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Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Vibration, Measurement & Diagnosis is the property of Nanjing Hangkong Daxue and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Large blocks of drift ice have posed a strong impact on the open channels in the long-distance water delivery projects in the alpine regions. The drift ice is easy to form with the different speeds and compression strength in the high latitudes of northwestern China, especially the north of 35°N latitude. Particularly, the ice period lasts for 4 to 5 months in the cold and dry winter, covering from the freezing in November to the open in the following spring. The long-term collision of drift ice can cause some serious damage to the concrete lining of an open channel, such as cracking or peeling of the surface. The lining structure can result in different degrees of damage and deformation, even a threat to the long-term stability of water supply, including the safe operation of the open channel, irrigation of farmland, and water use for humans and animals. Therefore, this study aims to clarify the impact of the drift ice on the open delivery channels in the long-distance water delivery projects in the alpine regions. A collision model of the drift ice and open channels was also established as a water-air coupling medium using the ANSYS/LS-DYNA platform. Specifically, the collision motion equation of drift ice in the open channel was obtained, according to the display of time integration. The contact-collision process was assumed as a symmetric penalty function. The fluid-structure coupling calculation was then implemented considering the coupling effect between water-air-flow ice-open channels. After that, LS-DYNA SOLVER software was used to simulate the collision and extrusion of drift ice and open channel under different working conditions. As such, the degree of the collision was classified to evaluate the damage caused by the drift ice to the lining of the open channel. An indoor model test was carried out to verify the model. A damage law of drift ice was thus found in the water-air coupling medium when colliding with the open channel. The results showed that there was an approximate Pseudo-Voigt function peak curve relationship for the maximum equivalent stress and the maximum displacement in the X direction of the impact of the ice velocity on the open channel lining. Besides, there was an approximately linear relationship for the maximum equivalent stress and the maximum displacement in the X direction of the impact of drift ice compression strength on the lining of open channels. Furthermore, a combination interval posed a significant impact on the open channel lining, where the compressive strength of the flowing ice was 1.825-3.199 MPa, and the speed of the flowing ice was 3.5-4.5 m/s. This equivalent stress value of impact was 4.3-16.8 MPa, and the maximum displacement value in the X direction was 2.59×10-5-5.52×10-5 m. More importantly, a two-factor combination was posed the greatest impact on the open channel lining impact, where the flow ice compression strength of 3.059 MPa, and the flow ice velocity of 4.0 m/s. This equivalent stress value of impact was 16.8 MPa, and the maximum displacement value in the X direction was 5.52×10-5 m. By contrast, the combination interval presented a fewer outstanding impact on the open channel lining, where the drift ice velocity of 0.5-1.0 m/s, and the compressive strength was 1.825-2.375 MPa. This equivalent stress of impact was 0.7-2.8 MPa, and the maximum displacement in the X direction was 0.24×10-5-0.52×10-5 m. Therefore, there was a significant correlation between the temperature and the compressive strength of drift ice, while the flow velocity and the speed of drift ice. Correspondingly, the influence of the ice load needed to be considered in the design stage of the open channel lining structure. The findings can also provide sound theoretical and technical support to the safe operation of long-distance water transportation projects for the alpine regions in winter. [ABSTRACT FROM AUTHOR]

Copyright of Yellow River is the property of Editorial Board of Yellow River and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In high latitude region of western China, the environment is in harsh condition that it is cold and dry in winter and has long ice period, which causes many water resource problems. In order to relieve the serious water shortage condition in cold and dry region, a large number of long distance water diversion projects were established to improve the water resource condition, such as increasing farm irrigation, human and animal drinking. While the ice damage occurs frequently under severe ice conditions in cold and dry region, especially in ice period in winter and thawing period in spring, it is easy to form drift ice with different velocities, different plan sizes and different thicknesses, which produces different extrusion forces or impact forces to damage tunnel lining, causing project failure. The failure project could not realize the original planning and construction goal, giving rise to the water allocation pressure. The water allocation would cause water shortage which influences diversion irrigation and farming production in spring. Based on the intense researches on the collision simulation problem of the interaction between drift ice and diversion tunnel, this paper used the symmetric penalty function in the finite element contact-impact algorithm to conduct the theoretical study on collision simulation problem between drift ice and water diversion tunnel. ANSYS/LS-DYNA was adopted as the platform to establish tunnel model and drift ice model. LS-DYNA SOLVER was used as the solver to solve and analyze the damage degrees of drift ice on tunnel. The physical model tests were conducted to verify and reveal the impact damage mechanism of drift ice on diversion tunnel. The physical model was constructed by the geometric scale of 28, which is the ratio of the experiment facility to the prototype in the test. The results show that tunnel lining surface will form varying degrees of deformation and failure when the tunnel lining is impacted by the drift ice with different velocities, different plane sizes and different thicknesses. It is also discovered that the impact stress increases with the flow velocity and their relationship presents linear variation. The impact stress also increases with the drift ice’s plane size and their relationship presents nonlinear variation. The impact stress increases with the drift ice thickness when the drift ice thickness is less than 0.5 m. While the drift ice thickness is greater than 0.5 m, the maximum stress value shows little change. The relationship between drift ice’s plane size and maximum stress shows approximately linear variation. Meanwhile, the software simulation and test observation results are almost the same. The impact of drift ice on the tunnel lining would cause the deformation of lining, but the deformation has little influence on the tunnel stability. The drift ice’s long time erosion would cause the tunnel lining surface to fall off, and further break the strength and stability of the tunnel structures. The study supplies theoretical support and technical guarantee for water diversion project security in cold and dry region of western China. [ABSTRACT FROM AUTHOR]