Methodology for Calculating Additional Dynamic Settlements of the Bases of Slab Foundations of Buildings and Structures from Vibrations Propagating in the Soil Environment

Abstract

The paper provides a method for calculating additional settlements of slab foundations of existing buildings and structures from vibration-dynamic influences that arise during various construction works near them (driving piles, vibra- tory driving of sheet piling beams, soil compaction with heavy rammers and vibrating hammers), as well as from industrial equipment and transport. The technique includes the following main steps. Using the finite element method, or measured existing vibration fields, the distribution of the maximum accelerations of ground vibrations under the base of the foundation along the depth is determined and the zone in which they exceed the critical accelerations at which volumetric and shear deformations of the soil begin to appear is identified. The soil at the base of the foundation is divided into elementary layers with a thickness of no more than 1/4 of the width of the foundation. Further, according to the known vibration-compression depen-dencies (the dependence of the change in the porosity coefficient e of soil samples on the acceleration of their vibrations a), which are obtained in laboratory conditions, the settlements of each layer are determined, the summation of which gives the total value of the additional dynamic settlement Sд. If it, together with the static settlement Sст, exceeds the maximum normalized settlement values, it is proposed to use three methods to reduce or eliminate Sд – drilling injection strengthening of the zone of development of additional settlements, the use of a horizontal inertial plate or a vertical barrier made of easily compressible materials in the path of vibration propagation, the use of which reduces the intensity of vibration-dynamic impacts transmitted to the foundations under consideration.