Travel Guides. & Seyed-Kolbadi, S. M. Seismic cracking and instability of concrete dams: Smeared crack approach. 2 and 22 arches. Rankovi V, Grujovi N, Divac D, Milivojevi N. Development of support vector regression identification model for prediction of dam structural behaviour. 4, 20 normal plumb lines (PL2PL5, PL6PL12, PL13-1, PL13-2, PL14PL21) used to monitor dam crest displacement are installed in No. It has undergone several reinforcements since it was put into service in the 1950s. These reinforcement projects are intended to prevent cracks. A large number of monitoring instruments provide a guarantee to master the change of water level, temperature, and the dam health state at all times. The maximum compressive stress of No. Ribeiro, L. S., Wilhelm, V. E., Faria, . F., Correa, J. M. & dos Santos, A. C. P. A comparative analysis of long-term concrete deformation models of a buttress dam. where D is an (m1) dependent variables vector of the dam displacement and m is the number of displacement measuring points. Qi He, Chongshi Gu, [], and Dongyang Yuan. 20 and and2121 respectively, in which No.12 and 13 buttresses are taken as examples. Fig. Support vector machine shows high accuracy in predicting dam displacement17,18. Media in category "Foziling Dam" The following 2 files are in this category, out of 2 total. It can be seen that: (1) There is a significant correlation between the radial displacements and season. 12 and 13 buttresses are 3.41 Mpa and 3.46 Mpa, respectively (cf. https://doi.org/10.1007/s11831-015-9157-9 (2015). (2) When there are no thermometers or few thermometers in the dam body and foundation, thermal displacement is generally assumed to follow the season evolution. The Foziling multi-arch dam, one of the few multi-arch dams in the world, was built on the bedrock with complicated geological conditions. & Loh, C.-H. 816 buttresses) as the midpoint, the tangential displacements of the buttresses on the left bank (No. 12 and 13 buttresses are 4.26 Mpa and 4.14 Mpa, respectively. 2 and 22 arches in C1 and C2. Dams play an important role in water supply, flood control, irrigation, navigation, sedimentation control, and hydropower generation. For instance, it is provided that the models based on the artificial neural network are more accurate in the prediction of the dam displacement than the MLR model13,14,15. (1982) suggests that the Earth's rotation slows by 0.005 seconds per year, every year (0.005 s/yr 2 ). It illustrates how temperature affects radial displacement, that is, the crest is displaced downstream when the temperature rises, and the crest is displaced upstream when the temperature drops. Theor. Struct. The previous record for the shortest rotation . Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. contribute to editing and reviewing the improvement of the manuscript. Jeon J, Lee J, Shin D, Park H. Development of dam safety management system. Yuan, D., Gu, C., Qin, X., Shao, C. & He, J. Performance-improved TSVR-based DHM model of super high arch dams using measured air temperature. J. Comput. Fig. Gan L, Shen Z-Z, Xu L-Q. Since the sensitivity of the multi-arch dam to temperature and the cumulative effect of deformation, the tangential displacements of No. Cheng L, Zheng D. Two online dam safety monitoring models based on the process of extracting environmental effect. https://doi.org/10.1016/j.engstruct.2019.05.043 (2019). 321 arches mainly occur at the elevation near 1/3 of the water depth in C1, and the maximum value reaches 3.54 Mpa, which is very similar to the distribution of the maximum compressive stress of buttresses. However, when they are viewed separately, their respective effects on the dam displacement are quite different. All of these indicate that the MLSR method performed well in fitting and predicting. 1316 arches, the steel pipes were reinforced in the buttresses, and shrinkage joints of each buttress were grouted. Monitoring date, MLSR model results for radial displacements at PL3, PL13-1 and PL21. Mata J. (4) The regression coefficients of Eq. This research was substantially supported by National Natural Science Foundation of China (Grant No. Long-term deformation analysis of the Jiudianxia concrete-faced rockfill dam. Valente, S., He, Q. 15c), and the crest of the buttress is displaced downstream when temperature drops (cf, Fig. The areas, the upstream and downstream surface of the arches and its left and right extensions 0.5m wide, were thickened by 0.15m and 0.1m, respectively. 3). Principal stresses under loading C2: (a) maximum and (b) minimum principal stresses on (i) arches, (ii) buttresses, (iii) No.12 buttress and (iv) No.13 buttress (unit: Pa). Combination forecast model for concrete dam displacement considering residual correction. It is necessary to point out that the harmonic function in HST models cannot effectively interpret the thermal displacement caused by the short-term dynamic temperature variations. In this case, d is taken as 6. In addition, fatigue damage may occur in areas with large stress variation, probably leading to crack initiation. Adv. As is shown in Fig. Because of the thin shape of the multi-arch dam, the influence of air temperature a month ago is accounted for in this study. Foziling Reservoir: 2020 Top Things to Do in Huoshan. https://doi.org/10.1016/j.advengsoft.2013.06.019 (2013). As for the arches, when the temperature rises, the buttresses are pushed downstream by the thrust induced by the thermal expansion of the connected arches (cf, Fig. foziling dam is worthy of being the first dam in new China and the first arch dam in Asia~#foziling hydropower station is also the first hydropower station in the Huaihe River Basin! Finally, a numerical model is established to investigate the stress state of the dam in different load cases. 2, the Foziling multi-arch dam is composed of 20 buttresses, 21 arches, and the gravity dam sections. Measured temperature inside and outside the insulation layer. where n is the number of samples; \(\delta_{i}\) and \(\hat{\delta }_{i}\) are the measured and calculated displacements, respectively; and \(\overline{\delta }\) is the mean value of measured displacement. Realized Price +43%. The solving steps of the MLSR model are as follows:(1) The optimal selection of model factors is started with no variables in the model, testing the addition of each variable by F-tests. In order to simplify the calculation, Td is set as T0, T1, T2, T35, T615, and T1630, where T0, T1, T2 are the measured air temperature of the monitoring day, the previous 1 and 2days, respectively; T35, T615 and T1630 are the average air temperature of the previous 3 to 5, 6 to 15 and 16 to 30days, respectively. Greater tensile stresses mainly occur close to the crown of No.2 and 22 arches and the bottom of arches and buttresses, especially in low temperature and high water level load cases. 3,13 and 21 buttresses. Valente S, Capriulo C, He Q. The observations from May 2006 to November 2016 are selected for training the model, while the observations from December 2016 to July 2018 are selected for testing the model. However, there is a shortcoming that over-fitting may occur. It can be seen that when the reservoir level is above H0 (113.92m), the radial displacement is positively correlated with the water level, i.e., the crest is displaced downstream as the water level rises, and vice versa. It can be seen that: (1) In the annual amplitude of the radial displacements of the No. orbit and such), then you have to take into account the rotation of the earth into the calculation of your target. Temperature contributes the most to the radial displacements of the buttresses, followed by water level, then time. [1] Because the rate of change of the rotation of the Earth is relatively predictable, we would predict a 22.7 hour-long day (in a year of 386.2 days) about 370 million years ago. Wang, Z., Liu, S., Vallejo, L. & Wang, L. Numerical analysis of the causes of face slab cracks in Gongboxia rockfill dam. Parameters about the dam body concrete and foundation rock, determining the stress strength and deformation characteristic, are important foundations for obtaining reliable results by numerical modeling. 12 and 13 buttresses reach 1.54 Mpa and 1.55 Mpa, respectively (cf. In the middle and lower areas of No. According to the results of the 2002 safety appraisal, the reservoir safety was rated as Class III, which belongs to the dangerous reservoir and needed reinforcement again. 181, 224232. Finally, the dam stress states in various operating conditions are evaluated by numerical simulation. Therefore, the flood control standard of the reservoir was improved. Three inverted plumb lines (IP3, IP13, IP21) used to monitor foundation deformation are installed in No.3, 13, and 21 buttresses. Foziling is a reservoir based project. Hence, only the water level and temperature variations are considered as the main loads after the geostatic state of the model. the display of certain parts of an article in other eReaders. Qu, X., Yang, J. Displacement observation, which is intuitive and reliable, and can explain the dam behavior itself, has been widely used in practice1,7,8. contribute to editing and reviewing the improvement of the manuscript. Control Health. With the construction of large and medium-sized reservoir project in the upper reaches of the Weihe River, irrigation works in the Weihe River basin have developed rapidly, and a number of irrigation projects have been built such as Xiaohe Irrigation Area, Weihe Irrigation Area and Wuyuan Canal Irrigation Area. 114, 2019. https://doi.org/10.1155/2019/4581672 (2019). Struct. It is not repeated here. Estimate . A compression-shear fracture growing on an arch-gravity dam. Follow @natureworld.02:) for more videos. Overview Nearby Reviews Win Prizes Details Recommended. Motion graphics animation of the planet at day time. where b and d are the statistical coefficients; T is the measured or average measured air temperature; d is the number of temperature factors. The measured and modeled displacements are shown in Fig. https://doi.org/10.1016/j.advengsoft.2008.10.009 (2009). How long is a full rotation on Earth? Arch. Sci. Fig. If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun? J. Eng. Water level fluctuations, dam displacements, and temperature variations including dam concrete, water in front of the dam, and ambient air, were continuously monitored during the operation of the reservoir. And the maximum values reach 1.46 Mpa and 1.27 Mpa, respectively. While the water level is below H0, the radial displacement is negatively correlated with the water level, i.e., the crest is displaced upstream as the water level decreases. https://doi.org/10.1002/stc.1575 (2014). 52, 4560. It has undergone several reinforcements since it was put into service in the 1950s. The calculations of these models are in the "black box", and no specific mathematical analytic expressions can be obtained to interpret the physical meaning of dam behavior. Article As the water level rises from low to high, the relationship between the displacement and the water level is firstly negative and then positive. The normal water level, design flood level, and check flood level of the dam are 125.56m (in the future), 125.97m, and 129.97m, respectively. In dam safety evaluation, the numerical simulation based on finite element models is often used to obtain the actual dam operation behavior3034. The above analysis results illustrate that temperature has the greatest influence on displacement. Figure16 reflects the relationship between the water pressure component and water level change. The maximum compressive stress of No. These spin-axis movements are scientifically referred to as "polar motion." Measurements for the 20 th century show that the spin axis drifted about 4 inches (10 centimeters) per year. Health Monit. However, on June 29, 2022 our planet completed its quickest-ever spin, followed quickly by a day that lasted 1.50 milliseconds less on July 26, 2022. The reason is that when the water level is lower (H
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