郑西高速铁路豫西段黄土现场浸水自重湿陷特征研究

通过现场浸水试验,研究了郑西高速铁路豫西段典型黄土场地浸水后的自重湿陷特征,分析了湿陷土层深度随浸水时间的演化规律,判定了浸水水平向影响范围。研究表明：浸水边界对沉降的影响十分明显,浸水后的湿陷速率呈现出慢-快-慢直至稳定的特点,在浸水10 d后已完成总沉降量的60%,浸水30 d时完成总沉降量的约90%;该场地实测因地区土质而异的修正系数 为1.30,大于规范推荐的0.9,说明该地区黄土的湿陷程度比以往认识地更为强烈;该场地自重湿陷土层下限深度室内试验值是19 m,而现场实测值是16 m,前者是后者的1.2倍。通过综合判定,该场地浸水后的湿陷变形范围为距试坑边缘20 m,与试坑的直径相当,建议在郑西高速铁路沿线此类黄土场地,线路两侧20 m范围内不得积水。该研究成果已在郑西高速铁路建设中得到应用,也可为该地区类似工程提供参考。     

空沟对列车运行引起的地基振动隔振效果研究

为研究空沟对高速列车引起地基振动的隔振效果,在已有研究基础上改进出一种新的解析研究模型。模型中首次运用了饱和半空间模型来研究地基上隔振沟对高速列车的隔振效果;隔振沟则通过在饱和半空间土体上设置3个合适宽度、截面为矩形的弹性层来模拟;中间矩形弹性层为路堤,路堤上方放置了枕木与轨道。枕木与轨道分别通过纵向异性Kirchhoff薄板与Euler梁来模拟,饱和土地基采用Biot多孔饱和介质理论来描述。控制方程通过傅立叶变换与傅立叶级数展开,在变换域中进行求解。研究表明,随着列车运行速度的提高,空沟的隔振效果明显提高;饱和土体固-液相的耦合作用对隔振沟的隔振效果的影响明显,尤其当列车运行速度超过土体表面Rayleigh波速时,随着土体渗透系数的增加,空沟隔振效果显著降低。此外,列车运行速度超过土体表面波速时,饱和土地基上空沟的隔振效果明显优于相应单相弹性地基上空沟的隔振效果。     

Dynamic responses of a saturated poroelastic half-space generated by a moving truck on the uneven pavement

A truck–pavement–ground coupling model was established to study the dynamic responses of a saturated poroelastic half-space generated by a moving heavy truck on the uneven pavement. The ground was simulated as a fully saturated poroelastic half-space governed by Biot’s theory. The overlying pavement was simplified as a Kirchhoff thin plate. With the assumption of a sinusoidal pavement surface, the dynamic wheel–pavement force was obtained through a linear Hertizian contact model. The numerical results showed that this dynamic load could make considerable contributions to the stress and excess pore water pressure responses in the ground. Furthermore, the effective stress path of the soil unit beneath the pavement caused by the moving truck was firstly calculated and presented. It was found that the differences between the total stress path and the effective stress path became significant as the truck speed increased, thus the effective stress path was more suitable than total stress path to reflect the stress history of soil elements in the saturated ground during the passage of high-speed traffics.     

The Chalukou deposit in the North Great Xing’an Range of China: A protracted porphyry Mo ore-forming system in a long-lived magmatic evolution cycle

The Chalukou deposit is located in the North Great Xing’an Range of the Xing’an-Mongolia Orogen bordering and to the northeast of the North China Craton. The deposit is a high-F-type porphyry Mo deposit hosted by the Chalukou composite igneous body containing small intrusive bodies genetically related to Mo mineralization. The composite igneous body includes pre-mineralization dolerite, monzogranite and syenogranite, syn-mineralization rhyolitic porphyry, granitic porphyry and fine-grained monzogranite, and post-mineralization rhyolitic porphyry, quartz porphyry, dioritic porphyry and andesitic porphyry. Detailed laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb zircon dating of the igneous components of the composite igneous body was carried out to determine the temporal framework for magmatism in the Chalukou region. The new LA-ICP-MS U-Pb ages constraint documented here, together with the published ages, indicate that there was a protracted porphyry Mo ore-forming event of approximately 7 million years between ca. 152 when the ore related rhyolitic porphyry was emplaced and ca.145 Ma when molybdenite ceased being deposited. The dating reveals that the mineralization is a part of relatively long-lived magmatic cycle involving the emplacement of small doleritic stocks at ca. 165 Ma that progressively evolved into extensive granitic intrusions at ca. 164 Ma, and then diminished with the emplacement of mineralization-related porphyries to ca. 152 Ma. The emplacement of barren Early Cretaceous magmatism, represented by volcanic units in the ca. 136 Ma Guanghua Formation and porphyries, followed the mineralized magmatism.The syn-mineralization porphyry units associated with Mo contain zircons assaying ∼15 times higher in U and Th than the pre-mineralization magmatic phases. This indicates that there was a significant enrichment of Mo, U and Th in the magma, and directly associated with ore fluid exsolution. The return to their normal levels in the three elements in the post-mineralization magmatic phases indicates that they were exhausted from the magma chamber in the later phases. A genetic model is proposed for the enormous introduction of ore metals and enrichment at the Chalukou deposit. The protracted and multiphase igneous activity during the long-lived magmatism reflects a multistage enrichment of metal, and may play a crucial role in the formation of a volatile-enriched, fertile and large-volume magma chamber beneath the Chalukou deposit. Such a chamber is envisaged to be required for the formation of porphyry Mo deposits in general.     

论党的第二代领导集体对政治民主化的贡献

政治文明是社会主义社会政治现代化建设的重要目标,而政治民主化是政治文明发展的重要体现。党的第二代领导集体在社会主义政治民主化方面作出了重要贡献,即健全与完善了人民代表大会制度、党内民主制度以及基层民主制度,积极推动了中国社会主义政治文明的发展进程。     

藏南日喀则地区白垩纪泥岩、页岩有机质丰度及其油气地质意义

对藏南发育完整的、厚度巨大的海相白垩纪地层中的暗色泥、页岩开展了有机质丰度研究。综合分析结果表明：该区泥、页岩中残余有机碳含量在0.05％~1.1％之间,平均值约为0.42％,其中下白垩统约为0.531％,上白垩统约为0.265％,有机碳平均含量变化特征与该区的古地理格局及海平面升降有关。氯仿沥青‘A’含量在0.0009％~0.0072％之间,平均含量约为0.0040％。有机碳与氯仿沥青‘A’最大值与最小值之比分别为22和8。有机碳与氯仿沥青‘A’这种弱负相关性与两者遭受剧烈的地表风化作用、强烈的紫外线照射和高程度有机质热演化后的损失量有关,后者远大于前者。白垩系残余有机碳含量大于0.6％的中等—好生油岩样10件,占样品总数的27％,下白垩统样品9件,占样品总数的24.3％,上白垩统样品1件,占样品总数的2.7％,表明来自北喜马拉雅地区东山组和康马—隆子地区甲不拉组的早白垩世泥、页岩为该区主要的有效生油岩。     

“Protecting” street children? Urban revitalization and regulation in Lima,Peru

In this article, I develop a critical analysis of the relationship between urban “revitalization” campaigns and the regulation of street children in Lima, Peru. Scholars writing mostly in the Global North have drawn attention to increasingly punitive policies regarding public space. While in many regards Lima’s urban policy is reflective of such larger trends, I consider whether the regulation of street children is as punitive as might be assumed. I am particularly concerned with the role that children’s rights play as another logic structuring urban regulation. I first show how a language of children’s rights has been manipulated to justify the removal of street children from public space, as is most evident through Peru’s Law to Protect Minors from Situations of Begging. However, there is also something more ambiguous occurring. In the second part of this article, I examine the uneven implementation of policy: street children themselves resist and rework policies “on the ground,” and children’s rights frameworks may offer possibilities for rupture of formal regulation. I suggest that these overlapping and competing dynamics sustain an uneven and contingent geography of urban regulation.     

Massively parallel spatial point pattern analysis: Ripley’s K function accelerated using graphics processing units

This study presents a massively parallel spatial computing approach that uses general-purpose graphics processing units (GPUs) to accelerate Ripley’s K function for univariate spatial point pattern analysis. Ripley’s K function is a representative spatial point pattern analysis approach that allows for quantitatively evaluating the spatial dispersion characteristics of point patterns. However, considerable computation is often required when analyzing large spatial data using Ripley’s K function. In this study, we developed a massively parallel approach of Ripley’s K function for accelerating spatial point pattern analysis. GPUs serve as a massively parallel platform that is built on many-core architecture for speeding up Ripley’s K function. Variable-grained domain decomposition and thread-level synchronization based on shared memory are parallel strategies designed to exploit concurrency in the spatial algorithm of Ripley’s K function for efficient parallelization. Experimental results demonstrate that substantial acceleration is obtained for Ripley’s K function parallelized within GPU environments.     

Source parameters of small and moderate earthquakes in the area of the 2009 L’Aquila earthquake sequence (central Italy)

The main goal of this study is to provide moment tensor solutions for small and moderate earthquakes of the 2009 L’Aquila seismic sequence (central Italy). The analysis was performed by using data coming from the permanent Italian seismic network run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the “Cut And Paste” (CAP) method based on broadband waveform inversion. Focal mechanisms, source depths and moment magnitudes are determined through a grid search technique. By allowing time shifts between synthetics and observed data the CAP method reduces dependence of the solution on the assumed velocity model and on earthquake location. We computed seismic moment tensors for 312 earthquakes having local magnitude in the range between 2.7 and 5.9. The CAP method has made possible to considerably expand the database of focal mechanisms from waveform analysis in the lowest magnitude range (i.e. in the neighborhood of magnitude 3) without overlooking the reliability of results. The obtained focal mechanisms generally show NW–SE striking focal planes in agreement with mapped faults in the region. Comparisons with the already published solutions and with seismological and geological information available allowed us to proper interpret the moment tensor solutions in the frame of the seismic sequence evolution and also to furnish additional information about less energetic seismic phases. Focal data were inverted to obtain the seismogenic stress in the study area. Results are compatible with the major tectonic domain. We also obtained a relation between moment and local magnitude suitable for the area and for the available magnitude range.     

Analyses multifractales et spatio-temporelles des précipitations du modèle Méso-NH et des données radar

Résumé

Dans le cadre des multifractals universels, il est possible de caractériser la variabilité spatio-temporelle de la pluie sur une grande gamme d’échelle à l'aide de trois paramètres invariants d’échelles. Dans cette étude, nous avons estimé ces paramètres multifractals sur des simulations numériques effectuées avec le modèle méso-échelle Méso-NH, développé par Météo-France et le Laboratoire d'Aérologie (Univ. P. Sabatier, Toulouse, France), et des images radar composites, couvrant le même événement pluvieux, à savoir un orage particulièrement violent, dit de type Cévenol, ayant eu lieu sur la partie sud de la France du 5 au 9 Septembre 2005. La comparaison des résultats montre que les deux types de données présentent des domaines d'invariance d’échelle relativement similaires, et dont les propriétés sont en accord avec les modèles de précipitation spatio-temporels unifiés et scalants les plus simples. Néanmoins l’évaluation de leurs exposants conduit à des valeurs parfois fortement différentes.

Citation Gires, A., Tchiguirinskaia, I., Schertzer, D. & Lovejoy, S. (2011) Analyses multifractales et spatio-temporelles des précipitations du modèle Méso-NH et des données radar. Hydrol. Sci. J. 56(3), 380–396.