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911.
Yang Che-Ming Chang Jui-Ming Hung Chi-Yao Lu Chih-Heng Chao Wei-An Kang Keng-Hao 《Landslides》2022,19(3):637-646
Landslides - Outburst flooding after a landslide dam breach causes global fatalities and devastation. Information on the timing, magnitude, and location of the landslide dam is crucial to hazard... 相似文献
912.
煤是对温度和压力等地质因素十分敏感的有机岩,各种构造-热事件控制下的物理化学条件,是促进煤岩演化的根本动力。本文对煤变质作用过程的研究现状进行了综述,着重讨论了煤岩在高煤阶-石墨演化阶段的控制因素、演化过程和演化机制。煤变质作用包括煤化作用阶段和石墨化作用阶段,共同构成一个连续的有机质演化过程,总体趋势是分子结构有序化、化学成分单一化,最终演变为以碳元素为主、三维有序结构的石墨。温度和压力(应力)是控制煤变质作用两大因素,在不同的演化阶段,这两大因素所起的作用和演变机理都有所差异。在低、中煤阶演化阶段,温度是煤化学结构演化的主要控制因素,为化学键断裂提供活化能,应力缩聚和应力降解则对煤化学结构演化具有催化作用。高煤阶-石墨化阶段的主要机制是导致基本结构单元BSUs之间相互联结使短程有序化范围增大的拼叠作用,构造应力在其中起到关键作用,BSUs定向和面网间距不断减小,促进大分子物理结构演化。加强煤变质作用的高级阶段-石墨演化过程的研究,将丰富和深化对煤-石墨物理化学结构完整演化序列的认识。煤系石墨成矿机制的高温高压模拟实验,则为煤变质作用构造物理化学条件研究提供了可行的技术手段。 相似文献
913.
走滑断控油气藏作为一种全新类型油气藏,其勘探潜力已初步显现。在对中国三大海相克拉通盆地内部走滑断裂发育特征与控藏作用开展对比分析的基础上,揭示了塔里木盆地、四川盆地、鄂尔多斯盆地内部走滑断裂空间结构与活动特征的相似性与差异性,并结合盆地动力学演化特征探讨了不同盆地内部走滑断裂成因机制,系统分析了三大盆地内部走滑断裂的控藏作用:(1)中国三大海相克拉通盆地内部均发育中小尺度滑移距走滑断裂,普遍具有“纵向分层,平面分段,垂向多期叠加”的空间结构特征。(2)三大克拉通盆地内部走滑断裂体系具有成因、分布和期次的差异性。塔里木盆地内部走滑断裂体系形成时间早,演化时间长,在盆地北部具有“南北对接,东西分区”特征;鄂尔多斯盆地西南缘受燕山期(侏罗纪—白垩纪)陆内挤压影响,形成了北西西向走滑断裂体系;四川盆地受控于二叠纪峨眉山大地幔柱影响,在盆地内部先存基底断裂基础上,形成了北西向、北西西向、近东西向张扭型走滑断裂。(3)中国三大海相克拉通盆地内部走滑断裂对油气成藏和富集具有重要的控制作用。在控储方面,受断裂-流体耦合改造控制,可形成断控缝洞型储集体、断-溶缝洞型或断控裂缝-孔隙型储集体;在控圈方面,在碳酸盐岩地层中可形成断控缝洞型、断溶缝洞型岩性圈闭;在控运方面,走滑断裂产状高陡,可直接沟通烃源岩和储层,构成重要的油气垂向输导体系。 相似文献
914.
Acta Geotechnica - In this paper, an elastoplastic constitutive model is proposed to uniformly describe the mechanical behavior of cemented/ non-cemented soil under different loading conditions. A... 相似文献
915.
Peng-fei Xie Lin Yang Qian-yong Liang Xu-hui Zhang Liang-hua Zhang Bin Zhang Xiao-bing Lu Hui-ce He Xue-min Wu Yi-fei Dong 《China Geology》2022,5(2):300-309
Natural gas hydrates (NGHs) are a new type of clean energy with great development potential. However, it is urgent to achieve safe and economical NGHs development and utilization. This study established a physical model of the study area using the FLAC3D software based on the key parameters of the NGHs production test area in the South China Sea, including the depressurization method, and mechanical parameters of strata, NGHs occurrence characteristics, and the technological characteristics of horizontal wells. Moreover, this study explored the law of influences of the NGHs dissociation range on the stability of the overburden strata and the casing structure of a horizontal well. The results are as follows. With the dissociation of NGHs, the overburden strata of the NGHs dissociation zone subsided and formed funnel-shaped zones and then gradually stabilized. However, the upper interface of the NGHs dissociation zone showed significant redistribution and discontinuity of stress. Specifically, distinct stress concentration and corresponding large deformation occurred in the build-up section of the horizontal well, which was thus prone to suffering shear failure. Moreover, apparent end effects occurred at the end of the horizontal well section and might cause the deformation and failure of the casing structure. Therefore, it is necessary to take measures in the build-up section and at the end of the horizontal section of the horizontal well to prevent damage and ensure the wellbore safety in the long-term NGHs exploitation.©2022 China Geology Editorial Office. 相似文献
916.
Genetic model and exploration target area of geothermal resources in Hongtang Area,Xiamen, China 下载免费PDF全文
The geothermal resources in Fujian Province are mainly hydrothermal resources of medium-low temperature. To better understand the whole process and conditions of heat control in the middle and deep crust, this study focuses on the analysis of heat accumulation model in Hongtang Area of Xiamen, and the main conditions of the model such as faults and sags are explored and interpreted in detail by using gravity and wide-field electromagnetic methods. 4 main faults (F33, F2, F12 and HT-F1) and 10 secondary faults (HT-F2, HT-F3, HT-F4, HT-F5, HT-F6, HT-F7, HT-F8, HT-F9, HT-F10 and HT-F11) were inferred, and the distribution range of sags was delineated. The convective geothermal system is composed of four components: Heat source, geothermal reservoir, heat-conductive fault and heat retaining cover, which form a quaternary heat accumulation model. According to the model, the intersection of the main faults F12, HT-F1 and F33 can be delineated as the primary target area of geothermal exploration, while the intersection of the secondary faults (F12 and HT-F6; F12 and HT-F2; HT-F9, HT-F10 and F12; F12 and HT-F11; F33 and HT-F3; HT-F8 and HT-F3; HT-F2, HT-F10 and HT-F1) can be delineated as the secondary target area. Borehole DR01, which is located in the primary target area, shows that the water temperature increases from fast to slow in the depth range of 0–500 m, and stays at 36℃ below 500 m. The reliability of the heat accumulation model and the target area was tested via geothermal boreholes, which is of great significance to the exploitation and utilization of geothermal resources in Hongtang Area of Xiamen. 相似文献
917.
Hu Qidan Xiong Feng Zhang Bowen Su Peiyang Lu Yang 《Bulletin of Earthquake Engineering》2022,20(11):5849-5875
Bulletin of Earthquake Engineering - Seismic loss prediction of regional-scale buildings provides key information for disaster management. However, previous seismic loss prediction models ignored... 相似文献
918.
919.
Using modern census and environmental factor data,this study first identified the environmental factors that significantly affect the population distribution through Geodetector analysis and then constructed a population spatial distribution model based on the random forest regression algorithm.Finally,with this model and historical population data that were examined and corrected by historians,gridded population distributions with a spatial resolution of 10 km by 10 km in the traditional cultivated region of China(TCRC,hereafter)were reconstructed for six time slices from 1776 to 1953.Using the reconstruction dataset,the spatiotemporal characteristics of the population distribution were depicted.The results showed that(1)the environmental factors that significantly affected the population density differences among counties in the TCRC mainly consisted of elevation,slope,relief amplitude,distances to the nearest prefectural and provincial capitals,distance to the nearest river and the climatology moisture index.(2)Using the census data of 1934 counties in the TCRC in 2000 and the abovementioned environmental factor data,a random forest regression algorithm-based population spatial distribution model was constructed.Its determination coefficient(R2)is 0.81.In 88.4%of the counties(districts),the relative errors of the model predictions were less than 50%.(3)From 1776 to 1953,the total population in the study area showed an uptrend.Prior to 1851,the population increased mainly in the Yangtze River Delta.During this period,the number of grid cells in which the population densities were greater than 500 persons per km2 increased from 292 to 683.From 1851 to 1953,the population increased extensively across the study area.In the North China Plain and the Pearl River Delta,the number of grid cells in which the population densities were greater than 500 persons per km2 increased from 36 to 88 and from 4 to 35,respectively.The spatial clustering pattern of the population distribution varied temporally.The potential reasons included the shifts in economic development hot spots,traditional beliefs,wars,famine,and immigration policies.(4)Between our reconstructions and the HYDE dataset,there are large differences in the data sources,selected environmental factors and modeling methods.As a consequence,in comparison to our reconstructions,there were fewer populations in the eastern area and more populations in the western area from 1776 to 1851 and more populations in urban areas and fewer populations in rural areas after 1851 in the HYDE dataset. 相似文献
920.
The analysis of wild rice cell structures,tissues,organs,and other morphological characteristics and the development of identification markers for wild rice are the basis for identifying the origins and evolution of prehistorical rice agriculture.However,contemporary wild rice strains are often subject to gene introgression from domesticated rice cultivated by humans during the evolutionary process,which may affect the accuracy of wild rice identification markers.This means that how to eliminate the effects of gene introgression from domesticated rice and other plants on the identification of origin markers,and the purification of the morphological characteristics of wild rice have become critical in research to identify the origin of rice.In this study,we compared and analysed the phytolith morphologies of three common wild rice species(Oryza rufipogon Griff.)from various habitats and one species of ectopically preserved homozygous common wild rice after six consecutive generations of self-crossing.We found that the morphology of the bulliform phytolith in the homozygous wild rice with reduced domestication gene introgression had three significant differences compared with native wild rice:(1)an overall reduction in size(body length decreased from 41.9μm in VLnativeto 38.6μm in VLhomozygous);(2)an increase in the proportion of the long-stalked phenotype,with the ratio of B/A decreasing from 1.22±0.47 in B/Anativeto 0.92±0.30 in B/Ahomozygous;and(3)a decrease in the number of fish-scale decorations,with the proportion of bulliform phytoliths with≥9 fish-scale decorations reduced from 53.4%in native wild rice to 37.2%in homozygous wild rice.Thus,this study provides a reliable reference for the identification of rice origins using rice phytolith morphology. 相似文献