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The developed vertical coupling model of Vehicle-Track-Subgrade which considered subgrade layer vibration is present-ed. The equations of motion for the ballast, top and bottom subgrade layers are pres... 相似文献
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By large-scale dynamic tests carried out on a traditional sand-gravel embankment at the Beilu River section along the Qinghai-Tibet Railroad, we collected the acceleration waveforms close to the railway tracks when trains passed. The dynamic train loading was converted into an equivalent creep stress, using an equivalent static force method. Also, the creep equation of frozen soil was introduced according to the results of frozen soil rheological triaxial tests. A coupled creep model based on a time-hardening power function rule and the Druker-Prager yield and failure criterion was established to analyze the creep effects of a plain fill embankment under repeated train loads. The temperature field of the embankment in the permafrost area was set at the current geothermal conditions. As a result, the permanent deformation of the embankment under train loading was obtained, and the permanent deformation under the train loads to the total embankment deformation was also analyzed. 相似文献
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Fred Pollitz Paramesh Banerjee Kelly Grijalva B. Nagarajan R. Bürgmann 《Geophysical Journal International》2008,173(1):189-204
The 2004 M = 9.2 Sumatra–Andaman earthquake profoundly altered the state of stress in a large volume surrounding the ∼1400 km long rupture. Induced mantle flow fields and coupled surface deformation are sensitive to the 3-D rheology structure. To predict the post-seismic motions from this earthquake, relaxation of a 3-D spherical viscoelastic earth model is simulated using the theory of coupled normal modes. The quasi-static deformation basis set and solution on the 3-D model is constructed using: a spherically stratified viscoelastic earth model with a linear stress–strain relation; an aspherical perturbation in viscoelastic structure; a 'static' mode basis set consisting of Earth's spheroidal and toroidal free oscillations; a "viscoelastic" mode basis set; and interaction kernels that describe the coupling among viscoelastic and static modes. Application to the 2004 Sumatra–Andaman earthquake illustrates the profound modification of the post-seismic flow field at depth by a slab structure and similarly large effects on the near-field post-seismic deformation field at Earth's surface. Comparison with post-seismic GPS observations illustrates the extent to which viscoelastic relaxation contributes to the regional post-seismic deformation. 相似文献
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Finiteelement simulations are increasingly providing a versatile environment for this topic. In this study, a two-dimensional finite element analysis is conducted to predict the deformation of highembankment in Bazhun heavy-haul railway, China. A recently developed nonlinear softening-type constitutive model is utilized to model the behavior of subgrade filling materials subjected to freeze-thaw cycles. For the convenience of practical application, the dynamic loading induced by a vehicle is treated as a quasi-static axle load. The deformation of this embankmentwith different moisture content under freeze-thaw cycles is compared. The results show that when subjected to the first freeze-thaw cycle, the embankmentexperienced significant deformation variations. Maximum deformation was usually achieved after the embankment with optimum moisture content experienced six freeze-thaw cycles, however, the embankment with moisture content of 8.0% and 9.5% deforms continuously even after experiencing almost ten freeze-thaw cycles. Overall, this study provides a simple nonlinear finite element approach for calculating the deformation of the embankmentinchanging climate conditions. 相似文献
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Influences of agricultural phenology dynamic on land surface biophysical process and climate feedback 总被引:1,自引:1,他引:0
Fengshan Liu Ying Chen Wenjiao Shi Shuai Zhang Fulu Tao Quansheng Ge 《地理学报(英文版)》2017,27(9):1085-1099
Response and feedback of land surface process to climate change is one of the research priorities in the field of geoscience. The current study paid more attention to the impacts of global change on land surface process, but the feedback of land surface process to climate change has been poorly understood. It is becoming more and more meaningful under the framework of Earth system science to understand systematically the relationships between agricultural phenology dynamic and biophysical process, as well as the feedback on climate. In this paper, we summarized the research progress in this field, including the fact of agricultural phenology change, parameterization of phenology dynamic in land surface progress model, the influence of agricultural phenology dynamic on biophysical process, as well as its feedback on climate. The results showed that the agriculture phenophase, represented by the key phenological phases such as sowing, flowering and maturity, had shifted significantly due to the impacts of climate change and agronomic management. The digital expressions of land surface dynamic process, as well as the biophysical process and atmospheric process, were improved by coupling phenology dynamic in land surface model. The agricultural phenology dynamic had influenced net radiation, latent heat, sensible heat, albedo, temperature, precipitation, circulation, playing an important role in the surface energy partitioning and climate feedback. Considering the importance of agricultural phenology dynamic in land surface biophysical process and climate feedback, the following research priorities should be stressed: (1) the interactions between climate change and land surface phenology dynamic; (2) the relations between agricultural phenology dynamic and land surface reflectivity at different spectrums; (3) the contributions of crop physiology characteristic changes to land surface biophysical process; (4) the regional differences of climate feedbacks from phenology dynamic in different climate zones. This review is helpful to accelerate understanding of the role of agricultural phenology dynamic in land surface process and climate feedback. 相似文献
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《地理学报(英文版)》2017,(9)
Response and feedback of land surface process to climate change is one of the research priorities in the field of geoscience. The current study paid more attention to the impacts of global change on land surface process, but the feedback of land surface process to climate change has been poorly understood. It is becoming more and more meaningful under the framework of Earth system science to understand systematically the relationships between agricultural phenology dynamic and biophysical process, as well as the feedback on climate. In this paper, we summarized the research progress in this field, including the fact of agricultural phenology change, parameterization of phenology dynamic in land surface progress model, the influence of agricultural phenology dynamic on biophysical process, as well as its feedback on climate. The results showed that the agriculture phenophase, represented by the key phenological phases such as sowing, flowering and maturity, had shifted significantly due to the impacts of climate change and agronomic management. The digital expressions of land surface dynamic process, as well as the biophysical process and atmospheric process, were improved by coupling phenology dynamic in land surface model. The agricultural phenology dynamic had influenced net radiation, latent heat, sensible heat, albedo, temperature, precipitation, circulation, playing an important role in the surface energy partitioning and climate feedback. Considering the importance of agricultural phenology dynamic in land surface biophysical process and climate feedback, the following research priorities should be stressed:(1) the interactions between climate change and land surface phenology dynamic;(2) the relations between agricultural phenology dynamic and land surface reflectivity at different spectrums;(3) the contributions of crop physiology characteristic changes to land surface biophysical process;(4) the regional differences of climate feedbacks from phenology dynamic in different climate zones. This review is helpful to accelerate understanding of the role of agricultural phenology dynamic in land surface process and climate feedback. 相似文献
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按照地理学科发展趋势,对城镇化与生态环境耦合的研究将由定量描述转入动态模拟。目前,城镇化与生态环境耦合动态模拟模型呈现多元化。论文系统梳理了其中4类常见的动态模拟模型,包括城镇化与生态环境耦合系统动力学模型、基于人工智能算法的城镇化与生态环境耦合动态模拟模型、基于土地利用变化的城镇化与生态环境耦合动态模拟模型以及基于多模型集成的城镇化与生态环境耦合复合模型。主要结论如下:系统动力学模型被广泛应用于城市复杂系统、城市转型和可持续发展以及城镇化与生态环境单要素耦合的动态模拟之中,但存在空间解释不足以及忽视系统自适应性等问题;人工智能算法(ANN和BN)在自学习、自组织、自适应系统或不确定性系统模拟中具有显著优势,并被应用于城市扩张、环境变化、资源需求以及生态脆弱性的识别之中,但应用面相对狭窄且限制条件偏多;土地利用变化模型(CLUE/CLUE-S、CA和MAS)局限于从土地城镇化视角模拟城镇化与生态环境耦合;基于多模型集成的复合模型实现了各模型之间的优势互补,已成为城镇化与生态环境耦合动态模拟模型的发展趋势。今后,应从技术和理论2个层面实现城镇化与生态环境耦合动态模拟模型的进一步发展,并加强对微观过程的模拟。 相似文献
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徐州张集水源地浅层地下水动态及其对不同开采方案响应 总被引:1,自引:0,他引:1
张集水源地是徐州市一个拟建水源地。了解浅层地下水动态变化规律是设计水源地最优取水方案、满足当地居民生活及工农业生产需水和水源地环境保护的重要前提条件之一。分析了水源地在现状以及不同开采条件下浅层地下水动态影响因素,建立了三维等参有限元数学模型模拟水源地地下水运动规律,利用大型群孔抽水试验资料进行参数识别和模型校正,预报了不同开采方案对水源地浅层地下水动态的影响,结果表明:水源地开采后,水源地开采将成为浅层地下水动态的主要影响因素之一;水源地允许开采量为13.71万m3/d是适合的,它不会引起地下水位的持续下降,不仅可满足当地居民用水需求,而且可以向徐州市稳定供水。 相似文献
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This paper reports on the dynamic response of highway subgrade under moving heavy truck in cold regions. Numerical simulations are
performed in two stages. In the first stage, the moving heavy truck vibration, induced by road roughness, is calculated through a
three-dimensional dynamic interaction model of heavy truck-pavement-subgrade, and the time-histories of nodal loads on the top of the
base are calculated through this model. In the second stage, a two-dimensional dynamic finite element model of the base-subgrade-ground
system is formulated, using the calculated nodal loads from the first stage as input. The dynamic response of the subgrade is validated by field
measurements, and the effects of truck type, axle loading, running speed, and road roughness on the vertical dynamic stress in the unfrozen
period and the spring thawing period are analyzed and discussed. 相似文献
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基于动力齿轮理论,修正了耦合协调模型和熵权赋值评价法,分析了2007—2015年浙江省11个地市的旅游产业与区域经济的耦合协调发展情况。结果表明:(1)浙江省旅游产业和区域经济发展协调水平逐步提高并在研究中期出现小的波动,地市间旅游产业发展水平的差异大于区域经济发展的差异;(2)2007—2015年,浙江省11个地市的旅游产业与区域经济耦合度和耦合协调度整体上呈"U"形时间变化趋势,可以划分为初步协调型、轻度失调型、中度失调型和重度失调型4种,提出了未来浙江省旅游业发展的优化措施。 相似文献
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基于土壤水动力学原理,建立了内陆河流域山前农田绿洲SPAC系统土壤水分运移的子模型。应用该模型对土壤剖面含水率、农田棵间蒸发和叶面蒸腾量进行了模拟研究,并以实测值进行了验证。对相同种植与田间管理条件下的春小麦生长季田间土壤水分、土壤蒸发和叶面蒸腾量进行了预报,得到了较满意的结果。对模型主要参数土壤饱和导水率Ks、土表排水系数Wmax、净辐射Rn、风速Uz、饱和差D、作物叶面指数LAI进行了敏感性分析,得出这些参数对土壤水分运移的影响显著。应用该模型对西北干旱区内陆河流域山前绿洲灌溉农田的土壤水分均衡和作物根系吸水规律以及SPAC系统中土壤水分运移规律进行了模拟研究。 相似文献
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Our objectives are as follows. First, we wish to develop a methodology to recover the long-term component of deformation from any set of distributed, time-averaged geodetic strain measurements that were subject to seismic disturbance, given a catalogue of local seismicity that occurred during the measurement period. Second, using seismic and geodetic data sets that span approximately 100 years, we apply this technique in the western Aegean to assess the role of local seismicity in regional deformation. The methodology is developed using a model for crustal deformation constructed from a long-term, smooth regional strain field combined with instantaneous, local perturbations from upper-crustal earthquakes approximated by static elastic dislocations. By inverting geodetic displacements for the smooth field while simultaneously floating influential but uncertain earthquake source parameters, an estimate of the regional component of deformation that is approximately independent of the seismicity can be made. In the western Aegean we find that the horizontal component of regional deformation can be described with minor inaccuracy by a quadratic relative displacement field. The principal horizontal extensional axes calculated from the regionally smooth displacement field agree in orientation with the T-axes of earthquakes in the region. These observations indicate that the instantaneous elastic strain of the 10 km thick seismogenic layer is driven by a stress field that is smooth on the scale of the geodetic network as a whole, 200-300 km. 相似文献
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A series of tests were conducted to analyze temperature field distribution and thawing settlement of a thawing soil under static and dynamic loading at various cooling and thawing temperatures. The res... 相似文献
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基于SD模型下的流域水资源-社会经济系统时空协同分析——以渭河流域关中段为例 总被引:18,自引:4,他引:14
以渭河流域关中段为例,以SD方法分别建立PRD系统线性增长模型、反馈增长模型和调水耦合模型,并采用Venp le软件进行系统仿真,结果显示:基于政府规划目标的线性增长模型是社会经济高速发展模式,但区内水资源供给与需求之间的缺口会持续加大;反馈增长模型可根据流域内水资源承载力状况调整社会经济发展目标,但难以完成关中地区所承担的发展和带动使命;调水耦合模型引入了区外水资源,地区缺水状况得到明显改善,社会经济发展保持较高的增长速度,是解决关中地区PRD问题有效途径,而调水工程和社会经济之间的协同则是近期需要解决的关键问题。 相似文献
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Dynamic performance of insulation is one of the key parameters during the insulation application for high-speed railway subgrade. This paper conducted laboratory and field tests for the materials and dynamic load,especially for thermal performance, elastic deformation, and accumulated deformation of insulation materials.Experiment results show that mechanical properties of insulation layer structure are stable, which satisfies the requirements of the high speed railway. 相似文献