زمین شناسی مهندسی

زمین شناسی مهندسی

ویژگی های مهندسی لس سیلتی آلوده به نمک های طبیعی

نویسنده
گروه مهندسی عمران
چکیده
بخش قابل توجهی از استان گلستان را خاک‌های لس پوشانده است که بیشتر آن‌ها از نوع لس سیلتی بوده، که یکی از مشکل‌سازترین خاک‌ها است. همجواری با دریای خزر منجر به شوری آب های زیرزمینی در برخی از مناطق استان می شود. به دلیل تبخیر زیاد، نمک ها به سطح زمین می رسند و باعث شور شدن خاک های لس سیلتی می شوند. وجود نمک های محلول می تواند منجر به تغییراتی در خواص مهندسی خاک های لس سیلتی در محل پروژه های عمرانی شود. بنابراین بررسی تأثیر نمک ها بر خواص ژئوتکنیکی خاک های لس سیلتی ضروری است. هدف از این مطالعه بررسی اثر نمک‌های کلرید سدیم یا هالیت (NaCl) و سولفات کلسیم یا نمک‌ گچ (CaSO4.2H2O) به عنوان دو نمک طبیعی فراوان، بر خواص مهندسی خاک‌های لس سیلتی می باشد. برای این منظور نمونه‌های خاک لس سیلتی از شهرستان مراوه تپه استان گلستان جمع‌آوری شد. سپس آزمایش‌های ژئوتکنیکی شامل مقاومت فشاری تک محوری، مقاومت برشی و آزمون‌های تراکم استاندارد بر روی نمونه‌های خاک در حالت طبیعی و با 3، 5، 7 و 9 درصد NaCl و CaSO4.2H2O انجام شد. بر اساس این آزمایش‌ها، تغییرات رطوبت بهینه، حداکثر چگالی خشک، مقاومت فشاری تک محوری، چسبندگی و زاویه اصطکاک داخلی مورد ارزیابی قرار گرفت. نتایج نشان داد که این پارامترها با افزایش غلظت هر دو نمک مورد مطالعه افزایش یافت. در نهایت در این مقاله علت تغییرات خواص مهندسی نمونه‌های خاک به دلیل وجود این دو نمک طبیعی مورد بحث قرار گرفته است.

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