土石坝外文翻译文档格式.docx

1、AbstractBoth the changes in temperature and strain during the process are used to reveal serious seepages and settlements occurring inside the embankment dam. A method for seepage and settlement monitoring in earth embankment dams using fully distributed sensing along optical fibres is proposed. The

2、 proposed monitoring system also offers the owner the strategy of the inspection and maintenance in earth embankment dams. The database in the control and maintenance center is described. In this paper, as an example, a model filled with the soil from Yellow River is built and bare optical fibers ar

3、e embedded under different soil layer near the seepage path. The configuration of optical sensing cable in series of embankment dams is developed. The simulated seepage flows under various flow rates are monitored using the optical fibers and measured by a DiTeSt STA202 distributed temperature and s

4、train analyzer. A partial settlement within the embankment dam model is observed. The continuously decreasing temperature curve shows an abrupt dramatic increasing rate, which shows that the change is not caused by the temperature of the seepage water but the strain. The information from the monitor

5、ing center provides important reference for the expert decision-making system to ensure the safety of the embankment dam long running.Keywords: Embankment dam; Safety inspection; Settlement and seepage, Optical fiber sensing1. IntroductionEmbankment dams are designed to remain functional despite som

6、e acceptable steady seepage. The background task for the surveillance of an embankment dam is to monitor the changes in temperature and pressure inside the embankment dam induced by those anomalous seepages which may threaten the structure integrity. Water pressure, which is usually detected with so

7、me borehole tubes distributed along a possible seepage path, is a traditional quantity being monitored for tracking a seepage flow 1, 2. Temperature can normally be easily measured in the standpipe using thermometers. Resistivity measurements are comparably more complicated since they require a comp

8、uter-based monitoring system and minor technical installations on the dam. In spite of the effectiveness of those existing methods, none of them is suitable for continuous monitoring. With the recent advances in optical fiber sensing technology, seepage monitoring systems measuring the temperature i

9、nside the embankment dam using distributed sensing along optical fibers have been developed 3. A preheated optical cable method is used in the dam filled with concrete core to detect seepage flow. The sensing cable is embedded at the dam toe filled with earth for the temperature measurement and othe

10、r independent cables are installed at other places for the strain measurement 4. Any excessive and unexpected seepage may lead to the failure of the embankment dam, especially in unconsolidated terrains, such as earth-filled embankment dams. However, if temperature and strain values are recorded sep

11、arately, which is difficult for an early warning of the settlement in the embankment dam caused by serious seepage or piping. Moreover, the temperature change due to the seepage may become relatively stable when a higher seepage rate flow finds a fixed path through the embankment dam. Nevertheless,

12、in dangerous cases such as those massive quake-induced lakes in China in 2008, the ability of the embankment to maintain itself under high stress needs to be investigated, since it is the main reference information for the crucial decision to either destroy the embankment dam, or to sluice by a dive

13、rsion facility, or to reinforce the embankment dam to prevent an unexpected dam-break in the weaken parts. With the development of scour holes, soil and sands, stone foundation of spur dikes will be taken away by the rapid flow and the vortical flow. Even worse, spur dike may collapse, which happens

14、 in a very short time and bring serious hazard to vicinity residents. Therefore, stability problems must be detected and repaired in a timely manner. A long rod is usually employed to detect and approximate the extent of scour. Since scour occurs underwater, inspection and circumstance in-field are

15、often rough and dangerous during flooding. The measurement results are therefore random and inaccurate which cannot be considered as foundation data to judge if a hidden disaster arises. An embankment dam especially for spur dike slide monitoring system based on fiber optic sensing technology has be

16、en proposed 5. However, the stability and safety of embankment dams are related to many impact factors, such as seepage flow which is another kind of disaster. The entire embankment should be routinely and closely inspected for seepages, cracks, slides, and settlements. These records can help determ

17、ine if a condition is new, slowly Changing ，or rapidly changing. A rapidly changing condition or the sudden development of a large crack, slide, or depression indicates a very serious problem. This paper presents an embankment dam safety management system including monitoring part to manage running

18、condition records of the embankment dam, information and make maintenance strategy.2. Maintenance StrategyA successful safety and maintenance system provides reliable and meaningful embankment dam performance data to the operations and engineering personnel who are responsible for operating and main

19、taining the projects. The monitoring and maintaining strategy of the system is essential. There are a variety of tools or methods that areavailable for embankment dam hidden disaster detecting and monitoring. The selection of methods to implement for a particular embankment dam project is in designi

20、ng a successful monitoring system. Many good references that currently exist regarding the selection, design, and installation of dam safety monitoring instrumentation are available. Optical fiber sensors are selected to build a monitoring system with high level of technology, which performs good mo

21、nitoring activities and mainly aims at two variables, the strain and the temperature corresponding to the information of the settlement and the seepage of embankment dams. This monitoring system excludes some places where serious destroy hardly happened or some failure is unwarranted typically fail

22、because the system is viewed as too complex and difficult to work with. The system is reliable and provides high quality data. Developed programs have friendly and clear interface which compensate perceived unreliability and the result of pooroperations and maintenance procedures by users that do no

23、t understand the technology. However the over-use of high technology also can result in high installation costs relative to the benefits provided. This can lead to a decision not to implement the needed system improvements. By developing an effective detection and maintenance strategy in these cases

24、, many of better benefits can be provided. A specially designed configuration to the implementation can also be very beneficial in managing the required annual capital expenditures, and also to aid in the acclimation of operations and engineering personnel to the new technology. The safety monitorin

25、g and management strategy architecture for embankment dams is shown in Figure 1. The embankment safety inspection and detection consiststwo parts. One is manual inspection of minor instabilities. This part is mainly for short and isolated cracks, shallowslide and minor settlement. The job for these

26、dam managers is to collect and evaluate the dam monitoring data by labor effort. The other part is automatically monitoring module based on DiTeSt-STA202 instrument. This part is especially for larger cracks, deep-seated slide, and larger settlement. Among mid-sized and big embankment dams, implemen

27、ting large amounts of leading and sensing cables can provide substantial benefits in the quality and reliability of the monitoring, not lower the total system cost in current market but simplify the configuration of the system. Applying the appropriate strategy of maintenance for those particular wa

28、rned positions or segments of embankment dams will form a successful management system according to both part one and part two warning reports. To accomplish this objective, proper steps and details must be followed in planning and designing the system. The following paragraphs discuss the monitorin

29、g module based on DiTeSt instrument and the details of configuration for two cases of the settlement and the seepage.1. Hidden Disast Monitoring System3.1 Monitoring system based on fiber optics sensorsInformation acquisition is the first step for a management system. The fiber optics sensing cable

30、serves as sensor unit, which is based on the mechanism of Stimulated Brillouin Scattering （SBS） in single mode optical fibers. By monitoring the Brillouin gain of the probe light in frequency domain, one can detect the temperature and the strain along optical fibers around these positions where abno

31、rmal seepage and the settlement occur. The optical fiber sensors are embedded in embankment dams and spur dikes. The configuration of the optical fiber sensors is shown in Fig.2. There are some leading cables between different spur dikes and embankment dams as well as linking DiTeSt analyzer. For th

32、e seepage, it can emerge at any location on the downstream face of embankment dams through the seepage line. If the seepage forces are large enough, the soil will be eroded from the foundation and be deposited in a cone-shaped surface near the outlet. The appearance of these boils is an evidence of a muddy seepage flow carrying soil particles. This shows the onset of piping and a complete failure of the dam may occur within hours. It can be manually inspected, but it may be late to implement maintenance and ensure the safety of embankment dams. The embankmen