This paper describes the main features related to lateral displacements with depth after successive lateral loading–unloading cycles applied to the top of reinforced-concrete flexible bored piles embedded in naturally bonded residual soil. The bored piles under study have a cylindrical shape, with 0.40-m in diameter and 8.0-m in length. Both bored piles types (P1 and P2) include an embedded steel pipe section in their center as longitudinal steel reinforcements: pile type P1 has another 16 steel rods as steel reinforcement to concrete while pile type P2 has no further steel reinforcement. Pile type P1 has three times as much stiffness (EI) and four and a half times the plastic moment (My) than pile type P2. A similar load–displacement performance was observed at initial loads as for small displacements of both piles. At this initial loading stage, the response of the reinforced concrete piles is a function of the soil characteristics and of a linear elastic pile deformation. During this stage, piles can even be understood as probes for evaluating soil reactions. For larger horizontal displacements, after the concrete section starts undergoing large deformations, approaching the ultimate bending moment, pile behavior and consequently the load–displacement relation starts to diverge for both piles. For pile P1 the values of relevant lateral displacements are extended to about 2.5-m in depth, while for pile P2 lateral displacements are mostly constrained to about 2.0-m in depth. Measurements of horizontal displacements of pile P1 against depth recorded with a slope indicator show that, after unloading, lateral loads at distinct stages (small and near failure loads), exhibits a much higher elastic phase of the system response. An analytical fitting model of soil reaction is proposed based on the measured displacements from slope indicator. The integration of a continuous model proposed for the soil reaction agrees fairly well with the measured displacements up to moments close to plastic limit. Results of load–displacement show that the stiffer pile (P1) was able to mobilize twice as much lateral load compared to pile P2 for a service limit displacement of about 20 mm. The paper shows results that enable the isolation of the structural variable through real scale pile load tests, thus granting understanding of its importance and enabling its quantitative visualization in examples of piles embedded in residual soil sites.
Hydrogeology Journal - The dynamics related to evolution of nitrate-contaminated groundwater are analyzed with focus on the impact of intrinsic aquifer properties, agricultural activities and... 相似文献
Landslides - This article describes the behavior of a talus-colluvium deposit up to 70-m thick located in the Serra dos Orgaos, Rio de Janeiro/RJ, Brazil. The monitoring dataset of 13 years... 相似文献
We present new U-Pb zircon and monazite ages from the Sunsas belt granitic magmatism in Bolivia,SW Amazonian Craton.The geochronological results revealed four major magmatic events recorded along the Sunsas belt domains.The older igneous event formed a granitic basement coeval to the Rio Apa Terrane(1.95-1.85 Ga)in the southern domain.The second magmatic episode is represented by 1.68 Ga granites associated to the Paraguá Terrane(1.69-1.66 Ga)in the northern domain.The 1.37-1.34 Ga granites related to San Ignacio orogeny represent the third and more pervasive magmatic event,recorded throughout the Sunsas belt.Moreover,magmatic ages of～1.42 Ga revealed that the granitogenesis asso-ciated to the Santa Helena orogeny also affected the Sunsas belt,indicating that it was not restricted to the Jauru Terrane.Lastly,the 1.10-1.04 Ga youngest magmatism was developed during the Sunsas oro-geny and represents the final magmatic evolution related to Rodinia assembly.Likewise,the 1.95-1.85 and 1.68 Ga inherited zircon cores obtained in the～1.3 Ga and 1.0 Ga granite samples suggest strong par-tial melting of the Paleoproterozoic sources.The 1079±14 Ma and 1018±6 Ma monazite crystallization ages can be correlated to the collisional tectono-thermal event of the Sunsas orogeny,associated to reac-tions of medium-to high-grade metamorphism.Thus,the Sunsas belt was built by heterogeneous 1.95-1.85 Ga and 1.68 Ga crustal fragments that were reworked at 1.37-1.34 Ga and 1.10-1.04 Ga related to orogenic collages.Furthermore,the 1.01 Ga monazite age suggests that granites previously dated by zir-con can bear evidence of a younger thermal history.Therefore,the geochronological evolution of the Sunsas belt may have been more complex than previously thought. 相似文献
Having a better understanding of air pollutants in railway systems is crucial to ensure a clean public transport. This study measured, for the first time in Brazil, nanoparticles (NPs) and black carbon (BC) on two ground-level platforms and inside trains of the Metropolitan Area of Porto Alegre (MAPA). An intense sampling campaign during thirteen consecutive months was carried out and the chemical composition of NPs was examined by advanced microscopy techniques. The results showed that highest concentrations of the pollutants occur in colder seasons and influenced by variables such as frequency of the trains and passenger densities. Also, internal and external sources of pollution at the stations were identified. The predominance of NPs enriched with metals that increase oxidative stress like Cd, Fe, Pb, Cr, Zn, Ni, V, Hg, Sn, and Ba both on the platforms and inside trains, including Fe-minerals as hematite and magnetite, represents a critical risk to the health of passengers and employees of the system. This interdisciplinary and multi-analytical study aims to provide an improved understanding of reported adverse health effects induced by railway system aerosols. 相似文献
Empirical evidence has shown that particle breakage affects the mechanical behaviour of granular materials. The source of this mechanism takes place at the particle scale, and the main consequence on the macromechanical behaviour is increasing compressibility. Due to the inverse correlation between particle size and particle crushing strength, coarse rockfill materials are particularly vulnerable to mechanical degradation due to particle breakage. However, such coarse materials do not fit in standard laboratory devices, and the alternative of large sample testing is usually unavailable or too expensive. Alternatively, recent works have proposed multi-scale approaches using the discrete element method (DEM) to carry out numerical testing of coarse crushable materials, although few studies have focused on size effects. This article presents the application of a DEM bonded-cell model to study particle size-strength correlation on angular rock aggregates. Each particle is modelled by a cluster of perfectly rigid polyhedral cells with Mohr–Coulomb contact law. Constant cell density within particles implies that the presence of potential fragmentation planes increases with size. Therefore, particle strength decreases with size. A comprehensive sensitivity analysis was carried out through 1477 particle crushing simulations in a given particle size. Based on published experimental data on calcareous rock aggregates, part of the simulations were used for calibration, and 97 additional simulations of a coarser size fraction were performed for validation. The results show a good agreement with the empirical data in terms of size effect and data scatter through Weibull statistics.
Mathematical Geosciences - A data-driven automatic well planner procedure is implemented to develop complex well trajectories by efficiently adapting to near-well reservoir properties and geometry.... 相似文献
Achieving long-term climate mitigation goals in Japan faces several challenges, starting with the uncertain nuclear power policy after the 2011 earthquake, the uncertain availability and progress of energy technologies, as well as energy security concerns in light of a high dependency on fuel imports. The combined weight of these challenges needs to be clarified in terms of the energy system and macroeconomic impacts. We applied a general equilibrium energy economic model to assess these impacts on an 80% emission reduction target by 2050 considering several alternative scenarios for nuclear power deployment, technology availability, end use energy efficiency, and the price of fossil fuels. We found that achieving the mitigation target was feasible for all scenarios, with considerable reductions in total energy consumption (39%–50%), higher shares of low-carbon sources (43%–72% compared to 15%), and larger shares of electricity in the final energy supply (51%–58% compared to 42%). The economic impacts of limiting nuclear power by 2050 (3.5% GDP loss) were small compared to the lack of carbon capture and storage (CCS) (6.4% GDP loss). Mitigation scenarios led to an improvement in energy security indicators (trade dependency and diversity of primary energy sources) even in the absence of nuclear power. Moreover, preliminary analysis indicates that expanding the range of renewable energy resources can lower the macroeconomic impacts of the long term target considerably, and thus further in depth analysis is needed on this aspect.
Key policy insights
For Japan, an emissions reduction target of 80% by 2050 is feasible without nuclear power or CCS.
The macroeconomic impact of such a 2050 target was largest without CCS, and smallest without nuclear power.
Energy security indicators improved in mitigation scenarios compared to the baseline.
Upwelling areas are among the most productive ecosystems on the planet, influencing the biology of marine organisms. This study investigated the population dynamics of the shrimp Artemesia longinaris in two regions in southeastern Brazil, one inside (Macaé—Rio de Janeiro State) and one outside (Ubatuba—State of São Paulo) the Cabo Frio upwelling area. The aim was to verify the influence of the upwelling phenomenon on the abundance, growth, longevity, size of sexual maturity, and reproductive period of the species. In total, 188,902 individuals were captured at Macaé and 3,461 at Ubatuba. Individuals captured at Macaé showed larger maximum size, higher longevity, and slower growth rate, besides reaching sexual maturity at larger sizes than at Ubatuba. Continuous reproduction was observed in both regions, with juvenile recruitment peaks in spring and summer. Local conditions observed at Macaé were influenced by the Cabo Frio upwelling zone, characterized by productive and cooler waters that are around 20°C during most of the year. The upwelling phenomenon is probably the main factor influencing the population parameters studied here, changing the geographic patterns previously observed for the variation of these parameters in A. longinaris. 相似文献
If point absorbers are employed in the extensive exploitation of the offshore wave energy resource, they should be deployed in arrays, the distance between the elements in the array being possibly tens of meters. In such cases, it may be more convenient that the array is spread moored to the sea bottom through only some of its elements, located in the periphery, while the other array elements are prevented from drifting and colliding with each other by connections to adjacent elements. An array of identical floating point absorbers located at the grid points of an equilateral triangular grid is considered in the paper. A spread set of slack-mooring lines connect the peripheric floaters to the bottom. A weight is located at the centre of each triangle whose function is to pull the three floaters towards each other and keep the inter-body mooring lines under tension. The power take-off system (PTO) is a linear damper activated by the buoy heaving motion. The whole system–buoys, moorings and power take-off systems–is assumed linear, so that a frequency domain analysis may be employed. Hydrodynamic interference between the oscillating buoys in array is accounted for. Equations are presented for a set of three identical point absorbers. This is then extended to more complex equilateral triangular grid arrays. Results from numerical simulations, with regular and irregular waves, are presented for the motions and power absorption of hemispherical converters in arrays of three and seven elements and for different mooring parameters and wave incidence angles. Comparisons are given with the unmoored and independently-moored buoy situations. 相似文献
