Distribution and Statistical Analysis of Discontinuities in Deep Drillcore

Junghae Choi; Youjin Jung; Dae-Sung Cheon

doi:10.9720/kseg.2024.3.415

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2024 Vol.34, Issue 3 Preview Page Next Page

Research Article

Distribution and Statistical Analysis of Discontinuities in Deep Drillcore 심부시추코어를 활용한 불연속면의 분포 특성 및 통계학적 해석

30 September 2024. pp. 415-427

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Abstract

This study undertook a quantitative analysis of the distribution of fractures in deep drillcore from a Precambrian metamorphic complex on the north face of Hongcheon-gun, Gangwon-do, Korea. The fracture distribution with depth, inclination of fractures, and grain size in the fracture zone were measured and statistical techniques applied to derive probability distributions of fracture intervals. Analysis of the inclination angles of fracture planes showed that sub-horizontal fractures are dominant, and fracture spacing is mainly ≤0.5 m, with a median of 0.09 m, first quartile of 0.04 m, and third quartile of 0.18 m, indicating very dense fracture development. Statistical analysis of joint properties was undertaken with fitting using five probability density functions (double Weibull, exponential, generalized logistic, gamma, and lognormal). The lognormal distribution (sum of squared errors, SSE = 2.80) yielded the best fit based on the sum of residual squares. Quantitative characterization of the fracture characteristics of deep bedrock in the Hongcheon area is important for various geotechnical applications such as groundwater flow modeling, slope stability assessment, and underground structure design. In future studies, it will be necessary to combine in situ stress measurements and geophysical surveys to determine the relationship between fracture development and the local stress field.

Keywords

joint distribution

deep drilling core

probability density function

joint spacing

본 연구는 강원도 홍천군 북방면에 위치한 선캄브리아기 변성암 복합체를 대상으로 심부 시추코어의 절리 분포 특성을 정량적으로 분석하였다. 절리의 분포 심도, 경사각, 그리고 파쇄대 내 파편입자 크기를 측정한 후, 통계학적 기법을 적용하여 절리 간격의 확률분포를 도출하였다. 절리면의 경사각 분석 결과, 아수평절리가 가장 우세하게 나타났으며, 절리면 간격 분석에서는 0.5 m 이하의 간격이 지배적이었으며, 중위수 0.09 m, 제1사분위수 0.04 m, 제3사분위수 0.18 m로 나타나 매우 조밀한 절리 발달 양상을 보였다. 통계학적 분석을 위해 double Weibull, exponential, generalized logistic, gamma, lognormal 등 5가지 확률밀도함수와의 피팅을 수행하였으며, 잔차제곱합(sum of squared errors, SSE) 기준 lognormal 분포(SSE = 2.80)가 가장 적합한 것으로 나타났다. 본 연구 결과는 홍천 지역 심부 암반의 절리 특성을 정량적으로 규명함으로써, 지하수 유동 모델링, 사면 안정성 평가, 지하 구조물 설계 등 다양한 지질공학적 응용 분야에 중요한 기초 자료로 활용될 수 있을 것으로 기대된다. 향후 연구에서는 현장 응력 측정 및 지구물리학적 탐사 기법을 병행하여 절리 발달과 현지 응력장의 관계를 규명하는 것이 필요할 것으로 판단된다.

키워드

절리 분포

심부시추코어

확률밀도함수

절리 간격

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Information

Publisher :Korean Society of Engineering Geology
Publisher(Ko) :대한지질공학회
Journal Title :The Journal of Engineering Geology
Journal Title(Ko) :지질공학
Volume : 34
No :3
Pages :415-427
Received Date : 2024-09-11
Revised Date : 2024-09-21
Accepted Date : 2024-09-25
DOI :https://doi.org/10.9720/kseg.2024.3.415

The Journal of Engineering Geology ISSN:1226-5268(Print) 2287-7169(Online) 지질공학

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