What are different types of dynamic compaction methods?

1. Conventional dynamic compaction method dynamic compaction of foundation

It refers to the medium and low-level dynamic compaction with single tamping energy below 6000kn · m, and its effective reinforcement depth is within 10m.

2. High energy dynamic compaction method

High energy dynamic compaction generally refers to dynamic compaction with compaction energy greater than 600xn · M. When the required effective reinforcement depth is greater than 10m, the conventional dynamic compaction methods and equipment are difficult to meet the requirements of foundation reinforcement, so it is necessary to develop and apply high energy level dynamic compaction (held) methods and equipment. Compared with conventional dynamic compaction method, high-energy dynamic compaction can further improve the strength and uniformity of subgrade, reduce compressibility, eliminate liquefaction and collapsibility, and fully exert the economic and efficient characteristics of dynamic compaction method.

3. Dynamic compaction mixing (mixing) method (DCM method)

Dynamic compaction (mixing) method is to pave 0.5-2.0m or thicker cushion on saturated soft clay (coarse particles such as slag, steel slag and gravel can be used as cushion materials), and use high-energy compaction to mechanically mix the upper cushion with the lower soft soil, change the composition of soft soil, and improve its engineering properties.

4. Dynamic compaction replacement method

(1) Unlike dynamic compaction mixing (mixing) in which the cushion material is relatively evenly mixed into the soil or exists sporadically in the treated soil, dynamic compaction replacement is to form a relatively independent, complete and continuous replacement body in the soil through dynamic compaction, so that the replacement body becomes a reinforcement of the foundation, thus forming the cushion or composite foundation.

Dynamic replacement is not completely unified in terms of name and technology, and it is often called dynamic substitution in English Or dynamic replacement. It is generally called dynamic compaction replacement (DR) in China. When it is used in muddy soil, it is called dynamic compaction and silt squeezing. The replacement body formed is called gravel pile, gravel column, gravel pier, etc.

Dynamic compaction replacement has developed rapidly in China, and the technical and economic effects of its application are also very obvious. This law was first listed in the technical specifications for foundation treatment in Shenzhen and other regions in China, and has been listed in the national technical specifications for foundation treatment at present. The application of dynamic compaction replacement in some large-scale engineering foundation treatment has achieved remarkable technical and economic results. For example, the construction of Shenzhen airport runway and taxiway; This technology is used in the industrial and civil construction sites of "land reclamation" in the western harbor of Nanshan District. The 200000 ton ore transfer wharf project of Ningbo Beilun port is also a successful example, and the above application has achieved good technical and economic benefits.

(2) Dynamic compaction replacement mixing method (DRM)

Dynamic replacement&mixing (DRM) is mostly used in organic clay and peat soil to eliminate or reduce the excessive settlement and secondary consolidation settlement under additional stress. Kwang Wei lo and Peng leeooi conducted a series of field tests in Singapore and achieved quite useful results.

(3) Dynamic compaction after replacement (RDC method)

Dynamic compaction after replacement is an organic combination of the reinforcement depth of replacement bodies such as gravel piles and the advantages of dynamic compaction in strengthening shallow layers in the treatment of saturated soft soil foundation.

5. Dynamic drainage consolidation method (DCP method)

Dynamic consolidation with pre compression is a combined reinforcement method of dynamic consolidation and surcharge preloading. Some scholars also call it "dynamic static combined drainage consolidation method", which is suitable for saturated soft clay, muddy sand, etc. this method uses dynamic compaction to produce high pore water pressure and dissipate under the action of surcharge preloading and static loading, which greatly shortens the time of surcharge preloading and improves the reinforcement effect. The dynamic compaction idea of adding vertical drainage body originates from the consolidation theory. Its starting point is to improve the drainage conditions by shortening the path, so as to accelerate the dissipation of excess pore water pressure produced by compaction

6. Deep dynamic compaction method in hole (DDC method)

Deep dynamic compaction in the hole, also known as DDC (down hole deep compaction) method or SDDC (supedown hole deep compaction), is an effective foundation treatment method. The main feature of the former is to first drill a hole with a diameter of 400mm in the site with a long screw drill, then fill the hole with plain soil, lime soil, construction waste or other materials, tamp it with a 20-60kn hammer, and repeat the operation from bottom to top until a pile with a diameter of 550~600mm is formed, and the soil between the piles is compacted, so as to form a DDC pile composite foundation. The latter is developed on the basis of the former, It uses a heavy hammer (maximum 150kn) to tamp into a hole with a diameter of about 500mm, compact the soil around the pile, and then fill the hole and tamp with a heavy hammer to form a pile with a diameter of up to 3000mm.

7. Rapid Impact Compaction

Rapid impact compactor plays an important role in eliminating the differences in construction progress and process conditions of different professional construction teams, as well as the differential settlement of the foundation caused by factors such as rush time and progress. The construction effect of Rapid impact compactor is mainly reflected in that it can eliminate or weaken the inherent defects and man-made defects of local road sections such as layered subgrade, abutment back, half filling and half excavation, local high filling, and the junction of new and old roads in advance, which may occur in the process of foundation use. Rapid impact compactor has very flexible applicability and effectiveness to solve the problem of low backfill quality at the abutment and Bridge Culvert sides of expressway. It can flexibly, accurately and quickly compact different compaction operation positions, or compact the operation area at a single point or continuously.