Radon variations in an active landslide zone along the Pindar River, in Chamoli District, Garhwal Lesser Himalaya, India     

V.M. Choubey  S.K. Bartarya  R.C. Ramola 《Environmental Geology》2005,47(6):745-750

Radon measurements were made in the soil and spring/seepage water in and around an active landslide located along the Pindar river in the Chamoli District of Uttaranchal in Garhwal Lesser Himalaya, to understand the application of radon in geological disasters. The landslide is a compound slide i.e. a slump in the crown portion, and debris slide and fall in the lower part. The bedrock consists of gneisses and schists of the Saryu Formation of the Almora Group of Precambrian age. The presence of several small slump scars and debris slide/fall scars along the length of the slide indicates continuous downward movement. The radon concentrations in the present study are much lower in comparison to values reported from other regions. However, the present radon data show relative variation in the slide zone. The concentration of radon measured in landslide zones varies from 3.1 Bq/l to 18.4 Bq/l in spring water and from 2.3 kBq/m³ to 12.2 kBq/m³ in the soil gas of the debris. Along the section of the slide, the radon values in water and soil are slightly higher in the upper slopes i.e. toward the crown portion of the landslide as compared to the distal portion. The relatively low concentration of radon both in soil gas and water in the toe portion of the landslide may be due to the high porosity of the debris, which does not allow radon to accumulate in the soil and water, whereas, towards the crown portion, the high frequency of fractures increases the surface area due to particle size reduction, and the near absence of debris enhances the radon emanation in soil.  相似文献   

Laboratory Tests on Shotcrete-Rock Joints in Direct Shear, Tension and Compression   总被引：1，自引：0，他引：1  

D. Saiang  L. Malmgren  E. Nordlund 《Rock Mechanics and Rock Engineering》2005,38(4):275-297

Summary. A series of laboratory tests was performed on cemented shotcrete-rock joints to investigate the strength and stiffness of the interfaces, while simulating field conditions as close as possible. The direct shear test formed the core of the experimental work, while the tension and compression tests were complementary. To simulate loading conditions experienced in practical cases the direct shear tests were performed under fairly low normal stresses. In most practical cases when shotcrete is used with rock bolts, the normal load on shotcrete lining seldom exceeds 0.2 to 0.5 MPa. The direct shear test results show that, for such normal load range the shear strength is determined by the bond strength for genuinely bonded shotcrete-rock interfaces. For higher normal stresses (σ_n > 1.0 MPa), which rarely exist at the shotcrete-rock interface, the shear strength is largely influenced by friction resulting in the cohesive strength being less significant. Assessment of the shear surface revealed that the steel fibres in the shotcrete appeared to contribute significantly to the frictional component. The shear and normal stiffnesses of the interface were also determined, which were in principal the stiffnesses of the bond. An interesting observation was the complex interaction at the interface and the mechanisms that controlled the peak shear strength which depended on the surface roughness, the existence of natural flaws and the normal load.  相似文献   

基体裂隙实测全迹长分布规律研究   总被引：3，自引：0，他引：3  

黄达  黄润秋  陈强  张敏  蒋良潍 《水文地质工程地质》2005,32(4):10-12

由于有很好的露头条件,作者对澜沧江小湾水电站坝肩基体裂隙的全迹长进行了现场测量,并统计了其分布规律。发现基体裂隙的全迹长分布特征与优势方位无关,全迹长主要集中分布在1～3m的范围内且在(1 0m ,2 0m ]和(2 0m ,3 0m]区间内大致服从正态分布,总体均值在2 6m左右,概率分布密度服从负指数函数关系。  相似文献   

Fractal dimension of profiles and surfaces using fuzzy morphological coverings     

Chin-Pan Huang  Luis F. Chaparro  Luis E. Vallejo 《Engineering Geology》1997,48(3-4):245-253

In this paper, we propose a new method, based on fuzzy morphology coverings, to estimate the fractal dimension of profiles and surfaces. This method is geometrically intuitive and simple to implement. Algorithmically, the method fits a covering to the frames or blocks of the profile or surface using fuzzy morphology. Varying the dimension of the frame or block, estimates of the length or area covered are then used to find the fractal dimension. Validation of the proposed method is performed by comparing its results with known fractal dimensions of mathematical profiles. The method is used to obtain the fractal dimension of rock profiles and surfaces.  相似文献   

地下连续墙槽段连接技术     

戴国忠 《地质与勘探》1995,31(2):55-57,62

他目前国内外地下连续墙的槽段之间连接技术与方法，介绍了接头管，接头箱，隔板式及套打一钻等槽段纵向接头的结构形式。  相似文献   

碳纤维布增强混凝土平面框架节点抗剪性能试验研究与机理分析   总被引：1，自引：0，他引：1  

王步  王溥  夏春红 《世界地震工程》2006,22(1):157-163

混凝土平面框架节点核心区不存在直交梁的影响,可以应用碳纤维布直接进行加固,以增强地震作用下节点核心区的抗剪承载力。根据足尺混凝土框架节点低周反复加载试验结果,对碳纤维布的增强机理进行了分析和讨论,并在此基础上提出了实用的加固计算公式。  相似文献   

混凝土框架节点碳纤维布抗震加固的试验与分析   总被引：1，自引：0，他引：1  

冼巧玲  江传良  周福霖 《地震工程与工程振动》2007,27(2):104-111

本文提出了用碳纤维布加固平面框架中间节点和空间框架中间节点的抗震加固新方法,通过5个框架中间节点(其中2个为拟三维节点)的足尺拟静力试验,以及用有限元软件ANSYS进行分析,验证了本文加固方法的有效性。试验与分析结果表明,对平面框架梁柱节点,本文的2种加固方法均能显著改善构件的延性,承载力也有一定的提高;对空间框架梁柱节点,采用碳纤维布与三角钢腋联合加固不但能够大大提高构件延性,而且能够提高节点的屈服强度、极限强度和屈服后刚度,加固效果十分明显。  相似文献   

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马春田  郭进京  刘林  王利晓  赵海涛 《大地测量与地球动力学》2015,35(2):273-277

????????κ?????????????????????μ?????????????????????????????????????????????????????????????????????????????????????????γ???????????4?????????????????????????????????????NW-SE???????????????????????????????NE-SW????????????????????????????????E-W????????????????????????????????S-N??4???????????м??????????δ??2??)???????????????????,??????????????????????????????????????????  相似文献   

浅成侵入岩储层分布模式——以新西兰Lyttelton火山中新世浅成岩脉为例     

郭天婵  唐华风  王寒飞 《地质学报》2021,95(12):3885-3898

侵入岩油气藏广泛分布于世界各盆地中,具有良好的油气勘探潜力.但对原生孔隙发育的岩脉储层模式的研究尚未引起足够的关注.本文以新西兰基督城Lyttelton火山西北部的中新世浅成岩脉为研究对象,根据野外露头调查、孔渗测试、图像分析和经验公式的渗透率计算,对其孔隙构成、储层分布模式和储层控制因素进行分析.结果 表明:该区浅成侵入岩为孔隙-裂缝型储层,储集空间以气孔为主,冷凝收缩缝次之;气孔可见定向拉长的大直径椭圆形和离散的小直径圆形两类,对孔隙度的贡献以前者为主;柱状节理可见规则和不规则两类,后者的裂缝面密度较高;具有中孔-中渗的特征,局部高孔-高渗;柱体横截面形态和规则性是影响地层渗透性的关键因素.整体上,浅成岩脉从下到上孔隙度由小变大,柱状节理由规则变为不规则;气孔可由柱状节理沟通,其连通性受柱状节理缝间距、缝宽,以及定向拉长气孔与柱状节理之间的夹角控制;Lyttelton火山的浅成岩脉显示,冷凝固结阶段气孔的初始连通率可高达35％.综上,浅成岩脉可具有良好的储集性能,气孔初始连通性较高,可作为有利的勘探目标.  相似文献   

峰前循环剪切作用下岩石节理剪切力学特性     

孙杰豪  郭保华  田世轩  程坦 《岩土力学》2022,43(Z2):52-62

微震、工程爆破等低应力循环剪切荷载作用对节理岩体工程失稳破坏具有重要影响。为研究峰前循环剪切加卸载作用下岩石节理剪切力学特性,采用RDS-200型岩石节理剪切试验系统对人工劈裂黄砂岩节理进行了峰前循环剪切下的直剪试验。通过与未进行峰前循环剪切加卸载时岩石节理力学参数预测值对比,得到峰前循环剪切加卸载作用对峰前剪切刚度、峰值剪切强度、峰值剪切位移与残余剪切强度的影响。结果表明：（1）峰前循环剪切加卸载后,当法向应力为2 MPa时,岩石节理峰前剪切刚度增大,当法向应力为4～10 MPa时,岩石节理峰前剪切刚度在循环剪切应力幅值范围内增大,在超出循环剪切应力幅值时减小;（2）峰前循环剪切加卸载后,峰值剪切强度降低了10%～20%,降低百分比随法向应力增大整体呈对数函数增大;峰值剪切位移增加了2%～40%,增加百分比随法向应力增大整体呈对数函数减小;（3）峰前循环剪切加卸载后,岩石节理残余剪切强度无明显变化,峰值剪切强度与残余剪切强度差值减小,峰后剪切应力做功损失百分比降低。  相似文献