多级边坡平台宽度对边坡地震动力响应 及破坏机制的影响     

言志信  郭斌  贺香  江平 《岩土力学》2012,33(Z2):352-358

以典型工程边坡为原型,利用FLAC3D有限差分软件建立一个三维土坡模型,分析地震作用下多级边坡平台宽度对边坡动力响应特性和动力失稳机制的影响。计算结果表明,边坡设置平台可以有效地提高地震动力条件下边坡的稳定性,且平台宽度越大则稳定性越显著;PGA放大系数随着平台宽度的增大而减小。结合频谱分析得到第一级边坡坡顶的动力响应较第二级边坡坡脚的大,边坡岩土体剪应变增量和位移响应也减小;地震作用下边坡塑性区从坡脚部位向坡体内部发展,随地震持时的增加,坡顶出现拉张变形,坡面及其浅表层发生拉张剪切变形,坡体内部一定部位发生剪切变形;坡面监测点位移时程曲线表明,地震作用下边坡坡脚位移向上,发生剪出变形或破坏,坡脚和变坡点均为薄弱部位,应加强支护。研究结果对多级土质边坡抗震设计具有一定指导意义。  相似文献   

直流电法电位测量中提高计算精度的方法技术研究     

张刚  贾正元 《现代地质》2012,26(6):1206-1211

直流电法是电法勘探中的重要分支,它是采用地表供电或者井中供电,在地面测量电位响应的勘探方法。利用地面测得的异常电位响应来分析地下的物性分布情况并推断地下矿体的空间位置。以采用方波供电方式所测得的电位数据为例来分析和研究计算人工电位的方法,结果表明:当采集电位数据质量好时,采用不同长度的窗口宽度计算得到的人工电位变化不大;当采集电位数据质量差时,采用不同长度的窗口宽度计算得到的人工电位变化比较大;假设加入不同比例的随机噪声理论电位数据,并采用不同窗口宽度进行理论计算人工电位时,取较小长度的窗口宽度计算得到的人工电位比较精确。这些为下一步的数据处理与解释奠定基础。  相似文献   

基于环境扩散条件的河流宽度分类判别准则   总被引：1，自引：0，他引：1       下载免费PDF全文

武周虎 《水科学进展》2012,23(1):53-58

在河流排污引起的污染物扩散计算中,不同河流宽度类别对应不同的移流扩散解析解算式,但缺少具体的河流宽度分类判别准则,给实际应用带来很大困难。按照河流污染物扩散受边界反射影响程度的不同,从移流扩散解析解算式的简化条件出发,提出了宽阔、中宽、窄小的分类方法和定义;根据二维可忽略边界反射的条件和达到全断面均匀混合距离小于等于河流宽度的条件,分别求解了河流宽阔与中宽窄小的分区临界关系线和中宽与窄小的分区临界关系线,提出了相应判据的数学表达式;给出了河流宽阔、中宽、窄小的分类判别准则以及各类别河流移流扩散解析解算式的对应关系。最后指出基于环境扩散条件的河流宽阔、中宽、窄小分区是相对的,对于同一河流在不同水力要素、扩散系数、排污强度和允许浓度升高值等条件下,可以得到不同的分区结果。  相似文献   

A hillslope-based hydrological model using catchment area and width functions     

DAWEN YANG  SRIKANTHA HERATH  KATUMI MUSIAKE 《水文科学杂志》2013,58(1):49-65

Abstract

A flow-interval hillslope discretization scheme is proposed for catchment hydrological modelling. By this scheme, a two-dimensional catchment is simplified into a one-dimensional cascade of flow intervals linked by the main stream. Each flow interval comprises a set of parallel hillslopes. The hillslope is the fundamental computational unit in the hydrological model providing lateral inflow to the main stream. The size of hillslope is determined by the catchment area and width functions. Catchment runoff is the total of hillslope responses through the river routing. Tests in four Japanese catchments showed that the model performed well on simulating the overall water balance, general flow pattern, and daily and hourly hydrographs of a whole catchment, as well as simultaneous simulation in different subcatchments. Characteristics of catchment hydrological responses and model applicability are discussed.  相似文献   

一种基于方向检测的等高线分离方法     

陈军  杨存建 《成都信息工程学院学报》2007,22(3):379-383

提出了一种地形图上等高线分离方法,方法建立在基于方向检测的线宽识别算法基础上,使等高线分离具有很强的宽度敏感性,同时由于在线宽识别过程中考虑了等高线的空间连续性,方法具有很好的分离效果.实践证明,算法可以为等高线进一步矢量化提供高质量的底图,减少等高线自动矢量化的后续编辑工作量,具有很强的实际意义和理论价值.  相似文献   

Solar x-ray spectrometer (SOXS) mission – Low energy payload – First results     

Rajmal Jain  Vishal Joshi  S. L. Kayasth  Hemant Dave  M. R. Deshpande 《Journal of Astrophysics and Astronomy》2006,27(2-3):175-192

We present the first results from the ‘Low Energy Detector’ pay-load of ‘Solar X-ray Spectrometer (SOXS)’ mission, which was launched onboard GSAT-2 Indian spacecraft on 08 May 2003 by GSLV-D2 rocket to study the solar flares. The SOXS Low Energy Detector (SLD) payload was designed, developed and fabricated by Physical Research Laboratory (PRL) in collaboration with Space Application Centre (SAC), Ahmedabad and ISRO Satellite Centre (ISAC), Bangalore of the Indian Space Research Organization (ISRO). The SLD payload employs the state-of-the-art solid state detectors viz., Si PIN and Cadmium-Zinc-Telluride (CZT) devices that operate at near room temperature (-20°C). The dynamic energy range of Si PIN and CZT detectors are 4–25 keV and 4–56 keV respectively. The Si PIN provides sub-keV energy resolution while CZT reveals ∼1.7keV energy resolution throughout the dynamic range. The high sensitivity and sub-keV energy resolution of Si PIN detector allows the measuring of the intensity, peak energy and equivalent width of the Fe-line complex at approximately 6.7 keV as a function of time in all 8 M-class flares studied in this investigation. The peak energy (E _p) of Fe-line feature varies between 6.4 and 6.8 keV with increase in temperature from 9 to 34 MK. We found that the equivalent width (ω) of Fe-line feature increases exponentially with temperature up to 20 MK but later it increases very slowly up to 28 MK and then it remains uniform around 1.55 keV up to 34 MK. We compare our measurements ofw with calculations made earlier by various investigators and propose that these measurements may improve theoretical models. We interpret the variation of both E_pand ω with temperature as the changes in the ionization and recombination conditions in the plasma during the flare interval and as a consequence the contribution from different ionic emission lines also varies.  相似文献   

Turbulence and Rainfall Microphysical Parameters Retrieval and Their Relationship Analysis Based on Wind Profiler Radar Data     

胡苏蔓  黄兴友  马玉蓉 《热带气象学报(英文版)》2021,27(3):291-302

Rainfall is triggered and mainly dominated by atmospheric thermo-dynamics and rich water vapor.Nonetheless, turbulence is also considered as an important factor influencing the evolution of rainfall microphysical parameters. To study such an influence, the present study utilized boundary layer wind profiler radar measurements. The separation point of the radar power spectral density data was carefully selected to classify rainfall and turbulence signals;the turbulent dissipation rate ε and rainfall microphysical parameters can be retrieved to analyze the relationship betweenε and microphysical parameters. According to the retrievals of two rainfall periods in Beijing 2016, it was observed that(1) ε in the precipitation area ranged from 10~(-3.5) to 10~(-1) m~2 s~(-3) and was positively correlated with the falling velocity spectrum width;(2) interactions between turbulence and raindrops showed that small raindrops got enlarge through collision and coalescence in weak turbulence, but large raindrops broke up into small drops under strong turbulence, and the separation value of ε being weak or strong varied with rainfall attributes;(3) the variation of rainfall microphysical parameters(characteristic diameters, number concentration, rainfall intensity, and water content) in the middle stage were stronger than those in the early and the later stages of rainfall event;(4) unlike the obvious impacts on raindrop size and number concentration, turbulence impacts on rain rate and LWC were not significant because turbulence did not cause too much water vapor and heat exchange.  相似文献   

矿井涌水量动态预测非稳定释水-断面流法     

傅耀军 《中国煤炭地质》2021,(1)

我国北方煤田上覆地下水系统含水层以砂岩为主,是矿井主要充水水源。除浅部、露头区外,上覆砂岩地下水系统总体上构成非径流型蓄水构造,弹性贮存是其地下水主要赋存状态,压力传导、局部渗流为地下水动力学模式,矿井涌水主要为承压含水层弹性释放。非充填开采,煤层上覆地层周期性冒裂形成冒裂二元结构体,其自身释水(弹性、重力)与其外侧含水层断面弹性释水叠加形成矿井涌水。冒裂二元结构体释水随冒裂周期发生,时间短暂。外侧含水层断面释水可用非稳定流定降深沟(渠)流方程描述,进而获得外侧含水层断面释水单宽流量。外侧含水层释水断面随冒裂周期性延展累积,迭代更新,矿井涌水流量随之变化。在研究、刻画外侧含水层释水断面延展、迭代时空规律基础上,给出含水层断面释水流量预测方法、公式,与冒裂二元结构体自身周期性释水流量叠加,获新的矿井涌水量预测方法—非稳定释水-断面流法。  相似文献   

A coupled sediment routing and lateral migration model for gravel‐bed rivers     

Emma K. Raven  Rob Ferguson  Stuart N. Lane 《水文研究》2011,25(12):1887-1898

We describe additions made to a multi‐size sediment routing model enabling it to simulate width adjustment simultaneously alongside bed aggradation/incision and fining/coarsening. The model is intended for use in single thread gravel‐bed rivers over annual to decadal timescales and for reach lengths of 1–10 km. It uses a split‐channel approach with separate calculations of flow and sediment transport in the left and right sides of the channel. Bank erosion is treated as a function of excess shear stress with bank accretion occurring when shear stress falls below a second, low, threshold. A curvature function redistributes shear stress to either side of the channel. We illustrate the model through applications to a 5·6‐km reach of the upper River Wharfe in northern England. The sediment routing component with default parameter values gives excellent agreement with field data on downstream fining and down‐reach reduction in bedload flux, and the width‐adjustment components with approximate calibration to match maximum observed rates of bank shifting give plausible patterns of local change. The approach may be useful for exploring interactions between sediment delivery, river management and channel change in upland settings. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

雷击风险评估中的位置因子C_d的探讨     

马金福  汝洪博  冯志伟 《南京气象学院学报》2012,4(5):415-419

从周边建筑物对所考虑建筑物的扩大宽度影响的角度,分析了周边有等高、更低或更高的其他建筑物3种情况下,周边建筑物对所考虑的建筑物截收面积的实际影响.在此基础上提出了周边建筑物的高度、相对位置、环绕程度等均对建筑物截收面积有较大影响,并不能将其乘以一个恒定的位置因子作为考虑了周边建筑物的影响,应根据建筑物所处环境的实际情况的不同做更为精确的计算,以提高风险评估的准确性.  相似文献