设计大坝监测系统

作者：Craig Hewes

In early 2017, winter storms filled and then overfilled reservoirs in California, USA, leading to the evacuation of hundreds of thousands of citizens near Lake Oroville, California’s second largest manmade lake.

大约160公里的地方，2017年风暴中的帕迪和卡曼奇水库也占据了3月的103％的容量，但水坝没有超过，并且在水道中发行了释放。

由于安装了美国最先进的基于GNSS的最先进的大坝监测系统之一，以及其他仪器改进，东湾市政公用事业区（EBMUD）已将技术融入到适当的技术监视这些大坝和堤防处的波峰高程with improved temporal resolution. Having this type of data available is one more tool in an infrastructure owner’s tool belt for monitoring the condition and performance of critical facilities.

Designing for better data

Consulting with Sensemetrics, a firm specialising in networked sensor applications based in San Diego, USA., EBMUD designed and proposed a sophisticated monitoring system based on:

• 31 Leica GMX901+ GPS sensors
• 四个Leica GM10 GNSS参考站
• A radio network consisting of 900 MHz mesh radios
• 4 GHz repeaters and two radio towers
• Leica GNSS Spider and GeoMoS software solutions.

The use of Geosystems receivers is important, according to Cory Baldwin, president of Sensemetrics:“GMX901+s是针对远程监视应用程序的专门构建的，具有不暴露的内置天线，” he says. “They were my first choice here, because other vendors don’t really have a good option for monitoring in this environment.”

Three of the GNSS reference station receivers are solar powered and one is powered by a 120v AC feed. All are securely fastened inside enclosures installed near the Leica AR20 antennas, which are mounted on concrete pedestals.The network is largely autonomous, needing only occasional attention。Data flow is through 900 MHz and 2.4 GHz spread spectrum radios into an existing microwave telemetry link to EBMUD’s business intranet at its Oakland headquarters, where a server runs the Spider and GeoMos software necessary to process the GNSS data and results. The results are then presented through software customised by Sensemetrics.

Five of the GMX901+ sensors as well as four seismographs are installed on the Pardee Dam connected via fiberoptic cable directly to the microwave business intranet. Theseinstruments continuously monitor dam movement and report remotely。两个GM10参考站安装在Pardee大坝的两侧和两侧，并通过2.4 GHz无线电连接连接到光纤线。

Downstream from Pardee Dam, the Camanche Reservoir site consists of one large earth-filled dam and six dikes. The Camanche Reservoir is primarily used to control releases to downstream agencies and maintain flows for the salmon. Twenty-six GMX901+ sensors are installed around the reservoir, and these also monitor and report continuously.

A complete picture of infrastructure performance

加利福尼亚州大坝安全部（DSOD）需要半年度监测调查。新系统提供accurate information more rapidly,reduces staff time spent on monitoring, and is capable of beingtied into state-wide emergency and seismic monitoring systemsas they emerge. After almost two years of service, DSOD monitoring requirements have been met with a more complete picture of overall performance.

“EBMUD’s infrastructure is spread out over a vast area and covers multiple counties,”鲍德温说。“In particular, the Pardee and Camanche sites are several hours away from main offices, and the semi-annual surveys [conducted previously] took over a week to complete. This new system provides more accurate data, more or less constantly, and, of course, reduces the time survey crews spend on this task. It’s a big improvement, and it is performing beyond expectations.”

鲍德温说，一个重要的设计目标是与现有和未来监控系统的互连性。潜力automate and improve emergency responses to seismic events是监视网络的主要优势。

EBMUD now hasmore survey information immediatelyat its fingertips regarding structure performance than at any previous moment in the district’s history. By being proactive and automating monitoring systems, EBMUD has greatly improved dam safety monitoring.

“The GPS system at Pardee Dam now gives us a complete picture of the seasonal deformations due to thermal expansion and contraction of the concrete structure,”says Steven J. Martin, survey supervisor for EBMUD.“With the Camanche Reservoir portion of the GPS monitoring system, we are able to meet DSOD monitoring requirements without long trips out of town by the survey crew and to check for any possible deformations remotely in near real time.”

Automated dam monitoring in action

自动化调查监测计划的最新示例来自美国加利福尼亚州圣巴勃罗大坝上的另一个EBMUD自动大坝监测项目。在2008年和2009年，大坝经过了地震改善，使用水泥深层土壤混合过程，以支撑大坝到基岩的脚趾。自动电动总站系统（AMTS）满足了DSOD的监控要求，自2009年该项目完成以来，该系统每天运行几次。地震后立即检查大坝和水库，以检查开裂或其他明显的损坏，以作为快速地面真相。

After a 4.4 magnitude earthquake in January 2018 on the Hayward fault centred in Berkeley, less than 8 km from the San Pablo dam site, EBMUD geotechnical engineers were able to log in to the AMTS automated monitoring system toreview whether there had been any actual movement or slumping on the dam他们确认没有重大运动。这种能够立即获得信息和触手可及的能力被证明是管理Ebmud的大坝安全的巨大资产。