Does anyone have a construction plan for the stone-filled subgrade test section of the highway project?

1. Project Overview

The entire line of the Neijiang to Suining Expressway in Sichuan Province is constructed according to the two-way four-lane expressway standard. The design speed is 80km/h, the roadbed width is 24.5 meters, and the bridge culverts and roadbed are the same. wide, the designed vehicle load level of bridges and culverts adopts highway-level I. This construction section is located in the hilly area of ??the Sichuan Basin. The landforms are roughly divided into valley accumulation landforms and hilly landforms. The mileage of the fifth construction section is K41+450~K56+563, with a total length of 15.056Km. The construction section is divided into three construction areas. Among them, the mileage of the third construction area is K53+780-K56+563. The construction area is mostly rocky mountains. The roadbed backfill material uses mountain blasting gravel. The roadbed backfill in the area is filled with Stone embankment construction. In order to ensure that the construction of stone-filled embankments meets quality requirements, it is necessary to conduct on-site backfill tests and determine relevant parameters to guide the subsequent construction of roadbed filling projects.

2. Basis for preparation

2.1 "Concise Highway Construction Manual" - People's Communications Press;

2.2 "Highway Subgrade Construction Manual" - People's Communications Publishing House;

2.3 "Technical Specifications for Highway Subgrade Construction" - JTG F10-2006;

2.4 "Highway Geotechnical Test Regulations" - JTG E40-2007;

2.5 "Highway Engineering Quality Inspection and Assessment Standards" - JTG F80-1-2004;

2.6 "Technical Specifications for Bidding Documents for Neijiang to Suining Expressway Project in Sichuan Province";

< p>2.7 "Two-stage construction drawing design of Neijiang to Suining Expressway in Sichuan Province" - Sichuan Provincial Department of Communications

3. Test purpose

3.1 Verify the reasonableness of the design standards for roadbed material filling properties, and provide physical index parameters of building materials;

3.2 Through on-site backfill rolling tests, determine the loose paving thickness, compaction machine model and combination, and compaction quality that meet the quality control standards for compaction of stone-filled embankments. Speed, number of compaction passes, settlement difference and other related parameters and quality control standards.

IV. Test Site Selection

According to the test section of this stone-filled embankment, it is planned to select the 100m roadbed backfill section in the third construction area K55+900-K56+000. All are backfill areas, the original land size is not much different, and the terrain is flat. It meets the relevant requirements of the technical specifications of the bidding document "the paving length of the fill test section is not less than 100m, and the full width of the roadbed"; the backfill materials are all taken from the mountain blasting gravel in the K56+035-K56+115 section, and the strength of the blasted rock meets the requirements for backfilling stone. .

5. Test preparations

5.1 Organize construction technicians to familiarize themselves with design documents and drawings, understand various construction specifications, conduct on-site verification and construction surveys, conduct technical explanations, and clarify the purpose of the test and construction methods.

5.2 According to the actual situation on site, determine the backfill material collection point, test the backfill material at the material collection point, and test the backfill particle gradation, uniaxial saturated compressive strength, and specific gravity. available.

5.3 Carry out construction stakeout measurements, lay out the middle piles and side piles of the roadbed, measure the filling elevation before filling, lay out the width of the roadbed, and use lime according to the amount of earth loaded by the dump truck, the thickness of the filling and the area of ??the filling. Draw grid lines to determine the amount of earth to be filled.

5.4 Provide training to all types of construction machinery personnel to familiarize them with operating procedures, technical requirements, construction methods and precautions, and conduct detailed technical explanations and division of labor for relevant personnel participating in the test, so that all types of construction workers can perform their respective tasks Its responsibility.

6. Resource Planning

6.1 Human Resources Planning

Serial Number Personnel Name Contact Number

1 Production Manager Wei Mingxiang 13198028999

2 Technical person in charge Wang Jian 13002872666

3 On-site construction management Wu Bin 13219573999

On-site construction scheduling Pan Xiaosheng

On-site quality responsibility Kang Kai

Wen Jianping, responsible for site safety

4 3 testers

5 3 surveyors

6 15 manipulators

7 Auxiliary workers 10 people

8 Total 37 people

6.2 Drafting of mechanical equipment

Serial number Equipment name Specification and model Unit Quantity Remarks

1 Excavator 1.2m3 set 2

2 Bulldozer Shantui 220 sets 2

3 Vibration roller YL20-6 set 1 20T

5 Dump truck 20T Station 10

6 Breastplate compactor - Station 3

7 Sprinkler 5T Station 1

6.3 Drafting of test and detection equipment

Serial number Equipment name Model Unit Quantity Remarks

1 Oven station 1

2 Pound scale 100kg station 1

3 Electronic balance 30kg/200g station 2

4 Electronic balance 3kg/0.1 set 1

5 Electronic balance 200g/0.001g set 1

6 Steel ring Φ120 cm 2

7 Water distiller 10L Set 1

8 Hydrostatic balance MP-5100g pcs 1

9 Graduated cylinder 1000ml pcs 10

10 Fully automatic pressure testing machine WYA-300B set 1

11 Vernier caliper 150mm 1

12 Total station Leica TC705 1

13 Level DS3200 1

7. Main construction technology and methods

7.1 Main construction process flow chart

7.2 Construction method

7.2.1 Measurement and setting out

According to the drawings and measurements provided by the supervision engineer Set up datum data for restoration alignment measurement, carefully check the permanent coordinate points, center line control piles, turning point piles, intersection piles, leveling points, etc., securely bolt the piles, and keep the results until acceptance after delivery. Before filling, according to the main line pile-by-pile coordinate table, use a level from the control point to select a measurement section every 10 meters in the longitudinal direction of the test section for cross-section re-measurement. Measure the original ground elevation of each section before filling, and arrange many measurement points for each section. At 8, the measuring points were recorded in detail, and the middle piles of the roadbed were released. After calculating the positions of the left and right side piles based on the cross-sectional view of the roadbed, the side piles of the test section were released on site, and white lines spread with lime were used to control the backfill edges. .

7.2.2 Surface cleaning and leveling

According to the actual conditions on site, the surface of the test road section shall be cleaned, and all tree roots, crop roots and topsoil on the surface shall be removed. The depth of surface cleaning shall be It can be controlled according to the actual situation; after the table is cleared and passed the inspection, a vibrating roller will be used to compact the foundation, and local potholes will be backfilled with qualified backfill material, and rolled flat and dense to ensure that the full range of roadbed will meet the load-bearing capacity after compaction force requirements.

7.2.3 Side slope coding

Before filling the stone embankment, side slope coding should be carried out. The particle size of the stones used for coding should be greater than 30cm and the strength should be greater than 30Mpa. , and try to be as regular as possible, and the masonry stones should be as close and dense as possible, without obvious holes or looseness. The load-bearing contact surfaces between the blocks are slightly inclined inwards. The width of the stone blocks should be no less than 2.0m, and the thickness of the blocks should be determined based on the thickness of the on-site paving layer. The slope surface can be constructed in a stepped manner.

7.2.4 Layered paving

Grid division before filling: In order to control the thickness of loose paving for layered filling and reduce the workload of paving, the grid should be divided according to the load of each vehicle before filling. The material volume is 11m3 and the loose paving is 40cm thick. Calculate that the paving area should be 27m2/car. Use lime powder to divide it into a 5.2×5.2m square grid (calculated based on the transportation volume of a 20t dump truck). Use hanging wires on both sides to control loose paving. Thickness, one car loaded per grid.

Stone filling embankments should be filled with stones with uniform stone quality and uniaxial saturated compressive strength not less than 5Mpa. The filling stone should be transported by excavators and dump trucks. When loading, try to use as much filling material as possible. Mix evenly to avoid excessive concentration of large particles. Stones with large differences in lithology should be filled in layers and sections. It is strictly forbidden to mix soft stones and hard stones. The stone paving is layered horizontally, first low and then high, and unloaded first on both sides and then in the middle. The stockpiling and paving of the stone-filled embankment are carried out at the same time. They are piled directly on the paved surface and paved forward by a high-power bulldozer. The thickness of the loose paving is controlled according to the planned test paving thickness of 40 or 50cm.

After the paver paving is initially completed, stones with excessive particle sizes must be manually crushed or removed to meet the technical specification requirements that the particle size should not be greater than 2/3 of the paving thickness.

For large-sized stones, they must be leveled manually. The stones should be close to the bottom and with the large side facing down. At the same position, large-sized stones cannot be stacked on top of each other. For areas where there is obviously less fine material, spread a layer of gravel or stone chips on the surface of the initially flat stone filling material. The dosage accounts for about 15%-20% of the large particle size to ensure that there are gaps between the large particle sizes. After filling, the surface of the compacted layer will be smooth and stable, and the stones will be tight, which is conducive to rolling construction.

7.2.5 Rolling

Since there is no cohesion between the granular materials, the stone-filled embankment mainly relies on the fillers to be embedded and tightly interlocked with each other to achieve sufficient friction. To resist roadbed deformation, therefore, large-tonnage vibration rolling equipment is required for rolling construction of stone-filled embankments, and a 20t vibrating roller is used for rolling construction during construction. During construction, the rolling speed is controlled at 2-4km/h. After the paving is completed, static pressing is performed once, then vibration rolling is performed until 8 passes are completed, and finally the surface is closed by static pressing once. The rolling sequence starts from both sides to the middle, and then from the middle phase to both sides. Each rolling requires a staggered wheel width of 1/3. For areas with obvious cavities and pores, add fine materials before rolling them. If there are still loose stones, use small stones of suitable particle size to caulk the joints and hammer them tightly with a hand hammer.

After each pass of rolling on the standard loose paving thickness of each layer, a section of every 10m should be selected according to the site conditions or under the instructions of the on-site supervision, and no less than 10 inspection points should be initially selected for each section. Carry out on-site testing and test. If the porosity of the last measured point meets the technical requirements and the settlement difference between the previous pass and the last pass is less than 3mm, this batch of loose paving stones will be deemed to be qualified for rolling. After the final pressure is completed, the final pressure elevation is measured at the measuring point corresponding to the elevation. The final pressure elevation is subtracted from the initial elevation and averaged to obtain the settlement difference of the section. The porosity test is planned to be carried out after 4 or more vibration rolling passes, and a representative testing location is selected, using the large pit (1.5-2.0 times the maximum particle size) and water bag methods. Carry out; use soft stone (15-30Mpa) to fill the stone embankment and compaction quality control standards: the porosity of the upper embankment is ≤20%, and the porosity of the lower embankment is ≤22%.

7.2.6 Acceptance

After the rolling is completed, the quality inspection engineer will lead the testers and surveyors to conduct random sampling inspections of the roadbed rolling. The testers will mainly conduct porosity inspections at the inspection points. For testing, surveyors should test the settlement, flatness and other items of the subgrade monitoring points after rolling. If there are any unqualified parts, immediately make up for the pressure or take other effective measures until they are qualified. After self-inspection and supervision sampling inspection, they pass the test. The lower layer can then be backfilled.

7.2.7 Summary

After the construction of the test section is completed, the data should be compiled in a timely manner to prepare a results report, and submitted to the supervision engineer for approval before guiding subsequent backfilling construction.

7.2.8 Illustration of roadbed backfilling and rolling method

7.2.9 Preliminary test parameter combination

field

tests

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Content Filling

Name Rolling

Machine Number of rolling passes (n) Soil thickness (cm) Porosity test

Each combination Points

1 Rolling

Test stone Zoomlion YZ20H type 20t vibrating roller Static pressure 2+4 throughout the above 40 8

2 Static pressure 2+ 4 and above 50 8

Total 16

8. Construction measures in rainy season

8.1 Arrange special personnel to collect weather forecasts from CCTV, local radio stations, etc., and prepare for rainy season Pre-construction precautions.

8.2 Before the start of roadbed construction, full consideration should be given to the layout of the drainage system to prevent water outside the line from flowing into the line during construction, and to quickly drain water within the line (including ground water, rainwater, and underground water seepage) roadbed to ensure the smooth progress of construction.

8.3 Stop roadbed earth filling construction when rainfall is heavy.

9. Quality, safety, and environmental protection measures

1. Construction shall be carried out in strict accordance with the current "Technical Standards for Highway Engineering" promulgated by the Ministry of Communications and relevant design and construction specifications and construction drawings. The quality of the project shall be implemented in accordance with the current "Highway Project Quality Inspection and Assessment Standards" promulgated by the Ministry of Transport.

2. Construction should be carried out strictly in accordance with the regulations, specifications and design technical requirements or the instructions of the supervising engineer, and the construction process should be controlled.

3. Implement key inspections and full-process control on key projects that affect project quality. The main key items in subgrade construction include: sampling test of materials, loose filler thickness, number of rolling passes, subgrade compaction porosity detection, drainage measures, stone blasting design and on-site construction control.

4. Set up full-time safety officers to conduct safety inspections every day, discover signs of accidents, analyze the causes in a timely manner, organize and deal with them in a timely manner, and nip various accident hazards in the bud.

5. Strictly implement the three-level safety education and technical briefing system. Personnel without safety education and briefing will not be allowed to work.

6. Be vigilant during blasting operations. The blasting time should be fixed, and residents and construction workers around the blasting operation area should be notified in advance to prevent casualties and property damage accidents.

7. Take reasonable preventive measures to avoid disturbing residents during construction operations, mainly to prevent the occurrence of public hazards, such as: minimizing noise pollution, frequently sprinkling water on construction roads on sunny days to prevent dust from rising, etc.

8. Waste oil, diesel, etc. generated from machinery and vehicle maintenance must not be discarded indiscriminately. They must be collected uniformly and discarded in designated locations to prevent contamination of local water quality.

10. Attachment

10.1 Quality Assurance System

10.2 Safety Assurance System