Underground Room Research Articles

Damage to the ground caused by caving and investigation of underground cavities

There are many abandoned coal and lignite mines, underground shelters excavated during the Second World War, hastily filled underground rooms and pipes during the re-construction following the Second World War all over Japan. Due to degradation of these cavities, sinkholes or ground subsidence resulting in casualties and damages to residential areas properties have been increasing in recent years. In addition, torrential rains and/or earthquakes make necessary to investigate the instability of such abandoned underground cavities.The behavior of rock mass between the ground surface and shallow underground openings is very complex and it is affected by the mechanical behavior (deformation, local failures, loosening), weathering, and deterioration, following the excavation, underground water seepage. In this article, the author describes damages caused by ground subsidence, sinkholes and their mechanism associated with environmental factors, the collapse risk of abandoned mines. Furthermore, the importance of the development of exploration and surveying techniques to detect the location and geometry of abandoned underground cavities is disccused.

Liquid Oxygen – Fire Hazards of Oxygen and Oxygen-Enriched Atmospheres

Oxygen, which is essential to life, is not flammable in itself but supports and accelerates combustion. The normal concentration in the air that we breathe is approximately 21% by volume. Most materials burn fiercely in oxygen; the reaction could even be explosive. As the oxygen concentration in air increases the potential fire risk increases. Being heavier than air, oxygen can accumulate in low lying areas such as pits, trenches or underground rooms. This is particularly relevant when liquid oxygen spills out. In that case the generated cold gaseous oxygen is three times heavier than air. As 1 l of liquid oxygen liberates circa 850 l of gas, the phenomenon of oxygen enrichment is massively amplified by a spill of liquid oxygen, and thus fire risk is increased.

Coal mining along the Warfield Fault, Mingo County, West Virginia: a tale of ups and downs

Mine development along a 15-mile (24 km) section of the Warfield Fault in Mingo County, West Virginia has broadened the geological understanding of the fault and its related structures. The fault has been exposed in two new road cuts, one in the northeast-trending segment at Neely Branch and one in the eastern east-trending segment at the head of Marrowbone Creek. Both exposures show a well-defined normal fault with a 45° to 55° N dip, juxtaposing sandstone/shale packages from the roof and the floor of the Coalburg seam. The fault is associated with a thin gouge zone, some drag folding, and parallel jointing. Its trace tends to run parallel to the crest of the adjacent Warfield Anticline. Based on underground mine development and detailed core drilling, the vertical offset along the fault plane ranges from a maximum of 240 ft (73 m) in the central part of the area near the structural bend to less than 100 ft (30 m) in western and eastern directions. The fault is located along the relatively steeply dipping (locally in excess of 25%) southern limb of the Warfield Anticline, and appears related to a late phase of extension involving folded Pennsylvanian strata. On a regional scale, the lithological variations across the fault do not suggest any appreciable strike-slip component. Underground room and pillar mines in the Coalburg seam north and south of the fault have been greatly impacted by the Warfield structures. Due to the combined (and opposite) effects of the folding and faulting, the northern mines are located up to 400 ft (125 m) higher in elevation than the southern ones. Overland conveyor belts connect mining blocks separated by the fault. The practical mining limit along the steep slopes toward the fault is around 15%. Subsidiary normal faults with offsets in the 5- to 15-ft (1.5–4.5 m) range are fairly common and form major roof control and production hurdles. Overall, the Warfield structures pose an extra challenge to mine development in this part of the Appalachian Coalfields.

A multi-sample liquid scintillation counting system for weak beta-emitting samples with single phototube detectors

The relative merits of low-level liquid scintillation counters with one and two phototubes, respectively, are discussed and an analysis of their background components is presented. A simple and compact system with manual sample changing is described. It counts four samples simultaneously, and it is based on the single-phototube arrangement where conical vials sit on the top of 28 mm diameter phototubes. A PC computer collects and processes the pulses from a specially designed electronic unit. The system is operated in a small underground counting room, a closet in the wall of a road tunnel under a fjord. Its performance is described.

Status report on the underground machine room at the Rogun hydroelectric power plant

Status report on the underground machine room at the Rogun hydroelectric power plant

The Monsters of Pergouset

The last underground room at Pergouset is engraved with a variety of signs and a series of unreal, or distorted, animal figures that are presented as variations on several themes. These fantastic creations are the Pergouset monsters. A few similar depictions are known mostly from nearby caves, but as a group the Pergouset monsters are unparalleled in Franco-Cantabrian art. The engravings of Room IV contrast with the conventional Upper Palaeolithic animal depictions found in the three preceding rooms but the use of particular tricks of depiction, as much as the style of certain figures, makes it likely that the same artist drew both conventional figures and monsters. Conditions in the cave suggest that few, if any, visitors reached this last room. In the light of these circumstances the authors consider possible explanations for the occurrence of the monster engravings and their implications.

Deep hydraulic fracture imaging: Recent advances in tiltmeter technologies

Standard metallic coaxial cables were installed at the Waste Isolation Pilot Plant (WIPP) to monitor shear deformation in the roof, floor and walls of a newly excavated underground room. The WIPP is being developed near Carlsbad, New Mexico, for the disposal of transuranic nuclear wastes in bedded salt 655 meters (2, 150 feet) below the surface. Data collected from WIPP geomechanical monitoring are used to characterize conditions, confirm design assumptions, and understand and predict the performance of deep salt excavations. In the past, the installation of metallic coaxial cables provided an excellent means of locating the areas of shear deformation using time domain reflectometry (TDR). However, this monitoring technique has been advanced by quantifying the amount of shear deformation occurring in the underground installations. To quantify field data, shear tests were conducted in the laboratory to simulate a typical field installation in salt rock undergoing shear deformation. Shear offsets were quantified with respect to change in waveform characteristics. This paper presents a comparison of field data collected at the WIPP to laboratory test results in order to quantify waveform characteristics to shear deformation. By quantifying the TDR monitoring system, the amount of deformation as well as the are a of deformation can be defined. This provides an excellent, as well as inexpensive, means of monitoring shear deformation in underground excavations. This work was supported by the U.S. Department of Energy under DOE Contract No. DE-AC04-86AL31950.

Time domain reflectometry (TDR): A comparison of field data to laboratory shear tests

Standard metallic coaxial cables were installed at the Waste Isolation Pilot Plant (WIPP) to monitor shear deformation in the roof, floor and walls of a newly excavated underground room. The WIPP is being developed near Carlsbad, New Mexico, for the disposal of transuranic nuclear wastes in bedded salt 655 meters (2, 150 feet) below the surface. Data collected from WIPP geomechanical monitoring are used to characterize conditions, confirm design assumptions, and understand and predict the performance of deep salt excavations. In the past, the installation of metallic coaxial cables provided an excellent means of locating the areas of shear deformation using time domain reflectometry (TDR). However, this monitoring technique has been advanced by quantifying the amount of shear deformation occurring in the underground installations. To quantify field data, shear tests were conducted in the laboratory to simulate a typical field installation in salt rock undergoing shear deformation. Shear offsets were quantified with respect to change in waveform characteristics. This paper presents a comparison of field data collected at the WIPP to laboratory test results in order to quantify waveform characteristics to shear deformation. By quantifying the TDR monitoring system, the amount of deformation as well as the are a of deformation can be defined. This provides an excellent, as well as inexpensive, means of monitoring shear deformation in underground excavations. This work was supported by the U.S. Department of Energy under DOE Contract No. DE-AC04-86AL31950.

Constitutive model of creep in rock salt applied to underground room closure

A multimechanism constitutive model of the creep of polycrystalline rock salt has been developed based on steady state creep as modified to incorporate transient creep through workhardening and recovery. Application of the model is in calculation of the closure of underground rooms excavated in a natural, bedded evaporite salt deposit. This requires an integrated technology consisting of not only the proper constitutive model, but also a range of other system elements relating to the site geology, initial and boundary conditions, and numerical methods peculiar to the application. Through finite element calculations, this model, with appropriate laboratory material parameters and a Tresca flow potential, has predicted the closure of a number of large, in situ experimental rooms at the Waste Isolation Pilot Plant (WIPP). In this paper, an overview of the model development, laboratory parameter generation and numerical simulation capability is given, together with a summary of the comparisons of the calculated and measured creep closure results. The comparisons encompass a range of test room configurations that exercise the predictive capability for stratigraphic setting, room geometry, thermal heating, stress field interaction and two and three-dimensional deformation fields. The simulations have proven satisfactory and suggest the general adequacy of the predictive technology.

東京都および隣接県における屋内・外ラドン濃度の測定および統計解折

Since the UNSCEAR Report published in 1982, radiation exposure to the respiratory tract due to radon and its progeny has been regarded as the single largest contributor to the natural radiation exposure of the general public. In Japan, the measurement of radon gas concentrations in many types of buildings have been surveyed by national and private institutes. We also carried out the measurement of radon gas concentrations in different types of residential buildings in Tokyo and its adjoining prefectures from October, 1988 to September 1991, to evaluate the potential radiation risk of the people living there. One or two simplified passive radon monitors were set up in each of the 34 residential buildings located in the above-mentioned area for an exposure pepiod of 3 months each. Comparing the average concentrations in the buildings of different materials and structures, those in the concrete steel buildings were always higher than those in the wooden and the prefabricated mortared buildings. The radon concentrations were proved to become higher in autumn and winter, and lower in spring and summer. Radon concentrations in an underground room of a concrete steel building showed the highest value throughout our investigation, and statistically significant seasonal variation was detected by the X-11 Method developed by the U. S. Bureau of Census. The values measured in a room at the first floor of the same concrete steel building also showed seasonal variation, but the phase of variation was different.Another multivariate analysis suggested that the building material and structure are the most important factors concerning the levels of radon concentration among other factors such as the age of the building and the use of ventilators.

Measured and calculated closures of open and brine filled shafts and deep vertical boreholes in salt : Munson, D E; De Vries, K L; Schiermeister, D M; De Yonge, W F; Jones, R L Proc 33rd US Symposium on Rock Mechanics, Santa Fe, 3–5 June 1992P439–448. Publ Rotterdam: A A Balkema, 1992

Shaft closure measurements are presented which are based on a rather unusual emplacement of very early time closure points. These data are in good agreement with calculations based on the prediction techniques developed for underground rooms in salt using a complete stratigraphy. However, a simplified calculational mesh also gives good agreement, which permits this mesh to be used for parametric studies of long term closures of open and brine filled shafts and boreholes.

Wave seismic action and design of the underground machine room of the Rogun hydroelectric station

Wave seismic action and design of the underground machine room of the Rogun hydroelectric station

Analysis of early creep closures in geomechanically connected underground rooms in salt : Munson, D E; Jones, R L Rock Mechanics as a Multidisciplinary Science: Proc 32nd US Symposium, Norman, 10–12 July 1991P881–888. Publ Rotterdam: A A Balkema, 1991

The waste Isolation Pilot Plant (WIPP) Project is chartered to develop a technology base for the safe disposal of the radioactive Transuranic (TRU) waste forms generated by the US defense programs. The WIPP facility has been constructed in the bedded geologic salt deposits of southeastern New Mexico and is in preliminary operation in anticipation of receipt of small quantities of radioactive waste for experimental purposes. In accord with existing regulations, the requirement is to assure that any proposed repository isolates the radioactive waste from the accessible environment and mankind for a long period of time. As a part of this requirement, the creep closure of the salt and waste encapsulation must be predicted far into the future. This necessitates significant developments in the predictive technology of the structural response of underground excavations in salt. To provide a database for the validation of the predictive technology, a series of large scale in situ experiments were fielded at the WIPP under the auspices of the Thermal/Structural Interactions (TSI) Program. One of these experiments was a three room mine-by test. In this paper, we present the results of the early time (unheated) response of this test, showing the influence of adjacent excavations onmore » each other and of multiple rooms on the closure rates. Also, the in situ results are compared with analyses making use of the most recent numerical predictive capability developed for describing the structural response of salt. 7 refs, 6 figs.« less

Development and validation of a predictive technology for creep closures of underground rooms in salt : Munson, D; Devries, K Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16–20 September 1991V1, P127–134. Publ Rotterdam: A A Balkema, 1991

Development and validation of a predictive technology for creep closures of underground rooms in salt : Munson, D; Devries, K Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16–20 September 1991V1, P127–134. Publ Rotterdam: A A Balkema, 1991

ドライエリアによる地下室採光の研究

I have examined the relation between the size of any dry area connected with an underground room and its daylighting performance by means of simulation. As a result, I proposed an equation by which we can approximately estimate the gain in daylight in any underground room with a dry area in terms of the ratio to that in the same room on the ground, and a nomograph in which we can read the above ratio corresponding to any size of dry area was presented. Moreover, another nomograph telling us the necessary amount of enlargement of the window's area to recover the shortage of daylight in an underground room was also presented. The measured values on a model room of 1/15 scale proved a good agreement with the computed values in the simulation.

Background characteristics of the underground laboratory of the hydrogeology and engineering-geology section of the academy of sciences of the georgian SSR

The laboratory is located in Tbilisi under Mount Mtatsminda at a depth of 170 m (water equivalent). An underground side room 120 m 2 in area at the center of a 300-m tunnel cut through low-level middle-Eocene rocks was used. The laboratory has stable power and water supply. The material silakpor, which has radiation-absorbing properties, was used for decorative finishing and heating of the working area. All structural materials in the laboratory were checked in advance for radiation purity. The temperature in the laboratory room is kept at 17 • 0.5~ year-round.

Mining subsidence in Lethbridge, Alberta

Coal mining in Lethbridge began in 1872 and continued until 1965. Workings were by underground room and pillar techniques on a single near-horizontal seam. Parts of the city, and particularly the recently developed or soon to be developed areas, to the north and west of the city, are underlain by mine workings. This has necessitated comprehensive geotechnical investigations to evaluate potential subsidence hazards and to enable guidelines for construction precautions to be developed. Because of the relatively uniform conditions throughout the area, the borehole data accumulated during these investigations illustrate well some aspects of the process of mining subsidence above abandoned workings. Another interesting aspect of the Lethbridge case history is the phenomenon of soil cracking that occurs around the edge of worked seams. Even though calculated potential tensile strains are small, it appears that they can be concentrated to form thin cracks in the very stiff, unsaturated overburden soils. These cracks can subsequently be exploited by surface erosion processes and result in voids or soft zones, which are a potential hazard to construction. Key words: mining subsidence, void migration, soil cracking, development guidelines.

Tracing of sliding lines in media with planes of weakness and stability analysis of underground rooms: Hudec, M; Frgic, L Proc 6th International Congress on Rock Mechanics, Montreal, 30 Aug–10 Sept 1987V2, P975–979. Publ Rotterdam: A A Balkema, 1987

Tracing of sliding lines in media with planes of weakness and stability analysis of underground rooms: Hudec, M; Frgic, L Proc 6th International Congress on Rock Mechanics, Montreal, 30 Aug–10 Sept 1987V2, P975–979. Publ Rotterdam: A A Balkema, 1987

The Brine Migration Test - A Nuclear Waste Repository Simulation Experiment at the Asse Salt Mine - Federal Republic of Germany

ABSTRACTA joint US/FRG nuclear waste repository simulation experiment was performed at the Asse Salt Mine in the Federal Republic of Germany (FRG). The High Level Waste (HLW) disposal in boreholes was simulated by the simultaneous emplacement of electrical heaters and cobalt-60 sources at four individual test sites located in a special underground test room at the 800 m-level.In order to resolve the issues of rock mass/waste package interaction the temperature field, brine migration into the heater boreholes, borehole gas pressure and composition, and rock mass stresses and displacements were monitored during the test. In order to validate computer code predictions the acquired data were compared to calculational results. Corrosion specimens remained in the heater boreholes during the course of the experiment and were afterwards examined.

Use of field data to evaluate and improve drift response models for the Waste Isolation Pilot Plant (WIPP) : Morgan, H S; Stone, C M; Krieg, R D In: Research and Engineering Applications in Rock Masses (paper to the 26th US Symposium on Rock Mechanics, Rapid City, 26–28 June 1985) V2, P769–776. Publ Rotterdam: A. A. Balkema, 1985

The Waste Isolation Pilot Plant (WIPP) is currently being excavated near Carlsbad, New Mexico by the US Department of Energy as a research and development facility to demonstrate the safe disposal of defense generated radioactive waste in bedded salt. Structural response data collected from underground rooms and drifts at the WIPP will ultimately be used to evaluate and improve computational models for predicting time-dependent room deformations caused by salt creep. An initial evaluation, based on a comparison of computed and measured room closures for one of the early WIPP excavations known as the South Drift, has already been completed. Some of the highlights of that evaluation are presented. First the finite element model used to compute the response of the South Drift is described. Then closure measurements from the South Drift are presented, and comparisons with the calculations are made. Attempts to resolve the resulting discrepancies are summarized next, and finally some directions for future work are offered. 7 figs.