Browsing by Author "Gebreanenia, Gebreselassie"

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    Investigations of Landslide Problem Using Geophysical Techniques around Debresina-Armanja Main Road in Tarmaber Woreda, Northern Shewa Zone, Ethiopia
    (Addis Ababa University, 2013-06) Gebreanenia, Gebreselassie; Haile, Tigstu (PhD)
    Geophys ical and geo logical in vesti gat ions have been conducted 1'01' land slide problcm characteri zation of the exist ing main road of the study area. The s ite is located in betlle~n Debres ina and Armaniya towns. Tarmaber Wereda. north ern Sheila Zone of Amhara Regiolllce of the problematic main asphalt road. identi fy tri ggering mechani sms of land slide problem. and recommend possible mitigation measures based on the geo-elect ri cal res isti vity stratil·ication of the site and magnetic anomalies obta ined over the survey area. Geophysical investigations using 2D electrical imaging and magnetic methods havc been conducted Il)r the land slide problem of the road located HI kebdc' Dokakitnear Sar Amba Kidan cm hir~tloe al it \ betlleenDebrL' Si na and l\rmania t""lh. 1- 1'0111 the resuhs or the survc). it has been possihk to map thl: ~ Iidillg ;-,tl b:-,u rl ~ ICl: or the g~ologiL' layers, their ve rti ca l and lateral extents. It has al so been poss ible to map areas 01· lIeaknc\S in the subsurlace that could be causing and damaging to the lile of the road. According t" the interpretation of the geophysical result s. the ncar stll·face geolog) of the study area includes fragmented and di sturbed la ye rs togcth er "ith expansive clay soils which have also conside rab l) cause of sliding problem over the area. In profile three the cia) so ils are mueh thicker than the oth er two profil es. In prolile three low res istiv ity deposits are dominant particularl) in the northeastern side of the survey area. These deposits are may be hugc deposits ol· the fragme nt al basalt and expansive clay so ils that arc moved down the slope and accllmulated in location " I' prolile three whic h is jll st do\Vn the road . Based on the joinl interpretation or the result s. the Slirve) ed area has possi ble slide lone II hich " characterized by Ij·agmented and structural I) disturbed po rt ion IIhicl! staib rrom "lnhlSt h,&"Cthe surveyed line to\Vards north cast direc tion . This is interpret ed to be the re'I)(>I"e 01· thL' "'lier saturated, lIeathercd and fractu red ba sa lt rocK . I·here is also l"nlbliLie "rkcted sllbsurillce tltal c.\hibib intermedi ate apparent re~istivit) \alue ~ l.'uillprise~ of thl' ~U Ulll\\t: ~t end or 1il(' ~lInc\l' d proli lcs. This zone consists orsurlitce orllcakncss and some displaced rock units. As conc ili sion I·j·om the work, the aspha lt road para ll el to the stll·ve) proliles has active slidillg problem and cracks espec ially at the two ends or the profi les. The clifterent weak zones. deeph IIcatheri ng cond ition s. ac tion of rain la lL springs and slope nature of th e stlld) arc" lIere the causi ng lactors l'or this sliding problem. Therel'ore. special alieni ion should be given to maintain and protect from further sliding problem.
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    Investigations of Landslide Problem Using Geophysical Techniques Around Debresina–Armania Main Road in Tarmaber Woreda, Northern Shewa Zone, Ethiopia
    (Addis Ababa University, 2013-06-06) Gebreanenia, Gebreselassie; Haile, Tigstu (PhD); Mammo, Tilahun (PhD)
    Geophysical and geological investigations have been conducted for landslide problem characterization of the existing main road of the study area. The site is located in between Debresina and Armania towns, Tarmaber Woreda, northern Shewa Zone of Amhara Regional State. The main objective of the study was to image subsurface of the problematic main asphalt road, identify triggering mechanisms of landslide problem, and recommend possible mitigation measures based on the geo-electrical resistivity stratification of the site and magnetic anomalies obtained over the survey area. Geophysical investigations using 2D electrical imaging and magnetic methods have been conducted for the landslide problem of the road located at kebele Dokakit near Sar Amba Kidanemhiret locality between Debresina and Armania towns. From the results of the survey, it has been possible to map the sliding subsurface of the geologic layers, their vertical and lateral extents. It has also been possible to map areas of weakness in the subsurface that could be causing and damaging to the life of the road. According to the interpretation of the geophysical results, the near surface geology of the study area includes fragmented and disturbed layers together with expansive clay soils which have also considerably cause of sliding problem over the area. In profile three the clay soils are much thicker than the other two profiles. In profile three low resistivity deposits are dominant particularly in the northeastern side of the survey area. These deposits are may be huge deposits of the fragmental basalt and expansive clay soils that are moved down the slope and accumulated in location of profile three which is just down the road. Based on the joint interpretation of the results, the surveyed area has possible slide zone which is characterized by fragmented and structurally disturbed portion which starts from almost half of the surveyed line towards northeast direction. This is interpreted to be the response of the water saturated, weathered and fractured basalt rock. There is also landslide affected subsurface that exhibits intermediate apparent resistivity values comprises of the southwest end of the surveyed profiles. This zone consists of surface of weakness and some displaced rock units. As conclusion from the work, the asphalt road parallel to the survey profiles has active sliding problem and cracks especially at the two ends of the profiles. The different weak zones, deeply weathering conditions, action of rain fall, springs and slope nature of the study area were the causing factors for this sliding problem. Therefore, special attention should be given to maintain and protect from further sliding problem.