Cross-hole Technique Application to Determine Allowable Bearing Capacity of Soil in an Engineering Site in Baghdad, Iraq

The seismic cross-hole method has been applied to calculate the subsurface allowable bearing capacity and detect the subsurface weakness of soil underneath the foundation of an engineering site. The study aims to calculate the allowable bearing capacity and other engineering properties such as bulk modulus, rigidity modulus, Young's modulus, and Poisson’s ratio by using seismic velocity, compressional, and shear waves. The cross-hole technique is applied along two profiles in the study site. The seismic and technical properties are investigated in the study site from a depth of 4 to 10 m along the two profiles. From seismic borehole velocities noticed that the measured shear wave velocity along profile 2 is higher than those encountered along profile 1 for a depth of 4 to 10 m, which indicates that the geotechnical properties of subsurface soil are not homogeneous along the site. this may lead that differential settlement will occur. To improve the geotechnical properties to sustain the design load, the grouting technique up to 3m depth below the existing foundation base was used.