The influence of the parameters of engineering protective structures on the effectiveness of their use in densely built-up territory

Abstract

A study of the influence of application of an engineering protective screen made of small-diameter driven piles on the existing building deformations, caused by the arrangement of the pit fence made of bored piles, was carried out. The study was carried out with the help of numerical modeling using the method of finite elements, which allowed to display the work of the system "soil base - engineering protective structures - the foundation of the existing building" with different parameters of the protective screen. The influence of the following parameters is shown:
 1) the depth of laying the protective screen L in relation to the depth of the compressible soil zone (Hst).
 2) the position of the protective screen between the retaining structures of the pit and the existing building.
 3) rigidity of the screen – the ratio of the step to the diameter of the piles of the engineering protective screen.
 4) the distance between the existing building and the pit in relation to the depth of the enclosing structures of the pit of the new construction.
 The tasks were modeled in a spatial arrangement with the task of the system "soil base - enclosing constructions of the pit - protective screen - foundations of the existing building". The soil environment was modeled using the Hardening Soil Model. The calculation was carried out in stages.
 The variation of the parameters of the protective screen was carried out for the historical building, which in most cases was made according to a rigid wall construction scheme with strip foundations.
 The foundation depth is 1.2 - 3.0 m and the foundation width is 1-2 m. The average pressure under the foundation is 150-250 kPa.
 The rational depth of the foundation and the position of the protective screen between the existing building and the pit of the new construction were established.
 The area of effective application of the protective screen was revealed, depending on the distance between the building and the pit fence.
 The effective stiffness is established depending on the change in the relative distance between the poles of the protective screen.