In projects that involve surcharge and prefabricated vertical drains (PVDs) systems for the treatment of weak underlying layers, embankment failures, tension cracks, and differential settlements, surficial heaves, and foundation failures were addressed in various literature. Overestimation and unrealistic design assumptions made by geotechnical and structural engineers are the main reasons for most of the cases. In all these cases a simple collaboration between different parties in the project ranging from designers to field engineers could have decreased or prevented these undesirable outcomes. The problem of neglecting the infiltration of the embankment in the ground as a new distinct layer with all the necessary requirements, and also disturbance caused as a result of PVDs installation in four cases: preloading case, fill removal, main structure construction, and post- construction phase are discussed. A few design recommendations are given regarding the stated issues. Since after the completion of soil treatment operations, the soil engineering parameters and in some cases even soil stratification had changed, care should be taken to use the new treated parameters in the final design process, not the preliminary site report parameters. Neglecting this issue may lead to severe malfunctions and even unpredictable failures. BIM technology has the possibility of integrating all aspects, and complexities of geotechnical engineering in the structural-architectural platform as a whole, which would revolutionize the construction industry. Till now only the structural-architectural part is done and further research and investment are necessary for the geotechnical aspect. تفاصيل المقالة

Marls are among the problematic soils that threaten developmental projects. As moisture increases, the resistance of these types of soil decreases and their deformability increases. During an earthquake, its parameters and properties are likely to alter. The effect of moist Marl quality is considerable on both static behavior and dynamic properties of soil. These parameters include shear and pressure wave velocity, natural frequency, shear modulus, and damping ratio. The mechanical properties of soil might be specified through both laboratory experiments and field experiments. This research study was carried out on Marls of the north of Shiraz city to identify their dynamic behavior. To achieve this, in addition to field and laboratory static tests, cyclic triaxial test was also done on the samples. The obtained results revealed that in these Marly Soils, as the confined pressure increased (increase in soil depth), the shear modulus also increased. It was also understood that the damping ratio behaved slightly different for less than 1% and more than 1% strains. However, in general, for strains more than 1%, increasing confined pressure led to reduction of damping ratio. The study also showed that as the percentage of moisture increased, the shear and compression resistance decreased which, in turn, led to an increase of soil consolidation. Comparing the static and dynamic behavior of soil indicates that the cyclic shear modulus in 100 kPa stresses and 1% strain is roughly 60%; and in 10% strain, it is less than static modulus by almost 48%. This difference reduces as the enclosing pressure increases. تفاصيل المقالة

با گسترش روزافزون شهرها و مناطق صنعتی نیاز به زمین های جدید جهت ساخت و ساز به امری اجتناب ناپذیر تبدیل گردیده است. عمده این زمین ها معمولا در مناطقی واقع شده اند که قبلا به خاطر وجود خاک های سست امکان ساخت و ساز در آن ها وجود نداشت. یک از روش های معمول جهت بهسازی خاک در این مناطق در صورت وجود لایه های نرم رسی، استفاده از خاکریز با یا بدون زهکش های عمودی و پیش بار گذاری خلاء می باشد. در این تحقیق ابتدا خلاصه ای از روش پیش بارگذاری با استفاده از بار سربار و خلاء و زهکش های عمودی عنوان گردیده و سپس یک مطالعه موردی که شامل پیش بار گذاری به وسیله خلاء و بدون استفاده از بار سربار است به صورت عددی توسط نرم افزار اجزای محدود بررسی گردیده است. نتایج بدست آمده نشان می دهد که در صورت وجود شرایط ژئوتکنیکی مناسب، استفاده از پیش بار گذاری خلاء به تنهایی نیز می تواند نتایج مطلوبی را از خود نشان دهد. استفاده از این روش در مناطقی که دسترسی به خاک مناسب جهت احداث خاکریز ممکن نبوده و یا به خاطر سازه ها و تاسیسات زیربنایی در مجاورت منطقه مورد بهسازی امکان احداث خاکریز ممکن نیست، می تواند گزینه بسیار مناسبی جهت بهسازی لایه ضعیف رس در آن منطقه باشد. نتایج این تحقیق می تواند مورد استفاده شرکت های و افراد فعال در زمینه بهسازی خاک های سست به خصوص در مناطق ساحلی قرار گیرد. تفاصيل المقالة