بررسی رابطه ی بین سن مخروط افکنه ها و پارامترهای مقاومتی خاک های تجمع یافته در آن ها (مطالعه موردی: مخروط افکنه های حاشیه طاقدیس دنه خشک) (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
فرآیندهای ژئومورفولوژی با تأثیر در ویژگی رسوبات موجود در مخروط افکنه ها باعث تغییر در پارامترهای مقاومتی خاک، ازجمله چسبندگی و زاویه اصطکاک داخلی می شوند. با توجه به هدف پژوهش حاضر ابتدا از طریق نقشه های زمین شناسی، تصاویر ماهواره ایی و بازدیدهای میدانی، سپس بر اساس شواهد ژئومورفولوژی دو مخروط افکنه حوضه قلعه شاهین و دیره که دارای بخش های قدیمی و جدید می باشد انتخاب گردید. نمونه برداری از سه بخش رأس، میانه و پایین دست بخش های قدیمی و جدید مخروط افکنه ها صورت گرفته است. نتایج بررسی شکل ذرات نشان می دهد از بالادست به سمت پایین دست ذرات متأثر از فرآیند های ژئومورفولوژی به صورت گرد شده، هم بعد، ریزدانه و دارای بافت سطحی صاف هستند. با توجه به آزمایش برش مستقیم میزان زاویه اصطکاک داخلی از ˚38.1 در بالادست تا ˚27.4 در پایین دست مخروط افکنه ها متغیر است. درنتیجه میزان زاویه اصطکاک داخلی از بالادست به سمت پایین دست رو به کاهش خواهد بود. همچنین مطابق با نتایج آزمایش مقاومت تراکمی تک محوری میزان چسبندگی ذرات از kpa45 در بالادست تا kpa150 در پایین دست متغیر است. به طوری که از بالادست به سمت پایین دست، میزان چسبندگی ذرات خاک در مخروط افکنه ها افزایش یافته استThe relationship between the age of alluvial fans and the resistance parameters of accumulated soils
The relationship between the age of alluvial fans and the resistance parameters of accumulated soils(acase study: alluvial fans on the edge of Daneh-Khoshk anticline)Maleki A .Ph.D., Associate professor, Dep. of Geography, Faculty of Literature and Humanities, Razi University, Kermanshah, Iran.Bahrami K.Ph.D., Assistant professor, Dep. of Geography, Faculty of Literature and Humanities, Razi University, Kermanshah, Iran.Moradi S.Postgraduate student., Dep. of Geography, Faculty of Literature and Humanities, Razi University, Kermanshah, Iran.AbstractGeomorphological processes, by affecting the characteristics of sediments in alluvial fans, cause changes in soil resistance parameters, including adhesion and internal friction angle. According to the purpose of the present research, first through geological maps, satellite images and field visits, then based on the geomorphological evidence, two alluvial fans basins of Qaleh Shahin and Deira basins, which have old and new parts, were selected. Sampling has been done from the top, middle and downstream parts of the old and new parts of the conifers. The results of examining the shape of the particles show that from upstream to downstream, the particles affected by geomorphological processes are rounded, dimensional, fine-grained and have a smooth surface texture. According to the direct cutting test, the internal friction angle varies from 38.1 ˚ in the upstream to 27.4 ˚ in the downstream of the alluvial fans cones. As a result, the internal friction angle will decrease from upstream to downstream. Also, according to the results of the uniaxial compressive strength test, the adhesion of particles varies from 45 kpa in the upstream to 150 kpa in the downstream. So that from upstream to downstream, the amount of adhesion of soil particles in alluvial fans has increased. As a result of the present research, by examining the geomorphological and geotechnical characteristics of the accumulated soils in alluvial fans deposits, it can be considered from the relationships obtained in locating the best options for development plans and the implementation of construction projects, including the macro issues of urban management, industrial estates, and the use of environmental planners. Extended AbstractIntroductionAlluvial fans are very important in terms of settlement and human activities as well as scientific research. alluvial fans are divided into old and new alluvial cones in terms of age. Different parts of a cone are also different in age. alluvial fans are divided into new and old parts based on geomorphological evidence such as drainage pattern, color tone in satellite images, topographical condition, grain and stone surface varnish, vegetation, etc. Geomorphological processes change the characteristics of sediments in alluvial deposits The characteristics of sediment particles, including their size and roundness, are different according to geomorphological processes in different environments.Paying attention to the importance of conifer sediments and also mentioning that there have not been many researches in the field of geomorphological processes in relation to soil engineering. Therefore, the aim of this research is to investigate the effect of geomorphological processes with emphasis on soil resistance characteristics in old and new alluvial depositsMethodologyIn this research, an inductive-experimental method has been used to compare the sedimentary structure of old and new alluvial fans with the geotechnical characteristics of the accumulated soils. Considering that the old and new parts of the upstream basin are the same in each alluvial fan, the sediments in each alluvial fan have relatively the same composition in terms of lithology. Sampling has been done from the top, middle and downstream parts of the old and new parts in both conifers. The samples were transferred to the laboratory and after the samples were granulated, a direct shear test according to ASTM D3080 standard and a uniaxial compression test according to ASTM 2166 standard were performed on the reconstructed samples. Results and Discussion the old alluvial fans have a darker tone due to the weathered sediments in the satellite images, and due to the process of sedimentation and erosion, the morphology is more uneven and has more topography. Due to the dominance of erosion and dissolution, old and inactive alluvial fans have more soil and more weathered cover than new alluvial fans. Due to erosion, the drainage network pattern in old alluvial deposits is convergent or tree network, and in active alluvial deposits, the drainage pattern is divergent or distributed According to the direct cutting test, the internal friction angle varies from ˚38.1 degrees in the upstream to ˚27.4 degrees in the downstream of the cones. Also, according to the results of the uniaxial compressive strength test, the amount of particle adhesion varies from 45 kpa in the upstream to 150 kpa in the downstream.ConclusionThe results obtained from examining the shape of the particles show that from upstream to downstream, the particles are rounded and dimensional under the influence of geomorphological processes, including weathering and erosion. Also, increasing the percentage of cement on the surface of the particles also causes the surface texture to deteriorate and reduce the size of the grains.The results of investigations carried out in the direct cutting test state that the changes in the internal friction angle of particles affected by geomorphological processes are different in different parts of the old and new conifers. So that the amount of internal friction angle in old alluvial deposits is higher than the new ones due to the sedimentation process and the internal friction angle has decreased from upstream to downstream in old and new alluvial deposits.The results of the uniaxial compressive strength test also show that according to the changes of geomorphological parameters, the adhesion of particles in old alluvium is more than new. In such a way that the adhesion of particles increases from upstream to downstream in old and new cone sprinklers. In addition to this, the uniaxial compressive strength of old siltstones is higher than that of new siltstones due to the coarser surface texture and higher percentage of clay particlesKeywords: old and new alluvial fans, geomorphological processes, angle of internal friction, adhesion
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