General geology and slope stability study in the Southern part of Sandakan Town area

Ali Andrea Hashim (2006) General geology and slope stability study in the Southern part of Sandakan Town area. Universiti Malaysia Sabah. (Unpublished)


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The general study area consists of two main formation, they are the Sandakan Formation and the Garinono Formation. The Sandakan Formation covers the study area extensively, and is of the Upper Miocene Age. The Garinono Formation lies unconformably below the Sandakan Formation and is of Middle Miocene in age. A volcanic fasies believed to have originated from the Dent Volcanics and interpreted as constituent to the Silabukan Formation can also be observed at the study area at Sim Sim locality. The Sandakan Formation was deposited in a deltaic environment with a sub-arkose sandstone classification. Petrographic thin section samples display spheroidial to sub-angular fragments and good sorting. Two episodes of tectonic deformation are believed to have occurred in the area due to the marginal evolution of the Sulu Sea Basin and subduction of the Proto South China Sea. The two deformation trends are in the Northwest - Southeast and Northeast - Southwest directions, as determined by lineament and joint analysis. These tectonic activities affect rock slope stability by virtue of the orientation of joint sets forms with respect to the slope face. Of the five rock slopes studied by using the discontinuity analysis or Markland Test, potential wedge, toppling and planar failures were ascertained. Stability analysis on soil slopes were conducted by using the slice method, were the Factor of Safety (F.O.S.) value was determined. The slice method analysis was supplemented by laboratory experiments to determine the engineering properties of soil and rock. The soils from the study area mainly consisted of Clayey Sand with high clay content, and low shear strength. Rock samples were found to be moderately weak. F.O.S values results range between 0.74 and 3.18, where 4 out of 5 slopes were deemed unsafe and failure is imminent. Mitigation methods such as slope geometry realignment, adequate monitoring, and sealing of cracks were recommended.

Item Type: Academic Exercise
Uncontrolled Keywords: General geology, Sandakan formation, Garinono formation, Sandakan
Subjects: ?? QE1-350.62 ??
Divisions: SCHOOL > School of Science and Technology
Depositing User: ADMIN ADMIN
Date Deposited: 23 Nov 2011 06:17
Last Modified: 12 Oct 2017 06:04

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