تعیین محتوای آب لنز برای چند چیدمان مختلف از ذرات بیضوی در خاک‌های غیراشباع

نوع مقاله: پژوهشی

نویسنده

دانشکده علوم و فنون نوین دانشگاه تهران

چکیده

تا به امروز کلیه محاسبات مربوط به تعیین مقدار محتوای آب موجود در بین ذرات خاک در حالت غیراشباع براساس فرض دایروی بودن دانه­های جامد خاک انجام گرفته است و با استفاده از این فرض ساده کننده بسیاری از کمیت­های دیگر نظیر مکش ماتریسی و تنش مؤثر ناشی از کشش آب اطراف ذرات نیز مورد بررسی قرار گرفته­است. لکن در مقاله حاضر با فرض بیضوی بودن دانه­های خاک برای سه حالت مختلف از چیدمان ذرات بر روی هم، مقدار محتوای آب لنز به روش حجمی مورد محاسبه قرار گرفته است و نتایج بدست آمده با حالت کروی ذرات مقایسه شده است. همچنین با تغییر کمیت­هایی نظیر شعاع­های کوچک و بزرگ ذرات بیضوی، زاویه پرکنندگی، شعاع­های لنز آب و مکش ماتریسی مقدار محتوای آب موجود در بین ذرات مورد مطالعه قرار گرفته و منحنی مشخصه آب و خاک نیز در چندین حالت ترسیم شده است. نتایج نشان می‌دهد که با افزایش زاویه پرکنندگی محتوای حجمی لنز برای چینش افقی حدود 2 تا 5 برابر بیشتر از سایر حالات است، در حالیکه با تغییر نسبت شعاع لنز، این مقدار برای چیدمان قائم بیشتر می‌باشد. همچنین مکش ماتریسی برای ذرات بیضوی با شیب اندکی نسبت به تغییر محتوای حجمی مقدار خواهد یافت که این موضوع برای نسبت قطر دوبرابری، با مکشی 4 برابر بزرگتر بدست می‌آید.



 

کلیدواژه‌ها


عنوان مقاله [English]

Determination of the lens water content for several different configurations of elliptical particles in unsaturated soils

نویسنده [English]

  • Mohammad Hossein Jahangir
چکیده [English]

Until now, all of the calculations about determining of water content around the particles in unsaturated soil have done with supposing the spherical shape of particles and most of quantities such as matric suction and interparticle stress due to water meniscus were calculated by using that simple assumption.

In this paper, three packing methods of ellipsoidal particles are studied and by considering changes in meniscus geometry, matric suction and water content volume are evaluated as functions of meniscus radii for soil particles under the pore-water regime. This analysis provides a theoretical basis for describing several well-known phenomena in unsaturated soil behavior. A series of rigorous analytical equations was developed for describing the total volume of menisci between contacting ellipsoidal soil grains by treating the zero contact angle. Matric suction characteristic curves modeled using the analytical solutions displayed behavior similar to real unsaturated soils by using the ellipsoidal particles.

The results show that by increasing the filling angle, the volumetric water content of horizontal arrangement is about 2 to 5 times higher than other states, while by changing in the radius ratio of the lens, this amount is more for vertical alignment. So, the matric suction for elliptical particles is quantified with little inclination towards the water content change which achieved four times larger for double diameter ratio.

کلیدواژه‌ها [English]

  • Unsaturated soil
  • water content of lens
  • matric suction
  • filling angle
  • soil-water characteristic curve

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