Rock Joint Surfaces Measurement and Analysis of Aperture Distribution under Different Normal and Shear Loading using GIS

Summary The geometry of the rock joint is a governing factor for joint mechanical and hydraulic behaviour. A new method for evaluating the aperture distribution, based on measurement of joint surfaces and three dimensional characteristics of each surface, is developed. This method allows one to determine and visualize the aperture distribution under different normal stresses and shear displacements, which is difficult to observe experimentally. A new laser scanner system is designed and developed for joint surface measurements. Special attention is paid to both surfaces’ data gained by measurements and processing, such as x-y coordinate table modification, data referencing, and matching between upper and lower surfaces. The surfaces of an artificial joint in granite are measured, processed, analyzed and three dimensional approaches are carried out for surface characterization. Parameters such as “asperity’s heights”, “slope angles”, and “aspects” distribution at micro scale, local concentration of elements and their spatial localization at local scale are determined by Geographic Information System (GIS). These parameters are used for joint surfaces matching and its real behavior quantitative analysis. The upper surface is brought down to make contact with the lower surface and the distance between the two surfaces is evaluated from the joint mean experimental aperture, which is obtained from normal and shear tests. Changes of aperture distribution at different normal stresses and various shear displacements are visualized and interpreted. Increasing normal load causes negative changes in aperture frequency distribution which indicates high joint matching. However, increasing shear displacement causes a rapid increase in the aperture and positive changes in the aperture frequency distribution, which could be due to un-matching, surface anisotropy and spatial localization of contact points with proceeding shear. Author’s address: Mostafa Sharifzadeh, Department of Mining, Metallurgy and Petroleum Engineering, Amirkabir University of Technology, Hafez 424, Tehran 15875-4413, Iran     

城市轨道交通的隧道结构断面测量方法研究

本文就城市轨道交通的隧道结构断面的测量方法进行了研究,提出了一种采用地面激光扫描仪技术的测量方法,研究了此方法的主要工作流程、基本原理和方法.把此方法用到天津城市轨道交通二号线工程,使用地面激光扫描仪测量隧道的结构断面,其精度和效率较常规仪器和方法都有显著提高.     

高精度影像扫描仪在边坡稳定性分析中的应用

松散堆积体的高陡边坡极不稳定,存在很大安全隐患,对其边坡稳定性进行科学、准确的评价十分必要。本文运用高精度影像扫描仪对存在安全风险的高陡边坡进行全区域扫描,同时获取了场区渣石堆的各种参数、拟评价边坡的参数和渣石堆所在区域的汇水面积等参数,为边坡稳定性分析提供了详尽、准确的数据,极大地提高了本次评价的准确性和效率。     

3D SLAM背包式扫描仪在旧建筑改造辅助测量中的应用

基于3D同步定位与建图（3Dsimultaneouslocalizationandmapping,3DSLAM）技术的背包式扫描仪,以旧建筑地下室和地上主体改造辅助测量项目为依托,介绍了该项目的作业流程,并利用人工量尺方式对点云量测结果进行精度评定,结果表明,所取得成果精度约为0.02m,基本能满足一般工程测量精度需求。同时,实验验证了3DSLAM技术在特定场景下的可行性及优越性。     

地面三维激光扫描仪系统误差模型研究及精度分析

分析了外部观测条件对地面三维激光扫描仪测距的影响,以空间相似变换为基础,提出了自检校法的优化模型,并给出了模型解算策略。通过实验对RIEGL VZ-400地面三维激光扫描仪进行检校和测量数据改正,结果表明:将外部观测条件影响因素纳入系统误差模型中后,可以提高地面三维激光扫描仪的数据精度,从而验证了优化模型的可行性与正确性。     

基于遗传算法的BP神经网络模型在岩心扫描仪测定海洋沉积物多种组分中的应用研究

海洋沉积物样品成分复杂,由于基体效应的影响,利用岩心扫描仪开展X射线荧光光谱分析只能得到目标元素的强度信息,不利于该方法在成矿机制和古环境等研究领域更好地发挥作用。本文采用岩心扫描仪测定海洋沉积物中的铝硅钾钙钛锰铁钒铬铜锌铷锶钇和铅15种元素,尝试引入BP神经网络模型利用其非线性拟合能力校正基体效应。实验表明,以水系沉积物、海洋沉积物和岩石国家标准物质以及定值海洋沉积物样品为训练样本,采用遗传算法优化BP神经网络的初始权值和偏置,可以有效校正除硅之外的14种元素基体效应的影响,实现了岩心扫描仪XRF测量结果由强度到浓度的转化。本方法的精密度为0.6%~6.8%(RSD,n=11),国家标准物质和海洋沉积物实际样品中15种组分的预测值与参考值的相对偏差在0.5%~17.5%之间,适合于海洋沉积物中多种主次量组分的快速分析,拓展了岩心扫描仪的功能。     

Palaeomagnetic results from the Lancer 1 stratigraphic drillhole,Officer Basin,Western Australia,and implications for Rodinia reconstructions

A partial record of the positions of Australia during Middle to Late Neoproterozoic time is provided by palaeomagnetic results for samples from the Lancer 1 stratigraphic drillhole in Western Australia. Lancer 1 was drilled vertically to 1501 m, through essentially horizontal Neoproterozoic strata of the western Officer Basin. We studied 123 samples from 28 intervals of drillcore which were oriented by matching features (fractures, cross-beds, etc.) in the core with oriented acoustic scanner images of the drillhole walls. Three new palaeopoles are reported for red mudstones and sandstones (redbeds) of the Browne (44.5°N, 141.7°E, dp = 5.1°, dm = 9.0°), Hussar (62.2°N, 85.8°E, dp = 7.3°, dm = 14.6°), and Kanpa (74.0°N, 128.8°E, dp = 7.7°, dm = 14.8°) Formations of the ca 830 – 720 Ma Buldya Group (Supersequence 1), which exhibit stable, two-polarity magnetisations carried by fine-grained hematite and magnetite. The overlying ca 610 – 590 Ma Wahlgu Formation glaciogenic diamictite (Supersequence 3) yielded dispersed directions and an imprecise palaeopole that overlaps results from the glaciogenic Elatina Formation and other Late Neoproterozoic rock units. The results help to elaborate the Middle to Late Neoproterozoic apparent polar wander path for Australia and indicate, in agreement with palaeoclimatic data and previous palaeomagnetic studies, that the continent was slow-moving and occupied low latitudes at this time. Assuming that Australia and Laurentia were still joined at ca 780 Ma, comparison of the new Hussar Formation palaeopole with coeval Laurentian data favours AUSMEX, rather than SWEAT or AUSWUS, as the most likely configuration of these two continents in Rodinia. This preliminary study of Lancer 1 demonstrates the utility of acoustic scanner logs for orienting drillcores, as well as the scope for additional sampling and palaeomagnetic studies of Lancer 1, and other oriented drillcores, to yield a more continuous record of Australia's past motions and to provide magnetostratigraphic data for enhancing inter-basin correlations.