What method is used for sand and gravel backfilling, and what specifications are not

Sand and gravel backfill sampling method:

1) Ring knife method. Each section and each layer should be inspected, and samples should be taken with a ring knife in the lower half of the tamping layer (to 2 3 places below the surface of each layer).

2) Tank sand method. It is used for graded sand and gravel backfill or soil that is not suitable for sampling by ring knife method.

When the tank sand method is used for sampling, the number of samples can be appropriately reduced compared with the ring knife method. The sampling site should be the full depth of each layer after compaction.

The sampling shall be taken by the construction unit according to the provisions of the site, and the samples shall be wrapped and numbered (the number shall correspond to the points marked on the sampling plan) and sent to the laboratory for testing. If the sampling equipment or standard sand is not available, the laboratory should be invited to take samples on site for testing. When the construction unit takes samples, it is advisable to ask the construction unit to participate and sign for it.

Sand and gravel backfill sampling specification:

The number of sand and gravel backfill sampling should be implemented in accordance with the current national standards and the regions or current standards.

1. Sampling according to the "Construction Engineering Quality Inspection and Evaluation Standards".

1) Backfill and column foundation, foundation pit, foundation groove and pipe trench.

a. Backfill of column base: 10% of the total number of column bases is extracted, but not less than 5;

b. Backfilling of foundation groove and pipe trench: 1 group of sampling per layer according to the length of 20 50m, but not less than 1 group per layer;

c. Foundation pit and indoor backfill: 1 group of sampling per layer according to 100-500m2, but not less than 1 group per layer;

d. Site leveling fill: each layer is sampled according to 400 900m2 1 group, but each layer is not less than 1 group.

2) The amount of sand irrigation or irrigation can be appropriately reduced.

2. Sampling according to the Shanghai Standard "Technical Specifications for Foundation Treatment".

1) Whole cushion.

a. When the area is 300m2: the ring knife method is 30 50m2 to arrange one; The penetration method is 10 15 m2 and arranges one.

b. When the area is 300m2: the ring knife method is 50 100m2 and arranges one; The penetration method is 20 30 m2 and arranges one.

2) Underlayment under the strip foundation.

a. Refer to the requirements of the whole cushion.

b. Ring knife method is arranged at least one every 20m; Penetration method at least one every 5m.

3) Separate underlayment of the foundation.

a. Refer to the requirements of the whole cushion.

b. There are no less than two measuring points under each separate foundation.

Remarks: 1. On-site sampling must be under the supervision of witnesses, and the sampling personnel shall take samples at the measurement points as required, and the sampling and witnesses shall pass the qualification assessment when necessary.

2. Accompanied by witnesses, the sample submitter should accurately fill in the following contents: the entrusting unit, the name of the project, the test project, the design requirements, the identification name of the on-site soil sample, the tamping method, the elevation of the measuring point, the number of the measuring point, the date of sampling, the sampling location, the date of filling in the form, the sampler, the person who sent the sample, the witness and the contact. At the same time, the plan of the measurement point should be attached).

Ring knife sampling, measuring compactness, of course, there are specifications.

No backfill is required, and the material generally does not need to be tested. The backfill sand brigade is widely used in the backfill of bridges and culverts, shallow soft soil replacement and other aspects of orange removal, but due to the characteristics of the sand is not easy to compact and the lack of necessary detection means for the compactness of the sand, the construction quality of the backfill sand is difficult to ensure well.

The bottom of the foundation pit disturbs the soil, the silt soil should be completely removed, and the small vibration rammer is used to compact the bottom of the foundation pit, and the degree of compaction must meet the requirements of the specification. The substrate is flat, and care is taken to prevent water from accumulating.

The slippery gravel backfill should be layered and compacted, and the degree of compaction should be controlled by the process method.

The maximum particle size of natural sand and gravel should not exceed 10cm or not greater than 2 3 of the compaction thickness. The thickness of layered compaction is 15-20cm, and the compaction process can be coordinated with sprinkling, and the water volume can be controlled by 12-16kg square meters.

Plate vibratory rammer or hand-held air rammer is used for compaction, and the number of compaction times needs to be determined by test.

In the test section, the natural sand and gravel and the soil with the highest dry density of the known heavy compaction of the same thickness were tamped under the same conditions, and the number of compaction times when the known soil reached the required compaction degree was taken as the minimum number of compaction times to control.

The vibratory roller can be used to compaction the thickness to take the excitation force value of the roller, such as a 25-ton roller with a thickness of 25cm. Crush all over the quietly and quietly defeat 5-7 times. The density of the inspection is difficult to dig with a shovel, and a crowbar is needed to loosen, all of which meet the requirements of dense waves.

Within 50cm of the pipe and pipe top, vibrating rollers shall not be used, and there shall be no stones with a particle size greater than 3cm.

In the case of allowable water sinking, the compactness effect needs to meet the above requirements.

How to sample the cement submitted for inspection? How to sample sand and stone?

How to sample the cement submitted for inspection? How to sample sand and stone? Dear, hello, cement sand and gravel raw materials should be sampled and sent for inspection according to each unit of project.

1. Cement: 1. Bulk cement: (1) The cement of the same variety, the same strength grade and the same factory number produced by the same cement plant in the same period shall be an acceptance batch, but the total amount of an acceptance batch shall not exceed 500t.

2) Randomly take the same amount of cement from no less than 3 tanks, mix evenly, and then weigh no less than 12kg of cement as a sample. 2. Bagged cement: (1) The cement of the same variety, the same strength grade and the same factory number produced by the same cement plant in the same period shall be an acceptance batch, but the total amount of one acceptance shall not exceed 200t.

2) Randomly take the same amount of cement from not less than 20 bags, mix evenly, and then weigh no less than 12kg of cement as a sample. 2. Sand: 1. In the same origin, every 400m3 or 600t of the same specification is an acceptance batch, and less than 400m3 or 600t is also counted as a batch.

One group (20kg) of each acceptance batch is sampled. 2. When the quality is relatively stable and the feeding volume is large, it can be inspected regularly. 3. The sampling parts should be evenly divided, and the same amount of samples (11kg per minute) should be drawn from 8 different parts on the stockpile.

It is then reduced to 20kg by quartering, and the surface of the sampling site is removed before sampling. 3. Stone: 1. In the same origin, every 400m3 or 600 of the same specification is an acceptance batch, and less than 400m3 or 600t is also counted as a batch.

One group (20kg) of each acceptance batch is sampled. 2. When the quality is relatively stable and the feeding volume is large, it can be inspected regularly. 3. A group of samples of 40kg (maximum particle size mm) or 80kg (maximum particle size mm) sampling parts should be evenly distributed, and 15 samples (top, middle, and bottom of the grain pile) should be drawn from five different parts on the pile.

Each serving is 5-40kg, then reduced to 40kg or 60kg for testing. This cement sampling standard is commonly used construction cement; The weight of each group of sand and gravel sampling may be slightly different in different regions, and the specific weight should be consulted with the local testing unit.

The sampling specifications of the earthwork backfill and sand filling method are as follows:

For projects above 1000 m2, there should be at least 1 point for every 100 m2, and for projects above 3000 m2, there should be at least 1 point for every 300 m2.

The number of soil samples should be carried out in accordance with the current national standards of the source bank and the current standards of the industry or region to which it belongs. According to the Code for Acceptance of Construction Quality of Building Foundation Engineering (GB50202 2002) and the Code for Design of Building Foundation (GB50007 2002), sampling should be taken in the process of compaction and filling, and the dry density and water content of the soil should be tested by layered sampling.

There should be an inspection point in every 50 100m2 area, and the compaction coefficient should be obtained according to the test results. (ring knife method) according to the "technical code for building foundation treatment" (jgj79 2002) sampling, when taking soil samples to test the quality of the cushion, every 50 100m2 of large foundation pit should be no less than 1 inspection point; There should be no less than 1 point for every 10 20m of the foundation groove; There should be no less than 1 point for each individual column base. Ring knife method:

1) Whole cushion.

1) When the area is 300m2; The ring knife method is 30 50m2 and arranges one; The penetration method is 10 15 m2 and arranges one.

2) When the area is 300m2; The ring knife method arranges one for 50 100m2; The penetration method is 20 30 m2 and arranges one.

2) Underlayment under the strip foundation.

1) Refer to the requirements of the whole cushion.

2) The ring knife method is arranged at least one every 20m; The penetration method is arranged at least one every 5m.

3) Separate underlayment of the foundation.

1) Refer to the requirements of the whole cushion.

2) There are no less than two measuring points in the underlay under each individual foundation.

According to the "Regulations for the Construction and Acceptance of Urban Road Engineering" (DBJ08 225 1997), the detection frequency of soil subgrade and limestone cushion: 1000m2 per layer, 3 points per group. Frequency of detection of pavement subgrade and dirt shoulder:

2 points per 100m.