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1.
Jun-Jie Wang Zhen-Feng Qiu Wen-Jie Deng Hui-Ping Zhang 《Marine Georesources & Geotechnology》2016,34(4):395-402
The present study focuses on the shear strength, deformation, and particle crushing of sand which is mixed by crushed sandstone and mudstone particles. Two triaxial tests—one for unsaturated specimens and the other for saturated specimens—were performed, along with sieve analysis tests. Results obtained from the triaxial tests indicate that, with the increment of the mudstone particle content by weight, the angle of internal friction decreases, the cohesion increases and then decreases, and both the initial angle of shearing resistance at the atmospheric pressure and decremental angle increase and then decrease. Compared to the unsaturated specimens, the deviator stress or normalized deviator stress of the saturated specimens at the same axial stress may decrease due to the wetting action. Thus, the shear strength of the tested materials may be reduced by the wetting action. Results of sieve analysis tests indicate that the mixing of some mudstone particles into the sandstone particle mixture may reduce the amount of particle crushing, but the wetting action may increase the amount. The amount of the crushed particle may arrive at a minimum of 40% of mudstone particle content by weight. 相似文献
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书法景观的文化地理浅释 总被引：8，自引：2，他引：6
书法地理学作为一门新兴的文化地理学的分支,它的基本理论研究对象之一便是书法景观。从文化地理学的角度出发,探讨了书法景观的概念,书法景观的分类。指出其构成除了自然因素以外,还应包括人文景观中的可视性因素、可悟性因素和氛围。书法景观是自然景观人文景观的统一体。 相似文献
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Abstract The Minshan Mountain and adjacent region are the major continental escarpments along the eastern Tibetan Plateau. The Minjiang drainage basin is located within the plateau margin adjacent to the Sichuan Basin. Based on the analysis of the digital elevation model (DEM) acquired by the Shuttle Radar Topography Mission (SRTM), we know that the Minjiang drainage basin has distinct geomorphic characteristics. The regular increasing of local topographic relief from north to south is a result of the Quaternary sediment deposition within the plateau and the holistic uplift of the eastern margin of the Tibetan Plateau versus the Sichuan Basin. Results from DEM-determined Minjiang drainage sub-basins and channel profiles show that the tributaries on the opposite sides are asymmetric. Lower perimeter and area of drainage sub-basins, total channel length and bifurcation ratio within eastern flank along the Minjiang mainstream are the result of the Quaternary differential uplift of the Minshan Mountain region. Shorter stream lengths and lower bifurcation ratio might be the indications of the undergrowth and newborn features of these eastern streams, which are also representative for the eastern uplift of the Minshan Mountain. 相似文献
4.
This paper studies the projectile electron loss cross sections of C3 + colliding with atomic hydrogen in the frame work of extended over-barrier model at intermediate velocities (25 keV/u--600 keV/u). The electron loss is calculated in terms of the interaction between the screened target nucleus and the active projectile electron and of the interaction between projectile electron and target electron. Compared with the convergent close-coupling calculations, screening and anti-screening calculations, this model satisfactorily reproduces the experimentally obtained energy dependence of the electron-impact ionisation cross sections and the single electron loss cross sections over the energy range investigated here. 相似文献
5.
Bi Yu Chen Donggen Wang Shih-Lung Shaw Hui-Ping Chen 《International journal of geographical information science》2017,31(4):783-804
Travel time uncertainty has significant impacts on individual activity-travel scheduling, but at present these impacts have not been considered in most accessibility studies. In this paper, an accessibility evaluation framework is proposed for urban areas with uncertain travel times. A reliable space-time service region (RSTR) model is introduced to represent the space-time service region of a facility under travel time uncertainty. Based on the RSTR model, four reliable place-based accessibility measures are proposed to evaluate accessibility to urban services by incorporating the effects of travel time reliability. To demonstrate the applicability of the proposed framework, a case study using large-scale taxi tracking data is carried out. The results of the case study indicate that the proposed accessibility measures can evaluate large-scale place-based accessibility well in urban areas with uncertain travel times. Conventional place-based accessibility indicators ignoring travel time reliability can significantly overestimate the accessibility to urban services. 相似文献
6.
Jun-Jie Wang Jing Zhang Zhen-Feng Qiu Hui-Ping Zhang 《Marine Georesources & Geotechnology》2019,37(1):109-115
While a crushed sandstone particle mixture, usually used as an engineering fill, is filled along bank of or in a large reservoir, it is subjected to periodic saturation induced by filling-drawdown cycles of reservoir water. The periodic saturation may induce post-construction settlement, and reduce stability of the filled body. In order to evaluate the effects of periodic saturation on stress–strain relationship of the mixture, several triaxial tests are carried out. According to experimental data, the periodic saturation may induce an increment of axial strain (Δε; <0.226%), a decrement of crest of deviator stress (Δ(σ1?σ3)f; <0.192?MPa) and a decrement of angle of shearing resistance (Δφ; <3.70°). With increment of the number of periodic saturation cycles, the variations of the three parameters may be fitted by logarithmic curves. And with increase in the stress level for periodic saturation, the variations of the three parameters may be fitted by straight lines. Three fitting equations to predict the three parameters’ values, and an equation to calculate the settlement induced by the periodic saturation of a large-area filled foundation, are suggested. 相似文献
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利用深部地球物理结果与浅部地质调查结果进行对比,并基于DEM的地貌分析,研究了中更新世以来北天山向北扩展的造山过程.中更新世以来,北天山地壳中存在南倾的低角度滑脱面,滑脱面之上,逆断裂和褶皱带组成的山前活动构造带整体向北滑脱并缩短变形.中更新世早期,气候暖湿,基岩山脉剥蚀强烈,在山前形成了大规模的洪泛平原.中更新世中期以来,持续的构造活动一方面使山前盆地卷入变形,另一方面使盆地遭受分隔,天山北麓地壳以阶梯式的形式自南向北逐步抬升.中更新世中期约600 ka以来,气候越来越干旱,山前盆地地表仅遭受了轻微剥蚀,地壳抬升全部转换为自南向北的地表隆起,隆起的北部向天山靠拢,隆起的南部逐渐成为山系,与天山相连,北天山得以向北扩展.中更新世以来的掀斜隆起造成山麓至盆地高差达1000多米的坡面,为30 ka以来的河流下切提供了坡度条件,造成了深达300多米的河流强烈下切. 相似文献
8.
Jun-Jie Wang Hui-Ping Zhang Ming-Wei Liu Ye-Ying Chen 《Marine Georesources & Geotechnology》2013,31(1):86-101
The authors deal with the computing seismic passive earth pressure acting on a vertical rigid wall. The wall is provided with a drainage system along soil-structure interface and retains the cohesionless backfill subjected to water seepage. A general solution for the seismic passive earth pressure is presented. The solution is based on Coulomb's theory wherein seismic forces are assumed to be pseudostatic. The solution considers the pore water pressures induced by water seepage and earthquake shaking. Some important parameters are included in the solution. The parameters are the soil effective internal friction angle, wall friction, soil unit weight, and horizontal and vertical seismic acceleration coefficients. The comparison of the total seismic passive earth pressure in horizontal direction from the present method with published works indicates that the present method may be reasonable. The variations of the passive earth pressure coefficient with the soil effective internal friction angle are investigated for different wall friction angles and seismic forces. The effect of the water seepage on the seismic passive earth pressure is also investigated. 相似文献
9.
深圳市土地利用社会经济效益与生态环境效益的耦合关系研究 总被引：15，自引：2，他引：13
深圳市是中国经济发展速度最快的沿海开放城市之一,其土地利用效益非常明显,并且具有耦合关系。根据系统科学理论与方法,建立了深圳市土地利用效益耦合模型和相应的指标体系, 当耦合度在0°~90°之间时,土地利用效益系统处于协调发展阶段;当耦合度等于45°时,系统最协调。根据此模型计算了1981~2004年间土地利用效益耦合度。结果表明,1981年以来,深圳市土地利用社会经济与生态环境效益都处于上升状态,前者持续快速上升;而后者总体上升,有所波动。深圳市土地利用效益的耦合度演化可分为4个阶段。1981~1985年间,土地利用效益耦合度从-36.29°快速上升到36.99°,从低级共生状态跃至相对协调状态。1986~1990年间,土地利用效益处于持续、稳定、最佳协调状态,耦合度介于43°~53°之间。1991~1996年间,土地利用效益处于耦合变化状态,耦合度从56.99°上升到79.47°,即从最佳协调状态向不甚协调发展。1997~2004年间,土地利用效益协调程度有所下降,耦合度介于81°~85°之间。 相似文献
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