HIGH ENERGY IMPACT COMPACTION (HEIC) TECHNOLOGY

HEIC is a procedure of compacting in-situ materials at depth. The HEIC application is used to improve the engineering properties of soils, both above and below the groundwater level. Soil strength is increased, and compressibility and settlements are decreased as a result of the HEIC process. The primary objective of HEIC is to change a heterogeneous soil into one that has more uniform and increased engineering properties. Basically, HEIC consists of providing repeated high energy impacts at the ground surface by rotating, at speed, Cam shaped and Pentagonal steel drums of 10 to 14 tonnes in weight from drop heights ranging from 150mm to 230mm.

In addition to strengthening the existing in-place materials, HEIC, like proof rolling, exposes pockets of soft material or materials that are unsuitable for compaction. These areas, when identified during HEIC, may either require additional treatment or undercutting and replacement with suitable materials. The degree of soil improvement depends to a large degree upon the total amount of energy applied to the soil, i.e., the more energy input to the soil, generally the greater the degree of improvement. The result of treatment by HEIC is immediate. Induced settlement is typically five to ten percent of the thickness of the material being treated and is noticed immediately. Strength and compressibility, as measured by in-situ tests, are typically improved by a factor of two to six.

The depth of influence is related to the HEIC drum weight and the rotational drop height, with improvement depths of 2m to 4m being commonly recorded by cone penetration tests, dynamic probes and heavy zone load testing. The depth of influence is dependant on a number of factors including the soil type and stratigraphic features, efficiency or energy loss of the HEIC process on soft surfaces, the contact pressure of the HEIC drum face, and the moisture content of the materials.