Reinforcement of shallow granular layers overlying bases of different compressibilities.

摘要

In this research the effect of reinforcement, placed in a granular soil, on the ultimate bearing capacity (UBC) of a load placed on the surface of the soil foundation was studied. This study started work on deposits of limited depth overlying material that was either rigid or compressible. The granular depths were less than or equal to the loaded area width.; In about two-thirds of the tests performed, compressible layers were placed below the granular soil layer in order to emulate the behaviour of an underlying soft, compressible foundation. Two different compressible bases and a firm base were used as variables in relation to the underlying material stiffness.; The results of the analysis of the UBC vs. depth of reinforcement over footing width (D{dollar}sb{lcub}rm R{rcub}{dollar}/B) contained some similar general features in each of the cases investigated. Most tests showed two distinct local maxima when the results were plotted. At depths greater than about one-half of the footing width the addition of the reinforcement had little effect and, in two circumstances, had a negative effect.; It is evident from these and other studies, by Ismail (1994) and others, that the inclusion of any type of reinforcement effects the UBC of the soil. However, this effect is not always a positive one. The presence of a horizontally placed grid will alter the mechanisms taking place in the ultimate failure of the soil-grid system. The inclusion of any reinforcing grid will generally cause one of the following to occur; either the failure wedge will become shallower, or the failure wedge will intersect the reinforcement.