库鲁克栏杆水文站水面流速系数率定方法及影响因素分析

以新疆库鲁克栏杆水文站为例,基于对比观测试验(经验法)对库鲁克栏杆水文站水面流速系数进行率定,并对影响流速系数率定精度的影响因素进行剖析。分析结果可知:从误差和检验结果可看出,库鲁克栏杆水文站15组比测试验数据中的平均相对偏差为2.31%。符号检验u值经统计分析为0.54,满足符号检验u值低于1.15的误差检验要求,表明库鲁克栏杆水文站流速率定系数取值为0.62具有合理性,可满足测验精度要求。研究成果可为叶尔羌河流域水文测站测次精简提供重要的依据。     

泥石流地质灾害专业监测预警选点工作探讨

泥石流灾害具有很强的危害性,专业监测预警成为泥石流防治的重要手段之一。但如何选择合适的监测泥石流沟,进行设备选型,选择合适的安装点位,是泥石流监测预警的发挥效果的基础。根据多年的工作实践,形成了一套泥石流监测预警选点工作程序。监测设备安装点位选择应先保证预警时间和预警距离,在设备本身安全的基础上,充分利用自然环境条件,以发挥设备功能和效果。     

泥石流地质灾害专业监测预警选点工作探讨

泥石流灾害具有很强的危害性,专业监测预警成为泥石流防治的重要手段之一。但如何选择合适的监测泥石流沟,进行设备选型,选择合适的安装点位,是泥石流监测预警的发挥效果的基础。根据多年的工作实践,形成了一套泥石流监测预警选点工作程序。监测设备安装点位选择应先保证预警时间和预警距离,在设备本身安全的基础上,充分利用自然环境条件,以发挥设备功能和效果。     

内陆河流域河流水面流速系数比测试验研究

水面流速系数是流量测验中经常使用的参数.目前,大部分水文站使用水面流速系数均选用经验值,为提高流量洲验精度,2003-2007年间.在内陆河流域代表站莺落峡、高崖、正义峡、祁连、肃南水文站开展了对水面流速系数的比测试验工作,取得大量比测试验资料.通过分析得出试验分析成果,并对试验分析计算方法和比测试验方法进行了探讨.水面流速系数分析计算方法采用算术平均法、回归分析法.两种分析方法得出的结论基本一致.算术平均法是对回归分析成果的校核.因此均采用回归分析法比测试验分析成果.以莺落峡站为例对垂线比测法和断面流量比测法两种不同比测试验方法进行对比分析和比测试验方法优选.垂线比测法和断面流量比测法均能得到比较满意的结果,相关系数均达O.95以上,分析成果比较接近.断面流量比测法理论比较严密,得到的水面流速系数适合全断面应用.这些试验分析成果为提高流量测验精度提供理论依据.     

泥石流地质灾害专业监测预警选点工作探讨

泥石流灾害具有很强的危害性,专业监测预警成为泥石流防治的重要手段之一。但如何选择合适的监测泥石流沟,进行设备选型,选择合适的安装点位,是泥石流监测预警的发挥效果的基础。根据多年的工作实践,形成了一套泥石流监测预警选点工作程序。监测设备安装点位选择应先保证预警时间和预警距离,在设备本身安全的基础上,充分利用自然环境条件,以发挥设备功能和效果。     

喀什地区水文站水面流速系数率定分析方法

以喀什水文站为研究实例,为对水面流速系数的率定方法进行研究,通过对2年内的水文站垂向平均流速系数进行率定,总共进行了30次高水位流速系数率定试验,31次中水位试验和30次低水位流速系数率定试验,最终对其水面流速系数进行率定,并对其流速系数率定影响因素进行分析。结果表明:采用流速仪的三点及五点法可满足其流速系数的率定要求。测速垂线的布设、流速的脉动误差、流速仪的测定误差以及流向的偏角是其率定精度影响的关键因素。     

黄河中游测区输沙率与流量异步施测法分析

在悬移质输沙率与流量异步施测法基本原理分析的基础上,采用理论公式法及经验相关法对测点位置流速权重系数进行了分析计算;根据河流断面特性,建立了多年综合及相邻流量测次累积面积百分数与累积流量百分数相关曲线法等不同的部分流量权重系数借用方案。经实测资料检验,输沙率与流量异步施测法的计算误差符合《河流悬移质泥沙测验规范》的精度要求,能满足悬移质泥沙测验的生产需求。     

二层测速方式超声波时差法测流参数自率定方法研究

为解决超声波时差法比测率定的难题,采用二层测速方式构建基于垂向流速分布的河流断面水平层流速与断面平均流速的转换数学模型,通过二个水平层流速的信息提取与流速分布模型参数识别,获取河流断面流速分布特征,进而完成流量计算参数的率定,实现水平层流速与断面平均流速的转换计算。通过湘潭水文站实例验证,水平层流速与断面平均流速转换模型计算的流量成果精度能够满足流量测验精度要求。     

雷达波流速仪流量测验水面流速系数分析

以具有不同河流特征的长冈水库水库、平江和孤江流域为例,进行了雷达波流速仪和LS1206B型流速仪水面流速的比测分析,并在比测试验的基础上,得出雷达波流速仪对水面流速的试验结果可以代表LS1206B型流速仪,同时用LS1206B型流速仪进行相对水深0.6 m测点流速的相关性分析,得出冈水库水库、平江和孤江流域水面流速系数...     

多要素相关法提高潮流量测验精度的探讨

在珠江三角洲潮流量巡测资料的分析基础上，探讨了提高潮流量测验精度的方法。采用代表线流速、潮位、潮位涨落率等多要素进行相关的方法，提高了潮流量代表线流速定线精度，不但能降低潮流量测验强度和成本，而且还能提高测验、整编质量和经济效益。     

北京山区泥石流专业监测技术要求及实践

泥石流是北京山区主要突发地质灾害之一,虽然发育规模以中小型居多,但危险性很大,开展专业监测十分必要。科学选取监测对象、合理选择监测方法、监测设备类型和可靠的安装位置,明确监测技术要求,是泥石流监测预警的关键。根据北京市突发地质灾害监测预警系统(二期工程)建设的工作实践,在北京山区泥石流特征分析的基础上,总结得出泥石流监测对象选择、监测方法及设备、监测点位确定方法及技术要求等,并以小梁后沟印子峪泥石流专业监测实践为例,验证了上述原则、方法和技术的合理性。研究成果可为泥石流监测预警的前期选点工作提供思路方法和借鉴参考。     

光纤传感技术在锚杆轴力监测中的应用

在简述了光纤Bragg光栅传感器基本工作原理的基础上,通过沪―蓉―西高速公路龙潭隧道支护锚杆轴力监测的工程应用,探讨研究了光纤传感技术用于岩土工程监测的几个重要环节--传感器选择、传感器安装、传感器标定及传感器埋设。通过现场监测获得了复杂地质条件下特长隧道支护锚杆轴力的变化特性,为光纤传感技术在岩土工程监测领域的应用积累了一定的经验。     

Optimizing groundwater monitoring systems for landfills with random leaks under heterogeneous subsurface conditions

Landfills are one of the most common human activities threatening the natural groundwater quality. The landfill may leak, and the corresponding plumes may contaminate an area, entailing costly remediation measures. The objective of the installation of monitoring systems at landfill sites is to detect the contaminant plumes before they reach the regulatory compliance boundary in order to enable cost-effective counter measures. In this study, a classical decision analysis approach is linked to a stochastic simulation model to determine the optimal groundwater monitoring system given uncertainties due to the hydrogeological conditions and contaminant source characteristics. A Monte Carlo approach is used to incorporate uncertainties. Hydraulic conductivity and the leak location are the random inputs of the simulation model. The design objectives are to: (1) maximize the detection probability, (2) minimize the area of contamination at the time of detection, and (3) minimize the total cost of the monitoring system. A synthetic test case based on a real-world case in the Netherlands is analyzed. The results show that monitoring systems located close to the source are optimal except for the cases with very high unit installation and sampling cost and/or very cheap unit remediation.     

黄土厚度变化较大地区煤田三维地震勘探时深转换方法的探讨

时深转换是煤田三维地震资料解释中非常关键的一步,时深转换方法的选取直接关系到地质成果的准确程度。针对山西某勘探区黄土覆盖厚度大且变化剧烈的实际情况,在比较大平均速度和分层速度两种时深转换方法的适应性和误差特点的基础上,优选分层速度计算方法作为本区时深转换方法。具体步骤为：根据地层沉积相和地质构造特点,结合由速度谱数据库和声波测井速度数据库确定的岩性分布规律,以单斜为基本单元进行区块划分;计算出各区块的新生界、煤系地层的厚度和速度后,从而求出较为准确的煤层埋深。实例表明,采用分区块、分层计算的煤层底板深度不仅准确程度高,而且还能克服由大平均速度时深转换方法造成的煤层假构造现象。     

含瓦斯煤样横向变形与瓦斯流动特性耦合关系试验研究

以二次成型煤样为研究对象,运用自行研制开发的含瓦斯煤热-流-固耦合三轴伺服渗流试验装置对含瓦斯煤样三轴加载过程中横向变形和与瓦斯流动特性的耦合关系进行了试验研究。结果表明：弹性力学定义的泊松比不能准确表征含瓦斯煤样的横纵应变特性,其关系可用二次函数表征;在预加载荷引起的横压向应变恢复阶段瓦斯流动速度变化呈先急剧降低再缓慢增加特性;在横向应变逐渐向扩张应化转变阶段,煤样内部的瓦斯流动速度呈单调缓慢增加趋势,且存在一个内部结构临界状态点使煤样内瓦斯流动速度最小;含瓦斯煤样处于横向压应变状态起始时的瓦斯流动速度要大于处于横向应变呈扩张状态末端时的瓦斯流动速度。     

Numerical analysis of the installation effects on the behaviour of soft clay improved by stone columns

This paper addresses the installation effects of stone columns in soft soils. Focus is made on the lateral expansion of stone material using the vibro displacement and substitution techniques by means of numerical simulations. The behaviour of reinforced soil after stone column installation is investigated to show how the properties of soft soils can be improved prior to final loading. The effect of such an improvement on the prediction of reinforced soil settlement is evaluated. The axisymmetric unit cell model (UCM) served for the comparison between numerical predictions made by the Mohr-Coulomb and hardening soil constitutive laws adopted for the soft soil. An equivalent group of end bearing columns model was investigated in the axisymmetric condition to predict the settlement of reinforced soil by adopting the Mohr-Coulomb constitutive model for soft clay. The reduction of settlements predicted by the unit cell and group of columns models, due the improvement of the Young’s modulus of soft clay, were compared. It is concluded that a significant reduction of settlement is expected when the group of columns model is considered.     

北京山区基于临界土壤含水率的泥石流预警思路

北京山区地质构造条件复杂,新构造活动频繁,人为活动剧烈,泥石流地质灾害较为发育,对人民的生命财产造成较大的威胁,如何利用泥石流发生前的物理特征进行预警,是北京市突发地质灾害防治的重要研究课题。本文首先介绍了以泥石流沟物源区土体的临界土壤含水率为短临预警的理论依据,然后以北京山区密云、门头沟、房山3个区县25条泥石流沟安装的土壤含水率仪为实例,详细阐述了土壤含水率预警系统建设的关键步骤,包括:监测沟谷的选择、土壤含水率仪的选型、仪器的安装及标定以及野外含水率数据的传输。预警研究成果,为首都地质灾害预警工作提供新的技术方法和手段。     

Three-dimensional numerical analysis of deep excavations with cross walls

Previous plane strain analysis of a case history has shown that cross walls in an excavation can effectively reduce movements induced by deep excavation. This study performed three-dimensional numerical analyses for 4 deep excavation cases with different installations of cross walls, including different excavation depths, cross wall intervals and cross wall depths. Both the observed and computed wall deflections for the 4 cases were compared with those of the same excavations that were assumed with no cross walls installed to demonstrate the effectiveness of cross walls in reducing lateral wall deflections. The results show that the cross wall also had a corner effect similar to that of the diaphragm wall. The deflection of the diaphragm wall was smallest at the location of the cross wall installed and then increased with the increasing distance from the cross wall, up to the midpoint between two cross walls. Many factors such as in situ soil properties, diaphragm wall properties, construction procedure, cross wall depth and so on may affect the amount of reduction in lateral wall deflections due to the installation of cross walls. Under the same condition, the amount of reduction was highly dependent on the depth of cross walls, distance to the cross walls and the cross wall interval.     

深圳地铁隧道区间盾构施工与配套机械配置分析

通过对深圳地铁五号线5304标民~五隧道区间盾构施工方法与机械配置分析,总结了实现地铁隧道盾构区间快速施工盾构配套设备选型,为类似城市地铁工程施工积累经验。     

Surface electrical resistivity tomography and hydrogeological characterization to constrain groundwater flow modeling in an agricultural field site near Ferrara (Italy)

A portion of an unconfined alluvial aquifer located in the Padana Plain (Italy) was characterized following an integrated hydro-geophysical approach. Initially an electrical resistivity tomography (ERT) survey was employed to localize the boundaries of a modest paleo-channel body and to design the installation of a groundwater monitoring network. Multilevel slug-tests were performed to estimate the aquifer’s saturated hydraulic conductivities. Determined permeability values together with electrical resistivity data were correlated. The correlation resulted in a site specific bi-logarithmic linear relationship. Based on this relationship, punctually determined hydraulic conductivities were spatially extended over the studied flow domain. Finally, continuously measured piezometric heads were used to calibrate a 3D flow model. Sensitivity analysis was performed to confirm the reliability of the reconstructed permeability field, as well as, to assess the minimum number of direct measurements needed to safely characterize the selected aquifer portion. The integration of the ERT survey results with the classical hydrogeological tests can be conveniently applied to constrain the permeability field during flow model calibration. Although the applicability of the determined relationship is site specific, the followed procedure is useful especially when there is a need to optimize the available resources and in case of small-scale pilot studies.