EXPERIMENTAL INVESTIGATIONS INTO FLOOR BEARING STRENGTH OF JOINTED AND LAYERED ROCK MASS

摘要

This paper presents an evaluation of the floor bearing strength of soft floor strata and the influence of various parameters on it. A series of model plate loading test on massive and jointed floor strata were carried out under confinement, in which the floor rock were simulated with the help of sand- cement mixture using equivalent material modeling technique (Chug et al., 1997). Physical modeling technique has been used for the laboratory investigation purpose. All the testing were done under confinement in the self developed testing blocks resembling the in-situ condition which are contrary to the work done earlier (Ramamurthy, 1995). Plate loading tests were carried out for varying size and shape of fooling plates. The nature, orientation and the location of joints present in the floor rocks were also varied. Based on the findings it was seen that for a given condition floor bearing strength is strongly related to footing plate size and shape. The investigation has indicated that for a given condition ultimate bearing strength decreases with the increase in the plate size and normalized settlement also decreases considerably. Based on the result obtained from the scaled model tests on jointed floor rocks it was found that bearing strength of floor rock is also related to location and orientation of the joints present there in. Bearing strength of jointed rock mass is almost 0.6 times the bearing strength of intact rock mass for joint located vertically. The ratio reduced to almost 0.3 for joint located at an angle of 80° with the direction of loading. In this paper the practical consequences of the investigation are also discussed.