High Energy Impact Compaction (HEIC) for Improved Excavation Stability
EngeoLabCC conducted an in-situ testing and soil stabilisation project at Esikhaleni Cemetery to address sidewall collapse issues during grave excavations. Using the High Energy Impact Compaction (HEIC) method, the project aimed to improve soil stability and ensure safe working conditions. Multiple testing phases were conducted to verify the compaction results and assess the effectiveness of the HEIC method for long-term soil stability.
- Company Details
- Sevices Provide
- Project Timeline
- Location
- City of uMhlathuze Municipality
- In-situ testing, impact rolling compaction, dynamic penetration testing (DPL), nuclear moisture-density testing, Marchetti flat dilatometer testing
- Not specified
- Esikhaleni Cemetery, uMhlathuze Municipality, South Africa
Project Description
EngeoLabCC was tasked with addressing the collapse of grave excavation sidewalls at Esikhaleni Cemetery, a challenge linked to the site’s loose sandy soils. The objective was to improve soil stability to a depth of at least 2.5m, ensuring safer working conditions for staff and improving the gravesite’s appearance during ceremonies.
The project employed High Energy Impact Compaction (HEIC) as a method to densify the soil through impact rolling. To validate the method’s effectiveness, a comprehensive in-situ testing programme was conducted both before and after compaction, along with control tests. The testing involved five trial lines, each measuring 100m long and 10m wide, with multiple rolling passes ranging from 10 to 50.
Various in-situ testing methods were applied, including nuclear moisture-density testing, dynamic penetration tests (DPL), and Marchetti dilatometer tests (DMT). Laboratory analysis of both disturbed and undisturbed soil samples was performed to compare pre- and post-compaction results. Additionally, a month after completion, further tests were carried out to evaluate the set-up effect, measuring the increase in soil stiffness and strength over time.
The results demonstrated a significant improvement in soil stability, with effective densification observed to a depth of 2.5m. Numerical modelling was also conducted to determine slope stability, with a provisional Factor of Safety (FoS) and a probability of sidewall failure (PoF) calculated to assess long-term excavation safety.
Key recommendations included:
- Recompaction of the top 0.5m using a smooth vibratory drum roller.
- Surface smoothing with a grader.
- Hydroseeding to prevent wind and water erosion.
The successful execution of this project provided improved soil stability and safer working conditions for cemetery staff, ensuring long-term structural integrity and compliance with safety standards.
