A, supervision basis

The supervision of retaining wall construction within the supervision scope of this resident office shall be based on the following documents:

1, Project Contract and Addendum between Owner and Contractor.

2. Supervision entrustment contract and addendum letter between the owner and the supervision unit.

3.JTGF 80/ 1-2004 Highway Engineering Quality Inspection and Evaluation Standards and Related Test Procedures.

4. Relevant chapters in the bidding documents of this project.

5. Design documents of this project and related design technical contact list.

6.JTJ04 1-2000-2000 Technical Specification for Construction of Highway Bridges and Culverts.

7.JTG E30-2005 Test Code for Cement Concrete in Highway Engineering.

8, the owner and the resident office and the superior quality inspection department notice and other regulations.

9, approved the construction organization design and subdivisional work report.

Second, the project overview

1, project introduction

This project is a civil engineering project from Ankang to Maoba expressway, Shaanxi Ankang Highway Development Project. The project under the jurisdiction of JL7 Station is located in Daba Mountain area, and the line is laid along Renhe Valley, which is a typical "downstream line" project. The main works of this bid include 1 multi-arch tunnel, with a length of 317m; Five extra large bridges are10531.03m long, four bridges are1654.92m long, and two medium bridges are 258.24m long. Y-shaped overpass 1 bridge length 1, 926.998m, single bridge length 1.437,1.88m, subgrade 261.3.5m. Therefore, bridge supervision is an arduous and leading project.

2. Topography, geology and geomorphology

The line is located in Renhe Valley, which is a U-shaped valley with steep mountains on both sides with a natural slope of 25-50 degrees. The engineering geology is mainly tabular marl and limestone, with metamorphic soft rock mixed with hard sandstone locally, and the surface rocks are severely weathered; Gravels and pebbles with a thickness of 2-20 meters are deposited on the bed of Renhe River, and the strength is low. The bad geology along the line mainly includes landslides, collapses and structural fracture zones, among which small landslides and collapses are more developed and the geological structure is more complicated.

3.[ Meteorology] [Hydrology] Hydrometeorology

Groundwater along the line is developed, and the main types are pore phreatic water in Quaternary unconsolidated layer and bedrock fissure water, which is rich in water. The water quality belongs to low salinity soft water, which is suitable for production and domestic water and has no corrosiveness to concrete. The annual rainfall in the project area is mainly concentrated in July, August and September, with annual average precipitation1130-1260mm, annual average temperature 15℃, extreme minimum temperature -7.6℃ and extreme maximum temperature of 42.3℃. The main river along the project is Ren River, which mainly occurs in July, August and September in flood season, with abundant water and rapid water level change. There is a small reservoir upstream of the project-Maoba Reservoir. The flood storage and detention capacity of the reservoir is not obvious, and it is mainly used for water storage and power generation. Basically, water is released every day to generate electricity, which leads to changes in the water level of people and rivers and increases the difficulty of construction.

Third, the preparation before the construction of subdivisional work

1, check the contractor's temporary construction, water supply, power supply, temporary roads, construction site leveling, etc.

2, traverse points, leveling points and other construction control piles have been closed, and checked and accepted by the supervision engineer.

3. The ground line survey has been checked and confirmed by the supervision engineer, and the engineering quantity has been examined and approved by the supervision engineer.

4, subdivisional work construction schedule (construction organization design) has been approved by the supervision engineer.

5, site management personnel and skilled workers have been implemented, the number of ordinary workers can meet the needs of construction.

6, material supply has been implemented, can guarantee the continuous construction and construction; The incoming materials have been inspected by the supervision engineer, and the supply quality is guaranteed.

7. All kinds of machinery and equipment used for subdivisional work have been implemented, and the machinery and equipment needed for construction have been put in place, and they have been checked by the supervision engineer to meet the requirements.

8. The field test equipment has arrived, and various standard tests have been verified and recognized by the supervision engineer.

9. The design drawings have been checked.

10. Environmental protection and safety measures have been implemented.

Four, supervision and control of rubble concrete retaining wall construction

1, check the contractor's engineering construction lofting, and check the quality of flaky and concrete raw materials.

2. The joint between the top surface of the bearing platform and the retaining wall should be chiseled, and laitance should be chiseled until the concrete is dense and qualified through supervision and inspection.

3, retaining wall template must use a large area of steel template, the template must be smooth, tight joints, do not leak slurry, and has a certain strength and stiffness, support firm and stable.

4. After the formwork is installed and the contractor's self-inspection is qualified, the supervision engineer shall review its plane position, section size, formwork height and embedded drainage pipe.

5.C 15 concrete must be centrally stirred by a forced mixer, and the quality of raw materials and mixing technology must meet the requirements.

6, in the process of concrete pouring, supervision engineer should supervise the whole process, according to the design and specification requirements for concrete pouring and flaky pouring. The quality of flaky must be qualified and cleaned and dried before use. When placing flaky, the distance between flaky and formwork shall not be less than 10cm, the spacing between flaky shall not be less than 20cm, and the amount of flaky shall not be more than 25%.

7. The position of settlement joint of retaining wall should meet the design requirements and be perpendicular to the foundation connection. Settlement joint treatment must meet the design requirements and specifications.

8, concrete must be covered in time, and water for more than 7 d. ..

9. When the retaining wall needs to be poured vertically in sections, the construction joint treatment must conform to the specification requirements, and the next working procedure can be carried out only after the supervision engineer has passed the inspection.

Five, the construction supervision and control of mortar rubble retaining wall

1, clean up the site first, carry out construction lofting, and review by the supervision engineer.

2. Foundation pit excavation

(1) adopt the method of mechanical excavation as the main method, supplemented by manual excavation, and clean the tank bottom to the design foundation bottom elevation, and do not overbreak. Pits and grooves should be set aside as required, and the slope or support of groove wall should meet the specification requirements.

⑵ Set a water collecting well at an appropriate position in the pit and groove, so as to eliminate the accumulated water in the pit and groove in time.

(3) The supervision engineer shall supervise the contractor to do a good job in basement bearing capacity test, and the foundation engineering construction can be carried out only after the approval of the supervision engineer.

3, masonry construction:

(1) Check the category, strength and specifications of the stone, which should meet the design and specification requirements; 2 masonry mortar and raw material quality meet the requirements of standards and specifications; Mortar mixing must be machine-mixed, and the strength must meet the design requirements.

(3) The stone must be watered before use to remove dirt and scale on the surface of the stone;

(4) When laying, vertical poles must be hung on both sides, and the lines should be corrected frequently to ensure that the masonry size meets the design requirements;

5] When the ground has a longitudinal slope along the wall, steps should be made along the longitudinal slope according to the design requirements. When laying in sections, the elevation difference between adjacent sections shall not exceed1.2m; ;

[6] When laying the first layer of foundation, if the basement is bedrock, the surface should be cleaned and wetted first, and then the slurry should be laid; If the basement is soil, it should be paved directly with mortar;

(7) Masonry should be layered with mortar. When laying the upper floor, the lower floor masonry shall not vibrate, and shall not throw, roll, turn or smash stones on the built masonry.

Being masonry work interrupted rear can masonry, build by laying bricks or stones layer surface should be clean and water wet;

Levies settlement joint setting and processing must be carried out according to the design and specification requirements;

⑽ Masonry should be closely engaged, staggered joints should be overlapped, mortar should be full, and there can be no joints, overlapping, sticking and floating plugs;

⑾ Mixing mortar should match the masonry progress, and it should be used as it is mixed;

⑿ According to the design requirements and specifications, bury drainage pipes.

Six, matters not covered, should be strictly in accordance with the design (or change documents) requirements and construction technical specifications.

Key points of retaining wall construction control

A, flaky concrete retaining wall

1, check and recheck the contractor's construction lofting, and recheck the quality inspection report of flaky and concrete raw materials.

2. Check the chiseling of the joint between the top of pile cap and retaining wall.

3, in the process of template installation, should check the template stiffness, height and flatness, etc. After the contractor's self-inspection is qualified, re-check the plane position, height, inclination, section size and support stability of the formwork.

4. Check the quality and stock of rubble for retaining wall before construction. In the process of construction, the quantity and quality of flaky shall be strictly controlled, and the construction shall be carried out in strict accordance with the design and specification requirements.

5, should focus on controlling the mixture ratio of concrete, especially the amount of water and admixture is more important, site supervision should spot check the slump of concrete at the pouring site.

6. Whether the pouring technology and vibrating technology of concrete pouring meet the requirements of specifications and construction organization design; Supervise and inspect whether the safety measures in the pouring process are in place, and watch the whole process.

7, check the retaining wall maintenance facilities and guarantee measures, sprinkler cover maintenance time of not less than 7 days.

8. Supervise and review the treatment and quality assurance measures of settlement joints and construction joints.

Second, the mortar rubble retaining wall

1, check and recheck the contractor's construction lofting.

2, review the flaky, mortar raw material quality inspection report.

3, check the basement geological conditions, and the contractor's basement bearing capacity test, comply with the design requirements and approved by the supervision engineer before the construction of next working procedure.

4, block should be watered before use, and remove the surface soil, scale.

5. When laying the first layer of masonry, if the basement is bedrock, the surface should be cleaned and wetted first, and then mortar masonry should be carried out; If the basement is earth, use mortar directly.

6, masonry exposed surface should be pointing, and should be reserved on the exposed surface when masonry about 2cm deep empty seam pointing. The dark joint of masonry can be leveled with the increase of masonry.

7, each build by laying bricks or stones a layer of blocks should be placed firmly, between blocks should be filled with mortar, firm bonding, not directly close to or virtual paste. When laying, the bottom slurry should be covered, and the vertical seam mortar should be laid on the side of the built stone, and then filled and compacted after the stone is put away.

8. When laying the upper block, avoid vibrating the lower block. When masonry works are resumed after interruption, it is necessary to clean and wet the joint surface of old and new masonry.

9. Mortar rubble should be built in layers, and a working face should be composed of 2-3 layers of blocks. The horizontal joints of each working layer should be roughly horizontal, and the vertical joints of each working layer should be staggered and not connected. When positioning columns and corner stones in the outer ring, flaky with relatively square shape and large size should be selected and attached to the inner masonry at intervals. In general, the joint width should not be greater than 40 mm 。

10, settlement joint construction, supervision engineer should strictly urge the contractor to carry out according to the design.

Measurement project of masonry retaining wall

Inspection method and frequency of specified value or allowable deviation of project inspection.

1△ mortar strength (MPa) shall be checked according to Appendix F within the qualified standard.

2 Plane position (mm)50 theodolite: check the outer edge of the top of the wall at 3 points every 20m.

3 Top surface elevation (mm) 20 elevation: check every 20m 1 point.

4 verticality or slope (%) 0.5 hanging vertical line: check 2 points every 20m.

5 △ Section size (mm) shall not be less than the design scale: 2 sections shall be measured every 20m.

6 Bottom elevation (mm) 50 elevation: check every 20m 1 point.

7 Surface flatness (mm) Block stone 20 2m size: check 3 places every 20m, and check the vertical direction and wall direction at each place.

Sheet 30

Concrete block stone 10

Pier and abutment body measurement project

Inspection method and frequency of specified value or allowable deviation of project inspection.

1 The concrete strength (MPa) shall be tested within the qualified standard according to Appendix D.

2 Section size (mm) 20 feet Quantity: Check 3 sections.

3 verticality or slope (%) 0.3% h and not more than 20 hanging vertical lines and theodolite: measure 2 places.

4 Top surface elevation (mm) 10 elevation: measured at 3 places.

5 Axis deviation (mm) 10 Total station or theodolite: measure 2 points vertically and 2 points horizontally.

The position of the 6th segment is (mm) 5 feet. Quantity: 4 inspections per section.

7 Large area flatness (mm)5 2m straightedge: check both vertical and horizontal directions, and measure 1 every 20m2.

8 The position (mm) of embedded parts meets the design requirements. If not specified in the design, it is 10 foot. Quantity: per piece.

Note: H is the height of pier and abutment.