A linear elastic design model for sprayed liners in damaged reinforced concrete pipes

摘要

? 2022Reinforced concrete pipes experiencing unsafe levels of deterioration, and which require repair or replacement may be rehabilitated using trenchless technologies that avoid traffic impediments and costly excavations. One such trenchless solution involves the application of cementitious liners which are centrifugally sprayed out onto the interior of the host pipe to provide additional structural capacity and/or hydraulic repairs to the buried pipe. This paper presents a method for selecting the required liner thickness to prevent cracking and further deterioration in damaged reinforced concrete pipes. The design method is dependent on the burial conditions and extent of deterioration present in the host pipe: cracking, loss of concrete cover, loss of tensile reinforcement or the total breakdown of the host pipe. The bending moments resulting from earth loads are considered the controlling load source governing design. Design equations are developed to permit selection of minimum liner thickness needed for each of the deterioration types, considering composite interactions between the sprayed liner and the remaining components (concrete and steel) of the reinforced concrete pipe. Sample calculations are presented for the liner thicknesses required to rehabilitate Class 3, Class 4 and Class 5 pipes experiencing varying extents of deterioration. The results from the design models are evaluated using finite element simulations of the repaired pipe system. Comparisons between the strain distributions calculated using the design model and the finite element analyses demonstrate that the design model produces safe estimates of required liner thicknesses.