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2026 Vol.36, Issue 3 Preview Page

Original Article

Comparison of Numerical Response Characteristics of DEM Contact Formulations under Varying Timesteps: Spring Model and Impulse-based Method

시간 간격 변화에 따른 DEM 접촉 해석 기법별 수치 응답 특성 비교: Spring model 및 Impulse-based method

Je-Kyum Lee1
,
Myung-Kyu Song2
,
Chang-Yong Kim3
,
Wan-Kyu Yoo4
,
Ji-Seok Yun1
,
Sean Seungwon Lee5*
이 제겸1
,
송 명규2
,
김 창용3
,
유 완규4
,
윤 지석1
,
이 승원5*
1Postdoctoral Researcher, Dept. of Geotechnical Engineering Research, Korea Institute of Civil Engineering and Building Technology
2Research Professor, Department of Earth Resources and Environmental Engineering, Hanyang University
3Senior Research Fellow, Dept. of Geotechnical Engineering Research, Korea Institute of Civil Engineering and Building Technology
4Senior Researcher, Dept. of Geotechnical Engineering Research, Korea Institute of Civil Engineering and Building Technology
5Professor, Department of Earth Resources and Environmental Engineering, Hanyang University
1한국건설기술연구원 지반연구본부 박사후연구원
2한양대학교 자원환경공학과 특임교수
3한국건설기술연구원 지반연구본부 선임연구위원
4한국건설기술연구원 지반연구본부 수석연구원
5한양대학교 자원환경공학과 교수
*Corresponding Author
30 June 2026. pp. 257-276
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Abstract

The discrete element method (DEM) is widely used to simulate the mechanical behavior of discontinuous rock masses; however, the numerical stability, reproducibility of contact history, and computational efficiency of the analysis can vary depending on the contact calculation method adopted. In this study, two representative DEM contact formulations, the spring model and the impulse-based method, were comparatively analyzed in terms of their numerical response to variations in the timestep under identical simulation conditions. To this end, static contact, quasi-static shear, rotational, and dynamic impact conditions were considered, and the contact force, shear resistance, velocity, position, and energy responses were compared. The results show that the spring model effectively reproduces the gradual mobilization of contact force and shear resistance under static contact and quasi-static shear conditions, but exhibits contact force oscillation, distortion of the energy response, and divergence as the timestep increases. In contrast, the impulse-based method maintains a stable kinematic response even at relatively large timesteps under rotational and dynamic impact conditions, yet shows limitations in reproducing the quasi-static shear behavior that relies on contact history. The difference in the contact calculation schemes of the two methods manifests as a difference in their sensitivity to the timestep, which in turn determines the suitability of each method depending on whether the analysis focuses on contact history or momentum change. These findings suggest that, if future studies address the limitations of the impulse-based method, its application can be extended to jointed rock mass analysis while preserving its computational efficiency.

Keywords
개별요소법
불연속 암반
접촉 해석 기법
Spring model
Impulse-based method

불연속 암반의 거동을 모사하기 위해 개별요소법(Discrete Element Method, DEM)이 널리 활용되고 있으나, 접촉 응답을 계산하는 방식에 따라 해석 결과의 수치적 안정성, 접촉 이력 재현성 및 계산 효율성은 달라질 수 있다. 본 연구에서는 DEM의 대표적인 접촉 해석 기법인 Spring model과 Impulse-based method를 대상으로, 동일한 해석 조건에서 시간 간격 변화에 따른 수치 응답 특성을 비교·분석하였다. 이를 위해 정적 접촉, 준정적 전단, 회전 및 동적 충돌 조건을 설정하고, 접촉력, 전단저항, 속도, 위치 및 에너지 응답을 비교하였다. 해석 결과, Spring model은 정적 접촉 및 준정적 전단 조건에서 접촉력 변화와 전단저항의 점진적 발현을 재현하는 데 유리하였으나, 시간 간격 증가에 따라 접촉력 진동, 에너지 응답 왜곡 및 발산이 나타났다. 반면, Impulse-based method는 회전 및 동적 충돌 조건에서 상대적으로 큰 시간 간격에서도 안정적인 운동 응답을 보였으나, 접촉 이력에 기반한 준정적 전단 거동을 재현하는 데에는 제한이 있었다. 두 기법의 접촉 계산 방식의 차이는 시간 간격 변화에 대한 민감성의 차이로 나타났으며, 이는 해석의 초점이 접촉 이력에 있는지, 운동량 변화에 있는지에 따라 각 기법의 적합성을 가르는 요인이 된다. 향후 Impulse-based method의 한계를 보완하는 연구가 수행된다면, 계산 효율성을 유지하면서 절리 암반 해석으로 적용 범위를 확장할 수 있을 것으로 기대된다.

키워드
Discrete element method
Discontinuous rock mass
Contact formulation
Spring model
Impulse-based method
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Information
  • Publisher :Korean Society for Rock Mechanics and Rock Engineering
  • Publisher(Ko) :한국암반공학회
  • Journal Title :Tunnel and Underground Space
  • Journal Title(Ko) :터널과 지하공간
  • Volume : 36
  • No :3
  • Pages :257-276
  • Received Date : 2026-04-13
  • Revised Date : 2026-06-08
  • Accepted Date : 2026-06-12
  • DOI :https://doi.org/10.7474/TUS.2026.36.3.257
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