Abstract Drilled shafts or bridge piers can transmit huge structural loads (both axial and lateral) through the overburden soil to the underlying rock mass. Drilled shafts are usually socketed into rock to increase their axial and lateral load carrying capacity. The part of the shaft, drilled inside rock, is called the socket length. Drilled shafts have become an appropriate and economical foundation solution for heavily loaded structures. Although axial load carrying capacity of a rock-socketed pile has been extensively studied, there are still some gaps in understanding the lateral load behaviour of a rock-socketed pile mainly because of the scarcity in field load test data available. An alternative way to minimize this gap is to take help of numerical modelling which can simulate the near-field conditions. For this, in this present work, a two-dimensional distinct element code, UDEC has been used for the discrete element modelling of a single pile socketed in jointed rock mass. Two lateral load field test results from previously published research have been validated by the established numerical model. This validation work is followed by parametric studies of a laterally loaded pile having aspect ratio or socket length to pile diameter ratio of 6 and 12 embedded in a sloping rock mass profile with two sets of joints dipping at different angles (0/90 degree, 15/105 degree, 30/120 degree, and 45/135 degree) from the horizontal. From the results of the parametric studies, non-linear P-y behaviour of the rock-socketed pile on a sloping ground has been formulated. These P-y response curves provide rock resistance as a function of lateral deflection of the pile inside rock. The effects of presence of two joint sets and their dipping angles on P-y behaviour of the pile with two different aspect ratios embedded in a sloping ground have been recorded. These parametric analyses will help in the best design of a laterally loaded pile foundation in sloping jointed rock mass. 1. Introduction A drilled shaft can transmit huge structural loads (both axial and lateral) through the overburden soil to the underlying rock mass. Drilled shafts have many synonyms, such as bored piles, drilled piers, drilled caissons, or cast-in-situ piles. Drilled shafts are usually socketed into rock which in turn, increases its axial and lateral load bearing capacity. The length of the shaft, drilled into rock, is termed as the rock socketed part. The drilled shaft may also be entirely embedded in rock where there is no sub-soil. A representative diagram of a usual drilled shaft, with some of its length socketed into a jointed rock is shown in Fig. 1.