مشخصات مکانیکی نمونه‌های خاک-سیمان با ساختار پایه ماسه‌ای و دوغاب ساخته‌شده با آب دریا در شرایط محیطی دریایی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران دانشگاه قم

2 مهندسی عمران، دانشگاه قم

3 استادیار گروه عمران، دانشگاه قم، قم، ایران

چکیده

اجرای ستون­‌های خاک-سیمان با استفاده از روش‌­های اختلاط عمیق و تزریق پرفشار، راهکاری مؤثر جهت مقابله با مشکلات ناشی از مقاومت کم خاک­‌های مسئله‌دار ساحلی است. آنچه در اجرایی این ستون­‌ها در جامعه مهندسی متداول است، الزام استفاده از آب شیرین در ساخت دوغاب مورد استفاده در این ستون­‌ها است. این موضوع هم از منظر محل تأمین و هزینه‌های حمل آن و هم از منظر نبود آب شیرین در بسیاری از نواحی، سبب تحمیل هزینه­‌های زیاد به پروژه­‌ها و تاخیرات زمانی اجرای آن‌ها می­‌گردد. این در حالی است که قبل از گیرش نهایی سیمان، آب‌ شور موجود در محیط اجرای ستون­‌ها با آب شیرین موجود در دوغاب حین ساخت آن‌ها در اعماق خاک آمیخته می­‌گردد. بررسی امکان‌­پذیری استفاده از آب‌ شور در طرح اختلاط این ستون‌­ها و ارزیابی رفتار نمونه­‌های خاک- سیمان در شرایط دریایی کمتر مورد توجه محققین قرار گرفته است. در این تحقیق سعی شده است عوامل مؤثر در طرح اختلاط دوغاب شامل میزان شوری آب مصرفی، درصد سیمان، نسبت آب ­به ­سیمان و زمان عمل­‌آوری بر مقاومت فشاری تک­‌محوری و کششی ماسه-سیمان بررسی شود. همچنین با استفاده از تصاویر میکروسکوپ الکترونی روبشی (SEM) به­ صورت ریزساختاری رفتار نمونه­‌ها ارزیابی‌ شده است. نتایج نشان می‌­دهد در بازه سیمان مصرفی 15 تا 25 درصد وزن ماسه خشک، استفاده از آب‌ شور در ساخت دوغاب، سبب کاهش مقاومت نمونه‌­های ماسه-سیمان در شرایط محیطی دریایی نمی­‌شود. بازه مقاومت فشاری حاصل‌شده برای نمونه‌­های ماسه-سیمان ساخته‌شده با آب دریا حدود (5/1 تا 6) مگاپاسکال و نسبت مقاومت کششی به فشاری این نمونه‌­ها در محدوده (15/0 تا 3/0) قرار دارد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effect of seawater in grout on the mechanical behavior of cement stabilized marine sand

نویسندگان [English]

  • mojgan geravand 1
  • hamed bayesteh 2
  • mahdi sharifi 3
1 Department of civil engineering, university of Qom
2 Department of civil engineering, university of Qom
3 Department of civil engineering, university of Qom
چکیده [English]

One of the challenges in the field of geotechnical engineering is the sustainable development of soil improvement methods in marine environments due to severe environmental conditions such as high salinity. Implementation of soil-cement columns using deep mixing method and jet-grouting methods is an effective way to deal with problems caused by low resistance of coastal problematic soils. What is common in the implementation of these columns in the engineering community is the need to use fresh water to make the grout used in these columns. This, both from the point of view of its supply and transportation costs and from the lack of fresh water in many areas, imposes high costs on projects and time delays. However, prior to the final cement retention, the saline water present in the environments of the columns was mixed with the fresh water in the grout as they were built deep in the soil. Investigating the feasibility of using seawater in mixing these columns and evaluating the behavior of soil-cement samples in marine conditions has received little attention. In this study, it has been attempted to investigate the effective factors in the grout mixing scheme, including water salinity, cement percentage, water-cement ratio and processing time on uniaxial compressive strength and sand-cement tensile strength. SEM images were also microstructurally evaluated for sample behavior. The results show that in the 15% to 25% cement content, the use of seawater in grout production does not decrease the strength of sand-cement samples in the marine environment. The obtained compressive strength range for sand-cement samples made with seawater is approximately (1.5 to 6) MPa and the tensile to compressive strength ratio of these samples is in the range (0.15 to 0.3).

کلیدواژه‌ها [English]

  • Soilcrete
  • seawater
  • marine sand
  • UCS
  • grout
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