Про короткочасну та довготривалу міцність відновлених за ін’єкційними технологіями елементів будівельних споруд

Abstract

Розроблено математичну модель деформування матеріалу в околі тонких тріщин, заповнених в’язкопружним матеріалом, та запропоновано методику визначення змінного з часом поля напружень і деформацій біля таких дефектів однорідної структури. Отримано розв’язки нових крайових задач, до яких зведені проблеми деформування навантажених довготривалими зусиллями розтягу або зсуву масивних тіл та пластин із тріщинами, що заповнені в’язкопружними матеріалами. Проаналізовано вплив повзучості та релаксації напружень на несучу здатність, пошкоджених тріщинами бетонних елементів конструкцій, які відновлені за ін’єкційними технологіями.

The paper is devoted to the important scientific, technical and practical problems of predicting both service life time and strength of damaged structure elements over long-term operation, bearing capacity of which was restored using the injection technology. In practice there are engineering problems, for solving of which linear elastic media models are insufficient, serviceability estimation of prolonged use is often associated with the need to take account of the phenomenon of creep material. Therefore there is a need to develop models, which would take into account such complex material properties as reological properties. One of such examples is the technology of injecting strengthening of damaged structures. When restoring damaged cracked bearing capacity of long operation building structures the technology of filling defective areas with liquid material which hardens in some time, becomes very popular. A mathematical model of the material deformation in the vicinity of thin viscoelastic inclusions filled with cracks and determination of the stress-deformation field near the defects of its homogeneous structure has been developed. New solutions of the boundary value problems, which have been reduced to the problem of tensile or shear both loaded plates and massive bodies with cracks filled with the viscoelastic material have been obtained. In particular, a solution for the three-dimensional problem for an elastic space with filled elliptical cracks loaded at infinity by long-term uniform stresses has been found. The distribution of stress intensity factors along the contour of the elliptical crack in body or plate has been determined. The influence of reological properties of injecting materials on the time-varying stress-strain state of the body with a filled elliptical crack is investigated. The strength changing over time of these bodies has been obtained by using fracture mechanics criteria. The influence of creep and stress relaxation on the carrying capacity of damaged cracked concrete structural elements recovered by injection technology has been investigated.