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Analysis of Permanent Deformation under Repetitive Load Based on Degraded Secant Modulus

할선탄성계수를 이용한 반복하중 하 지반의 영구변형 해석

Jaehun Ahn1
,
Jeongho Oh2*
,
Hosung Shin3
안 재훈1
,
오 정호2*
,
신 호성3
1Assistant Prof., School of Civil and Environmental Engrg., Pusan National Univ.
2Assistant Prof., Dept. of Railroad Facility Engrg., Korea National Univ. of Transportation
3Assistant Prof., Dept. of Civil and Environmental Engrg., Univ. of Ulsan
1부산대학교 사회환경시스템공학부 조교수
2국립한국교통대학교 철도시설공학과 조교수
3울산대학교 건설환경공학부 조교수
*교신저자. *Corresponding Author. 
28 February 2013. pp. 15-21
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Abstract

The analysis of long-term performance of pavement sections under wheel loads is normally conducted in two separated steps. First the resilient behavior of the pavement is calculated assuming the pavement is a layered or discrete elastic medium, and then the permanent deformation is evaluated based on empirical permanent displacement equations. Material properties required in both steps can be obtained from cyclic triaxial tests, in other words, resilient and permanent deformation tests. While this analytical approach is simple and convenient, it does not consider the modulus degradation caused by cyclic loads, and some types of reinforcements such as geosynthetic cannot be modeled in this type of analysis. A model for degraded secant modulus is proposed and suggested to be used for the analysis of permanent behavior of unpaved roadway sections. The parameter for suggested model can be obtained from cyclic triaxial tests, regular practice in pavement engineering. Examples to estimate the model parameters are presented based on both laboratory permanent deformation test and large-scale plate load test.

Keywords
Secant modulus
Permanent deformation
Subgrade
Pavement
Numerical analysis

일반적으로 도로 포장체 영구변형의 해석은, 먼저 포장체를 층이 진 탄성체로 가정하고 회복탄성계수를 통해 포장체의 회복변형률을 계산하고, 이로부터 다시 실내시험을 통해 얻어진 방정식을 이용하여 영구변형률을 산정하게 된다. 회복탄성계수를 통하여 포장체 내의 응력을 산정할 경우, 포장 내 노상토 상부의 응력은 반복하중으로 인한 노상토의 영구변형 증가를 고려하지 않은 회복탄성계수로부터 결정되므로, 영구변형이 지반 및 포장체에 미치는 영향은 응력 산정 시에 고려되지 않는다. 또한, 토목섬유 등으로 보강된 포장체 등의 거동은 해석에 한계가 있다. 본 논문에서는 기존에 회복탄성계수를 사용하여 포장체의 탄성거동을 계산하는 방식과 달리 하중반복회수의 함수인 할선탄성계수를 사용하여 영구변형을 측정할 수 있도록 새로운 모델을 제안하고, 본 모델 적용과 모델계수 산정의 예를 보인다. 제안된 할선탄성계수를 통한 해석은 비포장 도로 상의 교통으로 인한 영구변형의 예측이나 아스팔트 포장 전 노상토나 기층 상부에 가해지는 공사차량으로 인한 영구변형의 산정에 적용가능 할 것으로 판단한다.

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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 : 29
  • No :2
  • Pages :15-21
  • Received Date : 2012-02-29
  • Accepted Date : 2013-01-25
  • DOI :https://doi.org/10.7843/kgs.2013.29.2.15
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