地下的视野：地面穿透雷达

L.ike坑洼, only smarter. You’ve got the list of underground utilities with a drawing of their planned or located paths that may cross the designed path of your trenchless project.

your Geotech team took a shovel and dug some test holes - potholes - to spot-check the information, but…what if you strongly suspect there are things down there that aren’t on the drawings from One Call – some centuries-old obstruction, like a forgotten cemetery that potholing could miss?

简单的答案是使用地下透气雷达进行全面的外观，这是一个自20世纪80年代以来一直存在的技术，使您可以全面了解您正在钻取的内容。早期使用，它可以帮助您避免昂贵的延迟，错误和遗漏，这可能意味着新的最梦魇和一个有利可图的项目之间的区别。（也是“为什么岩土报告对您的绝抗项目取得成功。")

GPR：基本原则

人们询问的第一个问题之一地面渗透雷达（GPR）是，“是声学，还是真正雷达？”短答案是，它是雷达，而不是声音，声学替代品。它使用微波发射器将信号发送到地面。

W.hen the signal encounters a change in the subsurface makeup, it bounces back to the surface and the GPR’s receiver. The GPR then records the underground anomaly and creates a visual file for review. GPR has some constraints. Electrical conductivity in the ground tends to attenuate the depth at which it’s effective.

一世f, for example, your project’s design path is crisscrossed with electric power or communications cables, that limits how much and how deep your view is. There are tradeoffs available, though. Your geotechnical team can compensate for this with changes in the GPR transmitter frequency and power. A higher frequency means better image resolution, but shallower ground penetration.

你sing Ground Penetrating Radar

使用GPR有效地是一种专业的岩土技能。任何人都可以在地面上拖动GPR单元，将出现某些图像。也许这些图像将在一个简单的情况下回应您的需求，但是当您的项目的路径充满多次 - 也许数百个公用事业过境点时，乱丢有关未知和普通的“未知数”的怀疑，你有两个选择。

you can learn all there is to know about GPR, do the work in-house and hope you get it right, or you can retain the services of a firm that specializes in the subject to build your岩土工程。

喜欢使用与之相关的任何土地服务无牙接建筑，使用专门的GPR承包商或具有GPR技能的地理承包商取决于相同的成本/益处，导致您出价或通过项目。项目复杂性，更好的项目完成时间，从避免避免地下冲突和避免可追加的公共关系问题产生的利润潜力可以大量重视GPR使用。

同样，项目就像pipe bursting（有时需要pipe penetrating radar）和下水道的重新密切可能不值得纳入GPR。无论设计路径上的可用信息如何粗略或全面，都会考虑新项目的GPR，考虑GPR的健康剂量。

wysiawyg：你所看到的不是你得到的

与任何雷达图像一样，GPR为您提供来自发射机头的地下异常的位置和距离。这不是鸟瞰图。相反，它显示了顶部表面和异常的剖面视图 - 以及它们的深度和水平位置。

一种n existing pipeline may appear as nothing more than a hump or other trace underground that indicates the presence of something. It may be a facility that shows up accurately in the One Call data or it may be a pipe or cable that’s several feet away from the position found in the data. Or it may be something that was never entered into the system.

一世t is, however, a potential conflict with your project that you have to avoid, meaning additional investigation, whether with a shovel or a backhoe, is needed. (Read more in "T.he Science of Getting it Right: Locating Underground Utilities。")

W.hatever the result, GPR gives you a starting point. Like any radar system, it doesn’t always deliver a finished, defined image, but it does give you the edges, like a coastline to be investigated directly rather than by electronic means.

T.he Bottom Line of GPR

D.on’t expect GPR to give you the moon, stars and sun on a platter. Proper pre-planning, having an idea of what your target will show up as and foreknowledge make life easier. It can help keep you out of trouble, but it may add to your design team’s woes with the project design path, or change the method and manner of your digging altogether.

虽然GPR将向您向您展示一些您并不知道的事情，最好用它来确认您已经了解或怀疑的信息。超出这是偶然的。无论哪种方式，适当地下规划被推荐。