Avaliação da capacidade de carga de fundações diretas sobre camada suporte de blocos de rocha compactados

Abstract

The use of compacted rock block layers for shallow foundation settlement can occur when there is a need to replace one material with another of better quality, aiming to increase the load-bearing capacity of the soil-foundation systems. Due to the characteristics of the rock blocks, defining the shear strength parameters of the material through field or laboratory tests becomes costly or even unfeasible. This paper presents an assessment of the load-bearing capacity of a compacted rock block layer, whose shear strength parameters were obtained using the GSI (Geomechanical Strength Index) classification system, allowing the estimation of the load-bearing capacity of the soil-foundation system through the use of established theoretical methods. The evaluation of the behavior of the rock material was performed through a plate load test, complemented by numerical simulations that sought to describe the material's stress-strain behavior using a three- dimensional analysis. The simulations were conducted using the finite element method, with the assistance of the RS2 and RS3 software from Rocscience. The results indicated that the assumption of considering the layer of compacted rock blocks as a rock mass led to a load-bearing capacity consistent with that obtained in the plate load test. Moreover, the geotechnical parameters of the material resulting from the back-analysis of the field test results were compatible with those obtained from the application of the GSI system. Based on the three-dimensional analysis, it was observed that the compacted rock block layer meets the project requirements, validating the ground improvement technique. Therefore, the use of geomechanical classification systems proves to be a feasible methodology to be employed in the design of shallow foundations placed on rock block layers. This work provides a technical basis for the use of this geotechnical solution, promoting greater safety in projects.