Probabilistic Safety Assessment of Existing Ground-Anchored Slope during Earthquake

Abstract: Ground anchoring is one of the popular methods for maintaining the stability of slope. In this study, a quantitative probabilistic safety assessment (PSA) of existing ground-anchored slope during earthquake was proposed by using the residual tensile force of ground anchor. The PSA can reproduce former maintenance experiences qiuantitatively. The PSA approach consists of “saftey concept”, “probabilistic model” to estimate the failure probability and “thresholed” to evaluate the safety of the slope.
A failure probability of a ground-anchored slope during earthquake should be evaluated based on the variation of tensile forces acting in the ground anchors. Those residual tensile forces have been usually measured by lift-off tests, which typically require time and cost.
In order to overcome this shortcoming of the lift-off test, a non-destructive evaluation for residual tensile force of ground anchors was newly developed. In the developing process, the tendon tension part of a ground anchor is assumed to be a “string”. Therefore, the frequency of its free vibration can be determined by line density, tension length of the PC steel and the operation tensile force.
A series of large scale experiments were conducted by using a proposed measuring equipment shown in Fig.1. It is found out that the proposed technique can easily indicate the magnitude of the residual tensile force of the ground anchor.
The maintenance engineers can quantitatively evaluate the safety of the anchored slope during earthquake based on the failure probability calculated with only by the tensile force.

Biography

Dr. Atsushi Yashima is a Professor of geotechnical engineering in the Department of Civil Engineering at Gifu University, Japan. He earned his PhD in Geotechnical Engineering from Kyoto University, with specialization in excavation of shallow tunnel. Dr. Yashima’s areas of expertise are geo-disaster mitigation, earthquake engineering, pavement and numerical analysis. He has developed many numerical codes to predict geo-disaster and design new countermeasures. He has more than 250 publications and got 6 awards from the professional societies and Gifu Newspaper award for contributions to research.

Education

1979, Bachelor of Engineering, Department of Civil Engineering, Kyoto University

1981, Master of Engineering, Department of Civil Engineering, Kyoto University

1986, Doctor of Engineering, Kyoto University

Work experience

1981 Assistant Professor, Disaster Prevention Research Institute, Kyoto University

1987 – 1988 Visiting Researcher, University of Colorado, Boulder, USA

1990 Associate Professor, Department of Civil Engineering, Gifu University

1995 Visiting Researcher, Laval University, Canada

1998 Professor, Department of Civil Engineering, Gifu University

2003 Director of Regional Research Center, Gifu University

2010 – 2014 Vice President, Gifu University

2014 Professor, Department of Civil Engineering, Gifu University

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