The Constructor

Dynamic Compaction: Advantages, Purposes, and Uses

Dynamic-Compaction

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Dynamic compaction is an efficient and cost-effective soil improvement technique that uses the dynamic effect of high energy impacts to densify weak soil. The dynamic effect is generated by dropping a static weight (15-40 tones) from a defined height (10-30 m).

The drop weight, which manufactured from steel; steel box and concrete, or reinforced mass concrete, is commonly manufactured from steel and cranes are used to lift and release it repeatedly from a certain height. These droppings exert a vibration on the soil and improves it at a depth.

The dynamic compaction is used to improve weak soil such as loose medium to coarse grained sand with salt or clay content. It effectively enhances the soil to a depth of 10m, but its influences reach till 12m depth. Not only does it utilized for settlement improvement and liquefaction mitigation but also for improvement of long-term performance, and backfilling landfill sites or collapsing cavities.

Purpose

The purpose of dynamic compaction technique is to transmit high energy waves through a compressible soil layer to improve Geotechnical properties of soil at greater depths.

Fig. 1: How Dynamic Compaction Improve Soil Properties

Dynamic Compaction Process

The concept of Dynamic compaction is simple but experienced engineers and good planning is essential. Dynamic compaction process includes lifting and dropping a heavy weight several times in one place.

Fig. 2: Dynamic Compaction Process

It is repeated on a grid pattern across the site. The spacing of grid patterns is determined based on underground condition, foundation loading, and foundation geometry.

Fig. 3: Dynamic Compaction Grid

The resulting high energy impact transmits shock waves through the ground to the depth to be treated. This reduces air and water voids between soil particles resulting in enforced settlement.

Fig. 4: How Dynamic Compaction Densify Soil at Great Depth

Deeper layers are compacted at wider grid spacing and upper layers are compacted with closer grid spacing.

Fig. 5: Dynamic Compaction of Soil

Advantages

Fig. 6: Schematic Influence of Dynamic Compaction on Soil

Disadvantages

Applications

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