Effects of Release Conditions Uncertainty on Avalanche Hazard Mapping

Dynamical models for calculating snow avalanche motion have gained growingimportance in recent years for avalanche hazard assessment. Nevertheless, inherentuncertainties in their input-data specification, although well acknowledged, areusually not explicitly incorporated into the analysis and considered in the mappingresults. In particular, the estimate of avalanche release conditions is affected bystrong uncertainties when associated to a return period. These sources of error arenormally addressed through sensitivity analysis or conservative parameters estimate.However, each of these approaches has limitations in assessing the statistical implications of uncertainties.In the present paper the problem of release scenarios randomness is looked at following a Monte Carlo procedure. This statistical sampling-analysis method allows the evaluation of the probability distributions of relevant variables for avalanche hazard assessment – such as runout distance and impact pressure – once the release variables – essentially releasedepth and release length – are expressed in terms of probability distributions, accounting explicitly for inherent uncertainties in their definition. Both the theoretical framework of this procedure and its application to a real study case are presented. As initial step of this research in the present work the attention is mainly focused on flowing avalanches descending on open slopes. Therefore, the one-dimensional version of VARA dynamic models is usedfor avalanche simulations.     

滑坡预报的多元回归分析方法

在回顾了滑坡预报的概念、类型及已有滑坡预报的几种主要模型的基础上，利用多元回归分析方法，根据最小二乘法原理，建立了非线性回归预报模型，提出滑坡破坏的时间为位移．时间曲线的拐点，此方法一般适合于临滑预报。结合实例，利用黄龙西村滑坡位移．时间监测资料，采用该模型进行滑坡时间预报，和其他滑坡预报模型预报的结果接近，说明该模型具有一定的合理性。     

矿床统计预测方法流程研究

在矿床统计预测的方法流程研究中，采用了直接找矿和成矿预测相结合；获取第一手找矿信息和收集处理前人资料相结合；地质、物化探、遥感影象分析和数学地质方法的计算机处理相结合；大、中比例尺预测相结合的研究方法，其方法流程为资料收集整理，成矿区带划分和找矿远景区圈定；编制找矿信息卡片，野外找矿；找矿靶区圈定和优选；资源量预测；评述和建议，在新疆长期的科研实践表明，该项研究是一套行之有效的综合性的科学研究方法     

航空数字成图相机系统简介

航空数字成图相机系统是基于大面阵CCD的厘米级高分辨率多光谱全数字对地遥感成像系统,兼备传统航空摄影测量与现代光电子多光谱数字遥感的技术特点,已广泛应用于城市大比例尺测图、高精度环境及地质灾害监测中,在数字城市和重大工程勘测领域具有广阔的应用前景.     

地质钻探施工管理信息系统研究

计算机和网络技术的发展为地质钻探施工设计和施工过程管理信息化提供了技术基础。本文在分析地质钻探信息流和信息化需求的基础上,提出了地质钻探施工管理信息化的总体思路和技术方案,主要由钻探技术信息交互平台、钻探施工设计系统和钻探施工过程管理信息系统组成,包括合同管理、设计管理、钻孔管理、设备管理、材料管理、统计报表、领导关注、档案管理8大功能模块。该系统实施后可显著提高地质钻探设计、施工和管理水平,有较好的推广应用前景。     

以工序分析为基础的地质勘查工程监理理论探讨

建立了以工序分析为基础的地质资源勘查工程项目监理理论,即对工序活动条件和工序活动效果的质量控制.运用该理论选择盐井钻探工程为典型案例,初步分析推演了地质资源勘查钻探工程施工与监理过程中的一些基础理论问题,包括质量验收单元的划分方法与依据、质量验收的内容与监理资料的构成、监理方的质量控制手段、质量控制程序实施细则等核心内容及存在的问题,从而实现与其他行业实体工程的监理工作方法的统一.     

Analysis of shield tunnel

This paper proposes a two‐dimensional finite element model for the analysis of shield tunnels by taking into account the construction process which is divided into four stages. The soil is assumed to behave as an elasto‐plastic medium whereas the shield is simulated by beam–joint discontinuous model in which curved beam elements and joint elements are used to model the segments and joints, respectively. As grout is usually injected to fill the gap between the lining and the soil, the property parameters of the grout are chosen in such a way that they can reflect the state of the grout at each stage. Furthermore, the contact condition between the soil and lining will change with the construction stage, and therefore, different stress‐releasing coefficients are used to account for the changes. To assess the accuracy that can be attained by the method in solving practical problems, the shield tunnelling in the No. 7 Subway Line Project in Osaka, Japan, is used as a case history for our study. The numerical results are compared with those measured in the field. The results presented in the paper show that the proposed numerical procedure can be used to effectively estimate the deformation, stresses and moments experienced by the surrounding soils and the concrete lining segments. The analysis and method presented in this paper can be considered to be useful for other subway construction projects involving shield tunnelling in soft soils. Copyright © 2004 John Wiley & Sons, Ltd.     

地球化学模式程序在铀矿找矿中的应用——以巴音戈壁盆地塔木素地区为例

首先简述了地球化学模式程序、与铀成矿有关的水文地球化学参数及区域地质、水文地球化学概况,并研究了区内水文地球化学环境。在此基础上,依据区内水质分析资料,运用地球化学模式程序(PHREEQC)计算了下白垩统地下水中沥青铀矿饱和指数(SI)、Eh反应条件边界值(Ehb,U)及Eh反应条件指数(RCIEh)等。认为该区局部地段在下白垩统地下水的深部存在Ehw﹤Ehb,U,RCIEh<0,SI>0的条件,即地下水处于过渡环境中,地下水中铀处于沉淀析出的饱和或过饱和状态,与岩石地球化学环境吻合性较好。因而在区内具有铀矿化的可能性,已被区内发现的工业铀矿化得到了证实。     

Obtaining Accurate Isotopic Compositions with the Double Spike Technique: Practical Considerations

Ever‐increasing precision in isotope ratio measurements requires a concomitant small bias within and between laboratories. The double spike technique is the most suitable method to obtain reliable isotope composition data that are accurately corrected for instrumental mass fractionation. Compared with other methods, such as sample‐calibrator bracketing (SCB), only the double spike technique can correct for all sources of fractionation after equilibration of the sample with the double spike, such as that incurred during chemical separation and measurement. In addition, it is not dependent on a priori assumptions of perfect matrix matching of samples to reference materials or quantitative recovery of the sample through the chemical separation procedure to yield accurate results. In this review article, we present a detailed discussion of the merits of the double spike technique, how to design and calibrate a suitable double spike and analytical strategies. Our objective is to offer a step‐by‐step introduction to the use of the double spike technique in order to lower potential barriers that researchers new to the subject might face, such that double spiking will replace SCB as the measurement method of choice.     

河水样品中硼的分离及其同位素组成测定

对河水样品中低含量硼的分离方法及硼同位素组成的测定进行了研究。将约1000mL河水样品分别用硼特效树脂，混合树脂富集和纯化后，紫外灯照射去除有机质，蒸发浓缩至小体积，采用正热离子质谱法进行硼同位素组成的测定。全流程回收率在95％以上，同位素稀释法测得全流程空白为41ng。经该方法处理后的样品能满足同位素质谱测定的需要。不产生同位素分馏，测试精度基本在0.6‰以内。