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Wpływ temperatury na ugięcia płyt betonowych wbudowanych w nawierzchnię autostrady A4

100%

Szydło A. , Ruttmar I.

tom Nr 10

11--13

Podczas programu badawczego wykonanego na 90 km nowowybudowanej autostrady betonowej z płytami dyblowanymi oraz z nawierzchnią o ciągłym zbrojeniu, w pierwszych latach użytkowania nawierzchni przeprowadzono nieniszczące badania. Między innymi badania ugięć za pomocą Falling Weight Deflectometer - FWD mające na celu monitorowanie założeń projektowych. Zmieniająca się temperatura otoczenia oraz gradient temperatur w płycie podczas wykonywania badań miał jednak znaczny wpływ na rozrzut wyników pomierzonych ugięć. W celu określenia rozrzutu wyników spowodowanego różnicą temperatur zostało przeprowadzonych kilka eksperymentów polowych. Płyta obciążeniowa FWD była umieszczana w różnych pozycjach na betonowej płycie dyblowanej i ugięcia jak i temperatury były rejestrowane w tym samym miejscu w każdej godzinie dnia. Badania zostały wykonane na płytach ułożonych na warstwie chudego betonu oraz na podbudowie z kruszywa jak również na odcinku o ciągłym zbrojeniu. Pomiary zostały wykonane na dwóch skalibrowanych urządzeniach FWD w celu określenia odtwarzalności wyników badań. Artykuł opisuje wyniki analiz tych pomiarów.

During intensive investigation programme conducted on 90 km of newly constructed concrete motorway - doweled slabs and continuous reinforced pavement, a various non-destructive tests were carried out in first years of pavement life. Among others the deflection measurements using Falling Weight Deflectometer - FWD with the aim to monitor the design assumptions. Elastic modules of concrete slab and load transfer efficiency - LTE on doweled joints were calculated. Changing air temperature and temperature gradient in slab during testing had significant influence on variability of results of deflection measurements. In order to capture the variance of results caused by temperature differences some field experiments later on were executed. FWD load plate were placed in different positions of doweled slab and deflections as well as temperatures were measured every hour during day on same places. Tests were carried out on slabs placed on cement treated sub-base as well as aggregate sub-base. Measurements were carried out also by two calibrated FWD devices in order to establish reproducibility of test results. Article describes the results of analysis of these measurements.

Numerical simulation of the stress state of an erosion-worn tee of the main gas pipeline

80%

Doroshenko Y. , Zapukhliak V. , Grudz Y. , Poberezhny L. , Hrytsanchuk A. , Popovych P. , Shevchuk O.

tom Vol. 101, nr 2

63--78

Purpose: To investigate the strength of tees with regard to their erosion wear, it is necessary to consider the complex three-dimensional geometric shape of the erosion worn inner surface of the tee. In addition, the study of the strength of the erosion worn tees of the main gas pipelines is complicated by the occurrence of additional stresses caused by changes in the direction of movement of the gas stream, resulting in an uneven pressure distribution in the inner cavity of the tee, and the temperature difference in its walls. Design/methodology/approach: Methodology for complex numerical three-dimensional simulation of the stressed state of tees of the main gas pipelines, taking into account the gas-dynamic processes that occur in the places of these defects, erosion wear of the tee wall, temperature difference in the tee walls. Findings: The acceptable parameters of erosion defects of tees of gas pipelines, and residual life of tees with erosion defects of the wall should be determined. Research limitations/implications: The developed model does not take into account internal corrosion and corrosion products as an additional erosion factor. Further studies plan to develop a model of corrosion-erosion wear of pipeline elements. Practical implications: The developed technique allows determining the location of erosion defects, estimating the strength and determining the residual life of tees with erosion wear of the wall in order to ensure their reliability, to rank such defects according to the degree of danger, to determine which of them are critical and need an immediate repair. Originality/value: Based on the gas-dynamic processes occurring in the internal cavity of the main gas pipelines’ tees, the complex three-dimensional geometric form of wall erosion defects, and temperature difference, the technique of three-dimensional simulation of stress state of the main gas pipelines’ tees is developed