In this thesis, the dynamic response of single pile with a static load is studied under the dynamic load that were generated by use of an electric rotary motor with eccentric loading installed above cap pile, the tests are performed under dry and soaked states. . Many parameters are taken into consideration, including slenderness ratio (L/D) 12, 17, 22, 27 for solid steel pile with frequency 10 Hz and gypsum content 30%, different frequencies 10, 15, 20, 25 for solid steel pile with (L/D) 27, gypsum content 65% for solid steel pile, also (L/D) 27 and frequency 10 Hz, types of pile (concrete pile, hollow steel pile, rough steel pile, timber pile) with (L/D) 27 and frequency 10 Hz in all tests. . . The results of the tests showed that the velocity of vibration, acceleration of pile, displacement amplitude and settlement decrease with an increase in slenderness ratio and decrease in soaked soil compared to the corresponding values in dry soil where velocity decreased when increasing the slenderness ratio from 12 to 27 in the dry and soaked states by 78.2% and 77.2% respectively. Acceleration decreased by 84% and 80%, respectively, while the displacement amplitude decreased by 66.67% and 61.4%, respectively. As well, settlement decreased by 31.25%. . II The tests also showed that the velocity of vibration, acceleration, displacement amplitude of the solid steel pile with L/D 27 constant in all tests increased with increasing the frequency of the vibration source as the velocity decreased when the frequency is reduced from 25 to 10 Hz in the dry and soaked condition by 98% and 97.8% respectively, acceleration decreased by 98% and 97.8% respectively. While the displacement amplitude decreased by 84.7% and 80% respectively and the settlement is decreased by 31.25%. . . In addition, the results of tests showed that the displacement amplitude, velocity of vibration and acceleration increased with an increase in the gypsum content in soil, as the velocity decreased when decreasing the gypsum content from 65% to 30% in the dry and soaked states by 58.85% and 50% respectively. Acceleration decreased by 29.4% and 20%, respectively. While the displacement amplitude decreased by 20% and 30.5%, respectively and settlement decreased by 12%. . The results also showed that the velocity of vibration, acceleration and displacement amplitude are differed according to the type of pile. The dynamic response showed that an increase in timber pile compared to other type due to low hardness, while the settlement is less than in other piles as a result of friction between pile and soil.

Abstract

ABSTRACT The Screw piles are one of the best solution used in various engineering applications, which have relatively low capacity foundations offering stability against compression, overturning moment, uplift tension, and horizontal loads. This study presents a series of(42) practical model tests of practical to evaluate the behavior of the single screw pile and a group of screw piles that were placed in two shapes: square and triangle implanted in soft clay soil underneath a layer of sand under the influence of the compressive load. The effect of a number of factors was taken, including, the length of the screw pile (250, 320 and 390mm), the number of helix plates (single and double), in addition to that three different pile spacing were taken (1.5Dh, 3.5Dh and 4.5Dh) where Dh represents the diameter of helix plate. These factors used to both square and triangle shapes. The results of this study showed that the increase in bearing capacity for a group of screw piles under compressive load reached (34-49.6) times for the square pattern and (36-76) times for the triangular pattern when increasing L D ratio from (25 to 39), the number of helix that give the most ductility withstand pressure forces. Also, the results showed that the spacing between piles embedded in soft clay soil only, (L D=25 by1.5Dh) was more efficient to resist the forces of compressive loads of the square and triangular pattern, while pile spacing extended to the sandy soil II (L D=32 and 39 by 3Dh) was more efficient for square pattern, 1.5Dh pile spacing was more efficient for the triangle pattern. In addition, the settlement of screw piles group decreases by (25% -71%) with increasing of pile spacing to minimum value at 3Dh for the square pattern and decreases by (12% -30.7%) with the decrease of pile spacing, to minimum value at (1.5Dh) pile spacing for the triangular pattern. In general, the screw piles group are considered one of a best solution to carry compressive loads of different structures constructed on multi layers of weak soil and dense sand.