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A Research on the Mechanisms of the Temporal Change in Geophysical Parameters in an Underground Environment

地下环境地球物理参数随时间变化的机制研究

基本信息

批准号：
15360474
负责人：
SANO Osam
金额：
$ 8万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15360474/
关键词：
Precise Monitoring of Sound Velocity Crustal Movement Underground Environment Small Stress Change Mass and Heat Transfer 精密制御震源地層環境モニタリング地下水の移動熱の移動地球物理学モニタリング

项目摘要

To monitor very long-term stability and shield efficiency associated with underground construction is one of the important techniques in engineering field. In such a long-term monitoring, temporal change in observation parameters should be very small. Consequently, instruments with very high resolution and stability should be required for observation. In the Earth sciences, underground vault has been used for measuring very small change in strain and tilt of the ground, because underground is almost free from meteorological disturbances. However, because of their high resolution, the instruments for crustal deformation can easily detect possible effects of meteorological disturbances. Because of heterogeneity nature of surrounding rock, it is often difficult to determine major processes for such very small disturbances. French colleagues have an underground laboratory on the shores of the Roselend lake of which the annual variation in the water level is about 60 m in average. Such a la … More rge change in water level should bring significant change in stress field in surrounding rock of the vault and can be used for calibration of the observations. This study is focused on a development of precise measurement of sound velocity for estimating small stress change around a vault by the shores of the Roselend lake, Savoie, France. As the test site locates in the Alps mountain area and is not easily access in winter season due to heavy snowfall. It was needed to develop maintenance free system. In order to assure high stability in the measurement, the pulse generator was phase-locked with highly accurate OCXO by which the base clock of the digital oscilloscope was calibrated at the same time. The continuous measurement started in October 2004 and stopped in April 2006. The travel-time of the pulse was determined within the resolution of several ppm. Annual change in the travel-time was found to be about 1000 ppm. The correlation between the temporal change in water level and the travel-time was found good. However, phase shift was found, which indicates that the role of water in underground must be considered. Less

监测与地下施工相关的长期稳定性和盾构效率是工程领域的重要技术之一。在这样的长期监测中，观测参数的时间变化应该很小。因此，观测需要具有非常高的分辨率和稳定性的仪器。在地球科学中，地下拱顶已被用来测量地面应变和倾斜的微小变化，因为地下几乎不受气象干扰。然而，由于地壳变形仪器具有高分辨率，因此可以轻松检测到气象扰动可能产生的影响。由于围岩的非均质性，通常很难确定这种非常小的扰动的主要过程。法国同事在Roselend湖畔设有一个地下实验室，该湖水位年平均变化约60m。如此大的水位变化应该会引起拱顶围岩应力场的显着变化，可用于校准观测结果。这项研究的重点是开发精确的声速测量方法，以估计法国萨瓦省 Roselend 湖畔拱顶周围的微小应力变化。由于试验场位于阿尔卑斯山区，冬季由于大雪，交通不便。需要开发免维护系统。为了保证测量的高稳定性，脉冲发生器采用高精度OCXO锁相，同时校准数字示波器的基本时钟。连续测量从2004年10月开始，到2006年4月停止。脉冲的传播时间是在几ppm的分辨率内确定的。发现传播时间的年变化约为 1000 ppm。水位随时间的变化与行程时间之间的相关性良好。然而，发现了相移，这表明必须考虑地下水的作用。较少的