Response of Passive Footing on Gypseous Sandy Soil to the Dynamic Loading on Nearby Footing

Abstract

Abstract In this thesis, the dynamic-vibration response of a single footing resulting from a nearby-close footing is investigated. The source of vibration which is called in this study the (active footing) is generated by applying an electric-rotary motor with eccentric loading on a square footing with dimensions of (100x100) mm, and it is considered are the source footing. Near the source footing another footing is placed, which is called (passive footing on which the vibration effects are to be investigated. Both footings are placed over gypseous soil. Two types of passive footings are investigated, a square of dimensions (80x80) mm and a rectangular with (160x40) mm. Tests are performed under dry and soaking conditions. The passive footing is with constant static weight, while the other footing (source of vibration) is with its self-weight. The experimental work is carried out taking the following parameters into observance: shape of foundation (L/B =1, L/B =4), the spacing between the active footing (source of vibrations) and the passive footing (with static load), and operating frequency of the mechanical oscillator. All these tests are conducted on gypseous sandy soil which contain gypsum contents with 60%. Forty-eight tests are performed. Half of them are carried out for square shape foundation, and the other half for rectangular foundation, under three operating frequencies namely, 10, 20, and 30 Hz. The spacing(S) between the two footings as follows: (S=1B, S=2B, S=3B, S=4B) for square shape footing and (S=2B, S=4B, S=6B, S=8B) for rectangular shape footing. II The reduction in displacement amplitude of square footing when the spacing between the two footings increased from 1B to 4B at frequencies of 10, 20, 30 Hz was (56.9 %, 37.3%, and 26.4%) at dry state and (72.54%, 27.5%, and 54.78%) at soaking state. For rectangular footing, the reduction was (53.03%, 38.8 % and 17.9%) at dry conditions and (55.5%, 50.72% and 37.6%) at soaked state, when the spacing between the two footings increased from 2B to 8B. The settlement