Environmental Erosion Research

fa اولویت‌بندی عوامل مؤثر در ایجاد زمین‌لغزش با استفاده از مدل‌های فرایندمحور در روستای آب‌باد کامفیروز Prioritization of Factors Affecting Landslide in Abbad Village, Kamfiruz مدلسازی و تحلیل زمانی و مکانی رخداد انواع مختلف فرسایش محیطی مستخرج از پایان‌نامه / رساله / طرح پژوهشی شناسایی و بررسی عوامل مؤثر به صورت ناحیهای میتواند در جهت مقابله با زمینلغزش و کاهش خسارات ناشی از آن مهم و مؤثر باشد. در این تحقیق سعی شدهاست با استفاده از مدلهای فرایندمحور طالبی 2008 و بیشاپ اصلاح شده (ترکیب مدل  Bishopو مدل تحلیلی طالبی 2008)، ضمن تحلیل پایداری دامنهی لغزشی در منطقهی آب‌باد کامفیروز فارس، به اولویتبندی عوامل مؤثر در بروز زمینلغزش پرداخته شود. پس از تعیین تمامی پارامترهای مدل فیزیکی که از بازدیدهای میدانی، آزمایشگاهی و تجزیه و تحلیل توپوگرافی استخراج گردید، ضریب پایداری در دو مرحلهی قبل و بعد از لغزش برای دامنهی مورد مطالعه محاسبه شد. در ابتدا میزان ضریب اطمینان با استفاده از مدل طالبی 2008 محاسبه شد. مدل طالبی 2008 بر مبنای تئوری شیب بینهایت است که در آن فرضیهی موازی بودن سطح زمین با سنگ بستر (ثابت بودن عمق خاک) در نظر گرفته شدهاست. چون منطقهی مورد مطالعه دارای عمق خاک متغیر است، مدل مذکور نتوانست ضریب پایداری را به درستی محاسبه کند؛ بنابراین، از مدل بیشاپ اصلاح شده (مدل ترکیبی طالبی 2008 و بیشاپ) استفاده شد. در این روش، میزانFs  برای سطح گسیختگی در یک سطح دایرهای شکل با عمقهای متفاوت خاک و با در نظر گرفتن هندسهی دامنه محاسبه شد. ضریب پایداری مدل بیشاپ اصلاح شده مربوط به قبل از لغزش ـ که معادل 08/1 است ـ این امر را نشان میدهد که دامنه در آستانهی لغزش قرار داشتهاست، اما ضریب پایدرای بعد از لغزش ـ که معادل 19/2 است ـ بیانگر این است که در حال حاضر دامنه به پایداری رسیدهاست. آنالیز حساسیت منطقه با در نظر گرفتن عوامل مربوط صورت گرفت؛ از قبیل حداکثر بارندگی روزانه (N)، هدایت هیدرولیکی (K_s)، زاویهی اصطکاک داخلی (ᴓ)، شیب(ß) ، ضریب چسبندگی (c_co) و وزن مخصوص خاک ( ) . در این مطالعه با توجه به آنالیز حساسیت، مهمترین عوامل تأثیرگذار در لغزش دامنه شناسایی شد که عبارت است از: بالا بودن شیب (ß)، پایین بودن چسبندگی خاک (c) و افزایش وزن مخصوص خاک که ناشی از افزایش رطوبت در آن است. 1- Introduction      Landslide refers to geomorphologic processes and downward movements of the materials of the slopes, including rock, dirt, or a mixture of them (Moradi et al, 2012).Landslides are affected by various factors, including rainstorms, earthquake shocks, changes in the level of underwater, storms, rapid erosion and a series of factors reducing the strength of materials (Dai et al,2002) . Because of geological, geomorphological, and topographical variations resulted from the active seismic belt of the country, many areas are susceptible to landslides. Therefore, it is very important to detect and anticipate this phenomenon to prevent its occurrence. Due to mountainous conditions, the climate of the study area is prone to the domain instability. The road range is also possible to suffer from the same deficiency. Existence of large joints in masses of rocks and several landslides in the boundaries of the road double the importance of examining the stability of the slopes and the dangers of volatility (Khajevand,2017). Due to the high volume of damage and the direct and indirect costs of destruction that mass movement imposes on human societies and the environment, planning to carry out a systematic investigation of the effective factors of mass movements and providing appropriate management solutions in these sensitive areas seem crucial. Our country, Iran, mostly has a mountainous topography with tectonic activities, and is the subject of high seismicity of various climatic and geological conditions. These major natural conditions have the potential to create a wide range of landslides. 2- Methodology     The study area is located in Fars Province, Marvdasht, Kamfiroz Division. In the UTM coordinate system,it is placed in  X=619240 and Y=3347600. This area is situated one kilometer southwest of the village of Abbad. Access to the area is possible through the asphalt road to Sefid village. Abbad village is located in the outlet of the basin. Landslides are considered to be mass fractures. The mass fractures include those fractures in which a mass of crushed soil or crushed stone is disrupted on a curved slip surface.There are various methods for analyzing the stability of these types of ruptures: the equilibrium, the numerical, and the physical simulation methods. Due to  the ease of applications and the relatively good results, these methods tend to be more widely used than other methods of slope stability analysis. 3- Results In general, in order to study of landslides, an attempt was made to use a process-oriented (center-based) model. It can be concluded that the slope stability analysis model can be used to determine the instability of the slopes affected by natural conditions due to the morphology, hydrology, soil physics, and vegetation cover. However, artificial factors affecting landslides such as road constructions and distance from the river have no place in this model. One of the regions with high frequency of landslide in Fars province is the village of Abbad. The susceptible geological structure of this region, its climate, and the manipulation of its natural system (road construction and digging irrigation channels) have exposed it to slippage. In order to find critical slip surfaces in the range having various geometric characteristics, the Bishop circle method was combined with 2008 Taliban method. In this method, the Fs were calculated to find the rupture level at a circular surface using different depths of the soil, taking into account the domain geometry. 4- Discussion & Conclusions To implement the 2008 Talebi and Bishop combined model, the reliability coefficient was calculated using MATLAB software. All formulas and the information layers required for the model were codified in appropriate codes in the MATLAB environment, and the confidence coefficients (FS) were eventually calculated for the scope under investigation. According to the results of the model, the range before the slip (1.08) was in a critical state at the threshold of the slip and was unstable. In the second part of the modelling, when the slippery range was implemented, the results of the model indicated that the slip mass (2.19) had already reached sustainability. Sensitivity analysis was identified as the most important factor leading to slippage occurrence. Among the factors causing slopes, the effect of the sensitivity analysis is the most important; however, the effect of moisture cannot be ignored. The moisture formed during the road and canal construction was another reason for instability in the region.  اولویت‌بندی, مدل طالبی 2008, مدل Bishop, ضریب پایداری Prioritization, Taliban Model, Bishop Model, Sequential Coefficient 54 70 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-536-1&slc_lang=fa&sid=1 Fateme zare فاطمه زارع fzare076@gmail.com 10031947532846005105 10031947532846005105 Yes Yazd University دانشکده‌ی منابع طبیعی و کویرشناسی، دانشگاه یزد ali Talebi علی طالبی talebisf48@gmail.com 10031947532846005106 10031947532846005106 No Yazd University دانشکده‌ی منابع طبیعی و کویرشناسی، دانشگاه یزد Maryam Mokhtari مریم مختاری mokhtari@yazd.ac.ir 10031947532846005107 10031947532846005107 No Yazd University دانشکده‌ی مهندسی عمران، دانشگاه یزد