Frozen Wall Construction Control in Mine Shafts Using Land and Borehole Seismology Techniques
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Frozen Wall Construction Control in Mine Shafts Using Land and Borehole Seismology Techniques I. A. Sanfirova, A. G. Yaroslavtseva, A. V. Chugaeva*, A. I. Babkina, and T. V. Baibakovaa a
Mining Institute, Ural Branch, Russian Academy of Sciences, Perm, 614007 Russia *e-mail: [email protected] Received February 28, 2020 Revised March 5, 2020 Accepted May 29, 2020
Abstract—The article discusses feasibility of frozen wall construction supervision in salt rock mine shafts using seismology techniques. Shallow seismic survey locates wakened areas and intense water flows in rock mass near shafts. Borehole seismics, including crosswell shooting and vertical profiling by the common depth point method, allow estimation of frozen rock thickness. The proposed package of seismology techniques aims to reduce risk of emergencies in construction of mine shafts. Keywords: Remote control, frozen wall, soil freezing, mine shaft, acoustic measurements, ultrasonic logging, crosswell shooting, shallow seismic survey. DOI: 10.1134/S1062739120036641
INTRODUCTION
Construction of underground mines in salt rock mass starts with shaft sinking. A mine shaft is a complex geotechnical facility. It intersects rock strata from the ground surface to producing formations, including one or a few aquifers which constitute a major problem in construction and operation of shafts. The shafts should be protected from fresh water inflows by a special impervious seal. The most reliable method in this regard is artificial freezing of rocks. The thickness of the frozen wall is governed by the lithology and physical and mechanical properties of rocks per the crosssection intervals. Monitoring of the condition and thickness of the frozen wall is the mandatory requirement of sinking safety. To this effect, various acoustic measurements are used in combination with continuous thermometry [1–4]. The common approaches are crosswell shooting and ultrasonic logging along the perimeter of freeze pipes. High-resolution land seismic acquisition using reflected wave effectively locates softer zones in surrounding rock mass of various-purpose tunnels, galleries and mine openings [5–8]. Each method has its intrinsic shortages, for instance, the land seismic acquisition techniques solely are incapable to determine the current thickness of frozen wall. The standard ultrasonic tests of frozen wall are unintended to inform on properties of surrounding rock mass. For another thing, it is not always possible to withdraw freeze pipes from operation the the frozen wall measurements at a certain stage of freezing. This study suggests integration of different-scale seismic exploration techniques for assessing geometry of frozen wall and for better unde
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