Experimental Study of Estimating the Subgrade Reaction Modulus on Jointed Rock Foundations.

The subgrade reaction modulus for rock foundations under axial loading is investigated by model footing tests. This study focuses on quantifying a new subgrade reaction modulus by considering rock discontinuities. A series of model-scale footing tests are performed to investigate the effects of the unconfined compressive strength, discontinuity spacing and inclination of the rock joint. Based on the experimental results, it is observed that the subgrade reaction modulus of the rock with discontinuities decreases by up to approximately 60 % of intact rock. In addition, it is found that the modulus of subgrade reaction is proportional to the discontinuity spacing, and it decreases gradually within the range of 0°-30° and tends to increase within the range of 30°-90°. [ABSTRACT FROM AUTHOR]