Stress Analysis of Masonry Walls in Case of Limited Excavation for Foundation Underpinning

摘要

The assessment of safety and structural integrity of existing buildings is often an intricate task regarding the optimum structural intervention measures on superstructure, infrastructure or both. When the cause of structural deterioration is related to the geotechnical condition unfit for the new load regime, a widely used method for the rehabilitation of infrastructure is the underpinning of foundations. This paper is focused on the analysis of the stresses developing into a masonry wall when excavating in segmented areas with limited lengths under and on both sides of the continuous foundation. In this respect, a linear elastic analysis for a three-dimensional model was carried out by using finite element software ANSYS. The excavation for the underpinning is assumed to start from the middle of the wall, with variable lengths, from 0.60 m increasing with a rate of 0.10 m, up to 1.00 m. The depth of the excavation is considered constant, as 0.60 m under the foundation, to exceed the frost depth by a final value of the foundation depth of 1.20 m. The model of the wall, foundation and soil was developed with ANSYS interface for all excavation ranges, considering a frictionless contact between foundation and soil and the program run for all modulus variations and excavation geometries. The results are given in diagrams correlating the E modulus versus in-plane and vertical stress for all the excavation geometries.