Search Results (3)

This paper explores a solution to safeguard buried pipes located near constructions in the Al-Bisri region of Assiut Governorate by utilizing the concept of the characteristic damage state. This issue has escalated due to the increasing rate of construction activity near pipelines, resulting in a multitude of legal disputes. This study investigates the behavior of buried pipes when influenced by newly constructed buildings using the finite element method. The paper employs two-dimensional models of a 12-story reinforced concrete building with a raft foundation and a series of piles supporting the buried pipe. In this study, we used the PLAXIS software, a 2D plane strain program, to conduct numerical investigations. The soil was idealized using the Mohr–Coulomb model with a 15-node triangular element, while the piles and structures were idealized with a five-node isoperimetric beam element. The point of contact between the beam and the soil was represented by the interface element. Our research examined the distance between the pipe and the footing edge and the distance between the piles and the footing edge. The finite element model results provided nodal displacements and element straining actions for analysis. The results shed light on the behavior of the sheet pile wall and sewage pipe in various situations. The largest bending moment in the sewage pipe was seen in the absence of piling, in contrast, to pile support at Rx = 0.75. The bending moment in the pipe expanded and always occurred at the same location as Rx rose. The clay layer next to the pipe’s lateral deformation was significantly reduced after piling, with the greatest deformation occurring at Rx = 0. Full article

The main part of sewer pipelines is commonly made up of precast reinforced concrete pipes (RCPs). However, they often suffer from microbiologically induced concrete corrosion (MICC), which has made them less durable than expected. In this study, three-edge bearing tests (TEBT) are performed on full-scale RCPs with preset wall losses to determine how MICC influences their bearing performance. For this purpose, several bearing indices such as D-load, peak load, ultimate load, ring deflection, ring stiffness, and failure energy are presented or specified to characterize the load-carrying capacity, stiffness, and toughness of these RCPs. It is found that crown concrete corrosion hardly changes the mechanical behavior of the first elastic zone of RCPs, so that D-load is not affected, but it shortens the crack propagation zone significantly, leading to a reduction in ultimate and peak loads. Furthermore, RCPs’ ring stiffness and toughness are negatively correlated to thickness of wall loss, while the transverse deformability of the ring cross-section is positively correlated with it. Additionally, it was found that crown corrosion affects the ultimate load of different sizes of RCP in different ways. The 2000 mm RCP is affected the most, with a 50 percent reduction in ultimate load. The 1000 mm RCP follows, with a 36 percent reduction, and the 1500 mm RCP has a reduction of less than 20 percent. This research contributes to comprehending the degradation of in-service sewage pipes, hence informing decision making on sewer maintenance and rehabilitation. Full article

External load is one of the important reasons for structural damage and failure of reinforced concrete sewage pipelines, causing pipe leaks, pipe explosions, and even road collapses. In this paper, three-point loading experiments on full-size reinforced concrete pipes were carried out, and the damage state of the pipes was monitored by acoustic emission technology; the evolution trend of the mechanical properties and acoustic emission monitoring indexes under load was investigated. The experimental results showed that: (1) According to the change of acoustic emission energy and accumulated energy during loading, the mechanical response of the pipeline can be divided into an elastic compression phase, a plastic damage phase, and a residual strength phase; (2) The accumulated acoustic emission energy (∑E) and the maximum value of a single acoustic emission energy (E_max) can effectively characterize the different damage states of the loaded pipe; (3) A “double-peak” was observed in AF/RA data within the loading process. The appearance of the two peaks corresponds to the change of the loading phase of the pipeline and the occurrence of the major damage. Thus, the AF/RA index can effectively characterize the loading state and the damage degree of the pipeline. This study provides a valuable reference for pipeline health monitoring by using AE technology. Full article