The effect of Cyclic loading on the foundation behaviour of many engineering structures presents more important and related to many problems in geotechnical engineering, Especially when construction on soft ground area which represent one of the major concerns in geotechnical engineering. This paper is conducted to investigate the influence of using several improving techniques as (fly ash, Geo-grid, fly ash and Geo-grid) on the behavior of soft clayey soil subjected to cyclic loading. A total of twenty four models have been tested  which consists of a wide domain of boundary conditions, such as untreated model, Geo-grid reinforced models, fly ash treated models and models treated with fly ash incorporated with Geo-grid were conducted by varying parameters such as, footing elevations, test velocity and number of geogrid layers. The analysis demonstrates that the settlement behaviour of footing resting on treated models with fly ash and two Geo-grid layers perform better than other improving techniques.  Also observed there was an increase in settlement, which corresponds to the increase in test velocity from 6 to 9 mm/sec. Furthermore, it was conducted that the more depth of footing the soil settlement decreases. In general, when other factors remaining constant, the bearing capacity of soil goes on increasing when the depth increased.

/pdf/behaviour-of-soft-clayey-soil-improved-by-fly-ash-and-5by7wgji5g.pdf

Behaviour of Soft Clayey Soil Improved by Fly Ash and Geogrid under Cyclic Loading

يتم إجراء تحقيق تجريبي لدراسة تأثير شكل الاساس ، عندما تقع على تربة طينية تحت ظروف التحميل الدورية. النموذج المستخدم في هذه الدراسة لاساسين دائري ومربع. يتم إجراء اختبار الحمل الدوري على التربة المتماسكة بثلاث  قوة قص غير منفذة (20 كيلو باسكال و 40 كيلو باسكال و 70 كيلو باسكال). يستخدم عمقين للاساس (عند السطح و 5 سم) وثلاثة سرع مختلفة (3 مم / ثانية ، 6 ملم / ثانية و 9 ملم / ثانية). لقد لوحظ أن قدرة التحمل تختلف فيترتيب متزايد مثل دائري صلب ومربع. لقد وجد أن الهطول الدورية فيالاساس الدائري أعلى من الاساس المربع. أظهرت النتائج أن شكل الاساس له تأثير كبير على قدرته على التحمل وخصائص الهطول. يصل الضغط العمدي للتربة إلى قيمة ثابتة أكبر من الاساس الدائري وهي أكبر بحوالي (70.9 - 92.7)٪ أكبر من الاساس المربع.

/pdf/cyclic-settlement-of-footings-of-different-shapes-resting-on-1y735abmxv.pdf

Cyclic Settlement of Footings of Different Shapes Resting on Clayey Soil

Fuel tank footings are usually subjected to cyclic loads caused by filling and emptying of these tanks. In addition, in a multitude of geotechnical applications, soils are subjected to cyclic loading. Besides vehicle and traffic loads, cyclic loads also play an important role in pile driving processes and during the dimensioning of foundations for offshore wind craft plants. Research on the cyclic vertical loading problem for sand is particularly scarce, and most has been in commercial confidence. This paper is conducted to study the experimental behavior of dry sandy soil under foundations subjected to vertical cyclic compression load. A total of sixty-three models have been tested to study the behavior of shallow footings under cyclic load of different rates. A new compression machine was manufactured to apply both monotonic and cyclic loading. Three relative densities of sand, two footing shapes, three depths of foundation embedment, and three rates of loading were tried. It was concluded that with more depth of the footing (Df increasing), the soil settlement decreases. In general, when other factors are remaining constant, the bearing capacity of the soil goes on increasing when the depth or width of the foundation increases. The total settlement of a footing continues to increase during the time of the load and reaches a maximum value at the end of dwell time. During the decay period of the load, the footing rebounds to some degree.

Effect of Embedment Depth on Cyclic Behavior of Tank Footings on Dry Sand

This paper focuses on the response of circular machine foundation resting on different soils (sand and clay) through studying the variation of soil shear strength parameters and strain with the number of cycles. The objective of the current study is to explore the results related to the parameters of the dynamic load (number of loading cycles and frequency of load) related to the circular footing of a machine on the dynamic shear strength parameters (for sand soil (ϕ˚dyn) and for clay soil (Cudyn)) in addition to the amplitude strain foundation. A special setup was designed and manufactured to simulate the vertical vibration of a circular machine foundation. A steel circular machine foundation with a diameter of 150 mm was used to represent the footing. A total of 6 cases were examined to take into account the effects of different parameters including different frequencies (0.5, 1, and 2 Hz); state of sand (medium and dense) which corresponded to relative densities of (50 and 80%), while the state of clay (medium and stiff) corresponded to undrained shear strengths (50 and 70 kPa).  All tests were carried out under load amplitude of 2.5 kN. It was found that the rate of increase in shear strength parameters for the soil under a circular machine foundation decreases remarkably when increasing the frequency for both types of soil under the footing. While little change in the shear strength parameters, or even no change was observed under the effect of other locations. Moreover, the amplitude strain decreased when increasing the frequency for both types of soil.

https://www.ije.ir/article_108491_abe3bdaf5a3f4dfdb7223d1a6b12ce6c.pdf

Assessment of Changes in Shear Strength Parameters for Soils below Circular Machine Foundation

Vibrating Behavior of Foundations Resting on Salt-Encrusted Flat (Sabkha) Soil Improved Using Cement

Research on the cyclic vertical loading problem for sand is particularly scarce, and most has been in commercial confidence. This research is conducted to study the experimental behavior of dry sandy soil under foundations subjected to vertical cyclic compression load. A total of sixty three models have been tested to study the behavior of shallow footings under cyclic load of different rates. A new compression machine was manufactured to apply both monotonic and cyclic loading. Three relative densities of sand, two footing shapes, three depths of foundation embedment and three rates of loading were tried. It was concluded that the more the depth of footing (Df increasing), the soil settlement decreases. In general, when other factors are remaining constant, the bearing capacity of the soil goes on increasing when the depth or width of the foundation increases. The total settlement of a footing continues to increase during the time of the load and reaches a maximum value at the end of dwell time. During the decay period of the load, the footing rebounds to some degree. The effect of loading rate depends on the density of sand bed. In loose sand, the cyclic load settlement increases with the rate of loading, while in dense sand, the cyclic load settlement decreases with rate of loading.

/pdf/cyclic-behavior-of-footings-on-dry-sand-under-different-3hktxknqbw.pdf

Hiba H. Al-Qazzaz

Papers

Cyclic Behavior of Footings on Dry Sand under Different Rates of Loading

Effect of Embedment Depth on Cyclic Behavior of Tank Footings on Dry Sand