• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.335-342
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• 2003

The method of measuring ground deformation modulus, in situ-testing has the disadvantage where the exam number is limited because it needs counter weight and a lot of measurement times. Recently, it has supplemented this problem and the equipments by which measurement can be made quickly are developed and applied in field., That is Falling Weight Deflectometer(FWD), Light Drop Weight Tester(LDWT), Geogauge. Light Drop Weight Teste.(LDWT) is introduced firstly in the name of ‘a lightweight fall circuit tester for a railroad public corporation’ by KTX. Since KTX introduced LDWT, a number of research organizations have used LDWT to find out domestic standard for quality management of base ground. In this study we used ZFG 02 which was manufactured by Stendal in Germany and measured the dynamic deformation modulus in soil box and in-situ. And we analyzed the correlation of the dynamic deformation modulus with static deformation modulus based on plate test in the same ground.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.19-26
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• 2009

In this study, flowable backfill made with weathered granite soil is tested to provide basic engineering properties that can be used as design input to overcome settlement problems in road pavement due to low stiffness of backfill which is generated by porosity of the soil. For design purpose, a proper mixing ratio is developed first. Then several test methods including FF/RC, PMT and LDWT including axial compression test are adapted for checking stiffness and measuring axial strength of the material separately that can be used for design values.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.239-247
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• 2009

Pipe installation following excavation of pavement and underlying-soils induces settlements, cracks and bad roughness near utility cut. This study is to use PMT and LDWT in order to evaluate stiffness and/or degree of compaction of sublayers and backfill in utility cut section because no specially designed efforts for evaluating stiffness condition of the substructures below new pavement after pipe installation are offered at this time. From test results of PMT, comparable stiffness and/or degree of compaction in recompaction process is not obtained comparing to that of the existing sublayers before excavation. Thickness of the new surface layer after pipe installation must be designed thicker than that of the existing surface layer. It is verified that LDWT comparing to PMT is effective only to get stiffness and/or degree of compaction within limited depth from surface of materials, but it is not useful to evaluate stiffness of substructures in full depth in case of utility cut.

• Journal of Korean Society of Forest Science
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• v.108 no.3
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• pp.322-328
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• 2019

The purpose of this study was to provide basic data for maintenance and repair of the forest road surfaces using the light drop weight test (LDWT), density test, and grain size analysis at four sites in Yeongyang-gun Mt. (2011y, 2014y, 2016y, and 2017y). In terms of the density test results, the opening density in 2011 was the highest at $2.0694g/cm^3$, and the opening density in 2017 was the lowest at $1.7443g/cm^3$. The grain size analysis showed that the proportion of large aggregates was highest at the opening in 2017, and the proportion of large aggregates decreased with the delay of opening date. From the LDWT results, $E_{vd}$ (the dynamic deformation coefficient) of the 2011y forest road was $35.7MN/m^2$, 2014y was $30.5MN/m^2$, 2016y was $28.6MN/m^2$, and 2017y was $23.5MN/m^2$. The $E_{vd}$ value for the oldest forests opened with the 2011y forest road was the highest, the average $E_{vd}$ value of the center portion was $21.45MN/m^2$, the average $E_{vd}$ value of the wheel portion of the banking part was $31.31MN/m^2$, and the average $E_{vd}$ value of the wheel portion of the cut part was $36.71MN/m^2$.