Estimate of Bearing Capacity of Gypseous Soils from Field Data

Abstract

This research examined field data of 84 boreholes form ten chosen sites in Salah Aldeen Governorate. The soils for these sites are granular gypseous with gypsum content (Gyp. %) ranged from 8.37-51.14%. Based on Standard Penetration Test (SPT), the N values for each chosen site were corrected for field procedures and overburden pressure effects by exploiting NovoSPT program to get (N1)60 or NCor. values, where these values used later by this program for allowable bearing capacity calculations. To study the properties and illustrating the behavior of these gypseous soils, the SPSS and the Curve Expert programs were used to perform statistical analysis for the data of the chosen sites. For dry condition, it is concluded that (NCor.) values are increasing with (Gyp. %) after deactivating the effects of void ratio and average particles size. Also the allowable bearing capacity (qall) values are observed to be increased with (Gyp. %). Based on the stresses affecting the SPT sampler, the peck et al.,1974 Equation was proved to be the reliable formula among the others Equations for calculating (qall) from field N values. Depending on calibration chamber )laboratory SPT) tests results and cavity expansion theory, it is dependable to use 0.5 exponent for CN correction Equation of overburden pressure effect.