Evaluation of the structural and waterproof performance of a precast and assembly underpass under long-term surface dynamic loads

2021 ◽  
Vol 115 ◽  
pp. 104047
Author(s):  
Zhiyi Jin ◽  
Taiyue Qi ◽  
Xiao Liang
Keyword(s):  
Dynamic Loads ◽  
Surface Dynamic

scholarly journals Fatigue Life Characteristics of Segmental Lining Structure for the Shallow Buried Metro Tunnel under the Dynamic Load of a High-Speed Railway

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Wangping Qian ◽  
Taiyue Qi ◽  
Qing Zhao ◽  
Bingrong Pu ◽  
Jin Zhang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Failure ◽  
Dynamic Load ◽  
High Speed ◽  
Dynamic Loads ◽  
High Speed Railway ◽  
Segmental Lining ◽  
Lining Structure ◽  
Metro Tunnel

Shallow buried shield metro tunnels constructed underneath subgrade project of high-speed railways are becoming increasingly common in China, but the lower metro tunnel bears the fatigue effect of dynamic load induced by the upper high-speed railway, so the long-term durability of segmental lining is a nonnegligible problem. The segmental lining structure of metro tunnel is in a state of static-dynamic loads for a long time, especially when a high-speed railway passes above the metro line, and the long-term durability of segmental lining needs further research. Based on theoretical analysis, the effect of different forms of loads on the fatigue life was analyzed, the change law of the static-dynamic loads on segmental lining was summarized, and the method was put forward to evaluate the fatigue life characteristics of segmental lining. The research results reveal that the additional dynamic load is the fundamental reason for the fatigue failure of the structure, and the existence of static load can cause and accelerate the occurrence of structural fatigue failure simultaneously. The results indicate that the fatigue life decreases gradually with the increase of static-dynamic load. Based on coupling analysis of static-dynamic loads of segmental lining, the fatigue life increases first and then decreases with the increase of buried depth of metro tunnel, and it remains unchanged when the depth exceeds a certain value. According to the actual metro tunnel engineering, by using ABAQUS software, a three-dimensional numerical simulation was carried out to analyze the characteristics of the fatigue life and evolution rules of segmental lining. Based on the modified fatigue life formula and metro service life, the optimization design of the buried depth was carried out to determine the most reasonable range of the buried depth. This study provides a valuable reference for safe operation and long-term durability of metro tunnels under high-speed railways.

scholarly journals Study on Structural Service Performance of Heavy-Haul Railway Tunnel with Voided Base

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Zhiqiang Zhang ◽  
Bowen Zeng ◽  
Chaolong Dai ◽  
Wanping He
Keyword(s):  
Fatigue Life ◽  
Time History ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Dynamic Loads ◽  
Vehicle Body ◽  
Monitoring Point ◽  
Heavy Haul ◽  
Heavy Haul Railway

The structural design of heavy-haul railway tunnels still follows the design method of ordinary railway tunnels. Most of them do not take into account the influence of large axle load of 30 t or more, let alone such problems as void of surrounding rock under long-term dynamic loads. In order to analyze the dynamic response of heavy-haul railway tunnels under long-term reciprocating cyclic dynamic loads, considering the factors such as axle load of vehicle body, unsprung mass, and track irregularity, the vibration load time-history curve of heavy-haul railway trains is determined, the three-dimensional dynamics coupling model of dynamic load-tunnel-surrounding rock is established, and the fatigue life of the structure under different void conditions is analyzed based on the S-N curve of concrete. According to the study, the loading, unloading, and vibration caused by train passing will lead to fluctuations in the vertical displacement response of the monitoring point. The peaks and valleys of the response time-history curve correspond to the effect of the train wheels rolling through. When the void is 6 m wide and 10 cm thick, the vertical displacement of the inverted arch is increased by about 9 times, the peak velocity of the inverted arch is increased by about 3.8 times, and the maximum principal stress is increased by about 47.3%, compared with the condition without void. With the same void thickness, the vertical displacement and velocity curves of the inverted arch vary significantly with the increase of the void width. The width of the base void has a significant effect on the fatigue life of the structure of heavy-haul railway tunnels. Based on the operation requirement of 100-year service life, the ultimate void width is 2 m.

A System for Electromechanical Reliability Testing of MEMS Devices

2006 ◽  
Author(s):  
Stefan Spinner ◽  
Michael Doelle ◽  
Patrick Ruther ◽  
Oliver Paul ◽  
Ilia Polian ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Microelectromechanical Systems ◽  
Automated Analysis ◽  
Dynamic Loads ◽  
Reliability Testing ◽  
Mems Devices ◽  
Single Chip ◽  
Wafer Level ◽  
Optical Inspection

Abstract This paper reports on a setup and a method that enables automated analysis of mechanical stress impact on microelectromechanical systems (MEMS). In this setup both electrical and optical inspection are available. Reliability testing is possible on a single chip as well as on the wafer level. Mechanical stress is applied to the tested structure with programmable static forces up to 3.6 N and dynamic loads at frequencies up to 20 Hz. The applications of the presented system include the postmanufacturing test, characterization and stress screens as well as reliability studies. We report preliminary results of long-term reliability testing obtained for a CMOS-based stress sensor.

Dynamic Loads and Strength Requirements for Flapping Wing

2007 ◽  
Vol 348-349 ◽  
pp. 945-948 ◽  
Author(s):  
Peter Dabnichki ◽  
Marco La Mantia
Keyword(s):  
Wind Tunnel ◽  
Computer Program ◽  
Potential Flow ◽  
Hybrid Vehicle ◽  
Flapping Wing ◽  
Dynamic Loads ◽  
Experimental Simulation ◽  
Current Analysis ◽  
Harmonic Motion

The study is part of a wider biomimetic investigation focusing on flapping wing in water - penguin wing. The long-term aim is to design a hybrid vehicle capable of flying in fluids with very different densities. The paper analyses the dynamic loads on an oscillating wing used for obtaining the trust generated throughout harmonic motion. The strength requirements for such wing have not been analysed up to now and this study is to be followed shortly by experimental simulation in a wind-tunnel. The acting forces in the current analysis were obtained through a potential flow based panel method computer program.

scholarly journals A new design of support for burst-prone rock mass in underground ore mining

2018 ◽  
Vol 71 ◽  
pp. 00006 ◽  
Author(s):  
Krzysztof Skrzypkowski
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Tensile Tests ◽  
Rock Bolt ◽  
Dynamic Loads ◽  
Rock Bolting ◽  
Rock Bolt Support ◽  
Yielding Support ◽  
Bolt Support

The article presents the basic methods of strengthening room and roadway excavations in underground ore mining. In particular, it was pointed out that the mining support is very often exposed to additional dynamic loads resulting from the mining of the deposit by means of explosives (slight) as well as from the load arising from rock mass tremors. In the article a new design of arch yielding support adapted to dynamic loads, which can be used in long-term access excavations was proposed. For this case, an exemplary spring deflection, which is located in the support foot cylinder, based on the principle of work and energy was calculated. In the case of exploitation room excavations, laboratory tensile tests of the long expansion rock bolt support, which were carried out in the rock bolting laboratory at the Department of Underground Mining AGH were presented. Load-displacement characteristics for long expansion rock bolt support with a particular indication of the elastic and plastic range were presented. In the summary, it was concluded that with the increase in the depth of exploitation, safe and efficient mining will be possible only due to the use of a support with appropriate yielding.

scholarly journals Rheological Properties of Argillaceous Intercalation under the Combination of Static and Intermittent Dynamic Shear Loads

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xin Zhang ◽  
Qian Dong ◽  
Xiangping Zhang ◽  
Ming Lang ◽  
Suzhi Zhao ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Rock Slope ◽  
Soil Samples ◽  
Dynamic Loads ◽  
Shearing Stress ◽  
Dynamic Shear ◽  
Shear Loads ◽  
Dynamic Shearing ◽  
Static Shear

The construction and long-term operation stage of the rock slope with argillaceous interlayer will be subjected to intermittent dynamic loads, such as blasting and earthquake. For the argillaceous interlayer in the rock slope, its rheological properties are not only related to the initial stress state caused by the gravity of the overlying rock mass but also affected by intermittent dynamic loads. In order to investigate the rheological properties of argillaceous intercalation under the combination of static and intermittent dynamic shear loads, the rheological tests of argillic intercalated soil samples under static shear, static and cyclic dynamic shear, and static and intermittent dynamic shear were carried out, and the rheological deformation characteristics of soil samples under different shear conditions were analyzed. The results show that when the soil specimens in the static shear rheological process are disturbed by intermittent dynamic shearing load, the intermittent dynamic disturbances might have no remarkable influence on the rheological deformation of the specimens if the initial static shearing stress and intermittent dynamic shearing stress were comparatively low. However, low-intensity intermittent dynamic disturbances might accelerate the rheological deformation process of the specimens remarkably if the initial static shearing stress state was close to their shearing strength. There was a stress threshold when the soil specimens failed under the static and cycling dynamic shear and static and intermittent dynamic shear, which is determined by the sum of static shear stress and dynamic shear stress peak. For rock slopes controlled by rheological weak structural planes and influenced by long-term blasting vibrations, the transient and long-term dynamic stability should be comprehensively analyzed.

scholarly journals Design Provisions for An Easy Intervention in the Future Life of a Structure. The Case of the Post- Byzantine Timber-roofed Basilicas of Troodos Area in Cyprus

2019 ◽  
Vol 13 (1) ◽  
pp. 123-134
Author(s):  
Marios Pelekanos
Keyword(s):  
19Th Century ◽  
Seismic Design ◽  
Design Concept ◽  
Dynamic Loads ◽  
Late 19Th Century ◽  
Easy Task ◽  
The Future ◽  
Constructional Feature ◽  
Construction System

Background: This article deals with the timber- roofed basilicas of Troodos which were built from the mid-15th to the late-19th century AD. The most impressive constructional feature of these basilicas is the existence of two constructionally distinctive, but cooperating, parts of the roof. The basilicas’ construction system is mainly characterized by the ability to confront successfully the dynamic loads of an earthquake. Objective: This study investigates design provisions that can make easier any future intervention and retrofitting. Methods It is suggested that the design concept of these basilicas incorporated, among other objectives, a remarkable provision for an easy repair intervention and retrofitting, at a later stage during their life. The timber- roofed basilicas of Troodos demonstrate a cleverly designed structure, where the co-operation between the roof and masonry plays an important role in their anti-seismic design. Results and Conclusion: The timber-roofed basilicas of Troodos present a remarkable design provision that made intervention an easy task, at any stage of their future life. This particular design concept seems to be valuable even today and can be easily adopted when designing modern contemporary structures with a long-term life objective.

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