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边坡变形的分布式光纤监测试验研究及实践 总被引：1，自引：0，他引：1
布里渊光时域反射计（BOTDR）是一项新型光电传感仪器,可对沿光纤的轴向应变进行分布式监测。该技术采用光纤作为传感和传输介质,具有良好的抗干扰、长距离、可植入性和分布式监测等特点。本文总结了近几年来分布式光纤在边坡工程中监测的工程实践和试验研究结果。实践表明,将光纤传感器铺设在加固边坡的锚杆和框架梁中,在加固边坡的同时进行安全监测,可以取得良好的效果;而将光纤直接铺设在边坡浅层土体中进行监测,可以及时对边坡安全提供预警,但往往不利于长期监测。本文还介绍了将光纤传感器布设在用于加固边坡的土工织物中进行安全监测的室内试验研究。实验证明,不同的光纤类型、布设方法、土工织物性能等都会对监测结果产生影响。最后分析了分布式光纤监测在岩土工程监测中的应用前景,以及今后研究的关键技术问题。 相似文献
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《地球物理学进展》2016,(3)
煤炭资源开采的深部化发展,使得煤岩体的地质环境、应力状态、变形破坏特征发生了显著变化.其所引起地质条件的复杂化,常导致各类安全事故的发生.深入了解矿井灾害事故发生的机理、规律、控制及相应的防治技术对于矿井安全生产、运营具有重要的意义.本文针对近年光纤传感技术在井田建设、生产、安全评价等安全监测工程中的研究与应用展开论述,重点讨论了矿井光纤传感技术在瓦斯浓度、矿井温度场、围岩及支护结构中压力、应变、位移等参量测试的研究现状.文章结合方法技术、数据解释与评价、仪器设备三个发展方向对矿井光纤测试技术进行展望,提出矿井光纤测试技术能够实现矿井安全监测多参量的实时化、长期化智能监测.特别是随仪器设备、布设工艺等方面的创新发展,将会使矿井光纤测试技术成为未来矿山领域中最具发展前景的安全测试与监测方法. 相似文献
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光纤分布式声波传感技术(DAS)基于相位敏感光时域反射,是一种利用光纤后向瑞利散射干涉效应实现声波信号连续分布式探测的新型传感技术.在油气勘探开发领域,近年来在井中VSP、地表地震采集、时延或永久油藏监测、水力压裂监测等方面开展了试验和应用,取得了初步的成功.相比常规地面检波器及井中检波器,DAS技术具有低成本、高效率、密集采样、资料品质不低于传统地震检波器等优势.但DAS技术的局限性在于数据信噪比受光纤布设方式影响、单分量采集、保真距离有限.在综合分析的基础上,展望DAS技术未来发展方向:(1)螺旋缠绕技术等多分量DAS技术的发展及实用化和工业化,以及新型光纤电缆的发展,将大幅度地提高光纤的灵敏度和动态范围,DAS将逐渐克服其局限性.(2)DAS解调技术的发展和光纤采集方式的优化,包括新型采集观测系统、光纤与地层耦合技术等,以及针对性处理、成像技术发展将进一步提高DAS数据的信噪比和成像质量.(3)由于DAS具有成本低、采样率高等优点以及未来DAS技术在提高信噪比方面的进展,DAS技术在油气地球物理技术领域的应用前景将更广阔. 相似文献
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油气井永久性光纤Bragg光栅传感监测系统的安装设计是现场应用的一个重要组成部分,也是工艺最复杂、成本最昂贵的一个环节.本文简要地回顾了油气井光纤Bragg光栅传感监测系统安装现状,根据国内常用射孔完井方式,设计了两种单井光纤Bragg光栅井下安装模型.论述了井下安装前准备工作和主要注意事项,讨论了存在问题,对油气井永久性光纤Bragg光栅传感监测技术及其安装技术的前景进行了展望. 相似文献
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本文主要介绍了一套分布式光纤振动传感系统中的数据采集及信号处理系统,该系统设计采用高性能的运算放大电路完成光电信号调理,以高精度差动模数转换器AD9246完成模数转换工作,并选用高性能FPGA作为核心逻辑控制器,并以低功耗的OMAP-L137作为CPU负责振动数据计算、网络通讯等工作,从而使该-OTDR分布式光纤振动传感系统测量范围扩展到25 km范围。本文通过计算相邻测点振动增量方法检测是否发生了振动入侵,提高了分布式光纤振动入侵检测的灵敏度。该设计方法提高分布式光纤振动传感系统的信噪比,使得该系统振动检测灵敏度提高、抗干扰能力增强,因此该分布式光纤振动传感系统可以用于实际工程的振动监控。 相似文献
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阐述了应用于地下水ＰＨ实时监测的光纤传感技术，介绍了光纤地下水ＰＨ动态监测仪的工作原理、设计及其测试结果，并给出了它的主要特征参数。 相似文献
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孔中测温作为一种原位测试方法,是地热资源勘察、开发中重要的研究内容.分布式光纤传感测温技术,能够弥补传统点式测温耗时与漏测的不足,同时传感光纤具有耐高温、高压和抗(钻井液)腐蚀性等特点,可实现钻孔恶劣环境下的分布式温度测量.本文利用拉曼散射和光时域反射技术,设计了深井分布式光纤温度测试系统.该系统采用波分复用技术,将后向拉曼散射光中的斯托克斯光与反斯托克斯光分离,利用反斯托克斯光的温度敏感特性感知环境温度,结合同源斯托克斯光,解调温度信息;根据光纤中光的传输速率和背向拉曼散射光的回波时间,可以对温度点进行定位,实现对光纤温度场的分布式测量.通过多点数字累加平均技术的微弱信号处理方法,并引入光纤突变损耗修正系数、光电采集影响系数等,借助光纤环基准参考,实现测温数据的解算.同时本文设计的深孔耐高温铠装测试光缆,可实现-65~350℃范围内的温度测试;结合GH_DR2号地热孔野外测试实验,完成测深800m,孔内最高温度54.8℃,证明此种测温方法的有效性和潜在的推广价值. 相似文献
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本文采用基于FLAC^3D软件的数值模拟方法,对粤赣高速公路K3边坡工程锚杆的应力应变状态进行数值模拟,分析了全长粘结式锚杆的荷载传递机理;根据运用基于自发布里渊背向散射原理（BOTDR）的分布式光纤应变传感技术对锚杆的轴向应变进行的监测数据,分析了工程锚杆的变形特征。数值模拟与实测数据的对比分析表明,模拟曲线与监测曲线反映的工程锚杆的变形特征具有较高的一致性,验证了应用FLAC^3D有限差分软件模拟锚杆。框架体系应力应变特征的合理性,以及基于BOTDR的锚杆应变分布监测的可行性。 相似文献
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地面核磁共振方法是一种直接探测地下水信息的地球物理勘查方法,本文将该无损探测技术用于土石坝的渗流安全评估试验。由于探测的核磁共振信号源于地下水中的氢质子,则可以确保核磁共振响应仅与地下水信息有关。利用地面核磁共振方法直接找水的技术优势,探测堤坝的浸润面,以判断堤坝的渗流(漏)隐患,为堤坝尤其是小型病险水库堤坝、易发事故的堤防的病险诊断提供一种便捷、高效和可重复利用的方法。通过NUMISPOLY多道核磁共振探测系统在某原体大坝检测中的试验,得到原体大坝的浸润面,进而对土石坝进行渗流(漏)隐患的评估,该方法为堤坝渗流(漏)隐患探测提供了一种有效而可靠的新方法。 相似文献
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Field trial of seismic recording using distributed acoustic sensing with broadside sensitive fibre‐optic cables 
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下载免费PDF全文 J.C. Hornman 《Geophysical Prospecting》2017,65(1):35-46
Distributed acoustic sensing is an emerging technology using fibre‐optic cables to detect acoustic disturbances such as flow noise and seismic signals. The technology has been applied successfully in hydraulic fracture monitoring and vertical seismic profiling. One of the limitations of distributed acoustic sensing for seismic recording is that the conventional straight fibres do not have broadside sensitivity and therefore cannot be used in configurations where the raypaths are essentially orthogonal to the fibre‐optic cable, such as seismic reflection methods from the surface. The helically wound cable was designed to have broadside sensitivity. In this paper, a field trial is described to validate in a qualitative sense the theoretically predicted angle‐dependent response of a helically wound cable. P‐waves were measured with a helically wound cable as a function of the angle of incidence in a shallow horizontal borehole and compared with measurements with a co‐located streamer. The results show a similar behaviour as a function of the angle of incidence as the theory. This demonstrates the possibility of using distributed acoustic sensing with a helically wound cable as a seismic detection system with a horizontal cable near the surface. The helically wound cable does not have any active parts and can be made as a slim cable with a diameter of a few centimetres. For that reason, distributed acoustic sensing with a helically wound cable is a potential low‐cost option for permanent seismic monitoring on land. 相似文献
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Suitable materials for use as shell of embankment dams are clean coarse-grained soils or natural rockfill. In some sites these materials may not be available at an economic distance from the dam axis. The use of in-situ cohesive soils reinforced with geotextiles as the shell is suggested in this study for such cases. Dynamic behavior of reinforced embankment dam is evaluated through fully coupled nonlinear effective stress dynamic analysis. A practical pore generation model has been employed to incorporate pore pressure build up during cyclic loading. Parametric analyses have been performed to study the effect of reinforcements on the seismic behavior of the reinforced dam. Results showed that reinforcements placed within the embankment reduce horizontal and vertical displacements of the dam as well as crest settlements. Maximum shear strains within the embankment also decreased as a result of reinforcing. Furthermore, it was observed that reinforcements cause amplification in maximum horizontal crest acceleration. 相似文献
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Extraction of natural frequencies of a gravity dam or an embankment dam plays an important role in the seismic design of the dam because the seismic response of a dam is dependent largely on the dynamic characteristics of the dam. Owing to the lack of exact solutions and the geometry of a dam, numerical methods such as finite element methods have been often used to extract the natural frequencies of the dam. Since the finite element method is an approximate one, the resulting finite element solution to the natural frequency of a dam cannot be safely used unless its accuracy is evaluated within the acceptable range for the seismic design of the dam. To solve this problem, some asymptotic formulae for correcting the finite element predicted natural frequencies of a gravity dam and an embankment dam have been developed in this paper. Since the present asymptotic formulae are derived from the fact that the finite element solution tends to the exact one if the finite element size used approaches zero, they provide a corrected solution of higher accuracy for the natural frequency of a dam so that the accuracy of a finite element solution can be evaluated against this corrected solution. After the correctness and usefulness of the present formulae are assessed, two practical examples have been given to show how the asymptotic formulae can be used to correct and evaluate the discretization error for the finite element predicted natural frequencies of gravity dams and embankment dams. 相似文献