Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

The paper describes an electrical discharge technology, applied for soil compaction around a borehole, filled with hardening grout, in operations for erection of micropiles, cast piles, soil anchors and soil nails. The technology consists in that 150-250 microsecond long electrical sparks are generated with 6-second period in borehole. The sparks have 30-40 kJ energy, which is roughly of the same order of magnitude as a pile drop hammer. But a single electrical spark has 200-250 MW because of its short duration. Such pulses compact the contact layer of soil and thus increase bearing capacity of piles, anchors or soil nails times 1.5-2.0. Electrical spark in soil is a practically non-observable event, prohibiting any instrumentation near it, which so far can only allow its qualitative investigation in water rather than in soil. The experiments in water were staged in lab on a set-up, generating 5 kJ sparks, with electronic registration of time-dependent registration of pulse behavior. It was found that longer pulse efficiency is higher and can be increased by addition of special admixtures. Full-size bored piles, micropiles and soil anchors were tested in-situ on construction sites, having various soil conditions. The test data yielded that pile (anchor, nail) bearing capacity could be increased times 1.5-2.0 by high-energy electrical spark treatment, as compared to conventional technology (without electrical spark treatment).

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fifth Conference

Publisher

Missouri University of Science and Technology

Publication Date

5-24-2010

Document Version

Final Version

Rights

© 2010 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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May 24th, 12:00 AM May 29th, 12:00 AM

Application of High-Power Electrical Sparks for Dynamic Compaction of Soil

San Diego, California

The paper describes an electrical discharge technology, applied for soil compaction around a borehole, filled with hardening grout, in operations for erection of micropiles, cast piles, soil anchors and soil nails. The technology consists in that 150-250 microsecond long electrical sparks are generated with 6-second period in borehole. The sparks have 30-40 kJ energy, which is roughly of the same order of magnitude as a pile drop hammer. But a single electrical spark has 200-250 MW because of its short duration. Such pulses compact the contact layer of soil and thus increase bearing capacity of piles, anchors or soil nails times 1.5-2.0. Electrical spark in soil is a practically non-observable event, prohibiting any instrumentation near it, which so far can only allow its qualitative investigation in water rather than in soil. The experiments in water were staged in lab on a set-up, generating 5 kJ sparks, with electronic registration of time-dependent registration of pulse behavior. It was found that longer pulse efficiency is higher and can be increased by addition of special admixtures. Full-size bored piles, micropiles and soil anchors were tested in-situ on construction sites, having various soil conditions. The test data yielded that pile (anchor, nail) bearing capacity could be increased times 1.5-2.0 by high-energy electrical spark treatment, as compared to conventional technology (without electrical spark treatment).