scholarly journals Influence of Ground Temperature on Shotcrete-to-Rock Adhesion in Tunnels

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Limin Duan ◽  
Yuanhang Zhang ◽  
Jinxing Lai
Keyword(s):  
High Temperature ◽  
Adhesion Strength ◽  
Detrimental Effect ◽  
Ground Temperature ◽  
Geothermal Heat ◽  
Factors Affecting ◽  
Temperature And Humidity ◽  
Geothermal Environments ◽  
Relevant Factors

Long and deep tunnels are increasingly designed and built worldwide, often in severe geothermal environments characterized by high temperature in the rocks. This issue cannot be ignored because high temperature definitely affects the strength of the adhesion between the concrete and the surrounding rocks, whatever the lining cast in place, segmental or sprayed using shotcrete. The causes of geothermal heat and the effect of the temperature on tunnel linings during and after their construction are recalled and discussed in this paper. Both temperature and humidity are shown to be the most relevant factors affecting adhesion strength, whose loss is related to the microdamage in the shotcrete layers closest to the rock. Possible ways to improve adhesion strength and to minimize the high-temperature detrimental effect are also presented and discussed.

Effect of Temperature and Humidity on Degradation Behavior of Cu/Epoxy Interface under High Temperature and High Humidity Aging

2021 ◽  
Vol 1016 ◽  
pp. 1436-1442
Author(s):  
Riku Suzuki ◽  
Ikuo Shohji ◽  
Tatsuya Kobayashi ◽  
Yu Tonozuka
Keyword(s):  
High Temperature ◽  
Adhesion Strength ◽  
Degradation Mechanism ◽  
Effect Of Temperature ◽  
Joint Interface ◽  
High Humidity ◽  
Degradation Behavior ◽  
Temperature And Humidity ◽  
High Humidity Environment ◽  
Humidity Environment

This article reports on the degradation behavior of adhesion strength of the resin/copper interface under aging in high temperature and high humidity environment. The adhesion strength of a Cu joint with resin was investigated by a tensile test. The fracture surface was analyzed by Fourier transform infrared spectroscopy to investigate the degradation mechanism. As a result, it was found that the degradation of the adhesion strength is mainly caused by water absorption and subsequent volume expansion of the resin, and embrittlement of hydrogen bonding in the joint interface. Evaluation of deterioration life of the joint revealed that the relationships between the deterioration life and the temperature and humidity are confirmed above the glass transition temperature.

scholarly journals Laboratory-Scale Processing and Performance Assessment of Ti–Ta High-Temperature Shape Memory Spring Actuators

2021 ◽  
Author(s):  
A. Paulsen ◽  
H. Dumlu ◽  
D. Piorunek ◽  
D. Langenkämper ◽  
J. Frenzel ◽  
...  
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Detrimental Effect ◽  
Wire Drawing ◽  
Fast Heating ◽  
Heating And Cooling ◽  
Arc Melting ◽  
Ω Phase ◽  
And Performance

AbstractTi75Ta25 high-temperature shape memory alloys exhibit a number of features which make it difficult to use them as spring actuators. These include the high melting point of Ta (close to 3000 °C), the affinity of Ti to oxygen which leads to the formation of brittle α-case layers and the tendency to precipitate the ω-phase, which suppresses the martensitic transformation. The present work represents a case study which shows how one can overcome these issues and manufacture high quality Ti75Ta25 tensile spring actuators. The work focusses on processing (arc melting, arc welding, wire drawing, surface treatments and actuator spring geometry setting) and on cyclic actuator testing. It is shown how one can minimize the detrimental effect of ω-phase formation and ensure stable high-temperature actuation by fast heating and cooling and by intermediate rejuvenation anneals. The results are discussed on the basis of fundamental Ti–Ta metallurgy and in the light of Ni–Ti spring actuator performance.

scholarly journals Growth behavior of tin whisker and hillock on Cu/Ni/SnAg micro-bumps under high temperature and humidity storage

2021 ◽  
Vol 9 ◽  
pp. 100060
Author(s):  
Ke Lin ◽  
Jing Wang ◽  
Chenlin Yang ◽  
Menglong Sun ◽  
Anmin Hu ◽  
...  
Keyword(s):  
High Temperature ◽  
Growth Behavior ◽  
Tin Whisker ◽  
Temperature And Humidity

Behavioural aspects of microhabitat segregation of different age stages in the wetland land snail Vertigo moulinsiana (Eupulmonata: Vertiginidae) in the laboratory

2020 ◽  
Vol 86 (3) ◽  
pp. 228-232
Author(s):  
Zofia Książkiewicz-Parulska
Keyword(s):  
High Temperature ◽  
Land Snail ◽  
Snail Species ◽  
High Humidity ◽  
Short Period ◽  
Temperature And Humidity ◽  
In The Wild ◽  
Different Response ◽  
Behavioural Aspects ◽  
Microhabitat Segregation

ABSTRACT This laboratory study investigated behavioural differences between adults and juveniles of the wetland land snail species Vertigo moulinsiana with respect to temperature and humidity. Juveniles of V. moulinsiana, for example, tend to remain within the shaded, humid and cool layer of the litter, while adults usually climb above wet vegetation to a height of over 2 m. Adults are thus exposed to greater variation in temperature and humidity than juveniles. My experiments showed that adults of V. moulinsiana remain active longer than juveniles when subject to high temperature (36 °C) and low relative humidity (RH 30%). Conversely, juveniles stay active longer than adults in high humidity (22 °C, RH 100%). A short period of starvation lengthened the time needed for the juveniles to become active after dormancy, possibly indicating a different response between adults and juveniles to lack of nutritional reserves. These behavioural differences to food availability and the risk of water loss correspond to the microhabitat differences observed between adults and juveniles in the wild.

High Temperature Creep Behavior of Austenitic Fe-Ni-Cr Alloy

2013 ◽  
Vol 686 ◽  
pp. 170-179 ◽  
Author(s):  
Esah Hamzah ◽  
Maureen Mudang ◽  
Ang Khwang Jenq ◽  
Muhammad Adil Khattak
Keyword(s):  
High Temperature ◽  
Detrimental Effect ◽  
Creep Damage ◽  
Transgranular Fracture ◽  
Creep Fracture ◽  
Secondary Stage ◽  
Tertiary Stage ◽  
The Difference ◽  
Temperature Test ◽  
Section Form

Creep damage investigation was carried out in Fe-Ni-Cr alloy at 800°C, 900°C, and 983°C using rectangular section form of specimen. In all the tests conducted on this material, some creep curves showed primary stage, secondary stage and tertiary stage. The creep fracture shows ductile transgranular fracture where separation occurred at the dendrites carbide interface suggesting that the detrimental effect of creep was compounded by precipitation of carbides at matrix. The presence of cavities may be due to the difference in thermal expansion characteristics of the austenite and carbide during high temperature test. Coarsening of carbides lead to cavities formation within the dendrite and carbide interface and form cavities linkage due to formation of crack and finally cause creep fracture. Increase in creep temperature it will lead to increase in creep rate. The fracture modes of creep samples were investigated to predict the failure mode.

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