اثر فرآیندهای یخبندان- ذوب و گرمایش – سرمایش بر نفوذپذیری ماسه سنگ لوشان

حسینی, مهدی; فخری, دانیال

doi:10.30479/jmre.2019.1584

اثر فرآیندهای یخبندان- ذوب و گرمایش – سرمایش بر نفوذپذیری ماسه سنگ لوشان

نویسندگان

¹ دانشیار، گروه مهندسی معدن، دانشگاه بین المللی امام خمینی (ره)

² دانشجوی کارشناسی، گروه مهندسی معدن، دانشگاه بین المللی امام خمینی (ره)

10.30479/jmre.2019.1584

چکیده

در بسیاری از محیط‌ها، سنگ‌ها معمولا در معرض شرایط یخبندان – ذوب و یا گرمایش- سرمایش قرار می‌گیرند، بنابراین ضروری است که تاثیر این فرایندها بر روی خواص فیزیکی و مکانیکی سنگ از جمله نفوذپذیری بررسی شود. در این تحقیق از نمونه‌های ماسه سنگ سازند منطقه لوشان برای مطالعه استفاده شد و تاثیر تعداد سیکل های انجماد- ذوب و دما در فرآیند گرمایش- سرمایش روی نفوذپذیری ماسه سنگ مورد بررسی قرار گرفت. برای بررسی اثر تعداد سیکل‌ها آزمایش‌ها روی نمونه‌هایی که 1، 5، 10 و 20 سیکل انجماد- ذوب را تحمل کرده‌اند انجام شد. برای بررسی اثر گرمایش – سرمایش آزمایش ها بر روی نمونه‌هایی که یک سیکل گرمایش- سرمایش را تحمل کرده‌اند و در مرحله گرمایش دمای 60، 100، 200 ، 400، 600، 800 و 1000 درجه سانتیگراد را تحمل کرده‌اند و در محیط سرد شده‌اند انجام شده است. نتایج به دست آمده حاکی از آن است که با افزایش تعداد سیکل های انجماد- ذوب میزان نفوذپذیری بعد از یک سیکل کاهش پیدا کرد و این کاهش تا 5 سیکل ادامه می‌یابد، هر چند کاهش نفوذپذیری از 1 سیکل تا 5 سیکل بسیار ناچیز است. در 10 سیکل نفوذپذیری اندکی افزایش می‌یابد و در 20 سیکل این افزایش چشمگیر است. همچنین با افزایش دما در مرحله گرمایش در فرآیند گرمایش – سرمایش نفوذپذیری ماسه سنگ تا 100 درجه سانتیگراد کاهش و سپس افزایش می‌یابد. تغییرات نفوذپذیری در فرآیند گرمایش – سرمایش با تغییرات سرعت امواج طولی، وزن مخصوص خشک و تخلخل موثر تطابق دارد. مقدار سی تی محاسبه شده از تصاویر سی تی اسکن نیز تغییرات نفوذپذیری را تایید می‌کند.

کلیدواژه‌ها

موضوعات

مکانیک سنگ

عنوان مقاله [English]

Effect Of Freeze-Thaw And Heating-Cooling Processes On Permeability Of: Lushan Sandstone

نویسندگان [English]

M. Hosseini ¹
D. Fakhri ²

¹ Associate Professor, Dept. of Mining Engineering, Imam Khomeini International university, Qazvin

² B.Sc Student, Dept. of Mining Engineering, Imam Khomeini International university, Qazvin

چکیده [English]

Rocks are usually exposed to freeze-thaw and/or heating-cooling conditions in many environments. In cold regions, rocks are affected by long-time freeze and several freeze-thaw cycles. In addition, rocks are exposed to significant heat in some cases, such as explosions and fires; they are then cooled down due to fire extinguishing or cold ventilation and a heating-cooling- process occurs. Therefore, it is necessary to investigate the effects of these processes on the physical and mechanical properties of rocks, including permeability. In this research, sandstone specimens of Lushan area were applied to investigate the impact of number of freeze-thaw cycles and the effect of temperature in the heating-cooling process on sandstone permeability. The freezing temperature of -16°C was considered to study the effect of number of cycles. In this state, the tests were carried out on the specimens withstood 1, 5, 10, and 20 freeze-thaw cycles. To study the effect of heating-cooling, the tests were conducted on the specimens that withstood one heating-cooling cycle. The specimens withstood temperatures of 60, 100, 200, 400, 600, 800, and 1000 °C at the heating process and then cooled in the laboratory environment. Results indicated that permeability rate was reduced after one cycle of freeze-thaw cycles the reduction continued to 5 cycles; although, permeability reduction was negligible from cycle 1 to cycle 5. Permeability increased slightly in 10 cycles and the increase was significant in 20 cycles. Sandstone permeability was reduced up to 100 °C and then was increased with the temperature increasing at the heating-cooling process. Permeability changes in the heating-cooling process were consistent with the variations of velocity of longitudinal waves, dry unit weight, and effective porosity. CT scan images were used to examine permeability changes in the heating-cooling process and the CT value calculated by the images confirms the permeability variations.

کلیدواژه‌ها [English]

Sandstone
Permeability
Freeze-thaw process
Heating-cooling process
Rock

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