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51.
Dynamics of the Niumiangou Creek rock avalanche triggered by 2008 Ms 8.0 Wenchuan earthquake, Sichuan, China 总被引:3,自引:2,他引:1
The Niumiangou Creek rock avalanche was triggered by an Ms 8.0 earthquake that happened on 12 May 2008 in the Sichuan Province, China. The rock avalanche traveled a horizontal distance
of 3.0 km over a vertical elevation difference of 0.89 km, equivalent to a coefficient of friction of only 0.29. The travel
path of the rock avalanche can be divided into three segments: (1) failing and disintegrating, (2) flying, (3) flowing. In
the failing and disintegrating segment, the rock slope failed because of the coupled action of horizontal and vertical force
of the earthquake, then smashed into the opposite mountain and disintegrated. In the flying segment, the disintegrating rock
mass changed direction and flew into the Lianhuaxin Creek, which was different from the previous research results that concluded
rock debris flowed in Lianhuaxin Creek. A great amount of air trapped and compressed under the rock debris acted as air cushion
and supported the rock debris to fly a further distance. In the flowing segment, the rock debris flowed on the ground surface
in Niumiangou Creek. The flowing velocity has been estimated from the maximum elevation and runup according to the damaged
trimlines of the debris. The saturated fine material in Niumiangou Creek entrained by the failed debris mass is thought to
have contributed to the long runout of the debris. The Niumiangou Creek rock avalanche is one of the three longest rock avalanches
triggered by Wenchuan earthquake. The conclusions of the paper have implications for hazard assessment of potential rock avalanches
in the earthquake area and the other similar mountainous area in west China. 相似文献
52.
ZHANG Yongshuang DONG Shuwen HOU Chuntang GUO Changbao YAO Xin LI Bin DU Jianjun ZHANG Jiagui 《《地质学报》英文版》2013,87(3):646-657
Geohazards induced by the Lushan Ms 7.0 earthquake on April 20, 2013 mainly have four types: collapse, landslide, slope debris flow, and sand-soil liquefaction. These geohazards mainly occurred near the epicenter, on steep slopes or below cliffs in high mountain and deep valley areas, and at or near fault ends. They have no obvious relationships to active faults, but their relationships to the weathering degree and structures of rock and rock mass are obvious. Compared with the Wenchuan Ms 8.0 earthquake on May 12, 2008, the Lushan earthquake is relatively little in the impact force and the throwing amount. All of these should be related to the magnitude of this earthquake, not very large but not very little. This character of the Lushan earthquake would make some processes uncompleted so as to bring about some concealed geohazards. Finally, in order to deal with challenges presented by such conceal geohazards, some brief recommendations are put forward. 相似文献
53.
Chunyan Zhao Liang Chi Yongshuang Xiao Bing Li Yunliang Lu Yanting Cui Wenqi Wang Jun Li 《海洋学报(英文版)》2022,41(12):115-122
The brain plays a critical role in controlling reproduction through the hypothalamus-pituitary-gonadal (HPG) axis in vertebrates. Turbot (Scophthalmus maximus) has become an economically important marine fish in Europe and North China. Previous research investigating turbot reproduction has focused on the role of the HPG axis in regulating egg and sperm production. However, the morphology and histology of the organs in the HPG axis have not been studied. In this study, we investigated the morphology and histology of brains in female and male turbot at different stages of gonadal development. The results showed that the brains of both female and male turbot were composed of seven parts that are typical of advanced teleosts: the telencephalon, diencephalon, cerebellum, hypothalamus, pituitary gland, myelencephalon, and olfactory bulbs. The telencephalon was well-developed and contained five distinct lobes, with the contiguous diencephalon at the caudal portion. The torus longitudinales and rostral torus semicircularis of the mesencephalon flattened along the dorsal surface, and the rostral corpus cerebellum was located in the dorsal portion. The actual total brain volume in mature males was significantly greater (p<0.05) than that of females with gonadal development. Notably, the pituitary volume in male turbot significantly increased (p<0.05) from immature to mature stage, but this difference did not occur in females. The data together illustrate a distinct sex difference in the turbot brain during gonadal development, providing insight into their HPG axes. 相似文献
54.
川藏铁路是我国正在规划建设的重要铁路干线之一,是西部大通道的重要组成部分。该铁路线横跨扬子板块、川滇地块、羌塘地块和拉萨地块等大地构造单元,在复杂的地质构造背景条件下,川藏铁路沿线活动断裂、地震和地质灾害极为发育,严重制约着川藏铁路的规划建设。在野外地质调查、钻探、地应力测量和室内测试分析的基础上,对川藏铁路规划建设中可能遇到的活动断裂、高地应力、高地温、岩爆和地质灾害等主要环境工程地质问题进行了论述分析,认为:川藏铁路沿线及邻区发育有54条区域活动断裂,其中对铁路有直接重要影响的全新世活动断裂有17条;研究区内地震活动频繁,约有50%的规划线路位于地震动峰值加速度>02 g地区,部分地段>04 g,潜在地震风险大;铁路沿线主要的地质灾害类型为崩塌、滑坡和泥石流,地质灾害受活动断裂影响强烈,部分地段发育有高速远程滑坡;川藏铁路沿线构造应力场和地热场复杂,深埋隧道工程建设时容易发生岩爆、软岩大变形和高温热害等工程地质问题。 相似文献
55.
基于改进频率比法的川藏铁路沿线及邻区地质灾害易发性分区评价 总被引:2,自引:0,他引:2
川藏铁路是我国目前正在规划建设的重要铁路干线之一,地处地形和地质条件极为复杂的青藏高原东部,复杂的地质背景与脆弱的地质环境造成川藏铁路沿线及邻区地质灾害极为发育,严重威胁着川藏铁路的规划建设。在对地质灾害易发性评价方法分析的基础上,首先对传统的地质灾害易发性评价频率比方法进行改进,克服了传统通用方法中频率比值分布的不连续性,提高了各地质灾害影响因子敏感性的区分度,并减小了因子分级的主观性。利用ROC曲线与空间熵的定量对比验证表明,改进频率比法的地质灾害易发性评价模型优于传统方法。根据地质灾害的发育分布特征,选取地面高程、地形坡度、地形坡向、地形曲率、地形起伏度、工程地质岩组、地震动峰值加速度、断裂密度、水系距离、道路距离、降水量与植被指数等影响地质灾害的主要因素,结合地质灾害调查数据,首先分析各影响因子的地质灾害敏感性,并进一步对川藏铁路沿线及邻区的地质灾害易发性进行评价和分区。评价结果表明,研究区地质灾害的发育分布主要受控于断裂、水系和道路等线状要素,以及地形坡度和地形起伏度等地形地貌因素,并且断裂密度和地形起伏度相较其他因子具有更大的地质灾害敏感性区分度。地质灾害极高易发区和高易发区主要分布于大型水系两岸、道路两侧的高山河谷沿线的狭窄地带,使沿河谷与已有道路规划展布的川藏铁路面临着严重的地质灾害威胁,铁路规划建设部门应加强该地带的地质灾害排查、防治和线路优化工作。 相似文献
56.
地震通过改变地表岩体的物理力学性质而使得震区滑坡、泥石流等地质灾害显著增强的现象在震后持续相当长的一段时间。在研究分析国内外学者对地震地质灾害研究成果的基础上,系统总结了目前在地震诱发地质灾害的发育分布规律及其演化趋势方面的研究方法及成果,探讨了研究中存在的问题及薄弱环节,并对未来的研究方向及趋势进行了展望。研究认为目前国内外对地震地质灾害长期活动性的研究还没有形成体系,尚缺乏有效的研究方法与技术,并且研究成果存在较大差异性。地震扰动区地质灾害长期活动性研究可为震后地质灾害的长期防灾减灾和风险管控提供科学支持,也能对地震地质灾害相关问题的进一步深入研究提供参考。 相似文献
57.
2017年6月24日,四川省茂县叠溪镇新磨村发生高位顺层山体滑坡,滑动高差达1 160 m,滑动平距约2 200 m。该滑坡的滑动方量巨大,与其滑动过程中产生的铲刮效应有关。为分析其铲刮效应,文章通过现场调查、遥感影像解译和无人机航拍图像,确定该滑坡的滑动全过程为:多次历史地震造成滑坡源区岩体结构破碎,降雨沿顶部裂隙入渗导致水压力增大及石英砂岩中的薄层板岩软化,在长期疲劳效应下斜坡上部岩体最终发生滑动;上部滑体在运移过程中,对斜坡中部浅表风化层、部分基岩及下部老滑坡堆积体进行铲刮并重新堆积。采用Rockfall软件模拟源区滑体的运动路径、速度与能量,结果表明:在碎屑流区和老滑坡堆积区都存在明显的集中铲刮作用,整个滑坡的高危险区也主要位于该区域,所以危险性分区可代表不同滑坡区域的铲刮程度。计算得两个区域的铲刮方量分别为4.9×106,4.38×106 m3,滑坡总方量为13.35×106 m3。该模拟和计算方法迅速有效,可为以后类似滑坡的应急、救灾和铲刮方量计算提供参考。 相似文献
58.
Liu Guolin North China Institute of Science Technology Beijing Hu Shaoxiang Shandong University of Science Technology Tai''''an Lei Weizhi Zhang Yongshuang Institute of Geomechanics Chinese Academy of Geological Sciences Beijing 《中国地质大学学报(英文版)》2003,14(2):155-160
INTRODUCTIONTheloess,widelydistributedinthenorthwestplateauofChina ,hasatalltimesbeenanimportantresearchsubjectofthestudiesonengineeringgeology.Duetotheunfavorableengineeringpropertiesofloess,aswellasthespecialtopog raphyandclimate ,thenorthwestloessplateauisaregionwithfrequentgeologicalhazardsandcomplicatedgeologicalengineeringproblems.Inthepast,mostoftheresearchersconsideredthelandslideasthemainandseriousformoffail ureoftheloessslopes,soloesslandslidesweregivenmoreattention (DuanandLuo… 相似文献
59.
60.
高原山区铁路工程建设地质安全评价:思路与方法 总被引:1,自引:0,他引:1
工程地质评价是保障重大工程建设安全的重要工作内容。本文面向新时代重大工程规划建设需求,提出了地质安全评价的内涵和目标任务,以高原山区铁路工程建设为例,阐述了地质安全评价的方法、工作流程和应用实例。着重提出:服务铁路工程的不同规划建设阶段对应于不同的评价尺度要求,规划阶段适用区域廊带尺度,以区域地壳稳定性评价为基调,基本比例尺可≤1:5万,目的是定性给出廊带安全性或适宜性;可研阶段适用关键区段尺度,以工程地质稳定性评价为基调,基本比例尺1:1万~1:2.5万,目的是进一步厘定不良地质组合和重大地质风险,指导线路比选和优化;设计阶段适用工程场地尺度,聚焦具体的地质风险或工程岩体稳定性问题,基本比例尺1:2000,依据相关技术标准和专题分析研究进行专项评价。通常,随着地质风险等级从高到低,对应地质安全等级从低到高;地质安全评价结果可根据地质风险等级与防治难度划分为安全、较安全、欠安全和不安全四个等级,目前技术条件下达不到安全要求的地带应首先考虑避让。建议把地质安全评价纳入国家级工程建设管理的必要环节,并加快相关技术标准的制订。 相似文献