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1.
重庆万盛煤矸石山自燃爆炸型滑坡碎屑流成因探讨 总被引：9，自引：0，他引：9
2 0 0 4 - 0 5 - 0 5重庆万盛胡家沟煤矸石山发生滑坡碎屑流灾害。灾害发生时,伴随巨大的响声和刺鼻气味,约2 0×10 4m3 煤矸石碎屑以极高初始速度崩滑而下,滑体横扫运动途中一切障碍,垂直坡降32 0m ,水平运动距离6 0 0m。造成重大人员和财产损失。通过实地考察和实验研究,作者认为煤矸石山中硫铁矿和碳氧化物升温,煤矸石山自燃、内部热量大量积聚所导致的煤矸石山的爆炸,是使大量矸石脱离矸石山形成此次煤矸石高速滑坡碎屑流灾害的主要原因 相似文献
2.
Ejection of sand grains from a sand surface is assumed to result from cascade collision caused by the impact of a saltating particle. Allowing for only two-body cascade collision and introducing new quantities such as the cross-section for sand grain–grain collisions and sand surface binding energy, the theoretical model for the cascade collision of ion particles is applied to simulate sand grain/bed collision processes. The results of simulations indicate that the collision cascade events caused by impacting particles can eventually lead to the ejection of grains taking place from the sand surface. The number of ejected grains at any surface point is found to be proportional to the fractional energy deposited at that point and inversely proportional to the sand surface binding energy. This cascade collision model also confirms that the peak in the spatial distribution of ejected grains does not appear at the impact point but is located downwind, and that the speed distribution of ejected grains at a fixed angle exhibits a peak having a value directly related to the ratio of surface binding energy to the mass of the ejected grain. The angular distribution at a certain ejection speed also exhibits a maximum at an ejection angle near 90°. The model also offers a new interpretation for the observed variability in the number of ejected grains under constant impact velocity; this variability is directly related to the wide distribution of the energy deposition in the surface layer of the sand bed. 相似文献
3.
M.S. de Ruyter de Wildt E.J. Klok J. Oerlemans 《Geografiska Annaler: Series A, Physical Geography》2003,85(1):57-72
We present a Seasonal Sensitivity Characteristic (SSC) of Vatnajökull (Iceland), which consists of the sensitivity of the mean specific mass balance to monthly perturbations in temperature and precipitation. The climate in Iceland is predominantly maritime (high precipitation) although often the polar air mass influences the area. This results in temperature sensitivities that are high in summer and nearly zero during the winter months. In contrast, precipitation sensitivities are high in winter and low in summer. We use the SSC of Vatnajökull as a reduced mass balance model, with which we reconstruct the mass balance of Vatnajökull since 1825. The reduced model shows that changes in temperature and precipitation like the ones observed both have a significant impact upon the mass balance. The reconstructed mass balance records for two Icelandic glaciers correlate very well with mass balance records that are extracted from length records with a linear inverse model. This places confidence in both the reduced (forward) mass balance model and in the inverse model, although the forward method produces larger mass balance variations than the inverse method. For the south of Vatnajökull we find that after 1900, the length record is well explained by temperature variations alone, while another Icelandic glacier (Sólheimajökull) was also influenced by precipitation variations. 相似文献
4.
5.
土壤表面划痕与颗粒碰撞磨蚀实验研究 总被引：1，自引：0，他引：1
在沙漠地区,风蚀作用可以导致土壤表面破碎,土壤表面的性质不同,破碎的程度也不尽相同。划痕方法在测量土壤表面的比研磨能量上具有较好的效果,使用通用微型摩擦计(UMT)测量沙土、沙壤土、粉沙壤土、壤土,粉沙粘壤土和粉沙粘土6种不同土壤类型的土壤表面相对磨蚀能量和相对表面硬度,发现土壤表面相对硬度对土壤表面相对磨蚀能量有很大的影响。对沙土,沙壤土、粉沙壤土、壤土、粉沙粘壤土和粉沙粘土6种不同类型的土壤表面进行了颗粒碰撞磨蚀试验,结果表明,土壤表面的碰撞磨蚀速率与碰撞颗粒速度的平方成正比、土壤平均颗粒大小的2.6次方成正比,而与土壤表面相对磨蚀能量的1.5次方成反比,与土壤相对硬度的1.7次方成反比。 相似文献
6.
冲击起沙是最重要的起沙方式。鉴于Lu和Shao提出的体积模型的不足,通过分析沙床受到冲击后应力的传递规律,类比于电子的跃迁模型,提出了冲击起沙的跃迁模型来解决冲击起沙问题。该模型的基本思想是,沙粒冲击沙床时,能量会沿冲击点向周围粒子扩散,当某一粒子获得的能量大于跃出所需要的能量时,该粒子即从床面跃出;多余的能量将转化为该粒子的跃出初动能。冲击起沙问题由此变成了一个研究跃出能量的大小和能量传输规律的问题。根据该模型,基于能量传输的吸收系数法和传输方程近似法,给出了两维和三维情形下冲击起沙释放的粒子数、速度分布和冲击坑形状的表达式。两维情形下显示,冲击坑的大小与释放的粒子数和粒径大小正比,而且伴随着冲击坑的形成,可能会发生崩塌现象。吸收系数法显示,两维冲击坑随着吸收系数的增大是先增大,后反而出现了收缩。传输方程近似法显示,两维冲击坑的大小正比于kt。 相似文献
7.
《Geomorphology》2001,36(3-4):155-165
Sand transport by wind is a special case of two-phase flow of gas and solids, with saltating grains accounting for about 75% of the transport rate. This form of flow is not only the main external agent moulding aeolian landforms but also the motive force responsible for transport, sorting and deposition of aeolian sediments. High-speed multiflash photography is an effective method of studying the distribution of velocity and energy of saltating grains within the boundary layer of wind tunnel. The experimental wind shear velocities were set at 0.63, 0.64, 0.74 and 0.81 ms−1. The statistical study of the results showed that there is a power function relation between mean velocity and height of saltating grains. As the height is divided into 0.5-cm intervals, the sand grain velocities at various levels are consistent with the Pearson VII distribution pattern. The variations in kinetic energy and total energy of sand grains with height accord with the pulse peak modified with power term (Pulsepow) law; the maximum values occur at heights of 6 cm or so and tend to shift upward with increasing wind velocity. 相似文献
8.
Z. L. Wu 《Geophysical Journal International》2000,142(1):59-66
The frequency–energy distribution of global seismicity is studied using broad-band radiated energy of shallow earthquakes from January 1987 to December 1994 estimated by NEIC. Rank-ordering statistics are applied to enhance the resolution in retrieving the power-law distribution with undersampled data, namely a few tens of events. Seen in the perspective of broad-band radiated energy with higher resolution, a single (Gutenberg–Richter-type) power-law distribution can fit the data. For earthquakes with energy larger than 1014 J, the number N of events with energy E depends on E via N∝E −B , with the scaling constant B = 0.64 ± 0.04, corresponding to b = 0.95 ± 0.06. This relation is different from that of scalar seismic moment, which shows a transition of power-law distributions between small and large earthquakes. To demonstrate such a difference we use the same set of earthquakes with both broad-band energy estimation and CMT estimation. It is found that for the same data set, the energy distribution and the moment distribution show different patterns. The moment distribution has a clear kink between small and large earthquakes, while the energy distribution shows a single power law with no convincing kink between small and large earthquakes. To investigate the effect of different focal mechanisms and different seismic regions, events with strike-slip mechanisms and events within the Japan–Kuril region are considered. For these subsets of events, a similar pattern exists, in which the moment distribution shows a kink between small and large earthquakes, while the energy distribution shows a single power law. 相似文献
9.
幂次法则是一个普遍存在于自然科学与社会科学界的现象,在都市体系中亦可观察到此一现象。过去的文献仅仅对于幂次法则现象进行了观察和解释,并未能完整地解释其形成的机制。本研究尝试由复杂理论中“递增报酬”的观念来探讨幂次现象的成因,采用计算机程序来仿真都市聚落体系形成的过程,并观察递增报酬与幂次现象之关系。该仿真包含了3 种不同的区位发展吸引模式,分别为相邻关系、规模吸引以及同时考虑规模与相邻的混合模式。计算机仿真显示：① 规模吸引与混合两种模式比相邻吸引模式能够更好地解释都市聚落的成长;② 依照递增报酬法则而仿真形成的都市聚落,与幂次现象呈高度相关。随后的数理仿真演算显示,幂次法则为一统计上的普遍现象,但在递增报酬等经济因素驱动下的都市聚落体系结构与真实的状况较为吻合。因此我们推测,递增报酬极可能是形成真实世界幂次现象的机制之一。 相似文献
10.
基于对1980-2014年新疆能耗和终端能耗氮排放估算,选取能耗总量、电耗总量、工业能耗量和终端能耗氮排量,研究与新疆区域温度变化指标的关联系数,构建能耗对区域温度变化的胁迫模型。结果表明：（1）城市化高速期能耗和电耗增长显著高于加速期。（2）终端能耗氮排量和氮排放终端能源的结构变化指标1980-2014年均持续增加,终端能源氮排放向综合方向发展,各产业部门氮排放结构变化由工业主力型向多产业部门发展。（3）能耗指标和温度变化指标的关联系数均通过p=0.01水平显著检验,工业能耗总量和城郊温差关联系数略大于能耗总量和电力消耗。（4）工业能源终端消耗量的增加对城郊温差的胁迫关系呈三次多项式的形式增加。 相似文献
11.
山东南四湖水面蒸发实验研究 总被引：8，自引：0，他引：8
本文根据山东南四湖蒸发站1985-1990年的实验资料,分析了水面蒸发与气象因子、水体面积、水体深度、蒸发器结构和安装方式的关系,以及20m2蒸发池与各类型蒸发器蒸发量的关系,同时还分析了20m2池蒸发量的昼夜变化、年内变化、年际变化的特征。 相似文献
12.
Earthquake sequences on a frictional fault model with non-uniform strengths and relaxation times 总被引：1，自引：0，他引：1
Summary. The space and time characteristics of earthquake sequences, including a main shock, aftershocks and the recurrence of major shocks in a long time range, are investigated on a frictional fault model with non-uniform strengths and relaxation times, which is subjected to a time-dependent shear stress. Aftershocks with low stress drop take place successively in spaced regions so as to fill the gaps which have not yet been ruptured since the main shock, while those with high stress drop occur in and around the regions left unruptured during the main faulting. The frequency decay of aftershocks with time follows a hyperbolic law with the rates p consistent with observations. There are good linear relations in logarithmic scales for source area versus frequency and seismic moment versus frequency of the generated aftershocks. The b -value obtained in the present experiments appears slightly larger than that for observations. It was found that more heterogeneous distribution of the fault strength give smaller p and larger b -values. The recurrence of major shocks, particularly of very large shocks with high stress drop, is often preceded by a completely silent period of activity or very low activity with a small number of foreshocks. The major shocks take place successively in adjacent unruptured regions and sometimes show slow-speed migrations. These results provide explanations to various observations of earthquake sequences. 相似文献
13.
Stefan Bouzarovski 《Area》2009,41(4):452-463
Energy developments in the post-Communist states of Eastern and Central Europe (ECE) have a major impact on global energy security and sustainability, thanks to this region's key geographical position between the energy-exporting states of the former Soviet Union, on the one hand, and the energy-importing states of Western and Southern Europe, on the other. At the same time, post-socialist reforms of energy industries in this region provide unique insights into the complex relations of power, economic transformation and spatial inequality that govern energy production and consumption. This paper therefore aims to provide an initial look at some of the theoretical and policy issues that underpin the emergent 'geographies' of energy reform in ECE, as well as their embeddedness in relations of power stemming from organisational, infrastructural and economic inequalities in the region. It employs an analysis of local news reports, policy papers and statistical data to examine the intricate institutional networks and spatial formations that have governed the energy transformation process. In broader terms, the paper aims to emphasise the important role that human geography can play in making sense of the territorial differences and frictions that have emerged during the post-socialist reform process, while challenging the idea of a 'neat' neoliberal transition from a centrally planned to a market-based mode of energy regulation . 相似文献
14.
风沙流中沙粒旋转通常具有明显的三维旋转特性。本文通过数值建模考察了三维空间中不同沙粒旋转状态所产生的Magnus力对其跃移运动轨迹特征的影响。在三维坐标系中,X、Y、Z轴分别表示水平、垂直和横向方向,气流沿X方向流动,沙粒起跳时位于XY平面内。结果表明,跃移沙粒仅绕Z轴旋转起跳时,初始起跳角速度的增大会导致在XY平面内的跃移高度和跃移距离减小而降落角增大,但Z方向没有运动发生。跃移沙粒仅绕X轴或Y轴旋转起跳时,绕X轴或Y轴的初始起跳角速度的变化对在XY平面内的跃移轨迹特征量没有显著影响,但沙粒偏离XY平面的偏离距离和偏离角的绝对值随起跳角速度绝对值的增加而增大。因此,沙粒起跳旋转状态对其跃移轨迹有重要的影响。 相似文献
15.
The ability of seismological criteria to identify earthquakes from underground explosions depends partly on the orientation of the earthquake source. Well-determined double-couple moment tensor solutions for a large number of earthquakes have been published in the Harvard centroid moment tensor (CMT) and United Slates Geological Survey (USGS) catalogues. Statistical analyses of these catalogues indicate that the distribution of the orientation of earthquake mechanisms is not random. The distribution of the T axes shows significant clustering around the downward vertical, indicating that a larger number of earthquake mechanisms radiate compressional P -wave energy to teleseismic distances from near the maximum of the radiation pattern than is predicted if earthquake sources are randomly oriented double couples. The clustered T axes correspond to compressional dip-slip mechanisms, and it is this type of mechanism which is believed to cause both the m b : M s (the ratio of body-wave to surface-wave magnitude) and first-motion criteria to misidentify an earthquake as an explosion. 相似文献
16.
Implications of a percolation model for earthquake 'nucleation' 总被引：2，自引：0，他引：2
Z. L.Wu 《Geophysical Journal International》1998,133(1):104-110
A percolation model is applied to the explanation of some of the qualitative and quantitative aspects associated with the recent observations of earthquake 'nucleation'. An additional assumption is introduced that nucleation starts at the critical point of percolation. The model explains the order of magnitude of the seismic moment release during the nucleation, the dependence of the seismic moment of the main shock on the duration of the nucleation process, and the observation that the fraction of the moment release during the nucleation has no systematic variation with the size of the main shock. The model also suggests that the source time function of the nucleation phase may be complex, and also that not all earthquakes are accompanied by a nucleation process, which is supported by observational results. By assuming that there exists a scale invariance associated with the criticality, a Widom scaling model is proposed to describe the electromagnetic emission during earthquake rupture. 相似文献
17.
Vyacheslav M. Zobin Carlos Navarro Gabriel Reyes-Dávila Justo Orozco Mauricio Bretón Armando Tellez Gabriel Reyes-Alfaro Homero Vázquez 《Geophysical Journal International》2006,167(1):467-478
A methodology is proposed for the quantification of volcanic explosions based on three parameters derived from broad-band seismic signals: the counter force of the eruption F , the power of the explosion P and the duration of the upward movement of the gas slug in the conduit to the free surface of magma, D . This methodology was applied to the 2004–2005 sequence of explosions at Volcán de Colima, Mexico. The broad-band records of more than 100 explosive events were obtained at a distance of 4 km from the crater. We determined the counter force of the eruption by modelling the low-frequency impulse of the seismic records of 66 volcanic explosions and estimated the power of 116 explosions from the spectra of the high-frequency impulse. The power of Colima explosions spans five orders of magnitude; the counter force spans four orders of magnitude. We show that the power of a volcanic explosion is proportional to the counter force of the eruption. These parameters may be used for the elaboration of a scale of volcanic explosions. 相似文献
18.
中国能源-粮食生产对水资源竞争的关系——基于水足迹的视角 总被引：2，自引：0，他引：2
通过对水-能源-粮食系统的定量分析,能更好的探究三者之间的协同作用,对提高区域资源综合利用效率、促进区域可持续发展具有重要意义。本文基于水足迹视角探讨了1990—2017年中国31个地区能源-粮食生产对水资源的竞争关系,并借助ESTDA模型框架对其时空动态特征进行分析。结果表明：① 中国化石能源水足迹的时间演变特征可分为缓慢下降-快速上升-平稳下降3个阶段,其中化石能源灰水足迹平均占化石能源水足迹的70%以上;电力水足迹呈持续上升态势,其中电力蓝水足迹平均占电力水足迹的70%以上;粮食蓝水足迹上升幅度明显,平均占农业用水总量的70%以上。② 能源-粮食水足迹总量空间分布格局受区域资源禀赋差异影响较大。③ 时间序列上,中国能源-粮食生产对水资源竞争指数呈逐年上升态势;空间分布上,同时兼顾能源生产与粮食生产的黄河中下游区、东北地区为竞争指数高值集聚区,其余地区竞争指数相对较小。④ LISA时间路径分析显示,中国南方地区能源-粮食水资源竞争指数的空间格局的稳定性比北方更强;各地区在不同程度上均受局部结构的时空依赖效应影响;竞争指数空间格局变化具有较强的整合性且空间凝聚性较强。⑤ 能源-粮食生产对水资源的竞争在短期内难以得到有效缓解。 相似文献
19.
In this study, an attempt has been made to evaluate the temporal variations in specific stream power and the total energy available for geomorphic work during the monsoon season for the Tapi River, in central India. Continuous daily discharge data (1978–1990), hydraulic geometry equations and the relationship between discharge and water surface slope were used to compute the daily specific stream power (ω) for the Savkheda gauging site in the lower Tapi Basin. The total amount of energy generated by all the monsoon flows was estimated by integrating the area under the ω-graph derived for the monsoon season.The analyses of the 13-year daily discharge data reveal that the average and maximum ω values range from 4–20 W m− 2, and 22–964 W m− 2 respectively. Specific stream power duration curve derived for the site shows that for 25% of the time the power per unit area is > 10 W m− 2. Furthermore, unit stream power was found to be above the Williams' [Williams, G.P., 1983. Paleohydrological methods and some examples from Swedish fluvial environments. I. Cobble and boulder deposits. Geografiska Annaler 65A, 227–243.] threshold of pebble-movement (1.5 W m− 2), cobble-movement (16 W m− 2) and boulder-movement (90 W m− 2) for 71%, 15% and 2% of the time, respectively. Computations further indicate that the total amount of energy generated by the flows during the monsoon season is in the range of 37 MJ (deficit monsoon years) to 256 MJ (excess monsoon and/or flood years). Large floods have one-third share in the total monsoon energy expenditure. In the absence of appropriate data on the yearwise geomorphic effects, the geomorphic work was evaluated in terms of the total suspended sediment load transported. The total monsoon sediment load is strongly related to the total monsoon energy. The results of the study indicate that the average flow competence and capacity are remarkably higher during wetter monsoon seasons and flood years than during the shorter and drier monsoon seasons.The present analyses demonstrate that the flows are geomorphically effective for a greater part of the monsoon season, except during the deficient monsoon years, and there is little doubt that large-magnitude floods are effective agents of geomorphic change in monsoonal rivers. 相似文献
20.
Two general approaches have been applied to understanding the fractal structure of fluvial topography: (1) deterministic, process-based models, and (2) stochastic partial differential equations (PDE). Deterministic models reproduce the fractal behavior of fluvial topography but have two limitations: they often underestimate the amount of lateral valley and ridge migration that occurs in nature, and the complexity has made it difficult to identify the precise origin of fractal behavior in fluvial landscapes. The simplicity of stochastic PDE models has made them useful for investigating fractal behavior, but they incorrectly suggest that fractal behavior is only possible with stochastic forcing. In this paper I investigate whether simplified, deterministic PDE models of landform evolution also exhibit fractal behavior and other features of complexity (i.e. deterministic chaos). These models are based on the KPZ equation, well known in the physics literature. This equation combines diffusion (i.e. hillslope processes) and nonlinear advection (i.e. bedrock or alluvial channel incision). Two models are considered: (1) a deterministic model with uniform erodibility and random initial topography, and (2) a deterministic model with random erodibility and uniform initial topography. Results illustrate that both of these deterministic models exhibit fractal behavior and deterministic chaos. In this context, chaotic behavior means that valley and ridge migration and nonlinear amplification of small perturbations in these models prevent an ideal steady state landscape from ever developing in the large-system limit. These results suggest that fractal structure and deterministic chaos are intrinsic features of the evolution of fluvial landforms, and that these features result from an inverse cascade of energy from small to large wavelengths in drainage basins. This inverse cascade differs from the direct cascade of three-dimensional turbulence in which energy flows from large to small wavelengths. 相似文献