Using Blasting for Effective Soil Compaction

Soil compaction is crucial in construction projects, ensuring stability and durability. Blasting, an economical method, proves effective for various soil types, including granular, silt, clay, and loess. This technique, not limited to loose soil, can compact granular soil up to a depth of 40 meters.

The Blasting Process Unveiled

To utilize blasting for deep soil compaction, a systematic approach is necessary.

Assessment of Blast Impact

Before diving into blasting, it’s essential to evaluate potential structural damages and landslides caused by blast-induced vibrations. This requires a careful understanding of the expected blast impacts, introducing a potential challenge.

Securing Explosive Permissions

Acquiring permission to use explosives is a mandatory step. This ensures legal compliance and safety protocols.

Determining Explosive Quantity

Precise determination of the right amount of explosives is critical. Charges typically range from 1-12 kg or 10-30 g/m3 of the soil to be compacted.

Strategic Placement of Explosives

Explosive materials are placed in drilled or jetted boreholes at a depth of 50-75% of the intended soil compaction depth, below the water table.

Optimizing the Blasting Technique

For large-scale projects, engineers can conduct test blasting to fine-tune key parameters:

Borehole Spacing: Ranges from 5-15 m.
Charge Size: Adjusted based on project requirements.
Blasting Repetition: Limited to 2-3 times for optimal soil compaction.

Compaction Results and Considerations

Understanding the outcomes and limitations is crucial:

Relative Density Increase: Ranges from 15 to 30%, with variations based on soil characteristics.
Surface Settlement: Typically ranges from 2-10% of the total depth of the compacted soil layer.
Checking Compaction: Engineers can assess compaction using methods like surface settlement measurements or tests such as cone penetration and standard penetration.

Special Considerations and Efficiency Factors

Several factors influence the efficiency of the blasting technique:

Gas Influence: Even a small amount of gas in the soil can significantly reduce blasting effectiveness.
Pressure Generation: Blasting generates high pressure in saturated sand, emphasizing the importance of considering liquefied zones and pore water pressure.

Conclusion

Blasting, when used judiciously, emerges as a cost-effective and powerful method for deep soil compaction, providing stability and durability to construction projects. However, meticulous planning, adherence to safety protocols, and ongoing assessments are imperative for its successful implementation.