Back Issues 11-20

THE MAJOR CAUSE OF ANCHOR BLOCK SLOPE FAILURES

Tse-Shan Hsu
Department of Civil Engineering, Feng-Chia University
Taiwan R.O.C.
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Zong-Lin Wu
Ph.D Program in Civil and Hydraulic Engineering, Feng-Chia University
Taiwan R.O.C.

Chihsen T. Lin
Department of Construction Engineering,
National Kaohsiung First University of Science and Technology, Taiwan R.O.C.

Yi-Min Huang
Department of Civil Engineering, Feng-Chia University
Taiwan R.O.C.

Abstract
Currently, a large number of anchors are used in Taiwan to stabilize slopes. The design specifications have been continuously revised after the occurrence of anchor block slope disasters. However, disasters at anchor block slope that meet design specifications have become more and more serious, even in the absence of wind, rain, and earthquakes. This proves that the current design specifications do not include the major cause that induces anchor block slope failures. In view of this, this paper takes the anchor block slope disaster happened at 3.1km mark of the Formosa Freeway as an example. By comparing the endoscope inspection results and those results from in-situ tensile strength tests, it was found that, although the anchor was rusted, the tensile strength was still high. Therefore, in this paper, a theoretical equation is derived and used to find whether the anchor block slope has experienced a very slow sliding process before the disaster. During this process, the tensile strength of the anchor has been significantly reduced to zero with the increase in the amount of shear banding. Therefore, it is proven that shear banding is the major cause that causes the anchor block slope failure. Finally, it is suggested that anchor design specifications should restrict the amount of shear banding, as well as regulate that once anchors are used to stabilize a slope, the amount of shear banding must be monitored in order to greatly reduce the occurrence of anchor block slope failures.

Keywords: Anchor Block Slope, Disaster, Corrosion, Shear Banding.

Attachments:

0885 Final.pdf

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4172 kB