带保温层管道腐蚀状态的X射线检测方法研究

随着无损检测技术的飞速发展,X射线实时成像技术获得了广泛的应用.本文论述了带保温层管道的X射线实时成像检测方法,重在对管道腐蚀缺陷深度如何定量的实验方法研究,和管道缺陷处厚度与图像灰度的数学模型建立,从而对管道腐蚀厚度进行定量,管道缺陷的定量研究有助于管道安全运行的评价和隐患问题的及时发现.     

基于CBS的带保温层压力管道在线检测装置研制

本文针对我国石油化工行业带保温层压力管道在线检测的难题,基于CBS的技术原理,研制开发了一种带保温层压力管道在线检测装置,技术性能指标为:检测管道直径范围不限;保温层厚度≤145mm;钢材料管壁厚度≤40mm;精度为1.0mm.文中简要阐述了该检测装置的基本原理、具体结构设计,给出了外置铝皮带保温层40mm厚管道内表面双孔、单孔平面扫描实验的实验结果,实验结果表明用该装置对实际管道的检测结果是非常精确的,误差在允许的范围之内.     

基于工业CT的压力管道在线测厚仪研制

目的：本文针对我国压力管道检测技术的现状,基于透射式工业CT的基本原理,研制开发了一种新型的便携式压力管道在线测厚仪。方法：文中简要阐述了该仪器的具体结构设计,给出了实验室标定实验和管道验证实验的实验数据;结果：实验结果表明用该仪器对实际管道的检测结果是非常精确的,误差在允许的范围之内。结论：该仪器具有结构简单、使用方便、测量精确、反应速度快、安全可靠等优点。     

"γx103B型在役管道CT检测仪”问世

苏州兰博高科技企业集团有限责任公司与天津石油化工公司机械研究所联手研制开发出国内急需的‘ γｘ１０３Ｂ型在役管道ＣＴ检测仪’,已于 １９９９年 １０月１８日通过了中国石化集团公司组织的会议鉴定。鉴定委员会通过严格的审查、测试,认真的讨论一致认为：”该仪器将工业ＣＴ技术应用于工业管道的检测,可在装置运行或停车的情况下,对带保温层或不带保温层的管线、夹套管等的腐蚀、结垢、堵塞进行定量检测。该仪器能使用少量探测器,实现小型化,便携式、低价格,在重建方法、图像处理和机械设计上具有一定的创新。该仪器为国内首…     

地下油气管网建设中的若干地震安全问题浅析——以平陆城区为例

根据历史强震资料,简述1815年10月23日平陆63/4级地震的地震构造及活动背景。以平陆地区天然气管网建设为引,结合平陆城区天然气管网建设与城市规划发展现状,提出存在的一些问题,通过计算得出平陆地区适用于不同管道类型工程抗震设计的地震动参数区划结果,用于指导地下油气管道的建设。对城市地下油气管道在未来地震及非地震作用下如何安全可靠地运行,提出自己的见解。     

新型抗震支吊架振动台试验研究

在地震作用下,抗震支吊架理应保障建筑机电工程设施和管道系统均具备良好的服役性能。因此,对抗震支吊架的抗震性能进行检测至关重要。本文以某典型地下室抗震支吊架为对象开展了顺管向地震模拟振动台试验,通过多工况试验对比分析了不同支吊架的位移和加速度的地震响应。试验结果表明:抗震支吊架显著降低了管道位移,减振率最高可达到96%,但对于加速度响应的抑制作用较小。易损性分析表明:采用成品支吊架时,管道系统在遭受相当于设防烈度的地震作用时会发生严重损伤,而采用抗震支吊架的管道系统能够保全其功能。     

埋地管道综合参数异常评价法的应用效果

综合参数异常评价法是一种不同于其它地面检测的方法。本文在详细阐述了综合参数异常评价法机理的基础上，给出了在几种防腐保温管道上的应用实例。经过多个工程的实际检验证明：“综合参数异常评价法”适用于不同检测环境、输送介质(气相、液相)、规格与材质、防腐(保温)层结构的埋地金属管道的地面检测工作，能够对埋地管道腐蚀与防护状况做出较为完整的评价。     

岩性不一致地区的电阻率和激电异常与碳氢化合物的关系(加拿大阿尔伯达省落基山山麓丘陵地带)

在加拿大阿尔伯达省落基山脉的丘陵地带有几个开采的气田位于剧烈冲断层形成的圈闭中,该区以冲断层为特征,密西西比岩石(下石炭统)中发现了天然气,气藏埋深为3—6km,且距落基山脉的山前越近埋深越大,该区露头岩石是白垩纪砂岩及海源和陆源的页岩。整个地区为保留林带,与阿尔伯达省的其它油气田开采区不同,该区没有工农业电噪音(管道、输电线、电子围墙等),由于无电噪音,使得该区成为确定气藏能否产生用地面电法可以检测的电性异常的理想区域。     

城市供水管网震害概率预测

根据概率可靠性理论,计算了地震作用下地下直埋管道的各个震害等级的概率值。假定在一段管子中,其破坏为泊松公布,求得这段管道供水的可靠性,最后用并联和串联分析法,得出整个供水管网的供水可靠性。通过实际计算,结果较理想。     

城市地铁爆破开挖对浅埋地下大直径管道的安全影响研究

在城市浅埋地铁爆破开挖中,经常遇到地下管网、涵洞等构筑物,而爆破地震效应对其影响范围和程度的正确评价就显得尤为重要。本文以长沙地铁爆破开挖为例,以现场实测数据为基础,采用有限单元法,对爆破振动下大直径混凝土污水管道的动力响应、变形和动应力等进行了计算,评价了爆破地震对管道的安全影响。研究表明:管道在控制爆破作用下是偏于安全的;爆心距是影响管道受到爆炸作用力影响大小的最主要因素;对于以实测数据为基础,采用加速度激励的时程分析方法以爆破振动对埋地管道的影响进行评价,是一种可行且较为精确的方法。     

小波变换在探地雷达探测地下管线信号处理中的应用

阐述了小波变换的基本理论,给出了小波变换在探地雷达方面的应用实例．认为小波变换时频局域性好,是分析非平稳信号的有效工具之一。实例分析表明,小波方法在城市地下管线探测信号去除噪音分析处理方面具有优异性能。能有效提高探地雷达探测地下管线的精度。     

A semi-analytical model for estimating seismic behavior of buried steel pipes at bend point under propagating waves

A buried pipe extends over long distances and passes through soils with different properties. In the event of an earthquake, the same pipe experiences a variable ground motion along its length. At bends, geometrically a more complicated problem exists where seismic waves propagating in a certain direction affect pipe before and after bend differently. Studying these different effects is the subject of this paper. Two variants for modeling of pipe, a beam model and a beam-shell hybrid model are examined. The surrounding soil is modeled with the conventional springs in both models. A suitable boundary condition is introduced at the ends of the system to simulate the far field. Effects of angle of incidence in the horizontal and vertical planes, angle of pipe bend, soil type, diameter to thickness ratio, and burial depth ratio on pipe strains at bend are examined thoroughly. It is concluded that extensional strains are highest at bends and these strains increase with the angle of incidence with the vertical axis. The pipe strains attain their peaks when pipe bend is around $135^{\circ }$ and exceed the elastic limit in certain cases especially in stiffer soils, but remain below the rupture limit. Then equations for predicting the seismic response of the buried pipe at bend are developed using the analytical data calculated above and regression analysis. It is shown that these semi-analytical equations predict the response with very good accuracy saving much time and effort.     

Experimental and finite difference modelling of borehole Mach waves1

A series of model experiments was performed in an ultrasonic laboratory to study the radiation of downhole sources in a variety of formations. Three models were used in the experiments. They were a Lucite model, a Lucite model with a free glass pipe in the centre, and a glass-cased soil model. In addition, a finite-difference modelling technique was used to simulate the wave propagation in these models and the results of the laboratory and numerical experiments are compared. In the Lucite borehole model the waveforms recorded in the experiment agree very well with the finite-difference synthetics. The snapshots of the wavefield from the finite-difference simulation show the radiation pattern of the P- and S-waves in the Lucite formation. These patterns are consistent with the theoretical calculations. In the Lucite model with the free glass pipe, the finite-difference synthetics are also in good agreement with the experimental observations, especially for the conical P-wave arrival. The angle between the wavefront of the conical P-wave and the borehole axis, observed from the snapshot, agrees with the theory. In the cased soil model, the arrival time of the finite-difference synthetics is in good agreement with the laboratory measurements. The relative amplitudes of the P-wave and the Mach wave are not correctly modelled because intrinsic attenuation is not included in the finite-difference calculation. The Mach cone angle from the snapshot agrees with the theoretical prediction. Finally, a finite-difference method was used to simulate Mach-wave propagation in a formation with two horizontal layers. In the case of two slow layers, the Mach-wave generated in the first layer is reflected back from and transmitted through the boundary and another Mach wave is generated at the second layer when the Stoneley wave travels into the second layer. In the case of a formation having one slow and one fast layer, the Mach wave generated in the slow layer is reflected back at the boundary and leaked into the fast layer. There is no Mach wave in the fast layer.     

内蒙古2次5.9级地震的反思

简要介绍了内蒙古自治区2003年、2004年2次5.9级地震的概况,总结了地震现场工作的经验教训,提出了应探索与思考的几个问题,以对地震现场工作提供一定的指导和借鉴。     

跨断层水泥管试验的有限元分析

在考虑管道的材料非线性和几何非线性、管土相互作用的非线性和管道接口非线性的基础上,建立了由管体梁单元、三向土弹簧单元和接口单元组成的埋地非连续管道在断层位移作用下的有限元模型,并以美国密歇根大学Junhee等(2010)所做的跨断层水泥管试验为原型进行了模拟分析。有限元结果给出的水泥管最终变形、接口转角、接口位移与实验结果基本一致,表明本文提出的跨断层埋地非连续管道抗震计算的有限元分析方法具有一定的合理性。有限元结果和试验结果都表明,在逆冲断层作用下,水泥管的破坏主要是因为在管道接口处的轴向压力和弯矩的耦合作用,在断层附近的管道接口承受了较大的转动和压缩位移。本文所提出的分析方法可推广到埋地非连续管道在其它永久地面变形作用下的有限元分析。     

Dynamic response of pipelines to moving loads

Vibration of buried pipelines induced by moving axial and radial loads has been studied in this paper. A thin shell model has been used for the pipeline, which is assumed to be lying in an infinite isotropic homogeneous elastic medium. In order to allow for the possible motion of the pipe out of phase with the surrounding ground a very thin layer of viscoelastic material is assumed to separate the pipe from the ground. Calculations indicate the presence of the interfacial viscoelastic layer does not influence the pipe response in a significant manner. So all the numerical results presented here are for the case when the pipe is assumed to be perfectly bonded. These show that the maximum pipewall displacements and stresses occur in a soft soil at long wavelengths.     

Earthquake response of underground pipelines

Seismic response of underground pipelines is investigat?ed theoretically considering dynamic soil-pipe interaction. A lumped mass model of the pipe is employed with the soil reactions derived from static and dynamic continuum theories. The soil is supposed to be homogeneous or composed of two different media separated by a vertical boundary. Axial and bending stresses in the pipe due to travelling waves are examined. An extensive parametric study indicates that the axial stresses in the pipe are much higher than bending stresses. In a homogeneous medium, soil-pipe interaction reduces the stresses in the pipe compared to those calculated ignoring interaction. In a soil composed of two different media, the pipe stresses are highest close to the boundary and can exceed those predicted neglecting interaction.     

EFFECTS OF WELL CASING ON POTENTIAL FIELD MEASUREMENTS USING DOWNHOLE CURRENT SOURCES1

A mathematical formulation for the electric potential from point current-sources coaxial with a metal casing has been obtained. The excitation caused by the axial point-sources will produce currents in the pipe. By assuming that the pipe can be divided into many cylindrical ring segments with constant axially-directed current, the solution of the fields inside and outside the pipe can be formulated in an integral form. The integral equation applied to the segmented pipe yields a set of simultaneous linear equations which are solved for the currents in the pipe; these are then used to calculate the potentials anywhere outside the pipe in the medium. This solution has been used to study the distribution of the potentials in a half-space for a single current-source at and beyond the bottom of a finite length of casing. For a casing 0.1 m in radius and 0.006 m in wall thickness with a conductivity of 10⁶ S/m, in a half-space of 10^-2 S/m, it was found that only in a region very near the pipe does the pipe exert substantial influence on the fields of a point-source 100 casing diameters beyond the end of the pipe. It appears that cross-hole resistivity surveys can be implemented without corrections for the casing if the source is located at least 50–100 casing diameters beyond the end of the casing. Hole-to-surface surveys are much more affected by the pipe. For a pipe-source separation of 100 casing diameters, the surface measurements must not be closer than a half pipe length for a 5% or less field distortion.     

Perspectives on being a field-based geomorphologist during pregnancy and early motherhood

Many geomorphologists who are mothers find it challenging to balance field research alongside pregnancy and caring for young children. We offer perspectives on the challenges to conducting fieldwork as mothers and possible solutions, as a means of promoting conversations and highlighting issues that are less commonly considered in field-based geomorphic research. Although every mother's experience and needs are different, we discuss strategies for conducting fieldwork, addressing childcare issues, and dealing with financial considerations. We call for our community to support geomorphologists who are pregnant or caring for young children in carrying out fieldwork to help enhance the diversity of voices and perspectives within our discipline.     

A model for stress-controlled pipe growth

The rock mechanics theory for deformation of underground mining excavations under high stress conditions can be used to explain the growth and geometry of volcanic pipes. In an underground excavation stress concentrates greatest on the sides of an excavation perpendicular to the principal vector of compression. If the stress is high enough fractures will develop causing scaling of the tunnel sidewalls and tunnel growth perpendicular to the principal vector of compression. Pre-existing structures aid the physical mechanisms of pipe growth such as gravitational collapse, explosive fragmentation and turbulent erosion; and by reducing the strength of the rock mass should also aid stress-induced scaling. Universal Distinct Element Code numerical modelling demonstrated in this study reproduces the stress conditions around a circular pipe under uniaxial compression and simulates pipe growth as wedges bounded by failed pre-existing joints form around the pipe and are “assimilated” into the pipe. The results show how a volcanic pipe will tend to grow perpendicular to the principal vector of compression if the internal magma pressure is low or absent. The orientations of the pre-existing joints affect the exact direction of pipe growth in a predictable manner. Examples from other publications demonstrate that the model is consistent even in extensional tectonic environments. Case studies from kimberlite occurrences in the Limpopo Belt, at Finsch Mine and the Gross Brukkaros Volcanic Complex demonstrate that dykes and magmatic bodies of kimberlite with high overpressures during emplacement normally have geometries trending near parallel to the principal vector of compression. Yet pipes or parts of pipes that underwent strong underpressures during emplacement (often ending up comprising fragmental volcaniclastic infill) have an elongation near perpendicular to the same vector. Thus the stress-induced pipe growth model is demonstrated to be important for some pipes. The study of volcanic pipe and dyke shapes can therefore be used to determine the stress regime at the time of emplacement, and to distinguish between kimberlite occurrences formed at different times within different stress tensors.