New concepts for sustainable application of deep vibratory compaction-Paper

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The paper presents ways to make deep vibratory compaction (DVC) more effective, economical, and sustainable as an alternative to pile foundations in suitable granular soils. It argues that compaction is governed chiefly by cyclic shear strain, the number of vibration cycles, and changes in horizontal stress—not simply by particle acceleration. Ground vibration measurements can help estimate shear strain and assess the compaction effect.<br /><br />Vibratory treatment densifies soil and can permanently increase horizontal effective stress. This creates a prestressing effect that changes the soil from normally consolidated to overconsolidated, increasing stiffness and reducing settlement. The paper recommends accounting for this benefit in design, using CPT sleeve resistance or DMT measurements to estimate horizontal stress changes. CPT data can also inform settlement calculations through the tangent modulus method.<br /><br />A project should set settlement and liquefaction performance requirements, assess initial conditions using in-situ tests, determine the required improvement, select an appropriate method, conduct treatment trials, monitor work, and verify results. Trial compaction helps establish grid spacing, treatment duration, passes, and operating parameters, avoiding both inadequate treatment and overcompaction.<br /><br />A central optimization concept is to operate near the resonance frequency of the vibrator–probe–soil system. Resonance amplifies ground vibrations, improving energy transfer and compaction while potentially reducing energy consumption and equipment wear. Modern monitoring and process-control systems can track frequency, vibration velocity, hydraulic pressure, and probe penetration speed in real time. Together, these measures help operators adjust treatment to ground conditions and determine when the specified improvement has been achieved.

Keywords

deep vibratory compaction

granular soils

cyclic shear strain

horizontal stress

soil densification

resonance frequency

CPT sleeve resistance

DMT measurements

liquefaction mitigation

settlement reduction