Time-lapse crosshole seismic tomography for characterisation and treatment evaluation of the Ribeiradio dam rock mass foundation

2018 ◽  
pp. 893-900
Author(s):  
M.J. Coelho ◽  
R. Mota ◽  
A. Morgado ◽  
J. Neves
Keyword(s):  
Rock Mass ◽  
Seismic Tomography ◽  
Time Lapse ◽  
Treatment Evaluation

Application of geophysical methods for the investigation of the large gravitational mass movement of Séchilienne, France

2005 ◽  
Vol 42 (4) ◽  
pp. 1105-1115 ◽  
Author(s):  
O Meric ◽  
S Garambois ◽  
D Jongmans ◽  
M Wathelet ◽  
J L Chatelain ◽  
...  
Keyword(s):  
Rock Mass ◽  
Mass Movement ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Time Lapse ◽  
Gravitational Mass ◽  
Electrical Tomography ◽  
Refraction Tomography ◽  
Geophysical Surveys ◽  
Geophysical Techniques

Several geophysical techniques (electromagnetic profiling, electrical tomography, seismic refraction tomography, and spontaneous potential and seismic noise measurement) were applied in the investigation of the large gravitational mass movement of Séchilienne. France. The aim of this study was to test the ability of these methods to characterize and delineate the rock mass affected by this complex movement in mica schists, whose lateral and vertical limits are still uncertain. A major observation of this study is that all the zones strongly deformed (previously and at present) by the movement are characterized by high electrical resistivity values (>3 kΩ·m), in contrast to the undisturbed mass, which exhibits resistivity values between a few hundred and 1 kΩ·m. As shown by the surface observations and the seismic results, this resistivity increase is due to a high degree of fracturing associated with the creation of air-filled voids inside the mass. Other geophysical techniques were tested along a horizontal transect through the movement, and an outstanding coherency appeared between the geophysical anomalies and the displacement rate curve. These preliminary results illustrate the benefits of combined geophysical techniques for characterizing the rock mass involved in the movement. Results also suggest that monitoring the evolution of the rock mass movement with time-lapse geophysical surveys could be beneficial.Key words: gravitational movement, geophysical methods, Séchilienne.

Time‐lapse crosswell seismic tomography and well logging to monitor the injected in an onshore aquifer, Nagaoka, Japan

2005 ◽  
Author(s):  
Ziqiu Xue ◽  
Daiji Tanase ◽  
Hideki Saito ◽  
Dai Nobuoka ◽  
Jiro Watanabe
Keyword(s):  
Seismic Tomography ◽  
Time Lapse ◽  
Well Logging

Hydrologic Imaging of Fractured Rock

1994 ◽  
Vol 353 ◽  
Author(s):  
Kenzi Karasaki ◽  
Andrew Cohen ◽  
Paul Cook ◽  
Barry Freifeld ◽  
Ken Grossenbacher ◽  
...  
Keyword(s):  
Rock Mass ◽  
High Resolution ◽  
Seismic Tomography ◽  
Pressure Transducer ◽  
Fractured Rock ◽  
Geophysical Data ◽  
Pressure Measurements ◽  
Transient Pressure ◽  
Fractured Rock Mass ◽  
Hydrologic Connections

AbstractVarious geophysical and hydrologic tests were conducted in a cluster of nine wells to image the hydrologic connections of a fractured rock mass. Results of intra-borehole flow surveys and cross-hole radar and seismic tomography surveys correlated very well, and indicated that there is a major feature at a depth of 30m. Systematic injection tests were conducted in all nine wells. Three to four intervals in each well were isolated using pneumatic packers. Each interval was equipped with a high resolution pressure transducer. Some 130 injection tests were conducted, and more than 4,100 cross-hole transient pressure measurements were obtained. A computer algorithm was developed to analyze such massive interference data systematically. As a result of the analysis, an image of the fracture connections emerged which is consistent with the geophysical data.

The effect of weathering on rock wall erosion and rockfall generation at La Cornalle, Switzerland

2020 ◽  
Author(s):  
Li Fei ◽  
Marc-Henri Derron ◽  
Tiggi Choanji ◽  
Michel Jaboyedoff ◽  
Chunwei Sun
Keyword(s):  
Rock Mass ◽  
Monitoring Program ◽  
Time Lapse ◽  
Effect Of Temperature ◽  
Rock Surface ◽  
Rock Wall ◽  
Rock Face ◽  
Surface Areas ◽  
Thaw Cycle ◽  
Rock Temperature

<p>The weathering posing a significant influence on the rock wall retreat has been widely recognized. In this paper, multi-methods monitoring is designed to detect the erosion and rockfall activity on a rockslide cliff composed of marl-sandstone (maybe mixed with limestone) in Western Switzerland. The monitoring program includes weekly SfM and monthly LiDAR scanning measurements of rock cliff surface, hourly time-lapse imaging of the rock cliff, manual measurement of rock surface moisture, automated recordings of rock temperature and influencing meteorological factors (air temperature, humidity, wind, and precipitation) collected by a weather station. Sequential 3D Points Clouds acquired by LiDAR and SfM from December 2019 are used to visually identify the location of erosion and rockfall at monthly resolution. According to the rock wall structural analysis, the rock mass consists of a network of discontinuities mainly oriented nearly parallel and perpendicular to the direction of the layers. Some fractures are filled with calcite which might lead to a zone of weakness in the rock mass. During the field survey, we saw some calcite crystals covering on the rock block surface in the deposit area and exposed on rock cliff outcrop. We suppose that some rockfalls are generated along those discontinuities filled with calcite where the chemical reaction is active when there is constant water infiltrating during rainfall season. According to the preliminary panoramic thermal image of the cliff surface shot by DJI Mavic 2 Enterprise on 19 December 2019, some weathered and fresh surface areas show different temperatures in the same rock layers which suggest the thermal imaging monitoring may help us to identify the weathering spatial characteristics. In this study, we try first to reveal the effect of temperature variations (thermal stress) on crack deformation from rock temperature values extracted from thermal images and the deformation measured by the crack meter during 24h in winter and summer. Secondly, we explore the role of freeze-thaw cycle playing in the rock fall initiation and rock face erosion. Thirdly, we make clear the link between surface weathering spatial distribution and location of erosion, rockfalls. This provides a model of weathering and rockfall estimation.</p>

scholarly journals Applicability of time-lapse refraction seismic tomography for the detection of ground ice degradation

2010 ◽  
Vol 4 (1) ◽  
pp. 77-119 ◽  
Author(s):  
C. Hilbich
Keyword(s):  
Seismic Tomography ◽  
Time Lapse ◽  
Swiss Alps ◽  
P Wave ◽  
Permafrost Degradation ◽  
Travel Times ◽  
Ground Ice ◽  
Refraction Seismic ◽  
Velocity Changes ◽  
Ice Content

Abstract. The ice content of the subsurface is a major factor controlling the natural hazard potential of permafrost degradation in alpine terrain. Monitoring of changes in ground ice content is therefore similarly important as temperature monitoring in mountain permafrost. Although electrical resistivity tomography monitoring (ERTM) has proved to be a valuable tool for the observation of ground ice degradation, results are often ambiguous or contaminated by inversion artefacts. In theory, the P-wave velocity of seismic waves is similarly sensitive to phase changes between unfrozen water and ice. Provided that the general conditions (lithology, stratigraphy, state of weathering, pore space) remain unchanged over the observation period, temporal changes in the observed travel times of repeated seismic measurements should indicate changes in the ice and water content within the pores and fractures of the subsurface material. In this paper, the applicability of refraction seismic tomography monitoring (RSTM) as an independent and complementary method to ERTM is analysed for two test sites in the Swiss Alps. The development and validation of an appropriate RSTM approach involves a) the comparison of time-lapse seismograms and analysis of reproducibility of the seismic signal, b) the analysis of time-lapse travel time curves with respect to shifts in travel times and changes in P-wave velocities, and c) the comparison of inverted tomograms including the quantification of velocity changes. Results show a high potential of the RSTM approach concerning the detection of altered subsurface conditions caused by freezing and thawing processes. For velocity changes on the order of 3000 m/s even an unambiguous identification of significant ground ice loss is possible.

2D time-lapse seismic tomography using an active time-constraint (ATC) approach

2015 ◽  
Vol 34 (2) ◽  
pp. 206-212 ◽  
Author(s):  
M. Karaoulis ◽  
D. D. Werkema ◽  
A. Revil
Keyword(s):  
Seismic Tomography ◽  
Time Lapse ◽  
Time Constraint ◽  
Active Time
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