برآورد پارامترهای مقاومتی بستر نمکی تثبیت شده با سیمان و پسماند صنعتی با روش اجزای محدود

نوع مقاله : مقاله پژوهشی

نویسندگان

1 Payame Noor University

2 دانشکده مهندسی عمران، دانشگاه پیام نور، ص. پ. 3697-19395، تهران، ایران

3 دانشکده مهندسی عمران، دانشگاه پیام نور، ص. پ. 3697-19395، تهران، ایران،

چکیده

خاک­های نمکی یکی از انواع خاک‏های مسئله­دار هستند که در برابر پدیده­های انحلال و تورم بسیار آسیب­پذیر می­باشند. این نوع خاک در بسیاری از نقاط کشور ایران مشاهده شده و به عنوان بستر راه­ها مورد استفاده قرار گرفته است. برای بهبود خصوصیات مقاومتی بسترهای نمکی، معمولاً از روش‏های گوناگون اعم از تثبیت شیمیایی استفاده می‏شود و خصوصیات ژئوتکنیک بسترهای نمکی تثبیت­شده، با آزمایش‏های صحرایی و آزمایشگاهی ارزیابی می­گردد. اما، برآورد بعضی پارامترهای اصلی مورد نیاز برای طراحی راه، مانند ضریب برجهندگی، منوط به استفاده از آزمایش‏های سه­محوری سیکلی است که نیاز به صرف هزینه و زمان قابل توجه دارد. هدف این تحقیق، بررسی اثر بارهای رفت و برگشتی ترافیکی بر مصالح بستر نمکی تثبیت­شده با سیمان و پسماند کربناته، با مدل‏سازی پارامتر ضریب برجهندگی در محیط اجزای محدود، می‏باشد. خاک نمکی پایه این تحقیق، با درصدهای مختلف سیمان پرتلند تیپ 2 و یک نوع پسماند کربناته، بدون عمل‏آوری و یا عمل‏آوری شده با دو روش مختلف تثبیت تهیه شده و آزمایش‏های مقاومتی مانند برش مستقیم، مقاومت فشاری تک‏محوری محدود نشده و نسبت باربری کالیفرنیا (CBR) روی نمونه‏ها انجام شده است. پارامترهای مقاومت برشی حاصل شده، در مدل‏سازی پارامتر ضریب برجهندگی مورد استفاده قرار گرفت. با توجه به ماهیت بارگذاری ترافیکی و نوع آزمون، پس از بررسی مدل‏های رفتاری گوناگون، مدل رفتاری خاک سخت­شونده کرنش کوچک برای این تحلیل برگزیده شد. پس از انجام مراحل مدل‏سازی، شامل تعیین مقادیر پارامترهای مدل و توسعه (ساخت) و اجرای مدل، تحلیل نتایج نشان داد که پارامتر ضریب برجهندگی، با مجموع تنش‏های اصلی محوری و محدودکننده رابطه نمایی دارد. وابستگی ضرایب مدل نیز با استفاده از تحلیل‏های رگرسیونی چندمتغیره تعیین و ارائه گردید. همچنین، رابطه همبستگی ضریب برجهندگی و نسبت باربری کالیفرنیا ارائه شد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Estimation of Strength Parameters of Saline Subgrade Stabilized by Cement and Industrial Waste Using Finite Element Method

نویسندگان [English]

  • Amin Falamaki 1
  • MahmoudReza Keymanesh 2
  • Hadi Ghodrat 3
1 Department of Civil Engineering, Payame Noor University (PNU), P.O. Box 19395-3697, Tehran, Iran
2 Department of Civil Engineering, Payame Noor University (PNU), P.O. Box 19395-3697, Tehran, Iran
3 Department of Civil Engineering, Payame Noor University (PNU), P.O. Box 19395-3697, Tehran, Iran
چکیده [English]

Saline soils are one of the types of problematic soils which are very vulnerable to dissolution and swelling phenomena. This type of soil has been observed in many parts of Iran and has been used as road subgrade. To enhance the resistance properties of salt beds, various methods are usually used, including chemical stabilization, and the geotechnical properties of stabilized salt beds are evaluated with field and laboratory tests. However, estimation of some main parametersو required for road design, such as modulus of resilience, is dependent on the use of three-dimensional cyclic tests, which requires spending considerable time and cost. This article’s aim is to investigate the traffic loads effect on saline soil subgrade stabilized with cement and carbonated waste, by modeling the modulus of resilience parameter via finite elements method. The natural saline soil of this research was stabilized with different percentages of type 2 Portland cement and a type of carbonated waste, without treatment or treated with two different stabilization methods. Then, several resistance tests such as direct shear test, unconfined uniaxial compressive strength and California bearing ratio (CBR) were done on the samples. The obtained shear strength parameters were used in the modeling of the modulus of resilience. Considering the inherence of traffic loading and the type of test, after examining various soil constitutive models, the small strain hardening soil constitutive model was chosen for this analysis. After performing the modeling steps, including determining the model parameters, developing and running the model, analysis of the results showed that modulus of resilience has exponential relationship with the sum of the main axial and confining stresses. The model coefficients’ relationship was determined and shown using multiple regression analyses. Also, the correlation between modulus of resilience and California bearing ration (CBR) are presented.

کلیدواژه‌ها [English]

  • Saline subgrade
  • Stabilization
  • Industrial waste
  • Modulus of resilience
  • Finite element method
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