ارزیابی عددی اثر دما در مقاومت سطح مشترک با رویکرد شمع های حرارتی

انرژی زمین‌گرمایی یکی از منابع نامحدود انرژی در سطح جهان است. یکی از راه‌های برداشت انرژی مذکور، استفاده از شمع‌های حرارتی است که علاوه بر انتقال بار سازه‌ی بالایی، وظیفه‌ی انتقال حرارت بین زمین و ساختمان را دارند. از این رو توده‌ی خاک و شمع متحمل بارهای حرارتی می‌شوند که می‌توانند مشخصه‌های مکانیکی و مقاومتی سطح مشترک خاک و شمع را تحت تاثیر قرار دهند. به همین منظور، برای بررسی تاثیر دما در مقاومت سطح مشترک خاک و شمع، مجموعه‌ی آزمایش‌های برش مستقیم به‌صورت تحلیل همبسته‌ی ترموهیدرومکانیکی، برای اولین بار در نرم‌افزار المان محدود آباکوس بررسی شده است. در مدل‌سازی انجام شده، تغییرات مقاومت برشی سطح مشترک خاک رس ایلیت و بتن تحت تاثیر بار مکانیکی و ترمومکانیکی بررسی شده است. اصلی‌ترین نتیجه‌ی پژوهش حاضر نشان می‌دهد که با افزایش دما به میزان 50 درجه‌ی سانتی‌گراد، مقاومت سطح مشترک خاک و شمع به طور متوسط به اندازه‌ی 20 کیلوپاسکال افزایش می‌یابد.

Numerical Investigation of Temperature Effect on Interface Strength in Energy Piles

Due to the growth of energy consumption, air pollution and global warming in the world, the use of renewable energy has become popular in the world due to its variety of resources, lower economic cost and environmental compatibility. One of the unlimited sources of renewable energy, is geothermal energy. Since geothermal energy resources are unlimited and can be exploit in many parts of the world, its application as a reliable source of energy is growing. The use of energy piles as a heat exchanger is one way to exploit this energy. These piles are being used to serve dual purposes: transfer the structural load to the ground and act as heat exchanger elements to extract and inject heat from and to the ground. Energy piles are subjected to daily and seasonal cyclic temperature changes during their life span. These temperature changes (heat cycle) induce cyclic expansioncontraction along the pilesoil interface that may affect interface properties such as shear strength. The pilesoil interface is defined as a thin zone of soil that can be subjected to different boundary conditions with respect to the surrounding soil. Therefore, in order to investigate the influences of temperature on soilpile interface, a series of direct shear tests is modeled in ABAQUS software. In this modeling the shear strength changes of Illite clay and concrete interface, are investigated under mechanical and thermomechanical loading. A series of analysis are conducted with sample temperature of 50 and the normal stresses of the direct shear analysis are 50, 100 and 150 kPa. This analysis is done at a shearing rate of 0.006 mm/min. In this investigation, it is assumed that the properties of concrete materials are not temperature dependent and their behavior is thermoelastic. In this paper, the main results of modeling show that the shear strength of Illite clayconcrete interface, increases by an average of 20 kPa with increasing in temperature by 50 .