Bearing capacity of foundations on rock slopes intersected by non-persistent discontinuity

Abstract

Rocks encountered in foundations of heavy structures are invariably intersected by discontinuities (joints). In the past, several studies have been performed by researchers to incorporate the effect of fully persistent joints in the assessment of the load-carrying capacity of rocks. However, in the field, the joints are non-persistent, and an assumption of full persistency will underestimate the capacity. Recently, Shaunik & Singh have studied the influence of non-persistency, number of joint segments and discontinuity orientation on the strength behaviour of rock specimens (Shaunik and Singh, 2019). Bell’s approach can be used to obtain the bearing capacity of shallow foundations placed in jointed rocks. In the present study, results of the experimental work (Shaunik and Singh, 2019) conducted by Shaunik & Singh have been used to suggest expressions by extending Bell’s approach for computing bearing capacity of the foundation placed near the crown of a rock slope. Easy to use design charts are also presented for field application. Finally, a real-life problem from Indian Garhwal Himalayas is considered, and the approach suggested in this study is utilised to obtain the bearing capacity of a bridge foundation as a function of uniaxial compressive strength (UCS) of intact rock, joint friction, spacing and orientation of joint, non-persistency and number of joint segments.