon of the fine aggregate, and particularly, local coarse aggregate pits are removed and filled with a newly-mixed mixture.

(6) When the shovel is manually leveled, the cloth of the shovel is required to be buckled, the shovel is prevented from being lifted and thrown far, and meanwhile, the scraping and crawling dragging times are not more than 2.

(7) The spreading equipment is provided with a reverse blade on a material distribution bolt, and the angle is adjusted to prevent segregation.

(8) The hopper collecting times of the paver are properly reduced, and the hopper is not collected as much as possible.

(9) The screed height is suitably reduced.

(10) A rubber pad is added behind the spreading machine spiral distributor, so that the phenomenon that the large materials roll backwards to cause vertical segregation is prevented.

3. Flatness of

The flatness of the cement stabilized base layer is good in the construction quality of the surface layer, if the control is not good, the flatness of the surface layer can be influenced on the one hand, and the thickness of the surface layer is difficult to control on the other hand. In order to ensure the flatness of the water stable layer, the following points are realized:

(1) the lower bearing layer of the cement stabilized base layer can be paved only after meeting the specified flatness requirement, and if the surface of the lower bearing layer is wavy with poor flatness, the lower bearing layer is inevitably reflected to the surface of the base layer, so that the flatness of the surface of the base layer is difficult to control.

(2) The rolling is preferably completed within a delay time determined by tests before the initial setting of the cement and to achieve the required compaction without obvious tracking. The rolling process is strictly performed according to the construction scheme, so that the phenomenon that waves occur and the flatness is influenced is prevented.

(3) When people find the leveling by hand, people with rich experience and strong responsibility should be selected to take charge of leveling, and meanwhile, a ruler of about 6m should be equipped to assist in checking uneven parts.

(4) In the paving process of the paver, continuous and uniform paving is ensured, a material conveying vehicle is required to wait for unloading in front of the paver, otherwise, the paver is frequently stopped to influence the flatness.

(5) And immediately performing compaction test after rolling, and re-rolling if the test result does not reach the standard.

(6) The water consumption of the mixture is strictly controlled, and the excessive or insufficient water content is avoided.

4. Grinding quality

In order to ensure the compactness of the cement stabilized macadam base, the compaction machinery is the key and has higher requirements on the capacity of compaction equipment. In the construction process, a road roller must be equipped according to the rolling combination determined by the test section, so that the compaction degree is ensured. Quality assurance measures

5. And establishing a quality inspection system with effective control from transverse direction to edge direction and longitudinal direction to bottom direction. The project manager organizes a strictly perfect function management mechanism, and according to the requirement of normal operation of the quality assurance system and the management principles of labor division, responsibility and mutual coordination, the project manager can realize functions, responsibilities, risks and benefits layer by layer, and ensure the normal action and the guarantee function of the quality assurance system in the whole engineering construction process.

6. Construction process quality control

6.1 starting materials

(1) Materials such as cement, gravel and the like must be approved by a supervisory engineer, and are not allowed to be used without approval.

(2) Cement: the cement with longer final setting time (preferably more than 6 hours) is selected, and 32.5 cement is preferably used. Quick-hardening cement, early strength cement and cement deteriorated by moisture are strictly forbidden.

(3) Crushing stone: it is required that the crush value thereof is not more than 26% and the maximum particle diameter is not more than 31.5 mm; the particle composition of the macadam should meet the requirements of the specification gradation. A particle content of less than 0.075mm should be less than 20%.

(4) Water: drinking water is used.

6.2 composition design of the mixture

(1) The principle of composition design: the powder content is not suitable to be excessive; on the premise of achieving the strength, the optimal cement dosage is adopted; improve aggregate gradation and reduce cement consumption.

(2) The construction mix proportion is continuously optimized, so that the strength and the compactness of the concrete are optimal.

6.3 mixing of Cement stabilized base mix

The mixing station prepares the mixture, and the ash dosage, the water content and the gradation all accord with the design values. Due to the influence of factors such as machine operation error and climate, various indexes of the mixture deviate from the design values. The test personnel should monitor and adjust in time to keep it within the designed value.

6.4 controlling the water content of the mixture

The water content of discharged materials of the mixing station is about 1% higher than the optimal water content, and the average loss of the water content of the mixture is about 1% before the mixture is spread and rolled.

6.5 transportation of Cement stabilized base mix

The material transporting vehicle is covered by tarpaulin, and the tarpaulin is covered immediately after loading, and can be taken down until unloading, so as to prevent water evaporation from influencing the spreading and rolling quality.

6.6 spreading of Cement stabilized base mix

The time of the mixture from the mixing station to the paving place should be shortened as much as possible, and the mixing, transportation, paving, rolling and the like are completed within the initial setting time of the cement.

6.7 Rolling of Cement stabilized base mix

During rolling, a special person is arranged to detect the flatness according to the rolling principle.

The method is strictly carried out according to the steps, from the preparation of raw materials, the mixing to the transportation is strictly controlled, the preparation of a lower bearing layer → measurement lofting → mixture mixing → mixture transportation → mixture paving → mixture rolling → compactness detection → health preserving → finished product acceptance → the next process is carried out according to the following process, the rework process is reduced, and the quality and the efficiency of the construction of a test section are improved.

While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.

Claims (9)

1. The construction method of the double-layer combined paving test section of the guide way is characterized by comprising the following steps of: comprises the following steps of (a) carrying out,

s1, preparing a lower bearing layer, checking and accepting the lower bearing layer to be qualified before constructing the subbase layer, erecting a steel template on the inner side of the lower bearing layer, and then thoroughly cleaning the lower bearing layer;

s2, measuring and lofting, lofting out middle piles and side piles, determining the width of paving, facilitating hilling of road shoulders, setting reference points on two sides, and controlling elevation;

s3, mixing and transporting the mixture; the mixture is uniformly mixed, so that the water content of the mixture is not less than the optimal water content when the mixture is conveyed to a site for paving, the distance between a discharge port and the highest point of a carriage ledge is not more than 50cm when the mixture is conveyed and loaded, the mixture is naturally discharged into a hopper of a paver when the mixture is discharged, the discharging speed is coordinated with the paving speed, and the condition that a transport vehicle impacts the paver and discharges the mixture outside the paver is avoided;

s4, paving the mixture, namely, performing trapezoidal operation by adopting two pavers, lifting a screed plate of the paver at the paving starting point, putting the processed sleepers below according to the virtual paving thickness, placing the sleepers in balance to meet the virtual paving thickness requirement, then dropping the screed plate, and continuously and uniformly paving the sleepers during normal paving;

s5, rolling the mixture, wherein the driving wheel faces the direction of the paver, and the road is driven to roll by the road side, the road is light firstly and then heavy, slow firstly and then fast and low-speed, so that the phenomena of pushing, peeling and pressure leakage are avoided, and the road roller is strictly forbidden to roll or turn around or brake suddenly on the road section being rolled; the rolling process comprises initial pressing, re-pressing and final pressing, wherein the initial pressing enables the paved mixture to be in a stable state through initial pressing, the re-pressing carries out pavement compaction, and the final pressing carries out surface compacting;

s6, performing seam treatment to avoid longitudinal seams, manually filling a mixture with appropriate water content in transverse construction seams, placing square timbers perpendicular to the central line of the road, wherein the height of the square timbers is equal to the thickness of a compaction layer, and rolling and compacting;

s7, health preserving and quality inspection, finishing rolling of the cement stabilized macadam mixture, covering water-permeable geotextile for spraying water for health preserving after the cement stabilized macadam mixture is detected to be qualified, overlapping two geotextile layers by more than 20cm, ensuring the surface to be moist, wherein the health preserving period is not less than 7 days, and the quality meets the requirements of design and construction specifications.

2. The construction method of the double-layer combined paving test section of the guide way according to claim 1, which is characterized in that: in step S2, a reference point is set on both sides with a steel rod of phi 20mm, the elevation of the reference point is the designed elevation plus 20cm, when the reference point is set, one steel rod is set every 10 meters in a straight line segment, one steel rod is set every 5 meters in a curve segment, a steel wire rope is hung and tightened to ensure the level of the reference line, the reference line is fixed on the steel rod with a steel wire of phi 5mm, the length of each segment is less than 200m, and the reference line is tightened by a tightener, the tension of which is not less than 1000N.

3. The construction method of the double-layer combined paving test section of the guide way according to claim 1, which is characterized in that: in step S4, two pavers are used for trapezoidal operation, the outer one is in front, the inner one is behind, the outer side of the front paver is controlled by an elevation datum line, and a 6m long guide beam is used for control in the road; the outer side of the rear paver is controlled by adopting an elevation datum line; the distance between the front and the rear pavers is not more than 10m, the transverse lap joint width is 30cm, when the special-shaped road sections are paved manually, the elevation is controlled by adopting a hanging wire, the paving speed is uniform and is controlled to be 1.5m-2.0m/min, the speed is not changed in the midway, and the paving is not stopped or interrupted.

4. The construction method of the double-layer combined paving test section of the guide way according to claim 1, which is characterized in that: in step S5, a sand filling method is used to detect whether the compaction degree is qualified, if not, rolling passes should be increased, the compaction degree detection frequency is 2 per lane every 200m, the road roller should be stopped at staggered intervals of not less than 3m, the road roller is stopped on a rolled road section, after the re-rolling is completed, the rolling raised part is manually processed, and a special person is set to use a 6m ruler to detect the flatness and detect each lane.

5. The construction method of the double-layer combined paving test section of the guide way according to claim 1, which is characterized in that: before step S1, raw materials of the mixture are prepared, wherein the raw materials comprise cement, coarse aggregates and fine aggregates, the mixture is subjected to mix proportion design by adopting a vibration forming method, the gradation of mineral mixture is prepared, and different cement doses are prepared, and the cement dose is 4-6%.

6. The construction method of the double-layer combined paving test section of the guide way according to claim 5, characterized by comprising the following steps of: the cement is 32.5 ordinary Portland cement, the fine aggregate is stone chips with good gradation, the content of particles smaller than 0.075mm in the fine aggregate is not more than 15%, the plasticity index is not more than 8%, the methylene blue value of the aggregate is not more than 10g/Kg, and the sand equivalent is not less than 50%.

7. The construction method of the double-layer combined paving test section of the guide way according to claim 5, characterized by comprising the following steps of: after the mixing equipment debugging finishes, the material composition design is accomplished, carries out the debugging of construction mix proportion, including first stage trial production: taking materials and screening on a belt according to set construction parameters without adding cement and water, verifying whether grading meets design requirements, adjusting production parameters and making related records if necessary;

second-stage trial production: firstly, cement and water are added according to the designed mixing proportion, then the dosage of the cement and the water is adjusted according to +/-1% of the standard dosage, and the samples are respectively taken to carry out water content determination, cement dosage determination, standard density and unconfined compressive strength tests to determine the construction mixing proportion to guide construction.

8. The construction method of the double-layer combined paving test section of the guide way according to claim 5, characterized by comprising the following steps of: before formal mixing, an aggregate screening test is carried out, whether the gradation of the crushed stone mixture meets the requirements is checked, if a problem exists, adjustment is carried out in time, the passing rate of key sieve pores of 19mm, 9.5mm and 4.75mm is strictly controlled, when the particle gradation of the aggregate changes, the mixing proportion is readjusted, the gradation of the mixture is ensured to meet the design requirements, when mixing is carried out, the cement dosage ratio is increased by 0.5%, once mixture screening is carried out every half day, the accuracy of the gradation of mineral aggregate is ensured, when the gradation changes, calculation is carried out for adjustment, the mixture mixing is uniform, the phenomena of white stones and segregation are strictly forbidden, and the water content is 1.0-2.0%.

9. The construction method of the double-layer combined paving test section of the guide way according to claim 5, characterized by comprising the following steps of: during the stirring process, the segregation of the mixture is reduced, when the water-stable mixture is output from the stirring station, the discharging height is reduced, the finished product bin is required to intermittently discharge materials, and the vertical distance between the discharging port of the finished product bin and the material conveying carriage is not more than 0.5 m; in the spreading process, two thirds of the spiral material distributor of the spreading machine is embedded into the mixture, so that the spiral material distributor operates uniformly.

Images