Strength Characteristics of Small-Scale Sand Specimens Mixed with Fiber and Cement-Slurry Columns: Direct Shear Tests

Hong Duk Moon; Jong Yob Kim; Chao Wang; Hee-Young Sung; Seung-Wook Woo; Sung-Sik Park

doi:10.7843/kgs.2025.41.6.77

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2025 Vol.41, Issue 6 Preview Page Next Page

Strength Characteristics of Small-Scale Sand Specimens Mixed with Fiber and Cement-Slurry Columns: Direct Shear Tests 직접전단시험을 통한 섬유 및 시멘트 슬러리 기둥이 혼합된 소형 모래 공시체의 강도 특성

31 December 2025. pp. 77-87

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Abstract

Vegetation roots can increase ground mechanical stability, and many studies emulate this effect by randomly mixing fibers into soils. In this study, fiber bundles and cement slurry columns were embedded in uniform, columnar forms perpendicular to the shear direction rather than mixed randomly. Direct shear tests were conducted to investigate the effects of relative density, fiber content, and the distribution of cement slurry columns (having equal volume to the fiber bundles) on shear strength. The combined influence of fibers and cementation on sand shear strength was also evaluated. Results show that both fiber bundles and cement slurry columns increase peak shear strength. The internal friction angle of fiber-reinforced sand increased from 35° to 38° in loose specimens and up to 41° in dense specimens. Cohesion of sand reinforced with cement slurry increased from 0 kPa to 190 kPa in loose sand and from 11 kPa to 230 kPa in dense sand. Distributing the same fiber volume across multiple insertion points further improved shear strength. When both materials were combined, simultaneous increases in internal friction angle and cohesion were observed.

Keywords

Cement slurry

Direct shear test

Fiber

Sand

Shear strength

자연에는 다양한 식생이 토사 내에 뿌리를 내리고 지반의 물리적 안정성에 기여하고 있다. 대부분의 기존 연구는 섬유를 모래나 점토에 분산 혼합하는 방식을 사용하나, 본 연구에서는 전단 방향과 직각으로 기둥 형태로 일정하게 분산 매립하였다. 가는 섬유 다발과 시멘트 슬러리 기둥과 같이 강도와 강성이 서로 다른 물질을 모래에 혼합시켜 직접전단시험을 수행하였다. 두 종류의 상대밀도와 세 종류의 섬유비 그리고 섬유 다발과 동일한 부피의 시멘트 슬러리 기둥의 분포도에 따른 전단강도 변화를 연구하였다. 또한, 섬유 다발과 시멘트 슬러리 기둥을 복합적으로 매립하여 각각의 재료가 모래의 전단강도에 미치는 영향을 분석하였다. 그 결과, 섬유 다발과 시멘트 슬러리 기둥 모두 모래의 최대전단응력을 증가시켰다. 모래의 내부마찰각은 섬유로 보강한 경우 상당히 증가하였으며, 느슨한 경우는 35°에서 38°로, 조밀한 경우는 38°에서 최대 41°까지 증가하였다. 점착력은 시멘트 슬러리로 보강한 경우 느슨한 모래는 0 kPa에서 190 kPa로, 조밀한 모래는 11 kPa에서 최대 230 kPa까지 증가하였다. 특히 동일한 섬유비에서 더 많은 지점에 나누어 매립하는 것이 모래의 전단강도를 더 증가시켰다. 그리고, 두 재료를 복합적으로 모래에 사용한 경우 각각의 특성이 모두 발현되었으며, 즉 모래의 내부마찰각과 점착력이 모두 증가하는 효과를 얻을 수 있었다.

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Information

Publisher :The Korean Geotechnical Society
Publisher(Ko) :한국지반공학회
Journal Title :Journal of the Korean Geotechnical Society
Journal Title(Ko) :한국지반공학회 논문집
Volume : 41
No :6
Pages :77-87
Received Date : 2025-10-20
Revised Date : 2025-11-11
Accepted Date : 2025-11-11
DOI :https://doi.org/10.7843/kgs.2025.41.6.77

Journal of the Korean Geotechnical Society ISSN:1229-2427(Print) 2288-646X(Online) 한국지반공학회 논문집

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