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1

Optimization of heavy haul railway tunnel lining based on ultimate bearing capacity

Han Wei, Xiao Taoli, Shi Duanwen, Wang Yupeng

Archives of Civil Engineering

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2022

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Vol. 68, nr 4

493--511

EN

The optimization process of design parameters for composite lining of heavy haul railway tunnel is a key problem to be solved in tunnel engineering design. In order to put forward a better design scheme of composite lining for heavy haul railway tunnel, combined with field measurement and numerical simulation, the optimal working condition design is carried out by changing the thickness of shotcrete layer, the type of grid steel frame and the thickness of secondary lining. The influence of the above design parameters on the stress state of the composite lining is analyzed to obtain the optimal design parameters. Finally, the safety performance of the optimized lining is evaluated by the ultimate bearing capacity curve of the secondary lining section. The research shows that: 1) The optimal design parameters of the composite lining of the tunnel are the thickness of the shotcrete layer of 25 cm, the type of the grid steel frame of H180, the thickness of the secondary lining arch waist and the side wall of 40 cm and 35 cm respectively; 2) Different from the single-track heavy haul railway tunnel, the displacement value of the vault settlement of the double-track heavy haul railway tunnel is significantly greater than that of the inner convergence. Increasing the thickness of the shotcrete layer and changing the type of the grid steel frame have better effects on reducing the vault settlement, and have little effect on the inner convergence.

2

Mechanical and thermal insulate behaviors of pultruded GFRP truss-core sandwich panels filled with EPS mortar

Li Sensen, Zhang Bei, Yang Dapeng, Wang He, Liu Yang, He Huguang, Fan Hualin

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

593--604

EN

Pultruded sandwich panel (PSP) usually has light weight, but its flexural performance is limited by the weak shear strength. Filling into expanded polystyrene (EPS) mortar can effectively improve the mechanical properties. The bending performance and failure mode of the EPS mortar-filled PSP were investigated by flexural testing. The ultimate bearing capacity improved from 49.562 kN for unfilled PSP to 72.065 kN for EPS mortar-filled PSP. The equivalent shear modulus is increased from 140.068 to 354.685 MPa. Increasing the EPS mortar’s density, the failure of EPS mortar-filled PSP would change from core shear failure, local indentation failure to overall shear failure. According to the thermal insulation tests, which shows EPS mortar-filled PSPs have excellent thermal insulation, the thermal insulation performance of different types of filler PSPs are obtained. The research on the mechanical and thermal insulation properties of EPS mortar-filled PSP can provide technical support for its application in engineering.

3

Effect of random strength parameters of flange steel on bending resistance and deflections of girders with corrugated web

Basiński Witold

Architecture Civil Engineering Environment

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2020

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Vol. 13, no. 4

47--60

EN

The study presents results of statistical investigations into random strength parameters of steel used to manufacture flanges of plate girders with corrugated web. In the case of plate girders with corrugated webs, flanges are manufactured from flat sheet steel S235JRG2 or S355J2+N or S275. The guaranteed yield strength Remin is determined on the basis of tests conducted on steel samples. It should be lower than yield strength of flat sheets obtained as the result of testing mechanical properties. This value at the same time should be regarded as the margin of resistance of girders. The material tests were performed on samples randomly collected from 20 girders with corrugated web and flange thickness of 15 and 20 mm, which had been already examined. Coefficients of variation of yield strength VRe=D(Re)/E(Re) and partial factors of yield strength γm were selected on the basis of the conducted analysis of material tests. The obtained results were related to factors γm determined from the tests on thin flat sheets. The impact of yield strength and random cross-sectional area of flanges on bending resistance of girders with corrugated web was shown. Also the effect of the spread of the Young’s modulus values and semi-rigid connections on global displacements of tested plate girders with corrugated web was analyzed.

4

Wpływ typu wzmocnienia oraz osnowy kompozytu na wytrzymałość na zginanie

Dzianok D., Postawa P.

Przetwórstwo Tworzyw

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2016

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T. 22, Nr 4 (172)

223--232

PL

W artykule przedstawiono wyniki badań trójpunktowego zginania kompozytów na bazie dwóch żywic z trzema rodzajami zbrojenia. Zastosowanymi żywicami były Aropol M105TB i Sirca HN800 natomiast zbrojeniem mata szklana emulsyjna 300 g/m², mata szklana proszkowa 300 g/m² i tkanina Saerex (COMBO 600/300). Próbki w postaci płyt zostały wykonane metodą ręcznego laminowania a następnie wycięte na określony wymiar metodą cięcia wodą. Otrzymane próbki poddano badaniu wytrzymałości metodą trójpunktowego zginania. Prawidłowość badań potwierdza mała rozbieżność wyników pomiędzy poszczególnymi próbkami wykonanymi z tych samych materiałów. Artykuł zawiera zdjęcia z przebiegu przygotowania próbek i ich badań oraz wyniki zarówno w formie tabelarycznej [Tab. 1] jak i w postaci wykresów [Rys. 11-17]. Badania dowiodły, że największy wpływ na właściwości kompozytu powstałego z żywicy oraz maty szklanej bądź też tkaniny ma zastosowane wzmocnienie.

EN

The article presents the results of three-point bending for two types of resins combined with three types of reinforcement. Applied resins were AROPOL M105TB and HN800 Sirca while the reinforcements were glass mat emulsion of 300 g/m², glass mat powder 300 g/m² and fabric Saerex (COMBO 600/300). The samples in form of plates were made by hand lamination then cut to a specific dimension by the method of water cutting. Prepared samples were tested for flexural strength by three point bending. Correctness of study is confirmed by small discrepancies between results for individual samples made of the same material. The article contains both images of the sample preparation process and the results of their research in tabular form [Tab. 1] and in the form of diagrams [Fig. 11-17]. Studies have shown that the largest effect on the properties of composite created from resin and glass mat or fabric has the applied reinforcement.

5

Crease-resistant Finish of Linen/Viscose Blend Fabrics

Kut D., Güneşoğlu C., Orhan M.

Fibres & Textiles in Eastern Europe

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2010

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Vol. 18, no. 6 (83)

91--93

EN

Linen/viscose blend fabrics are treated in different conditions with various concentrations of polycarboxylic acids (BTCA, CA, GA and MA) and N-methylol reagent (DMDHEU) with a relevant catalyst. The characterisation of such fibres is dependent on the degree of crosslinking, which is evaluated by the dry wrinkle recovery angle and tensile strength retention. In trials BTCA showed much better effects on the crease resistant finish of linen/viscose blend fabrics; when comparing the mixture of polycarboxylic acids, BTCA/GA treatment also gives moderate effects. High temperature curing is a handicap for linen/viscose blend fabric treatment when considering strength loss, whereas DMDHEU solutions give better results due to their lower acidity. In order to optimise the crease resistant finish of linen/viscose blend fabrics, it is acceptable to add a triethanolamine additive with the same ratio of the catalyst and cure at 160°C.

PL

Tkaniny wykańczane były za pomocą kwasów polikarboksylowych (BTCA, CA, GA i MA) o różnym stężeniu oraz N-hydroksymetylowego reagentu (DMDHEU) z dodatkiem odpowiedniego katalizatora. Charakterystyka obrabianych włókien zależy od stopnia usieciowania, ocenianego poprzez kąt odprężności i zmianę wytrzymałości na rozciąganie. Najlepsze wyniki uzyskano przy stosowaniu BTCA, a umiarkowane przy stosowaniu BTCA/GA. Optymalna temperatura obróbki wykańczającej wynosiła 160°C natomiast przy 180°C utrata wytrzymałości mechanicznej po obróbce był mniejsza. Korzystne wyniki uzyskuje się przy zastosowaniu katalizatora w postaci trietanoloaminy.

6

Study of some factors affecting bending resistance of polyethylene ropes

Sharrouf A. A. M., Salem M. M., Gad M.

Autex Research Journal

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2008

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Vol. 8, no. 4

111--119

EN

The ease of accomplishing a tight knot in a rope depends mainly on the bending resistance of that rope, hence the bending behaviour of ropes becomes a matter of considerable importance. Reducing the bending resistance of ropes, while retaining their other physical and mechanical properties unchanged is a demand of rope consumers. Unfortunately there is no standardised method to measure the bending resistance of ropes. The bending resistance as a mechanical property depends on many factors, such as the type of material used, the processing methods, and the technical specification of the rope. In the present work, four factors were subjected to study, these being: filament denier twist in the primary strand, twist in the final strand, and percentage distribution of filament between core and sheath. A simple method, similar in principle to that used in the Shirley Fabric Stiffness Tester, was used to measure the bending length of polyethylene ropes. A simple model was derived to calculate the bending resistance of ropes. Multiple regression analysis was used to determine multiple correlation factors, degree of contribution of each factor to the measured properties, and its significant levels. Surface plots are used to demonstrate the shape of the effect of the factors that have significant effects.