Influence of unsupported length on underground cavity stability in sandstone stratum with weak interlayer

2021 ◽  
Author(s):  
Chenyang Zhao ◽  
Qiang Zhang ◽  
Mingfeng Lei ◽  
Yintao Song ◽  
Guodong Liang ◽  
...  
Keyword(s):  
Underground Cavity ◽  
Weak Interlayer ◽  
Cavity Stability

Finite-frequency effects for imaging underground cavities

2021 ◽  
Author(s):  
Felix M. Schneider ◽  
Petr Kolínský ◽  
Götz Bokelmann
Keyword(s):  
Analytical Approach ◽  
Nuclear Test ◽  
Underground Cavity ◽  
Finite Frequency ◽  
Cavity Detection ◽  
Frequency Effects ◽  
The Past ◽  
Nuclear Tests ◽  
Seismic Anomalies ◽  
Test Ban

<p>We study finite-frequency effects that arise in cavity detection. The task comes along with the Onsite-Inspection part for the Comprehensive Nuclear Test Ban Treaty (CTBT), where the remnants of a potential nuclear test need to be identified. In such nuclear tests, there is preexisting knowledge about the depths at which nuclear tests may take place, and also about sizes that such cavities can attain. The task of cavity detection has consistently been a difficult one in the past, which is surprising, since a cavity represents one of the strongest seismic anomalies one can ever have in the subsurface. A conclusion of this study is that considering finite-frequency effects are rather promising for cavity detection, and that it is worthwhile to take them into account. We utilize an analytical approach for the forward problem of the a seismic wave interacting with a underground cavity in order to develop an inversion routine that finds and detects an underground cavity utilizing the transmitted wave-field.</p><p> </p>

scholarly journals New robust observables on Rayleigh waves affected by an underground cavity: from numerical to experimental modelling

2019 ◽  
Vol 218 (3) ◽  
pp. 1903-1918 ◽  
Author(s):  
C Filippi ◽  
D Leparoux ◽  
G Grandjean ◽  
A Bitri ◽  
Ph Côte
Keyword(s):  
Rayleigh Waves ◽  
Underground Cavity ◽  
Experimental Modelling

Dynamics of heat exchange for gases in an underground cavity

1983 ◽  
Vol 19 (1) ◽  
pp. 128-133 ◽  
Author(s):  
E. G. Basanskii ◽  
N. A. Kudryashov ◽  
A. L. Moiseev ◽  
V. I. Nekrasov
Keyword(s):  
Heat Exchange ◽  
Underground Cavity

scholarly journals A Method for Determining the Thicknesses of the Reserved Protective Layers in Complex Goafs Using a Joint-Modeling Method of GTS and Flac3D

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Xin Zhao ◽  
Dianshu Liu ◽  
Shenglin Li ◽  
Meng Wang ◽  
Shuaikang Tian ◽  
...  
Keyword(s):  
Thin Plate ◽  
Plate Theory ◽  
Three Dimensional ◽  
Joint Modeling ◽  
Modeling Method ◽  
Underground Cavity ◽  
Protective Layers ◽  
Safe Production ◽  
Thin Plate Theory ◽  
The Stability

In this study, a C-ALS underground cavity scanner was used to detect the shapes of mining goafs. In addition, GTS software was adopted to establish a three-dimensional geological model based on the status of the stopes, geological data, and mechanical parameters of each rock mass and to analyze the roof areas of the goafs. In regard to the morphology of the study area, based on a thin plate theory and the obtained field sampling data, a formula was established for the thicknesses of the reserved protective layers in the goafs. In addition, a formula for the thicknesses of the protective layers in the curved gobs was obtained. The thickness formula of the protective layers was then successfully verified. The detection results showed that the roof shapes of the goafs in the Yuanjiacun Iron Mine were mainly arc-shaped, and the spans of the goafs were generally less than 20 m. The stability of the arc-shaped roofs was found to be greater than that of the plate-shaped roofs. Therefore, by reducing the thicknesses of the protective layers in mining goafs, the ore recovery rates can be increased on the basis of safe production conditions. The formula of the thickness of the security layers obtained through the thin plate theory was revised based on the statistical results of the roof shapes of the goafs and then combined using GTS and FLAC3D. The modeling method successfully verified the stability of the mined-out areas. It was found that the verification results were good, and the revised formula was able to improve the recovery rate of the ore under the conditions of meeting safe production standards. Also, it was found that the revised formula could be used in the present situation. At the same time, it was also determined that the complexity of the rock masses obstructed the full identification of the joints and fissures in the present orebodies. Therefore, it is necessary to incorporate C-ALS underground cavity scanners to regularly observe the shapes of the goafs in order to ensure that stability and safety standards are maintained.

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