优质膨润土泥浆在大直径深桩基工程中的应用

为解决在澳门美高梅金殿超濠博彩场及酒店项目桩基工程中大直径深护筒无法回收的难题,笔者在分析港澳地区灌注桩传统工艺缺陷的基础上,采用具有预处理能力的优质膨润土泥浆.施工实践表明,2#配方泥浆能有效的保持桩孔稳定性,桩孔的平均充盈系数为1.0794;改善了钻进泥浆的性能,使泥浆的重复利用率提高到45.33%,泥浆废弃率仅为2.38%;降低了工程成本,减小了对环境的影响.同时,为钻孔灌注桩施工总结了各个阶段泥浆性能标准.     

Effect of sand on the vacuum consolidation of dredged slurry

Vacuum preloading is often used to improve the geotechnical properties of dredged slurry. Although the performance of this method has improved with rapidly developing technology, soil columns usually formed on the drainage boundary induce the decrease of permeability around the boundary, thereby limiting the further development of this method. To address this issue, this paper proposes a method for pretreating the slurry combined with sand prior to vacuum consolidation. This method partially replaces the fine particles with sand to reduce the formation of soil columns. Two groups of vacuum preloading tests were performed to investigate the effect of sand content and sand grain size on the vacuum consolidation of dredged slurry. The test results revealed that for a given sand grain size, increasing the sand content of the sand–slurry mixture increased the pore water drainage and accelerated the dissipation of pore water pressure, thereby increasing the vane shear strength. In contrast, for a constant sand content, the samples containing coarse sand exhibited increased pore water drainage and accelerated dissipation of pore water pressure, thereby increasing the vane shear strength of the soil.     

船载物探电子设备的接地问题及解决方案

船栽物探电子设备,是一个电气结合复杂的数据采集记录系统.各系统电子线路因船舶配电方式、工作环境的特殊性,其接地很重要,但容易被忽视.而接地处理不当,在使用时会受到噪声干扰、振荡;或造成仪器的输出榆入电路损坏,不能正常工作.更严重地甚至机壳漏电,危及人身安全.船栽物探电子设备接地问题.可分为"接地保护"和"接地故障"."接地保护"是将电气设备的金属外壳、支架和电缆的护套与大地等单位的金属船体(船壳)作永久性良好的电气连接,它分为保护接地和功能接地."接地故障"是指因设备不正确接地或由于绝缘层的破损、老化及环境恶劣引起绝缘电阻低下或者接地干扰等问题.文中从船载物探电子设备的使用特性出发.讨论在实际接地处理中出现问题的原因,分析了各种接地干扰的原理.并提出了相应的解决方案,对于船栽物探电子设备的实际安装应用有一定的指导意义.     

Late Pan-African magmatism and crustal development in northeastern Egypt

The voluminous Pan-African calc-alkaline granitic suite of the Ras Gharib crustal segment in northeastern Eygpt provides a typical example of orogenic magmatism. The 552 ± 7 Ma-old granodiorite–adamellite and leucogranite suite is compositionally broad (58 to 77 wt.% SiO₂) and exhibits calc-alkaline geochemical trends and trace-element characteristics typical of the volcanic-arc granites. The rocks contain oligoclase, albite, K-feldspar, calcic amphibole, biotite, titanite, zircon, and magnetite. The suite exhibits typical features characteristic of I-type granites. We contend that the magma was formed by partial melting of a modified oceanic crust at an active continental margin during the late stage of the Pan-African orogeny. The process may have involved assimilation of Early Pan-African dioritic country rocks. The more felsic units were produced by progressive fractionation of that magma. The petrological–geochemical evidence suggest that the Pan-African crust in northeastern Egypt did not develop in an extensional tectonic regime, as proposed recently.     

新型移动三维激光扫描技术在盾构管片椭圆度检测中的应用

铁运营阶段对隧道结构的变形监测保证了地铁运行的安全,而椭圆度检测是地铁隧道结构检测的重要工作。本文简单介绍了传统椭圆度检测的基本方法,分析了新型移动三维激光扫描检测系统基本原理及隧道椭圆度检测的方法和处理流程。通过工程案例实际应用以及对检测结果的综合分析,证明了移动三维激光扫描技术在盾构管片椭圆度检测中的优势。     

近景摄影测量支持下的地铁盾构管片姿态测量方法及其应用

传统的地铁盾构管片姿态测量的方法存在作业时间长,与施工流水线交叉作业劳动量大,且无法实时测量等不足。本文提出了利用近景摄影测量的方法对盾构管片姿态进行测量,通过在盾构管片环上铺设人工标志点,使用数码相机进行拍摄,利用光束法平常对摄影图片进行数据解算,得到解算标志点坐标后,再根据空间三点定圆心原理确定盾构环圆心点的坐标。试验结果表明,对比传统测量方法,新方法误差不超过3 cm,能够完全满足盾构管片姿态的测量精度要求,具有很好的推广价值。     

Accuracy of tretyakov precipitation gauge: Result of wmo intercomparison

The Tretyakov non-recording precipitation gauge has been used historically as the official precipitation measurement instrument in the Russian (formerly the USSR) climatic and hydrological station network and in a number of other European countries. From 1986 to 1993, the accuracy and performance of this gauge were evaluated during the WMO Solid Precipitation Measurement Intercomparison at 11 stations in Canada, the USA, Russia, Germany, Finland, Romania and Croatia. The double fence intercomparison reference (DFIR) was the reference standard used at all the Intercomparison stations in the Intercomparison. The Intercomparison data collected at the different sites are compatible with respect to the catch ratio (measured/DFIR) for the same gauge, when compared using mean wind speed at the height of the gauge orifice during the observation period. The Intercomparison data for the Tretyakov gauge were compiled from measurements made at these WMO intercomparison sites. These data represent a variety of climates, terrains and exposures. The effects of environmental factors, such as wind speed, wind direction, type of precipitation and temperature, on gauge catch ratios were investigated. Wind speed was found to be the most important factor determining the gauge catch and air temperature had a secondary effect when precipitation was classified into snow, mixed and rain. The results of the analysis of gauge catch ratio versus wind speed and temperature on a daily time step are presented for various types of precipitation. Independent checks of the correction equations against the DFIR have been conducted at those Intercomparison stations and a good agreement (difference less than 10%) has been obtained. The use of such adjustment procedures should significantly improve the accuracy and homogeneity of gauge-measured precipitation data over large regions of the former USSR and central Europe.     

地表不具备钻探条件下的盾构机通过空洞地段施工技术

本区间因隧道下穿南航酒店和火车站地中海商场及停车场,大部分区域无法实施钻探。而由周边地质资料及施工所反映的情况推测,该区域有存在空洞的可能。未探明的空洞可能对盾构机掘进造成不利影响,如盾构机栽头、地层塌陷等。因此,在盾构机通过未探明区域前必须进行探测和预处理,以指导盾构机掘进。     

Magnetics in geoexploration

The magnetic method is the oldest and one of the most widely used geophysical techniques for exploring the earth’s subsurface. It is a relatively easy and inexpensive tool to employ, being applicable to a wide variety of subsurface exploration problems involving horizontal magnetic property variations occurring from near the base of the crust to within the uppermost meter of soil. Successful applications of the magnetic method require an in-depth understanding of its basic principles and careful field work, data reduction, and interpretation. Commonly, interpretations are limited to qualitative approaches which simply map the spatial location of anomalous subsurface conditions, but under favourable circumstances the technological status of the method will permit more quantitative interpretations involving specification of the nature of the anomalous sources. No other geophysical method provides critical input to such a wide variety of problems. However, seldom does the magnetic method provide the complete answer to an investigation problem. As a result, it is generally used in concert with other geophysical and geological data to limit its interpretational ambiguities.