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Elyas Hayati Ehsan Abdi Mohsen Mohseni Saravi John L. Nieber Baris Majnounian Giovanni B. Chirico 《水文研究》2018,32(16):2570-2583
An experimental campaign was set up to quantify the contribution of evapotranspiration fluxes on hillslope hydrology and stability for different forest vegetation cover types. Three adjacent hillslopes, respectively, covered by hardwood, softwood, and grass were instrumented with nine access tubes each to monitor soil water dynamics at the three depths of 30, 60, and 100 cm, using a PR2/6 profile probe (Delta‐T Devices Ltd) for about 6 months including wet periods. Soil was drier under softwood and wetter under grass at all the three depths during most of the monitoring period. Matric suction derived via the soil moisture measurements was more responsive to changes in the atmospheric conditions and also recovered faster at the 30 cm depth. Results showed no significant differences between mean matric suction under hardwood (101.6 kPa) with that under either softwood or grass cover. However, a significant difference was found between mean matric suction under softwood (137.5 kPa) and grass (84.3 kPa). Results revealed that, during the wettest period, the hydrological effects from all three vegetation covers were substantial at the 30 cm depth, whereas the contribution from grass cover at 60 cm (2.0 kPa) and 100 cm (1.1 kPa) depths and from hardwood trees at 100 cm depth (1.2 kPa) was negligible. It is surmised that potential instability would have occurred at these larger depths along hillslopes where shallow hillslope failures are most likely to occur in the region. The hydrological effects from softwood trees, 8.1 and 3.9 kPa, were significant as the corresponding factor of safety values showed stable conditions at both depths of 60 and 100 cm, respectively. Therefore, the considerable hydrological reinforcing effects from softwood trees to the 100 cm depth suggest that a hillslope stability analysis would show that hillslopes with softwood trees will be stable even during the wet season. 相似文献
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Soil water dynamics under different forest vegetation cover: Implications for hillslope stability 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Elyas Hayati Ehsan Abdi Mohsen Mohseni Saravi John L. Nieber Baris Majnounian Giovanni B. Chirico Bruce Wilson Moharramali Nazarirad 《地球表面变化过程与地形》2018,43(10):2106-2120
Though it is well known that vegetation affects the water balance of soils through canopy interception and evapotranspiration, its hydrological contribution to soil hydrology and stability is yet to be fully quantified. To improve understanding of this hydrological process, soil water dynamics have been monitored at three adjacent hillslopes with different vegetation covers (deciduous tree cover, coniferous tree cover, and grass cover), for nine months from December 2014 to September 2015. The monitored soil moisture values were translated into soil matric suction (SMS) values to facilitate the analysis of hillslope stability. Our observations showed significant seasonal variations in SMS for each vegetation cover condition. However, a significant difference between different vegetation covers was only evident during the winter season where the mean SMS under coniferous tree cover (83.6 kPa) was significantly greater than that under grass cover (41 kPa). The hydrological reinforcing contribution due to matric suction was highest for the hillslope with coniferous tree cover, while the hillslope with deciduous tree cover was second and the hillslope with grass cover was third. The greatest contributions for all cover types were during the summer season. During the winter season, the wettest period of the monitoring study, the additional hydrological reinforcing contributions provided by the deciduous tree cover (1.5 to 6.5 kPa) or the grass cover (0.9 to 5.4 kPa) were insufficient to avoid potential slope failure conditions. However, the additional hydrological reinforcing contribution from the coniferous tree cover (5.8 to 10.4 kPa) was sufficient to provide potentially stable hillslope conditions during the winter season. Our study clearly suggests that during the winter season the hydrological effects from both deciduous tree and grass covers are insufficient to promote slope stability, while the hydrological reinforcing effects from the coniferous tree cover are sufficient even during the winter season. Copyright © 2018 John Wiley & Sons, Ltd. 相似文献
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Investigation of the relationship of seismic intensity measures and the accumulation of damage on concrete gravity dams using incremental dynamic analysis 下载免费PDF全文
下载免费PDF全文 Nonlinear analysis tools are gaining prominence for the design and evaluation of concrete gravity dams. The performance limits of concrete gravity dams within the framework of performance based design are challenging to determine in comparison to those used for the assessments based on linear elastic analyses. The uncertainty in quantifying the behavior of these systems and the strong dependence of the behavior on the ground motion play an important role. The purpose of the study is to quantify the damage levels on a representative monolith using incremental dynamic analysis (IDA). For this purpose, the constitutive model utilized was calibrated first to the existing experimental results to verify the ability of the utilized cracking model to simulate the crack propagation process. Next, the relation between the damage levels on the monolith and the ground motion characteristics was investigated. The results of the conducted IDA showed that the engineering demand parameters (EDP) such as the crest displacement and acceleration showed weak correlation with the damage states. The spectral velocity and the peak ground acceleration were determined to be better predictors for the damage on the monolith. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Baris Anna Spacagna Rose Line Paolella Luca Koseki Junichi Modoni Giuseppe 《Bulletin of Earthquake Engineering》2021,19(10):3963-3986
Bulletin of Earthquake Engineering - The damage on supply and drainage water networks is a serious cause of economic disruption for urban systems affected by earthquakes. Among various concerns,... 相似文献
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Observing permanent seals with different physical and mechanical characteristics under various conditions in the field is almost impossible. In conjunction with the development of high-speed computer algorithms, numerical simulation has become one of the major means to study the dynamics of such problems. Therefore, this study covers only the numerical approach to analyze the stability of underground seals. In this regard, the purpose of this study is to provide an insight to the design of underground seals by numerically analyzing their behaviors under different static and dynamic explosion overpressures using a geo-technical commercial software FLAC3D. For this purpose, a series of numerical models were constructed for a typical seal in an underground gallery with different properties such as seal thickness, seal dimensions, gallery geometry, and strength of the seal material to investigate the stability of seals exposed to various static and dynamic explosion overpressures. A total of 896 numerical analyses (512 static and 384 dynamic) were performed and evaluated. Regarding the gallery geometry, it was found that seals constructed in trapeze-shaped galleries are more stable than those constructed in horseshoe-shaped galleries having the same dimensions. Moreover, the results showed that the seal stability increases with the increasing seal thickness rather than the strength of the seal material. The statistical analyses suggest that there is a very strong exponential relationship between the seal thickness and the maximum displacement measured at the midpoints of the outer surfaces of the seals. The coefficients of determination values obtained are in the range of 0.92–0.93 and 0.92–0.95 for static and dynamic analyses, respectively. We proposed formulas which use the longer dimension of the seal (W max ), maximum allowable displacement on the seal (D max ), explosion overpressure applied onto the seal (P exp ), and compressive strength of the seal material (σ c and σ cd for static and dynamic conditions, respectively) to predict the minimum required seal thickness (T s ) for static and dynamic conditions. The proposed formulas enable calculating the necessary seal thickness easily if the explosion overpressure (or hydrostatic pressure) is known or approximated. 相似文献
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Deniz Bozkurt Ufuk Turuncoglu Omer Lutfi Sen Baris Onol H. Nuzhet Dalfes 《Climate Dynamics》2012,39(1-2):207-225
The outputs of three GCMs, ECHAM5, CCSM3 and HadCM3, are downscaled for the eastern Mediterranean–Black Sea region for the period 1961–1990 using a regional climate model, RegCM3, to assess the capability of these models in simulating the climatology of the region. In addition, the NCEP/NCAR Reanalysis data are also downscaled for the same period to display the performance of the regional climate model for the same region, which constitutes a relatively complex terrain and rich variety of climates. The gridded observational dataset of CRU is primarily used in the evaluation of the models, however, a regional dataset, which is based on a relatively dense gauging network, is also used to see how it affects the performance measures of the models. The reanalysis simulation indicates that RegCM3 is able to simulate the precipitation and surface temperature as well as the upper level fields reasonably well. However, it tends to overestimate the precipitation over the mountainous areas. All three GCM models are found to be highly skilled in simulating the winter precipitation and temperature in the region. The two models, ECHAM5 and HadCM3, are also good at simulating the summer precipitation and temperature, but the CCSM3 simulation generates dryer and warmer conditions than the observations for the whole region, which are most likely a result of the dryness in the upper levels of the original outputs. The use of the regional observational dataset does not necessarily improve the pattern correlations, but it yields better match between the modeled and observed precipitation in terms of variability and root-mean-square difference. It could be said that the outputs of these GCMs can be used in the climate change downscaling and impact assessment studies for the region, given that their strengths and weaknesses that are displayed in the present study are considered. 相似文献
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This paper employs a computable general equilibrium model (CGE) to analyse how a carbon tax and/or a national Emissions Trading System (ETS) would affect macroeconomic parameters in Turkey. The modelling work is based on three main policy options for the government by 2030, in the context of Turkey’s mitigation target under its Intended Nationally Determined Contribution (INDC), that is, reducing greenhouse gas (GHG) emissions by up to 21% from its Business as Usual (BAU) scenario in 2030: (i) improving the productivity of renewable energy by 1% per annum, a target already included in the INDC, (ii) introducing a new flat rate tax of 15% per ton of CO2 (of a reference carbon price in world markets) imposed on emissions originating from carbon-intensive sectors, and (iii) introducing a new ETS with caps on emission permits. Our base path scenario projects that GHG emissions in 2030 will be much lower than Turkey’s BAU trajectory of growth from 430 Mt CO2-eq in 2013 to 1.175 Mt CO2-eq by 2030, implying that the government’s commitment is largely redundant. On the other hand, if the official target is assumed to be only a simple reduction percentage in 2030 (by 21%), but based on our more realistic base path, the government’s current renewable energy plans will not be sufficient to reach it.
Turkey’s official INDC is based on over-optimistic assumptions of GDP growth and a highly carbon-intensive development pathway;
A carbon tax and/or an ETS would be required to reach the 21% reduction target over a realistic base path scenario for 2030;
The policy options considered in this paper have some effects on major sectors’ shares in total value-added. Yet the reduction in the shares of agriculture, industry, and transportation does not go beyond 1%, while the service sector seems to benefit from most of the policy options;
Overall employment would be affected positively by the renewable energy target, carbon tax, and ETS through the creation of new jobs;
Unemployment rates are lower, economic growth is stronger, and households become better off to a larger extent under an ETS than carbon taxation.
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Two‐story, three‐bay reinforced concrete (RC) frames with and without internal steel frame (ISF) retrofits were tested using continuous pseudo dynamic test method. The ISFs were installed to the middle bay of the RC frame. Test results indicated that ISF retrofit was beneficial in resisting deformation demands without significant damage under simulated ground motions. The ISF shifted the failure mode of the system from a brittle to a ductile mode. The test results were compared with the results of the nonlinear time history analysis. The analysis results were capable of tracing the overall behavior of global response parameters; however, estimations of local demand parameters were less accurate. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Inspired from the simplified single degree of freedom modeling approach used in the preliminary design of concrete gravity dams, a pseudo‐dynamic testing method was devised for the seismic testing of a concrete gravity dam section. The test specimen was a 1/75 scaled section of the 120‐m‐high monolith of the Melen Dam, one of the highest concrete gravity dams to be built in Turkey. The single degree of freedom idealization of the dam section was validated in the first stage of the study using numerical simulations including the dam–reservoir interaction. Afterwards, pseudo‐dynamic testing was conducted on the specimen using three ground motions corresponding to different hazard levels. Lateral displacement and base shear demands were measured. The crack propagation at the base of the dam was monitored with the measurement of the crack widths and the base sliding displacements. After the pseudo‐dynamic loading, a static pushover test was conducted to determine the reserve capacity of the test specimen. Despite major cracking at the base of the monolith, neither significant sliding nor a stability problem that might jeopardize the stability of the dam was observed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献