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탄성영역이 없는 J2-경계면 소성모델

J2-bounding Surface Plasticity Model with Zero Elastic Region

  • 신호성 (울산대학교 건설환경공학부) ;
  • 오세붕 (영남대학교 건설시스템공학과) ;
  • 김재민 (전남대학교 토목공학과)
  • 투고 : 2023.01.19
  • 심사 : 2023.05.10
  • 발행 : 2023.08.01

초록

반복하중이나 동적하중에 대한 지반의 소성모델은 지반구조물의 비선형 수치해석에 매우 중요하다. 단일 항복면 모델은 반복하중에 대해 선형적 거동을 보이는 반면, 개발된 탄성영역이 없는 J2-경계면 소성모델은 동일한 물성치로 효과적으로 지반의 비선형성을 모사할 수 있다. 경계면 내부 항복면의 반경을 0으로 수렴시켜 탄성영역이 사라지도록 수식화하고, 소성경화 계수과 팽창률을 이용하여 소성변형 증분을 정의하였다. 개발된 모델의 응력-변형률 증분식을 제시하고, 쌍곡선 모델에 대한 소성경화 계수를 유도하였다. 삼축압축조건과 얕은기초의 반복하중에 대한 비교해석은 개발된 모델의 안정적인 수렴성, 이론식과의 일치성, 그리고 이력경로을 보여 주었다. 또한, 수정된 쌍곡선함수에 대한 소성경화 계수를 제시하여, 1차원 등가선형모델에 부합하는 모델변수 산정법을 제안하여 지반의 다차원 거동을 모델링할 수 있도록 하였다.

Soil plasticity models for cyclic and dynamic loads are essential in non-linear numerical analysis of geotechnical structures. While a single yield surface model shows a linear behavior for cyclic loads, J2-bounding surface plasticity model with zero elastic region can effectively simulate a nonlinearity of the ground response with the same material properties. The radius of the yield surface inside the boundary surface converged to 0 to make the elastic region disappear, and plastic hardening modulus and dilatancy define plastic strain increment. This paper presents the stress-strain incremental equation of the developed model, and derives plastic hardening modulus for the hyperbolic model. The comparative analyses of the triaxial compression test and the shallow foundation under the cyclic load can show stable numerical convergence, consistency with the theoretical solution, and hysteresis behavior. In addition, plastic hardening modulus for the modified hyperbolic function is presented, and a methodology to estimate model variables conforming 1D equivalent linear model is proposed for numerical modeling of the multi-dimensional behavior of the ground.

키워드

과제정보

본 연구는 한국연구재단 중견연구자지원사업(NRF-2022R1A2C200823612)과 한국수력원자력(주) 해오름동맹출연사업(원전지역 특화연구)의 지원으로 수행되었으며, 이에 깊은 감사를 드립니다.

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