外文翻译=水平定向钻机障碍检测传感器运行建模=4000字符

附录：翻译原文 Modeling of an obstacle detection sensor for horizontal directional drilling (HDD) operations A.P. Jaganathan a, J.N. Shah a, E.N. Allouche a, M. Kieba b, C.J. Ziolkowski b Keywords: Look-ahead； Numerical modeling； Differential impedance； Obstacle detection； Horizontal directional drilling Abstract: Horizontal Directional Drilling (HDD) is a commonly used construction method for the installation of underground pipelines, conduits and cables in urban areas and across obstacles such as rivers, railways and highways. A key concern in using the HDD method is the risk of hitting existing buried utilities during the pilotboring operation, which could potentiallly result in significant economic losses, disruption of services and injuries and/or loss of life. The Differential Impedance Obstacle Detection (DIOD) is a “look-ahead” sensory system, developed for the purpose of detecting metallic and thermo plastic pipes in the path of the boring head. The DIOD sensor was numerically simulated, and the model was validated by comparing its predictions with experimental measurements performed on a physical prototype in a controlled environment. Following validation of the model, a parametric study was undertake n to predict the performance of the DIOD under various scenarios that could be encountered in practice. 1、 Introduction Beneath the US landscape lie a vast network of buried utilities and pipelines, stretching for nearly 10.6million miles, which include natural gas lines, power lines, water distribution and collection systems and optical-fiber communication lines 1. The need for laying new utilities to support newtechnologies (i.e., the lastmile program), coupled with increasing dem ands of an ever growing population, has resulted in a highly congested underground space, particularly in urban areas. A parallel trend is the increase in the utilization of newer construction methods that minimize excavation, and reduce disruption to traffic patterns and the built environment. Horizontal Directional Drilling (HDD), a trenchless method for installing pipelines and conduits underground, has become in recent years a midstream construction method due to its versatility, cost effectiveness and relatively small foot print 2. A major concern in employing t he HDD method is the occurrence of an inadvertent utility strike during the boring process. As the drill head advances underground, it might damage an existing utility located along its path. Such utility strikes can cause significant economic losses (i.e., service interruptions, damage to a buried utility or building foundation) as well as injuries and fatalities if a hazardous utility (i.e., flammable liquid lines, electrical conduits, natural gas lines) is hit. Thousands of inadvertent utility strikes have been reported over the past fifteen years, some with severe consequences. The Damage Information Reporting Tool (DIRT), sponsored by the Common Ground Alliance, reported 258 HDD related utility hits in 2005 alone across the country 3. A specific concern during HDD installations in urban areas is the accidental placement of a natural gas line in a way that it transects a lateral connection or a gravity sewer line. Such occurrences, commonly named cross-bores, could create a long-term risk as an attempt to remove blockade in the drain (induced by the presence of the transecting gas line) could compromise the gas line, resulting in leakage of natural gas into adjacent homes via the sewer system4. Fig. 1 shows photographs of typical cross-bores created during HDD installations. Between 1996 and 200 6 at least 20 explosions occurred in 13 states due to attempts to clear sewer laterals that were blocked by a natural gasline, resulting in loss of life, severe injuries and over one hundred million dollars in damages. In one case (Madill, Oklahoma), the explosion (November 14, 2007) occurred 15 years following the installation of the natural gas line (1992). Projects undertaken by various utilities for identifying legacy cross bores resulted in the detection of an average of 2 to 3 cross bores of natural gas lines into sewer mains and laterals per each mile of sewermain inspected, which translate into several hundred cross-bores for some cities 5. Current practices for avoiding physical damage during HDD operations include search of GIS based databases (i.e., One Call system in U.S) to identify existing buried utilities within the project boundaries and surface surveys using geophysical tools such as cable locators, ground penetrating radar (GPR) and other locating methods. However, in some cases the One Cal l system is not fully effective due to inaccurate (or non-existing) records, cluttered environment (e.g., utilities that are stacked vertically or that are braided horizontally), excessive environ mental noise (e.g., overhead power lines, reinforced concrete pavement) and/or loopholes in local legislations that exempt owners of non-pressurized pipeline networks from the need to locate their assets in advance of construction projects .In recent years there were multiple efforts to develop a look-ahead sensor technology that can be incorporated within the HDD drill head in an effort to eliminate HDD related utility hits. Fig. 1. Utility hits (cross-bore) resulting from HDD installations A literature review of current and emerging look-ahead technology development efforts is presented. Thereafter, a description of the Differential Impedance Obstacle Detection DIOD system developed by the Gas Technology Institute (GTI) in collaboration with the Trenchless Technology Center (TTC) is provided. The DIOD system induces a low frequency electric fie ld within the soil medium surrounding the drill head. The obstacle is detected by measuring changes in impedance occurring due to distortion of the electric field caused by the presence of the obstacle 7. This paper describes the development and validation of a comprehensive 3-D numerical model created to predict and optimize the performance of the DIOD system. Following experimental validation of the numerical model, an extensive parametric study was undertaken to study the performance of the DIOD under varying conditions expected to be en countered in practice, including various soil types, different orientations of the obstacle with respect to the advancing drill head and different pipe (or obstacle) materials. 2、 Current and emerging borehole technologies for obstacle detection To avoid a utility strike, HDD operators have to detect buried utilities before a physical contact between the drill head and the utility takes place. In recent years several efforts have been made to develop sensor technology that could be incorporated into the HDD drill head with the capablity of detecting both, metallic and nonmetallic obstacles in near real-time. Nakauchiet al. 8 developed a small ground-penetrating radar system that is incorporated within a HDD drill head. It consists of a pair of antennas located at the cutting edge of th e drill head and protected by a ceramic cover, a signal generator, a receiver and a communication link for transfering data gathered to the ground surface. The principle of operation behind this technology is similar to that of a pulsed GPR, where an electromagnetic signal with duration of 0.6 ns is transmitted ahead of the drill head and the backscattered electromagnetic wave is used to discriminate the obstacle 8. Another GPR based technology for HDD was reported by Hirsch 9. This particular radar employed electromagnetic signals with frequencies between 25 MHz and 500 MHz. Hirsh reported that a proof of concept for the sensor was tested by pulling the prototype device through a 100 mm diamet erpolyethelene conduit, simulating the borehole created by a HDD rig, while attempting to locate metallic and non-metallic pipes located adjucent and perpendicular to the polyethelene conduit from a distance of 1 to 2 m ahead. California Energy Commission (CEC) 10 reported the development of a multisensory platform named SafeNav for HDD operations. The SafeNav system has been coupled with the AccuNav guidance system, used for establishing the location of the drill head 11. Safe Nav and AccuNavwork in conjunction to detect underground obstacles, and also to communic ate the information gathered by the various sensory systems to the surface 12. The system consists of 25 sensors including two sets of magnetometers for detecting buried electrical power lines, two sets of triaxial sensors for tracing specific frequencies for the purpose of detecting telecommunication lines, geophones for detecting acoustic signals, accelerometers for tracking the drill heads position, and temperature sensors for monitoring the operating condition of the electronics in the harsh operating conditions often associated with HDD operations. The sensors were designed to locate obstacles situated either parallel or perpendicular to the trajectory of the drill ahead. The design is compatible with most conventional directional drilling rigs. Various field tests were conducted resulting in several design enhancements 12. SoniPulse Inc. has developed a seismic based obstacle detection system for HDD. It employs an array of geophones located on the ground surface above the HDD path for detecting the seismic signals generated by the drill head 13. The seismic energy generated by the drill head is scattered by the buried obstacles along its path, and this scattered energy is recorded by geophones located 0.3 m apart. The geophones were coupled with the ground such that the signal-to background noise ratio was minimized. The high-intensity sound was continuously monitored, cross-correlated, and processed to detect peaks in the intensity. As the sound wave s generated by the drill head are too weak to detect below a certain depth, a noisemaker consisting of a rotating hammer that generates specific sound frequency was added to the drill head assembly. The technology has been tested for detecting large-diameter pipes at distances of 5 to 10 m and small diameter pipes at distances of 2 m ahead of the drill head. Fig. 2. A HDD drill mounted with DIOD； original device (top) and the corresponding CAD model (bottom). 3、 Differential impedance obstacle detection (DIOD) sensor The operating principle of the DIOD sensor is based on the Wheat stone bridge circuit. When the sensor is buried within a homogeneous soil with no obstacles (e.g., metallic pipe) in its vicinity, the bridge circuit is in a balanced state with the differential output between the sensing electrodes returning a null value. As the sensor approaches the obstacle, the impedance of the soil medium changes, and as a result the bridge reaches an unbalanced state with differential voltage observed between each pair of diametrically placed sensing electrodes. Fig. 2 show an image of a prototype DIOD sensor integrated within a mock HDD drill head as well as a 3-D CAD rendering of the sensory system. The prototype drill head is 900 mm long and 63 mm in diameter. The cutting edge (blade) of the drill head is used to inject a low frequency (50500 kHz) signal into the formation. There are four electrically isolated sensing copper electro des placed orthogonally around the circumference of the drill head ,which are in resistive cont act with the ground. In an earlier version of the sensor, the copper electrodes were capacitively coupled with the soil (copper electrodes were covered with an external plastic tube and were not in direct contact with the soil). In later versions the copper electrodes were redesigned to have a resistive coupling with the soil (direct contact with the soil) to improve contact potential 14. A practical implication of this modification is that the width of the slanted face duck-bill will need to be approximately equal diameter of the drill rod. A potential difference is maintained between the blade and the sleeve, such that the electric field originating from the blade intersects the sleeve. The differential voltage between the diametrically placed copper electrodes is measured after amplification and filtering. In a homogeneous soil medium, the output signal from the electrodes will remain steady as the drilling rod advances forward .However, when an obstacle is presents the output signal changes indicating its presence. Compared with expensive and complex high frequency electronics used in GPRs, which generally operate at from few hundred megahertz to about 2.5 GHz, the low frequency electronics (50500 kHz) used in the DIOD sensor is significantly lower in cost and complexity. This cost-effective technology concept has the potential for detecting metallic and nonmetallic objects in the soil medium, as well as identifying the position of the buried obstacle with respect to the drill head. A limitation of the DIOD sensor when compared with ground penetrating radar technology is that GPR has better spatial resolution due to shorter signal wavelength. Also, with DIOD sensor it is difficult to directly estimate the distance to the detected obstacle, whereas in a GPR the time-of-flight principle is used to calculate the separation distance from the sensor to the obstacle. 4、 Finite element modeling Numerical modeling of the DIOD sensor was carried out using the commercially available finite element software COMSOL Multiphysics with AC/DC module 15. Since the wavelengths of the electric signal used in DIOD are very large compared with the dimensions of the modeled structure, the problem was treated as static/quasi-static in nature 15. Two separate numerical models were created using the electrostatic and quasi-static modes available in CO MSOL AC/DC module. The electrostatic mode was used to predict the performance of the sensor while the drill head was suspended in open space (i.e., surrounded by air； =1), while the quasi-static mode was used to predict the performance of the sensor within a partially conductive dielectric medium (i.e., the soil formation). During simulations using the quasi-static mod e, two separate cases were considered. In the first case, approximations were made by neglecting the coupling between the magnetic and electric fields using the quasi-static electric current mode. In the second case, the coupling between the electric and magnetic fields was considered using the quasi-static electromagnetic mode。 Fig. 3. 3-D mesh of the numerical model containing a HDD drill mounted with DIOD. A 3-D rendering of the numerical model (approximately 220,000 interior elements and 19,500 exterior elements) is shown in Fig. 3. The cutting edge of the drill was assigned a value of +30 V and the sleeve was assigned a value of 30 V, similar to the actual system. The external boundary of the modeled domain was assumed to be grounded as it was sufficiently distanced from the modeled device. The interfaces between the dielectric mediums were assigned electrical continuity boundary condition. To electrically isolate each electrode from directly influencing every other electrode, a grounded metallic cylinder was placed within the Teflon cylinder. In simulations conducted using the electrostatic mode, the four electrodes we re assigned a floating potential boundary condition. In simulation runs where the quasi-static electromagnetic mode was deployed, the exterior boundaries were assumed to be magnetically insulated and the electrodes were assigned impedance boundary conditions, a condition commonly used for modeling conductive films 16. The geometry of the borehole was modeled based on the assumption that the soil was in contact with the drill head. 附录：翻译 水平定向钻机障碍检测传感器运行建模 A.P. Jaganathan a, J.N. Shah a, E.N. Allouche a, M. Kieba b, C.J. Ziolkowski 关键词： 预见性；数值模拟；差分阻抗；障碍物 探测；水平定向钻机 摘要： 水平定向钻进 (HDD)是一种常用的安装地下管道的施工方法 ,管道和电缆在城市地区和跨越障碍 ,如河流、铁路和高速公路。使用 HDD 方法的一个关键问题是钻孔过程中有破坏现有的公用设施造成生命威胁。差分阻抗的障碍检测 (二极管 )是一种“预见性”传感系统 ,开发的目的是检测金属和热塑性塑料管道在镗头的路径。采用二极管传感器数值模拟 ,并通过比较其预测模型进行验证与实验测量物理原型在受控的环境中执行。验证后的模型中 ,参数研究能对二极管在实践中可能遇到的各种情况进行预测。 1. 引言 美国景观下埋着庞大的网络 工具和管道，绵延近 10.6 百万英里，其中包括天然气线，电源线，配水和收集系统和光纤通信线路。需要铺设新的管道，以支持新技术 （即“ 用户距离 ”计划） ，再加上不断增长的人口的不断增长的需求，导致了高度拥挤的地下空间，特别是在城市地区。新的施工方法能最大限度地减少开挖，减少对交通的影响和建筑环境的利用率。水平定向钻进（ HDD） ，一个非开挖方法安装管道和地下管道的技术，已成为近年来流行的施工方法，由于它的多功能性，成本效益和相对较小的施工破坏。使用 HDD 方法的主要问题是在枯燥的过程中错误操作造成危险的发生。 它可能会破坏位于沿其轨道上的现有工具。这种操作错误可能会导致极大的经济损失（即损坏地下管道或建筑物导致服务中断），以及受伤和死亡，过去十五年来已经报道过上千起由于操作失误导致危险管道被破坏引起事故的案例，造成了一些严重的后果。应用于 HDD 的损伤信息报告工具（ DIRT ），由通用地面联盟发起，仅 2005 年就在全国推广。由于天然气管线或者下水道横切横向连接的布置形式，在城市地区特别关注损伤信息报告，。这种情况的发生，通常称为“交叉孔”，这种布置形式在施工过程中可能导致天然气泄漏通过下水道系统进入相邻的家庭。图 1 示出的 HDD 中安装的典型的跨孔案例。 1996 至 2006 年在 13 个州至少有 20 起爆炸事故发生于试图清除废弃的天然气管线的过程中，造成了生命损失，严重伤害下水管管道和超过上亿美元的损失。在一个案例中（马迪尔，俄克拉何马州） ，继西气东输一线（ 1992）安装的 15 年发生爆炸。运用各种实用程序检测管线项目导致的遗留跨孔，污水干管及支管每公里监测到天然气线 2 3个横孔，部分城市有几百个交叉孔。 为避免 HDD 造成物理损坏目前的做法包括搜索基础地理信息系统数据库（即，在美国一个电话系统）利用地球物理工具，如电缆定位仪， 探地雷达，以确定项目边界和表面调查，在现有的地下公用设施（ GPR）和其他定位方法。然而，在某些情况下，一个电话系统由于不准确的（或不存在）的记录，杂乱的环境（例如，被垂直堆叠，或在水平方向上编织的实用程序），过度的环境噪声（例如，架空电力线完全有效，钢筋混凝土路面）和 /或在当地的立法漏洞，非加压管网从需要免除业主找到他们的资产提前建设项目。近年来做了很多尝试，开发出“预读”传感器技术，可以在硬盘驱动器钻头内运行，以努力消除 HDD 造成破坏。 图 1. HDD 中的典型案例 当前新兴的预测技术是在研发文献回顾中 提出的。此后，差分阻抗障碍物天然气技术研究所（ GTI）与非开挖技术中心（ TTC ）合作开发检测（ DIOD ）系统的描述提供。该 DIOD 系统引起周围钻头土壤介质中低频电场。所述障碍物是通过测量发生由于电场引起的障碍物的存在的失真变化，阻抗检测 7。本文介绍了创建预测和优化 DIOD 系统的性能进行全面的三维数字模型的开发和验证。以下数值模型的实验验证，一个广泛的参数研究的目的在于研究预计在实践中遇到的各种条件，包括各种土壤类型，障碍物的不同方向就前进的钻头，并根据不同的 DIOD 的表现管（或 障碍 ）的材料。 2. 当前和新兴的钻孔障碍检测技术 为了避免公用事业遭到破坏， HDD 在钻头和工具接触地下公用设施之前先检测。近年来已经开发出了一些传感器技术，可以纳入 HDD 钻机动力头中以检测金属和非金属障碍的能力。 Nakauchi et al. 开发的是在一个 HDD 钻头中的小探地雷达系统。它由一对设在钻头的切削刃和陶瓷盖组成，一个信号发生器，一个接收机和一个通信链路聚集到地面传输数据的保护天线。该技术的原理是类似脉冲 GPR 的，其中的电磁信号以 0.6 纳秒的持续时间发送领先于钻头和背散射电磁波被用于区分所述障碍物 8。 另一种基于探地雷达技术， HDD 报告了赫希 9。这种特殊的雷达采用电磁波信号， 25 MHz 和 500 MHz 的频率。赫希报道，证明了该传感器是通过一个直径 100 毫米的聚乙烯管道拉动原型设备进行测试。 加州能源委员会（ CEC） 10报道了一个名为安全导航 HDD 运作的多感官平台的发展。安全导航系统已被加上准确导航引导系统，用于确定所述钻头 11的位置。安全导航，准确导航协同工作，以探测地下障碍物，并且还要通过各种传感