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1

Dynamic characteristics of fault-controlled earth fissure sites in Jingyang County, Weihe Basin, China

Xuan You, Deng Yahong, Chang Jiang, Mu Huandong, Cao Ge

Acta Geophysica

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2022

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Vol. 70, no 4

1687--1700

EN

Jingyang County is located in the northern part of the Weihe Basin, which is an important part of the Fen-Wei graben system. Nearly half of earth fissures located in northern Jingyang County have East–West orientations that match the orientation of the nearby Kouzhen–Guanshan active fault. In order to analyze the superficial structures and dynamic characteristics of earth fissures, we conducted trenching and microtremor testing at two earth fissure sites that are largely controlled by activity along the Kouzhen–Guanshan fault. Our main results are as follows: (1) The presence of earth fissures has little to no effect on the predominant frequencies and natural periods that excite the maximum response acceleration during a microtremor. (2) Three specific amplitudes, including the Fourier amplitude at the predominant frequency, the maximum response acceleration, and the Arias intensity, are smaller at site 1 than they are at site 2. (3) Amplification occurs at both earth fissure sites. These three amplitudes have high values at distances less than ~6 m from the crack, attenuated values at distances of ~6–20 m from the crack, and low stable values at distances greater than~20 m away from the crack. (4) We calculated the amplification factors for these two earth fissure sites and identified regions that experience varying degrees of this amplification. Based on our analysis, we recommend seismic fortification for buildings in areas affected by these earth fissure sites.

2

Research on reinforcement technology of existing double-way curved arch bridge

Zhang Kexin, Qi Tianyu, Xue Xingwei, Li Yanfeng, Zhu Zhimin

Archives of Civil Engineering

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2021

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Vol. 67, nr 2

581--595

EN

Two-way curved arch bridges inherit the fine tradition of masonry structures, making full use of the advantages of prefabricated assembly, it adapts to the situation of no support construction and no large lifting machine and tools, and has the characteristics of convenient construction method and saving material consumption. In appearance, the two-way curved arch bridge has strong national cultural characteristics. The prefabricated components of the two-way curved arch bridge are fragmentary, complicated in bearing and poor in integrity. Most of the two-way curved arch bridges in service have been built for a long time and lack of maintenance and management. Increasing the cross-section reinforcement method is one of the two-way curved arch reinforcement methods. It has a significant effect, convenient construction, good rigidity and stability characteristics after the reinforcement. Through theoretical analysis, combined with a static load test results of the assessment of the bridge reinforcement effect. Through load test, it is found that the deflection of the arch rib after reinforcement is reduced by 9%~19% and the strain of the arch rib is reduced by 12%~22%. Through finite element calculation, the crack width of the reinforced arch rib decreases by 8.3%~14.2%. The results show that the stress and deflection are greatly improved by the method of increasing section.

3

Application research of high pressure jet grouting pile in an underground engineering in Vietnam

Nguyen Xuan Loi, Wu Li, Nguyen Khanh Tung, Bui Quang Anh

Archives of Civil Engineering

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2020

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Vol. 66, nr 3

575--593

EN

High-pressure jet grouting pile is a kind of stratum reinforcement technology developed in recent years. Due to its characteristics of high solid strength, fast construction, low noise, safety and reliability, low cost, controllable reinforcement diameter, strong adaptability to stratum, and good reinforcement effect for soft soil, loose soil and water-rich stratum, high-pressure jet grouting pile technology has been more and more widely used in foundation treatment, water stop, and seepage prevention, tunnel lining and other fields in recent years. As a country with a relatively late development of underground construction engineering, Vietnam has little research on special geotechnical reinforcement technology, especially on special geotechnical reinforcement technology around urban underground construction engineering, especially on its theoretical analysis and practical application. Therefore, this thesis combines the Vietnam Trung Hoa tunnel project as an example, using the theoretical calculation formula and field monitoring measurement comparing the two methods, the high pressure jet grouting pile system research in Vietnam in the underground engineering reinforcement principle and application effect, get to the actual engineering design and construction has a guiding significance to the research, provides the reference for future similar projects. Finally, the application effect of high-pressure jet grouting pile in underground building reinforcement project is evaluated, which proves that high-pressure jet grouting pile has good applicability and economic benefit in underground building reinforcement project in Vietnam.

4

The influence of cyclic loading on the static strength of cement-bound sand – qualitative analysis

Brzeziński K., Adamczewski G., Tutka P.

Roads and Bridges - Drogi i Mosty

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2017

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Vol. 16, no. 1

37--46

EN

The main purpose of the paper is to evaluate the effect of cyclic loading on the static bending strength Rb of cement-bound sand (CBS). The mixture contained graded standard quartz sand bound with cement added at a proportion of 10% of the weight of sand. The main part of the experimental research were three-point bending tests performed on rectangular specimens. The specimens were subjected to cyclic pre-loading with different numbers of cycles and different bending force values. Strength tests were then conducted on pre-loaded specimens and the results were compared with non-preloaded specimens. ANOVA statistical analysis method was applied to the comparison of average strengths. This revealed an increase of static strength for specific cyclic pre-loading conditions. The influence of the number of pre-loading cycles and of the bending force value on the strength of specimens was checked as the next step.

PL

Głównym celem pracy jest ocena wpływu obciążeń cyklicznych na statyczną wytrzymałość na rozciąganie przy zginaniu Rb piasku związanego cementem. Badana mieszanka składała się z piasku kwarcowego o normowym uziarnieniu związanego cementem w ilości 10% w stosunku do masy piasku. Zasadnicze badania przeprowadzono na prostopadłościennych próbkach zginanych metodą 3-punktową. Próbki poddawano wstępnym obciążeniom cyklicznym przy różnych zakresach liczby cykli i siły zginającej. Następnie wytrzymałość próbek wstępnie obciążonych porównano z wytrzymałością próbek niepoddanych wstępnemu obciążeniu. Porównanie średnich wytrzymałości przeprowadzono z zastosowaniem testu statystycznego ANOVA. Zaobserwowano w ten sposób efekt zwiększenia wytrzymałości statycznej, przy określonych warunkach cyklicznego obciążenia wstępnego. W dalszej kolejności przeprowadzono wstępną analizę wpływu dwóch czynników obciążenia wstępnego (liczba cykli i poziom siły zginającej) na zmianę wytrzymałości próbek.

5

Wpływ modyfikacji fizycznej sadzy piecowej na właściwości mechaniczne wulkanizatów kauczuków polarnych i niepolarnych

Potocki K., Lewandowski M.

Elastomery

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2015

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T. 19, nr 2

35--39

PL

Badano właściwości mechaniczne wulkanizatów SBR i NBR zawierających aktywną sadzę piecową modyfikowaną i niemodyfikowaną. Zastosowaną sadzę modyfikowano powierzchniowo za pomocą silanu zawierającego grupy aminowe. Stwierdzono, że wulkanizaty NBR zawierające sadzę modyfikowaną wykazywały lepsze właściwości wytrzymałościowe w porównaniu z wulkanizatami z sadzą niemodyfikowaną.

EN

Strength properties of SBR and NBR vulcanizates filled with modificated and unmodificated furnace carbon black were investigated. Modification was carried out by use of silane containing polar amine groups. As a result of modification reinforcement effect of modificated carbon black mixed with NBR rubber was found.

6

An Analysis Of Stress Intensity Factor Due To Normal Stress For A Cracked Plate Reinforced With A Sheet By Seam Welding

Kim O.-H., Kim Y. C.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1441--1444

EN

It is essential in damage tolerance design to determine the stress intensity factor theoretically. The stress intensity factor for a cracked plate that is reinforced with a sheet by seam welding is determined theoretically and plotted as function of the seam welding location and stiffness ratio. The singular integral equation is derived based on the compatibility condition between the cracked plate and the reinforcement plate, and it is solved by means of Erdogan and Gupta‘s method. The theory is verified by comparing the results of the present analysis with those of a numerical analysis. The results from the present analysis show that the reinforcement effect improves as the welding line is situated closer to the crack and as the stiffness ratio of the cracked plate and the reinforcement plate increases.