非开挖工地的地下管线调查与探测     

彭万利 《岩土钻凿工程》2009,(3):47-49

本文概述了探测地下管线的基本方法、地下管线探测仪的选择及地球物理探测方法的选择,介绍了在非开挖工地调查探测地下管线的步骤和方法。  相似文献   

Assessment of Risk Due to Debris Flow and Its Application to a Marine Environment     

Sungduk Kim 《Marine Georesources & Geotechnology》2013,31(6):572-578

The purpose of this study is to evaluate the behavior and mechanism of a debris flow on various slopes through numerical simulation. The numerical simulation consisted of using equations related to mass conservation and momentum conservation in order to consider erosion and deposition, and the Finite Difference Method was applied. As the inflow water discharge in the upstream of the channel increases, the curve of the water discharge exhibits instability and, as time passes, the fluctuation of the high water discharge continues. In regions where the mountain areas and the ocean are connected, it is deduced that the high level of sediment concentration can greatly affect the environment surrounding the ocean. The numerical model of this study was applied in Kangwon Province of South Korea. The results show that when the debris flow reaches downstream, the flow discharge and water flow depth increase. Erosion occurs more than deposition and much of the sediment runs off downstream. The result of the simulation performed at point of sediment discharge runoff is 114,216 m³. This study will provide useful information in predicting disasters caused by debris flow and in planning for various countermeasures to prevent debris-flow-related disasters.  相似文献   

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刘 强姚宜斌  陈浩朋仲崇豪 雷祥旭 《大地测量与地球动力学》2013,33(6):86-89

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不同节点布置下二维涡激振动的无单元法参数化分析     

杨林  李华军 《中国海洋大学学报(自然科学版)》2012,42(5):105-110

尝试建立1种基于无单元法的涡激振动数值模拟算法,并给出适用于涡激振动分析的前处理自动布点方法.基于无单元法理论,使用动最小二乘法构造形函数,利用无单元伽辽金法,采用速度和压力分离模式,及手工布点和自动布点2种方法所得出的节点布置形式,对流场控制方程进行空间离散,模拟二维涡激振动的流场形态,并对VIV相关参数进行分析,计算不同节点布置情况下的升力系数(Cl)、曳力系数(Cd)及斯特罗哈数(St),并与物理模型实验结果进行对比.计算结果表明,无单元伽辽金法应用于立管VIV分析是可行的,且文中采用2种布点方法均能较好的模拟流场中泻涡脱落的形态,计算结果与传统方法和物理模型实验结果吻合良好.证明文中2种布点方法都能用于固定圆柱的二维VIV分析,但自动布点法能够更好地适用于复杂问题的计算及圆柱体在流场中的VIV动力响应分析.  相似文献   

西安白鹿塬北缘黄土边坡稳定的可靠度分析   总被引：4，自引：1，他引：3  

王阿丹  王昌业  李萍  李同录 《地球科学与环境学报》2012,(1):104-110

在西安白鹿塬北缘实测了14个黄土自然边坡断面,建立了地质模型,通过采样测试并收集已有的测试资料,获得了各时代黄土地层的物理力学参数,将Morgenstern-Price法稳定性计算公式作为极限状态方程,分别采用Monte-Carlo法和Duncan法进行了边坡稳定的可靠度分析。结果表明:采用Monte-Carlo法和Duncan法得到的14个边坡稳定系数分别为1.11～1.41和1.09～1.33,显示这些边坡处于基本稳定—稳定状态;采用上述两种方法得到的边坡可靠指标分别为0.56～1.79和0.39～1.60,得到的失效概率分别为3.4%～29.0%和5.5%～34.8%,并且共有75%的边坡失效概率大于10%,失效可能性较大。统计结果表明:白鹿塬区边坡的坡高和坡度存在负相关性。低而陡的边坡潜在最危险滑面剪出口较高,失效概率较小;坡高达到50m及以上时,边坡高而缓,剪出口较低,失效概率较大,其中河流下切深,有N2泥岩出露的极高边坡,稳定性最差。Duncan法求解的稳定系数略小于Monte-Carlo法求得的结果,而前者求解的失效概率略大于后者,两种方法计算结果较为接近。由于Duncan法理论简单,计算量小,更宜于在实际工程中应用。  相似文献   

基于报纸媒体内容分析和信息熵的广交会综合影响力时空分布   总被引：3，自引：0，他引：3  

戴光全  谭健萍 《地理学报》2012,67(8):1109-1124

从报纸媒体的角度研究广交会作为重大事件的综合影响力的时空分布特点。以中国知网(http://www.cnki.net/) 所属“中国重要报纸全文数据库”(CCND) 2000-05-05 到2011-05-30 时间段内“广交会”为主题的4333 条新闻报道为研究文本, 通过传播学中的内容分析法建构分析类目, 统计类目包括新闻的时间、所属的届数与期数、报社所在城市、新闻版面、新闻字数等, 共由3 个编码员进行统计, 并对类目编码进行信度检测。在对新闻内容进行计量统计的基础上, 引进信息熵度量信息量, 利用信息熵和报道篇数构建广交会综合影响力指标, 进一步构建广交会空间综合影响力指数方程, 分析广交会综合影响力在全国的分布情况, 并检验综合影响力指标和经济指标的相关性。结果发现:① 从时间分布来看, 以新闻报道数量来衡量, 在事件(广交会) 进行时其综合影响力存在时间衰减现象, 各展期综合影响力的年际变化则呈现为周期性的年度重复现象。② 从空间分布来看, 广交会综合影响力空间分布与城市参展商数量、经济情况和距离有着密切的联系:受影响大的城市主要集中在沿海经济发达的省份, 受影响小的城市主要分布在西部和北部, 整体上综合影响力大小和城市分布的密度由东到西递减;综合影响力总体上存在显著的空间距离衰减, 但对于北京和上海这两个特殊城市而言, 空间距离已经不是广交会综合影响力的主要因素, 而在广交会举办地的“当地”(广东省内) 较短的距离内, 距离衰减并不显著, 当空间距离超出一定范围, 则存在明显的距离衰减现象。  相似文献   

Landslide susceptibility analysis with a heuristic approach in the Eastern Alps (Vorarlberg, Austria)   总被引：5，自引：0，他引：5  

M. Ruff  K. Czurda   《Geomorphology》2008,94(3-4):314

The aim of the study is landslide hazard assessment carried out on a working scale of 1:25 000. The study area within the Northern Calcareous Alps was geologically and geotechnically mapped in order to identify causes and mechanisms of active mass movements. The field surveys were digitised by a Geographical Information System and divided into data layers. The geological units were classified according to their geotechnical properties. All layers were converted into grids and spatially analysed together with a Digital Elevation Model. Comparing the layers with the inventory of active landslides, the prevailing factors leading to sliding movements were identified. Because of the complex tectonic setting and the small number of active landslides, a statistical method of hazard assessment was not applicable. Using the heuristic approach of an index method, the data layers of geotechnical class, bedding conditions, tectonic layouts, slope angles, slope orientations, vegetation and erosion were analysed. The susceptibility of each layer has been evaluated with help of bivariate statistics. The layers have been weighted with indices due to their importance iteratively and were combined into a landslide susceptibility map.  相似文献   

Evaluation of active and passive seismic earth pressures considering internal friction and cohesion     

《Soil Dynamics and Earthquake Engineering》2015

The Log-Spiral-Rankine (LSR) model, which is a generalized formulation for assessing the active and passive seismic earth pressures considering the internal friction and cohesion of backfill soil, is reviewed and improved in this study. System inconsistencies in the LSR model are identified, which result from an inaccurate assumption on the vertical normal stress field (σ_z=γz) in a general c–ϕ soil medium, and from omitting the effect of soil cohesion when solving for the stress states along the failure surface. The remedies to the said inconsistencies are presented, and local and global iteration schemes are introduced to solve the resulting highly coupled multivariate nonlinear system of equations. The modified LSR model provides a more complete and accurate solution for earth retaining systems, including the geometry of the mobilized soil body, the stress state along the failure surface, as well as the magnitude and the point of application of the resultant earth thrust.  相似文献   

基于氮气吸附-核磁共振-氩离子抛光场发射扫描电镜研究川西须五段泥质岩储层孔隙结构   总被引：7，自引：5，他引：2  

庞河清  曾焱  刘成川  黎华继  彭军  严焕榕  陈俊 《岩矿测试》2017,36(1):66-74

微观孔隙作为泥质岩的有效储集空间,其孔隙结构参数是作为气藏评价及资源量估算的重要依据。本文应用氮气吸附法(NAM)、核磁共振法(NMR)、氩离子抛光及场发射扫描电镜(AIP-FESEM)研究川西须五段泥质岩微观孔隙特征,结果表明:1氩离子抛光及场发射扫描电镜在表征微观孔隙形态与类别时有一定优势,但定量表征孔隙参数时,受图像二值化阈值的影响,表征结果偏差较大,可结合氮气吸附法来定量表征其孔径大小;2核磁共振受岩石骨架影响小,能够更精细反映岩石的物性条件,可定量计算孔隙度与可动流体饱和度,但对样品的孔隙形态反映较差;3综合上述三种方法,在须五段泥质岩中可识别出一定量的纳米级中、大孔,孔径大多介于几十纳米到几百纳米之间,孔隙连通性差,孔隙度主要介于2.3%~7.4%之间,孔隙类型以粒间孔、晶间孔最发育,有机孔隙、微裂缝次之,粒内孔隙最不发育。总体而言,融合了三种技术方法能更精确、更全面地反映泥质岩孔隙结构特征,能得到更完善的储层孔隙结构参数,在定量表征泥质岩孔隙结构中具有广泛的应用前景。  相似文献   

Determination of microscopic parameters of quartz sand through tri-axial test using the discrete element method     

《Computers and Geotechnics》2017

A calibration procedure, in which coupled effects of microscopic parameters are considered, is proposed to determine the values of the microscopic parameters in the Discrete Element Method (DEM) for Fujian quartz sand. Laboratory tri-axial tests are conducted to be compared with the DEM simulations and the effects of end restraint in the laboratory tests are eliminated through a digital image measurement system. Sensitivities of the macroscopic behaviour of the specimen to the microscopic parameters are analyzed through DEM simulations. Four coupled effects of the microscopic parameters on the macroscopic behaviour are investigated through a graphic method and then considered in the calibration procedure.  相似文献