Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : settlement

Settlement of Shallow Foundation in Dry Sand Under an Earthquake

Mohammed A. Al-Neami; Falah H. Rahil; Ahmed F. Hussain

Engineering and Technology Journal, 2021, Volume 39, Issue 8, Pages 1206-1215
DOI: 10.30684/etj.v39i8.527

Seismically induced settlement of buildings with shallow foundations resting on dry sand soils has resulted in severe damage in recent earthquakes. A multi-degree of freedom shaking table and a fixed container were manufactured and used to study the foundation settlement. Series of shaking experiments on the shallow foundation situated in a center of the container and atop of a dry sandy soil has been performed to identify the mechanisms involved to calculate the foundation settlement induced by earthquake shaking. In this research, the important factors are identified, including shaking intensity, the soil relative density, the degree of freedom and the building’s weight. Two relative densities (55 % and 80%) are used and three local magnitudes of earthquakes (5.8, 6.4, and 7.2) (Anza, Jalisco, and Guerrero) respectively with one and two degrees of freedom. The results of the shaking indicated that shallow foundation settlement on the dry sand increases with the increase of the local magnitude of earthquakes and maximum acceleration. In the case of Anza, the percentage decrease in the settlement between the relative density of 55% and 80% for systems (x and xy) is (47% and 42%) respectively. While in the case of Jalisco and Guerrero, the percentage decreases in their settlement and for the same systems is (11% and 57%), (36% and 36%) respectively. The degree of freedom has an impact on the foundation settlement; it is proportional to the degree of freedom. Also, the results show that the settlement decreases when the relative density of sand increases.

Studying The Settlement of Backfill Sandy Soil Behind Retaining Wall Under Dynamic Loads

Reham E. Hamdi; Mohamed Youssef Fattah; Mohammed F. Aswad

Engineering and Technology Journal, 2020, Volume 38, Issue 7, Pages 992-1000
DOI: 10.30684/etj.v38i7A.528

For a long time, the seismic examination of retaining walls has been contemplated by a few strategies dependent on the basic augmentation of Coulomb's limit equilibrium investigation. These techniques cannot gauge the removal of the refill soil upheld by the wall. A trial examination is completed to contemplate the vertical settlement on sandy soil under dynamic loads with other burden amplitudes, vibration frequencies, relative density, and various separations between the establishment and holding divider. The model balance utilized in this investigation is square. Dynamic burden test is done on cohesion less soil with three burden amplitudes (0.25 ton, 0.5 ton and 1 ton), three vibration recurrence (0.5 Hz, 1 Hz and 2 Hz), two density of sandy soil (30% loose sand and 70% dense sand) and three unique separations between the establishment and retaining wall. It has been seen that the change is increment with the burden of abundance and decreased by increasing the separation between the establishment and retaining wall. There is an unimportant result of recurrence on the aggregate settlement. The settlement decrement by incrementing the relative density.

Cyclic Settlement of Footings of Different Shapes Resting on Clayey Soil

Aseel N. Najim; Mohammed Y. Fattah; Makki K. Al-Recaby

Engineering and Technology Journal, 2020, Volume 38, Issue 3A, Pages 465-477
DOI: 10.30684/etj.v38i3A.483

An experimental investigation is carried out to investigate the impact of the footing shape, when rested on clayey soil under cyclic loading condition. The model footings used in this study are circular, square and the area of footings is fixed. Cyclic load test is carried out on the cohesive soil with three undrained shear strengths (20 kPa, 40 kPa and 70 kPa). Two depths of foundation embedment (at surface and 5 cm) to know the effect of the depths of the foundations on the change of settlement and total vertical stress and two rates of loading (3 mm/sec and 6 mm/sec) are used. It has been observed that the bearing capacity varies in increasing order as Solid, Circular and Square. It is found that the cyclic settlement in the square foundation is less than the circular foundation. The results reveal that the shape of the footing has a significant effect on its bearing capacity and the settlement characteristics. The vertical stress reaches a constant value which is greater below circular footing and it is about (70.9 - 92.7) % greater than below square footing.

Reducing Settlement of Soft Soils Using Local Materials

Mohammed A. Mahmoud Al-Neami

Engineering and Technology Journal, 2010, Volume 28, Issue 23, Pages 6649-6661

The present work investigates the settlement behaviour of weak soils which cover the middle and southern part of Iraq. Physical and chemical properties were studied for weak soil brought up from Baladroz city, Dyalah Governorate. To decrease the excessive settlement of soft soil under study, reed materials which are widespread at Iraq marshes and geogrid materials were selected as reinforcement materials. For this purpose, steel container with dimensions (500 ×250 ×20 mm)
and square footing (80 × 80 mm) were used.To prepare the soil with same
properties of soft soils, the quantity of water was calculated using the liquidity index formula with LI equal to (0.42) corresponding to undrained shear strength of (10 kPa). This value of liquidity index was chosen according to the previous studies which showed that the liquidity index of such soil is ranging between (0.2 – 0.5).
The results of soil model under the applied stress (5, 10, 15, 20, and 25 kPa) marked that the maximum settlement reduction (S/B) is get when the reed mat or geogrid mat is used directly under the footing and this value decreases with increase of the distance between the surface layer and position of the reinforcement. Also, the settlement improvement (St/Sunt) can be clearly seemed for all cases of improvement compared with settlement of untreated soil It is worth noting, that to achieve the durability of the reed in the soil, asphalt coating must be used to prevent the reed decay.