Centrifuge modelling of a rigid footing on jointed rock

A shallow foundation derives its support from the soil or rock close to the lowest part of the structure that it supports. When suitable rock is located at or near the ground surface, shallow foundations are built directly onto that rock. The engineering behavior of such a foundation on rock is highly controlled by the discontinuities present in the rock mass.; Four series of centrifuge tests were performed at the University of New Brunswick for this study using a model rock made from a mixture of sand, bentonite, cement, and water. A prototype footing measuring 1 meter x 1 meter was simulated in the study. Tests were conducted to determine the effect of horizontal and vertical discontinuities on the load-settlement response of a rigid footing on rock.; Results from this study are compared to the existing correlations and methods used to predict ultimate bearing capacity and settlement response. It is found that measured values of bearing pressures were in agreement with published correlations for bearing capacity estimates at settlements. Back-calculated bearing capacity factors were compared to published correlations for specimens with horizontal joints. It was found that the present code is very conservative in its estimate of bearing capacity. Back-calculated values of bearing capacity factor for vertically jointed specimens indicate a good correlation with the ratio a/B, where a is the distance from footing edge to the nearest vertical joint, and B is the width of the footing. The Schmertmann strain influence method was used to predict prototype settlement for the model footing tests. This prediction gave good correlations for horizontally jointed specimens at low settlements, but gave unconservative predictions of settlement in specimens with no discontinuities and specimens with vertical discontinuities. (Abstract shortened by UMI.)...