音频大地电磁法在川藏铁路折多山隧道某斜井勘察中的应用

川藏铁路是世界上建设难度与风险最大的铁路工程,桥隧工程量大,勘察难度极大,勘察环境极其恶劣,其中,物探勘察为整个勘察工作中最主要的深部勘察手段,故选择合适的物探勘察方法对于整个勘察工作的重要性及准确性不言而喻。音频大地电磁法(AMT)具有覆盖频率宽、探测深度大、使用天然场源、施工轻便及观测时间短等优势,本次工作选用音频大地电磁法(AMT)在川藏铁路折多山隧道某斜井进行勘察,准确划分了斜井沿线地层岩性及其分界面,同时精确划定了区域大断层的里程位置,取得了较好的勘察效果。通过本次勘察工作认为音频大地电磁(AMT)法为长大深埋铁路公路隧道工程勘察的最佳物探勘察手段之一。     

试论地基设计和岩土工程勘察过程中的常见问题及对策

相关建筑工程、市政基础工程等项目的有效设计和施工,必须以地基设计与岩土工程勘察为前提。本文就地基设计和岩土工程勘察过程中的常见问题与对策进行分析,首先阐述了地基设计和岩土工程勘察施工前期准备不充分、设计和勘察过程不规范等问题,进一步提出了地基设计和岩土工程勘察工作的优化策略,包括提高对前期准备工作的重视、应用创新方法、提升勘察技术水平。     

水泥搅拌桩施工技术在软土路基中的应用

水泥搅拌桩多用于软土层的地基加固处理工程中,其基本原理是基于水泥加固土的物理化学反应过程,可通过专用机械设备将水泥喷入待处理的软土地基内,并在喷注过程中上下搅拌均匀,使水泥与土发生水解和水化反应,使软土硬结而提高地基强度,达到提高地基承载力的目的。但如何有效地控制水泥搅拌桩的成桩质量,确保软基处理的效果成为实际施工中需要探索和研究的关键问题。     

城市建设中常见不良地基土的处理办法

在建造建筑物之前,用临时堆载(砂石料、土料、其他建筑材料、货物等)的方法对地基施加荷载,给予一定的预压期。使地基预先压缩完成大部分沉降并使地基承载力得到提高后,卸除荷载再建造建筑物。     

CFG桩复合地基在焦作马村靳作安置房项目中的应用

依托焦作市马村区靳作城中村改造项目CFG桩复合地基处理实例,采用ABAQUS数值模拟软件建立CFG桩复合地基三维模型,研究CFG桩复合地基的桩土承载性状以及桩土发挥系数变化特征,同时进行现场载荷试验验证.研究表明:CFG桩单桩、复合地基的荷载与沉降曲线均表现出加载初期为线性关系,塑性变形阶段为非线性关系,与单桩不同,C...     

日照风化岩地基地下水抗浮设计水位取值方法及建议

地下水抗浮设防水位的确定一直是勘察技术工作的难点,相关规范的要求大同小异,本文通过对日照风化岩地基岩性及工程地质、水文地质条件的阐述,概括了该区基岩裂隙水具有的工程特性,通过工程案例分析了不同岩性地基地下水抗浮发生工程事故的原因,总结了日照风化岩地基不同地形条件下,地下水抗浮设计水位的取值,对于区域勘察技术工作具有指导意义。     

高密度电法在工程勘察中的应用

高密度电法属于工程勘察中比较常用的一种物探方法,其具有工作效率高、自动化程度高、异常现象直观等特点,因此在煤矿工程开采过程中得到了广泛的应用。借助高密度电法可以对煤矿井下的采空区、断层、含水层等有个直观的了解和掌握,从而为煤矿工程后续的开采工作提供一定的借鉴和参考,有效地降低了不必要的灾害,提高了煤矿工程的开采效率。     

预制桩复合地基在闸站工程中的应用

介绍了复合地基的定义和主要类别,并对复合地基的优化设计展开细致分析,同时对底板、桩和桩间土三者之间在工程实践中的相互作用进行深入探析,总结了预制桩复合地基在外部荷载作用下发生沉降、桩顶水平位移以及桩间土荷载分担份额的变化规律.     

桩基础施工新技术专题讲座（二十一） 双向螺旋挤土灌注桩（SDS桩）

国外短螺旋挤土灌注桩非挤土干作业法和泥浆护壁法灌注桩具有低噪声、低振动、能按荷载与地基条件灵活选择桩径与桩长等特点。但存在桩端虚土的测定与处理、排土的处理（干作业灌注桩）、废弃泥浆的处理（泥浆护壁灌注桩）、防止孔壁坍塌方法及桩顶超打混凝土的处理等诸多问题。     

浅谈公路软土地基处理

软土地基具有孔隙比大、天然含水量高、压缩性强、承载能力低等特点,因此软土地基处理是公路工程施工中遇到的难点之一,也是勘察设计及施工单位重点解决的一个环节。否则,随着时间的推移,将会出现路面沉陷、桥头跳车等病害,直接影响到交工后公路的使用功能。因此,在公路建设过程中,对软土地基的处理要引起高度重视。本文主要对公路软土地基处理进行简要探讨。     

GEOSCOPE and GEOLIDAR: Integrated Instruments for Underground Archaeological Investigations

Modern subsurface prospecting makes use of advanced technologies: coring, geophysical methods, and remote sensing. In the framework of this exciting progress, we have developed two integrated instruments for archaeological investigations. GEOSCOPE consists of a coring machine and a probe: the coring machine bores the soil while recording drilling parameters, the probe performs visual inspections and data acquisitions in the hole. GEOLIDAR is a laser range-finder conceived for the volumetric characterization of buried cavities by means of a motor-driven three-dimensional scan. The data are recorded and displayed to the archaeologist by a user-friendly computer interface. This paper describes the two systems, outlines the rationale that guided their conception, discusses the measurement accuracies and reports the first results.     

Monitoring the yield of a borehole neutron generator

In mining, it is important to improve the precision of geophysical instruments in mineral prospecting, especially in the exploration of oil and gas fields. The possibility of creating instruments for monitoring the neutron yield of a borehole neutron generator in neutron–neutron logging systems is considered. One possibility is to employ detectors based on natural diamonds, which are a valuable resource. Their use in hightech geophysical instruments for prospecting may be regarded as a valuable step in the efficient utilization of natural resources, which is an important goal at this time. Experience shows that Russian-made diamond detectors of the proposed design are satisfactory replacements for the instruments currently used to monitor the yield of a borehole neutron generator in neutron–neutron logging systems. Tests of the detectors in the AINK-43M pulsed neutron–neutron logging system demonstrate the improved productivity and precision of the measurement system.     

电法地质状况勘探交流激电系统研究

文中研究用直接数字合成技术芯片AD9850构成频率可调交流激电系统.按键设置交流信号频率,随即键盘驱动芯片CH451向单片机发射对应的频率指令.单片机识别频率指令后并行向AD9850送出频率编码,AD9850输出的信号经过滤波放大,零点调节和V-I转换送出激电信号.将该信号源用于交流激发极化探地测量,保证了测量时频率精度和稳定性,而且频程转换快,噪声小.     

地下电磁波CT法在工程勘查中的应用

岩溶、破碎发育地带是碳酸盐地区工程施工的安全隐患,因此在施工之前需要进行勘察,地下电磁波法是常用的地球物理方法之一。本文将电磁波CT技术成功应用于某地工程勘查中,并应用收敛性较好、收敛速度较快的SIRT算法进行电磁波视吸收系数成像,推断出了岩石破碎发育带,为工程施工提供技术支持。试验结果表明,电磁波CT法分辨力强,精度高,效果好,而且可利用的参数多,通过这些参数可以对地质体进行详细的研究,推断结果的可靠性和实用性较好。     

A geophysical device for automation of multielectrode electrical prospecting

A self-contained unit used in the resistance method of the geophysical electrical prospecting in order to switch two supply and two receiving lines with 24 electrodes installed on the Earth’s surface is described. The possibility of connecting in series several devices and their soft-and hardware interfacing to the control personal computer allows the number of electrodes to be increased to several hundred. As a result, the performance and flexibility of the data acquisition system as a whole increase, allowing one to conduct investigations at a higher methodological level. The unit is a portable device with a built-in storage battery and a control panel. There are connectors for ensuring control from the computer and connecting other devices.     

新型煤矿巷道随掘超前探测方法研究

本文提出了新型煤矿巷道随掘超前探测方法,为实现巷道掘进和超前探测并行作业提供了可行思路。首先,提出随掘超前探测方案,将掘进机的截割头作为随掘场源,融合物探方法与掘进主体;然后,构建随掘超前探测理论模型并获取测点电位变化规律,与有限元计算结果比对,验证了测点电位数值计算方法的准确性与可行性;最后,确定随掘场源的分流规则,以正常地质体作为参照,对比研究随掘过程中低阻和高阻两类不同异常体的视电阻率演化规律,当场源越接近低阻含水带,视电阻率均值降幅从5.40%提高至29.80%,越接近高阻断层,视电阻率均值增幅从7.12%提高至35.53%,水箱模拟实验表明,所提煤矿巷道随掘超前探测方法可实时、连续探测掘进工作面前方地质状况。     

Electrophysical and structural optimization in monitoring the neutron yield of borehole generators

In mining, it is important to ensure effective monitoring and to improve the precision of the geophysical instruments used in mineral prospecting. The electrophysical and structural optimization of instruments for monitoring the neutron yield of borehole generators in neutron–neutron logging systems is considered. Diamond detectors have been developed and successfully employed for this purpose. The expanded use of diamonds, especially in instruments, improves the utilization of natural resources. In regular equipment for monitoring the neutron yield of borehole generators in neutron–neutron logging systems, the consequences of introducing Russian diamond detectors are studied. Specifically, the influence of the ambient parameters on the borehole instrument (temperature stability of the diamond detector in the range 20–140°C) is determined; and the linearity of the conversion characteristic of the fast-neutron monitor in the system is investigated by measuring the fluctuation of the output-signal amplitude in the range 20–140°C.     

三分量光波导加速度传感器数字信号处理系统

为进一步提高三维地震勘探技术,设计以DSP芯片为基础的集成光波导地震波加速度传感器的数字信号处理系统,对调制后的干涉光信号进行分析处理,并对传感系统进行反馈调节。实验结果显示,测试系统的输出信号跟随输入信号,实现载波信号的解调输出,满足加速度传感器对信号处理的要求。     

GPR—History, Trends, and Future Developments

Ground penetrating radar (GPR) is a relatively new geophysical technique. The last decade has seen major advances and there is an overall sense of the technology reaching a level of maturity. The history of GPR is intertwined with the diverse applications of the technique. GPR has the most extensive set of applications of any geophysical technique. As a result, the spatial scales of applications and the diversity of instrument configurations are extensive. Both the value and the limitations of the method are better understood in the global user community. The goal of this paper is to provide a brief history of the method, a discussion of current trends and give a sense of future developments.     

Joint Interpretation of Geophysical Data for Archaeology: A Case Study

Interpret-joints within geophysical data recorded in a complex area where ruins do not outcrop and only earthenware remains within the surficial layer are present. The study area, located in central Italy, consists of Roman, medieval and modern ruins that are included in reworked sediments. The geology is formed by inhomogeneous alluvial sediments (sand and gravel) several meters thick with diamagnetic character. To reduce the ambiguity in the subsurface reconstruction, a joint interpretation of georadar, magnetic and electrical tomography data was performed. The georadar was chosen to reconstruct detailed subsurface features, the electrical tomography to distinguish resistive bodies (stones, voids, etc.) from conductive (cavities filled by clay) and, because of the diamagnetic character of in situ sediments, the magnetic method was chosen to detect the earthenware ruins. The geophysical data were controlled by excavation, which detected silos of 1 m in diameter and a concrete layer at a few centimeters from the topographic surface. Time slices in the georadar data allowed us to detect the silos and to define the lateral edge of the concrete layer. Silos were also indirectly detected by the magnetic data because of the earthenware present in the filling sediments. Electrical tomography detected the concrete layer and an ancient anthropogenic surface of few centimeter depths. The study demonstrates that, because the geophysical methods are based on different physical characteristics, they can have different resolution and therefore detect different bodies.