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:: Volume 36, Number 158 (9-2017) ::
JHRE 2017, 36(158): 77-88 Back to browse issues page
Effects of Landslides on the Safety of Roads and Rural Settlements in Iran and Stabilization Methods (Case Study of Naghan-Karoon 4 Road Landslides)
Mohsen Salehi , Majid Safamehr, Masoud Nasri, Hossein Boor
Faculty Member Faculty Member of Islamic Azad University of Ardestan Branch , salehi_m4000@yahoo.com
Abstract:   (146 Views)
This study investigates landslides occurred in Chahar Mahal – Bakhtiari Province in Iran, using a probability analysis for describing landslide mechanism. Two case studies of landslide in this province (Naghan – karoon 4 Road) are analyzed using software analysis and empirical methods.The mountainous topography, various geological structures, crust mobile zones and humid climate can trigger geological hazards including landslides in Chahar Mahal – Bakhtiari Province. Identification of the landslide area is important for site selection and development planning of human settlements and infrastructure within the landslide prone regions. Landslide prone areas can be identified through landslide susceptibility zonation maps. This paper describes a method to identify those slopes that are vulnerable to landslides through the statistical analysis of geological data.
The landslides statistical data was collected in the Landslide Department of Forests Range and Watershed Management Organization of Chahar Mahal- Bakhtiari Province. This statistical data was recorded  in the period of 1987 to 2014. During this period 319 landslides were detected and recorded. In this study the landslides of Chahar mahal and Bakhtiari province have been analyzed base on the watershed and sub watersheds, and their impact levels. The probability analysis of this data is used for describing landslide mechanism.
A high frequency of landslide events can be linked to the geographical and climatological condition in Chahar Mahal and Bakhtiari province, which is a mountainous and rainy region. Aside from these factors, the lithology, stratigraphy and geometrical design of roads also affect on landslide events.  A number of landslides in the study area (Naghan – Karoon 4 road) and stabilization methods that are used for slopes are described. Considering the location of some of the landslides in the vicinity of Deh Kohneh and Gandom Kar villages and the possibility of life-threating landslides, a comprehensive study is conducted for investigating these landslides and suggesting stabilization methods for slopes. Important causes of landslides in Naghan- karoon 4 slopes are water runoff and marl and clay layers in slopes.
Almost all landslides of the Naghan – karoon 4 Road  affect surrounding villages and human settlements. This study suggests a number of stabilization methods for soil and rock mass slopes based on the software analysis (Geoslope software and stereographic analysis) and field observations. Stabilization methods for Naghan – karoon 4 slopes include retaining structures, surface and subsurface drains.
In geographic areas with limited data availability, where there was a fundamental need for land-slide hazard information, a combination of landslide inventory and topographic data can provide an effective estimate for landslide susceptibility.  Some of the methods of slope stabilization such as slope weight reduction for decreasing trigger forces are not useful for all cases of landslides. Based on result of analyses the water pore pressure in soil mass and impermeability of marl layers are main causes of soil movement. Utilizing drainage systems for draining water pore pressures can reduce displacements in landslides. In order to drain water table of slope, we need to install screen and perforated polyethylene pipes to the horizontal boreholes. Usually a layer of nonwoven geotextile wrapped around pipes can prevent filling the pores in polyethylene pipes. This function of geotextiles filtration can increase the life time and quality of drainage boreholes. Another type of drainage systems is superficial channels. The construction of channels to direct run off water from slops has also been prevalent.The depth and width of these channels is 1.5 m and 2.5 m respectively for a trapezium form in channel section. Superficial channels should have been waterproofed by concrete or bentonite in order to prevent water infiltration in slops.
 
Keywords: landslide, Trench, stabilization methods, surface drain, subsurface drain, Naghan.
Full-Text [PDF 1121 kb]   (82 Downloads)    
Type of Study: Applicable | Subject: عمران و شهرسازی
Received: 2015/05/20 | Accepted: 2017/04/4 | Published: 2017/09/10
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Salehi M, Safamehr M, Nasri M, Boor H. Effects of Landslides on the Safety of Roads and Rural Settlements in Iran and Stabilization Methods (Case Study of Naghan-Karoon 4 Road Landslides) . JHRE. 2017; 36 (158) :77-88
URL: http://jhre.ir/article-1-1066-en.html
Volume 36, Number 158 (9-2017) Back to browse issues page
فصلنامه مسکن و محیط روستا Journal of Housing and Rural Environment
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