Seepage and settlement monitoring for earth embankment dams using fully distributed sensing along optical fibers

Abstract

A method for seepage and settlement monitoring in earth embankment dams using fully distributed sensing along optical fibres is proposed. A model is developed for simulating and monitoring seepage and settlement systems. This model relates the strains and the temperature changes to the fiber Brillouin gain spectrum in the embankment dam embedding the optical fiber sensors. The model consists of two parts. Submodel 1 addresses the simulation of seepage inside the embankment dam. Submodel 2 relates the measurement of the fiber Brillouin gain spectrum to the changes in temperature and strain inside the embankment dam. Both the changes in temperature and strain during the process are used to reveal serious seepages and settlements occurring inside the embankment dam. 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. In this paper, as an example, a model filled with the soil from Yellow River is built and bare optical fibers are embedded under different soil layers near the seepage path. The simulated seepage flows under various flow rates are monitored using the optical fibers and measured by a DiTeSt -STA202 distributed temperature and strain analyzer. A partial settlement within the embankment dam model is observed.

Field validation of fibre Bragg grating sensors for measuring strain on driven steel piles

“…Fibre optic sensors have been used successfully on a number of geotechnical instrumentation projects, for example the monitoring of tunnel linings (Cheung et al, 2010), embankment settlement (Zhu et al, 2008), bored piles (Lee et al, 2004) and jacked piles (Liu & Zhang, 2012). However, FBGs have not been used to monitor driven steel piles and as a result there is concern about the survivability and robustness of the sensors under high impact accelerations and harsh pile driving conditions.…”

Data processing in safety monitoring for earth embankment dams using fully distributed sensing along optical fibers

“…The data of for-processing-part are processed regularly according to special software system [4,5], which directly provides results for the user from the monitoring system. Since the results are obtained from the original measured-data themselves, the environment parameters were not taken into account.…”

Experimental Study of Leakage Monitoring of Diaphragm Walls Based on Distributed Optical Fiber Temperature Measurement Technology

“…Some studies applying distributed optical fiber sensing technology to monitor the leakage in geotechnical engineering projects were also conducted. Zhu et al [10] proposed a distributed temperature sensing (DTS) technology based on Brillouin scattering light to monitor dam leakage. Tylerd et al [11] put forward the singular value decomposition method in the process of DTS temperature measurement.…”