For foundation reinforcement, the appropriate reinforcement method should be selected according to the design requirements and the soil quality of the foundation. Before the formal construction, the contractor is required to carry out trial filling, trial tamping and pile testing to determine the construction parameters and verify the foundation treatment effect. The contractor shall provide the supervision engineer with complete data on trial filling, trial tamping and pile test. There are many methods of foundation reinforcement. This paper mainly lists the foundation treatment methods such as replacement of foundation, heavy hammer, dynamic compaction, compaction pile, sand pile, gravel pile, dry jet grouting pile and so on.
1. Foundation replacement
(1). Check whether the materials used for foundation replacement meet the following requirements:
① The replacement sand should be medium-coarse sand, and the organic matter and silt content should not be greater than 5%;
(2). Gravel particle size shall not be greater than 100mm, and silt content shall not be greater than 5%;
(3). The lime grade shall not be lower than Grade III.
Sand and gravel are of the same origin, variety and specification, and the number of continuous entry is one batch every 400m3, and less than 400m3 is also counted as one batch; Lime of the same origin, variety and specification shall be counted as a batch every 200t, and less than 200t shall be counted as a batch. Require the contractor to carry out screening test, silt content test and organic matter content test on sand and gravel; Test the undigested residue content of lime. The supervision engineer checks the contractor's test report.
⑵. Check whether the replacement range and filler proportion meet the design requirements, and whether the filling compaction process meets the requirements of the design and construction technical scheme. In winter construction, anti-freezing measures should be taken.
(3) In the construction of replacement foundation, the proportion of fillers should be accurate, mixed evenly, filled by layers and compacted by layers. Check whether the compaction density meets the design requirements. The contractor is required to use humidity densimeter, water injection method or sand filling method for testing, and each layer shall be tested at least 5 times per1100m2. The supervision engineer shall witness and inspect each floor at least 1.
(4) Check whether the elevation of the bottom and top of the replacement foundation meets the design requirements. The contractor is required to inspect at least 5 places at the bottom and top of each replacement foundation pit.
5]. Check whether the basement treatment and drainage meet the design and specification requirements.
2. Heavy hammer ramming
(1). Check whether the scope and construction method of heavy hammer compaction meet the requirements of design and construction technical scheme.
[2]. Check whether the compactness of the foundation compacted by heavy hammer meets the design requirements. The contractor is required to carry out standard penetration test or circular cutter geotechnical test, and the contractor shall conduct at least 5 foundation pits. The supervision engineer shall witness at least 3 tests.
(3) The final total settlement of heavy hammer compaction should be greater than 90% of the total settlement of trial tamping. The allowable deviation and inspection method shall comply with the provisions of the Acceptance Standard for Construction Quality of Railway Bridge and Culvert Engineering TB 104 15-2003, requiring the contractor to inspect at least 5 places in each foundation pit. Supervision engineer focuses on spot check of basement flatness and tamping point spacing.
3. Dynamic compaction
(1). Check whether the scope of dynamic compaction, the arrangement of tamping points and the construction method meet the requirements of the design and construction technical scheme.
2. Check whether the bearing capacity and effective reinforcement depth of dynamic compaction foundation meet the design requirements. The contractor is required to carry out standard penetration test or static (dynamic) cone penetration test, with at least 5 places in each foundation pit. The supervision engineer shall witness at least 1.
(3) It shall not be used when it is found that the dynamic compaction vibration has a bad influence on the adjacent buildings or equipment. If local liquefaction of foundation soil is found, compaction shall be stopped, and it shall be continued after the pore water pressure dissipates until the design requirements are met.
(4) The allowable deviation and inspection method of dynamic compaction construction shall comply with the provisions of the Acceptance Standard for Construction Quality of Railway Bridge and Culvert Engineering TB10415-2003 TB10415-2003. Focus on spot check of basement flatness and tamping point spacing.
4. Dense piles
(1). Check whether the quality of lime meets the design requirements. When there is no design requirement, the CaO content in lime is not less than 80%, the particle size is less than 5mm, and the stone content is not more than 5%. According to the same manufacturer and the same place of origin, every 200t of continuous entry quantity is counted as a batch, and less than 200 is counted as a batch, and the contractor is required to check every batch. The number of inspections by the supervision engineer is 20% of the number of inspections by the contractor, but at least once. The contractor shall check the product certificate and carry out lime material test. The supervision engineer shall check the product certificate, test report and witness sampling inspection.
(2) Check whether the cement quality meets the current Acceptance Standard for Construction Quality of Railway Concrete and Masonry Engineering (TB 10424-2003) of the Ministry of Railways.
(3) Check whether the mixture ratio of filler, the number, type and arrangement of piles meet the design requirements.
(4) Check whether the contractor's construction method meets the requirements of the design and construction technical scheme.
5]. Check whether the compaction density of the pile meets the design requirements. Require the contractor to conduct deep sampling or standard penetration test. The contractor shall check 2% of the number of piles, not less than 5. The supervision engineer shall witness at least 1 piece.
[6]. Check whether the bearing capacity of foundation meets the design requirements. Require the contractor to carry out static cone penetration test or standard cone penetration test. Each foundation pit of the contractor shall have at least 5 places. The supervision engineer shall witness at least 1.
Once. The content of soil organic matter in compacted lime-soil pile should not be greater than 5%. The allowable deviation and inspection method of compaction pile construction shall comply with the provisions of the Acceptance Standard for Construction Quality of Railway Bridge and Culvert Engineering TB10415-2003 TB10415-2003. The supervision engineer focuses on the spot check of hole position, verticality, pile diameter and depth.
4. Sand pile
(1). Check whether the quality of sand meets the design requirements. When there is no requirement in the design, it should be medium-coarse sand, with silt content not more than 3% and organic matter content not more than 5%. According to the same origin, the same variety and the same specification, every 400m3 of continuous entry quantity is regarded as a batch, and less than 400m3 is also regarded as a batch. The contractor is required to carry out screening test, silt content test and organic matter content test for each batch. The supervision engineer checks the test report.
2. Check whether the scope, quantity and arrangement of sand piles meet the design requirements.
(3) Check whether the sand pile construction meets the requirements of the design and construction technical scheme.
(4) Check whether the bearing capacity of foundation meets the design requirements. Require the contractor to carry out static cone penetration test or standard cone penetration test. Each foundation pit of the contractor shall have at least 5 places. The supervision engineer shall witness at least 1.
5]. The sand filling amount of pile body shall not be less than 95% of the design value. The allowable deviation of construction and inspection method shall comply with the provisions of the Acceptance Standard for Construction Quality of Railway Bridge and Culvert Engineering TB10415-2003tb10415-2003. The supervision engineer focuses on spot check of hole position, verticality, pile diameter, pile length and pile top elevation.
5. Gravel pile
(1). Check whether the gravel quality meets the design requirements. When the design has no requirements, the particle size should not be greater than 50mm, and the silt content should not be greater than 5%. According to the same origin, the same variety and the same specification, the number of continuous entry is counted as a batch every 400m3, and less than 400m3 is also counted as a batch. Summary of supervision method of foundation reinforcement project: check whether the unconfined compressive strength of cement injection pile meets the design requirements. The contractor is required to carry out unconfined compressive strength test. 2% of the number of piles inspected by the contractor
According to the contract model, the contractor is required to carry out screening test and silt content test for each batch. The supervision engineer checks the test report.
2. Check whether the scope, quantity and arrangement of gravel piles meet the design requirements.
(3) Check whether the gravel pile construction method meets the requirements of the design and construction technical scheme.
(4) Check whether the bearing capacity of foundation meets the design requirements. Require the contractor to carry out static cone penetration test or standard cone penetration test. Each foundation pit of the contractor shall have at least 5 places. The supervision engineer shall witness at least 1. If necessary, carry out single pile load test.
5]. During construction, parameters such as dense current, water pressure and vibration time should meet the requirements of pile test. The rock filling quantity should not be less than 95% of the design quantity. The allowable deviation of construction and inspection method shall comply with the provisions of the Acceptance Standard for Construction Quality of Railway Bridge and Culvert Engineering TB 104 15-2003, and the supervision engineer shall focus on spot checking the hole position, verticality, pile diameter and pile length.
6.DJM reactor
(1). Check whether the cement quality meets the current Acceptance Standard for Construction Quality of Railway Concrete and Masonry Engineering TB 10424-2003 of the Ministry of Railways.
⑵. Lime powder should be ground quicklime with a particle size of not more than 0.2 mm and CaO content of not less than 80%. According to the same manufacturer and place of origin, every continuous entry quantity of 200t is regarded as a batch, and less than 200t is also regarded as a batch. The contractor is required to inspect each batch. The number of inspections by the supervision engineer is 20% of the number of inspections by the contractor, but at least once. The contractor shall check the product certificate and carry out lime material test. The supervision engineer shall check the product certificate, test report and witness sampling inspection.
(3) Check whether the scope, type, quantity and arrangement of the DJM pile meet the design requirements.
⑷. Check whether the construction method of DJM pile meets the requirements of design and construction technical scheme. Before construction, test piles shall be carried out, and the number of test piles shall not be less than 10.
5]. Check whether the unconfined compressive strength of djm piles meets the design requirements. The contractor is required to carry out unconfined compressive strength test. The contractor shall check 2% of the number of piles, not less than 5. The witness sampling quantity of the supervision engineer is 20% of the contractor's inspection quantity, and not less than 1.
[6]. Check whether the bearing capacity of foundation meets the design requirements. Require the contractor to carry out static cone penetration test or standard cone penetration test. Each foundation pit of the contractor shall have at least 5 places. The supervision engineer shall witness at least 1.
First, the allowable deviation and inspection method of powder jet grouting pile construction should comply with the provisions of the Acceptance Standard for Construction Quality of Railway Bridge and Culvert Engineering TB 104 15-2003, and the supervision engineer should focus on spot-checking pile diameter, pile spacing, verticality, pile length, powder spraying amount and pile top elevation.
7. Jet grouting pile
(1). Check whether the cement quality meets the current Acceptance Standard for Construction Quality of Railway Concrete and Masonry Works (TB 10424-2003) of the Ministry of Railways.
2. Check whether the cement slurry mixture ratio meets the design requirements.
(3) Check whether the scope, type, quantity and arrangement of jet grouting piles meet the design requirements.
(4) Check whether the construction method of jet grouting pile meets the requirements of design and construction technical scheme.
5]. Check whether the unconfined compressive strength of jet grouting pile meets the design requirements. The contractor is required to carry out unconfined compressive strength test. The contractor shall check 2% of the number of piles, not less than 5. The witness sampling quantity of the supervision engineer is 20% of the contractor's inspection quantity, and not less than 1.
[6]. Check whether the bearing capacity of foundation meets the design requirements. Require the contractor to carry out static cone penetration test or standard cone penetration test. Each foundation pit of the contractor shall have at least 5 places. The supervision engineer shall witness at least 1.
Once, the allowable deviation and inspection method of jet grouting pile construction shall comply with the provisions of the Acceptance Standard for Construction Quality of Railway Bridge and Culvert Engineering TB 104 15-2003. The supervision engineer focuses on spot check of pile location, pile diameter, verticality and pile length.
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