The geologic setting and physical and dynamic properties of foundation beds are playing a crucial role in the stability of building, especially in case of the subjection of building to dynamic forces associated with the earthquake occurrence. The present work is concerned with the application of shallow geophysical investigations to delineate the shallow subsurface geologic characteristics and determine the physical and dynamic properties of foundation beds in New Cairo city. The electric resistivity survey was applied by using Schlumberger array to identify the resistivity and thickness of the different shallow layers. The shallow seismic refraction technique was also used to evaluate the foundation rock properties in the area by recording the time arrivals of seismic waves and their interpretation in terms of subsurface geoseismic layers and their physical and dynamic properties.
The shallow section of New Cairo city, could be divided into four types of lithologic units; sandy soil (a resistivity from 15 to 100 Ohm-m and thickness from 0.6 to 36m), gravely soil (sand and gravel with a resistivity from 100 to 500 Ohm-m and thickness from 0.7 to 37m), clayey soil (silty clay of less than 15 Ohm-m and thickness is varying from 0.7 to 25m) and rocky soil (sandstone, sandy limestone and weathered basalt of more than 500 Ohm-m). The ultimate bearing capacity in the second layer is ranging from 898.72 to 1614.07 gm/cm2,the allowable bearing capacity in the second layer is between 299.57 and 538.02 gm/cm2 and hence the factor of safety is equal to 3.