تأثیر تغییر مشخصات مایع روزنه‌ای بر خصوصیات فیزیکی و ریز‌ساختاری بنتونیت

اوحدی, وحیدرضا; گودرزی, امیررضا

تأثیر تغییر مشخصات مایع روزنه‌ای بر خصوصیات فیزیکی و ریز‌ساختاری بنتونیت

نویسندگان

دانشگاه بوعلی سینا

چکیده

هدف اصلی این پژوهش، با توجه به اهمیت مشخصات ریزساختاری کانی‌شناختی و زیربافت در رفتار مهندسی خاک‌های ریزدانه، بررسی تأثیر خصوصیات شیمیائی مایع روزنه‌ای خاک‌های رسی بر تغییر ریزساختار آن است. بدین منظور نخست با استفاده از مخلوط خاک بنتونیت و نمک‌های سدیم با منشأ آنیونی متفاوت، مجموعه‌ای از نمونه‌های مصنوعی خاک- الکترولیت به نسبت 1:50 تهیه و سپس با آزمایشهای فیزیکی و آزمایشهای SEM و XRD تغییر رفتار خاک بررسی می‌شود.

نتایج آزمایشهای فیزیکی نشان می‌دهد که، با افزایش غلظت الکترولیت، رفتار خاک از نظر تمایل به برهم‌کنش با آب کاملاً تغییر می‌کند. نتایج تصاویر SEM نیز نشان می‌دهد که با حضور کاتیون سدیم و در غلظت‌های کم نمک، نخست ساختار خاک حالت پراکنده و با افزایش بیشتر غلظت نمک به لخته تبدیل می‌شود که ناشی از غلبه نیروهای جاذبه بر نیروهای دافعه بین سطوح رسی است. همچنین با تغییر مایع روزنه‌ای بنتونیت، تغییرات عمده‌ای در موقعیت و شدت قله پراش پرتو X ایجاد می‌شود. بر این اساس، تغییرات ایجاد شده در رفتار مکانیکی را می‌توان به تغییر نیروهای بین سطوح ذرات رسی در مقیاس ریز ساختاری نسبت داد.

کلیدواژه‌ها

عنوان مقاله [English]

The effect of Variations in Pore Fluid Properties on the Physical and Micro-structural Characteristics of Bentonite

چکیده [English]

Considering the importance of micro-structural characteristics of clayey soils on their behavior, the main objective of this research is to investigate the effect of pore fluid properties variations on clayey soils and their physical and micro-structural changes. For experimental purposes, soil-electrolyte solutions with the ratio of 1:50 prepared. A series of physical experiments, as well as, SEM and XRD experiments performed to investigate any variation on the soil behavior due to the changes in pore fluid properties. The results of the physical experiments indicate that, with increasing the electrolyte concentration, one will be faced with a change on the soil behavior including its interaction with water. The SEM pictures indicate that with the presence of sodium ions at low concentration, first soil takes a dispersive structure. With a further increase in salt concentration, and due to an increase in attractive forces in comparison with repulsive forces within clay particles, a flocculated structure forms. In addition to the above, during this process, a change will happen on the intensity and basal spacing of clay mineral. It is concluded that the main reason for a noticeable change in physical behavior of soil can be attributed mainly to the significant change in electrostatic forces of clay particles.

کلیدواژه‌ها [English]

Micro-structural characteristics
Bentonite
Pore fluid
SEM
XRD

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