DD277492A1 - ARRANGEMENT AND METHOD FOR MONITORING TECTONIC DARK ZONES IN THE DECK MOUNTAIN - Google Patents

Abstract

The invention relates to an arrangement and a method for the monitoring of tectonic weak zones in the overburden. Areas of application: Monitoring of mines and underground landfill of nuclear fuel. According to the invention, the arrangement consists of over- and underground networks of fault monitoring stations (FUeM). An overseas FUeM is realized by two long-base level variometers 10 measuring between reference points 11 above the scratches and both banks of the tectonic weakness zones 13. To a subordinate FUeM belong two arrangements of two inclinometers 8 and one pressure pad sensor 9, which register sudden changes in the piercing pressure on both sides of the weakening zone. The measurement results of both fault levels separated in the first step are calibrated in step 2, normalized in step 3, and the parameters obtained in step 4 are compared with the results of earlier measurements. Fig. 1

Description

For this 3 pages drawings

Field of application of the invention

The invention relates to an arrangement and a method for monitoring tectonic weak zones in the overburden of minefields or underground dumps of nuclear fuel with the aim of determining the current geomechanical behavior of tailings cutouts. From this behavior, the accumulation of mining-related deformation energy in the overburden and thus also the tendency to tectonic rock strikes depends. In the case of underground storage of nuclear fuel days comes according to patent DE 3403521 as bergbaufremdß energy source nor the radiation-induced heating of the mountains in landfill close to temperatures up to 200 ⁰ C added, resulting in corresponding thermoelastic voltages.

Potential applications of the invention are, for. Mining, in particular low-loss mining at great depths, and the underground sediment deposits of nuclear fuel, usually in salt mines. In addition, there are still applications in certain branches of basic mountain mechanics research.

Characteristic of the known technical solutions

The monitoring of tectonic zones of weakness (8ALAVDSE, ABASCHIDSE: Noklony i deformacii zemnoj kory ν rsyone Ingurskoj GES, Tbilisi [1985]), which has long become common practice in the valley, is also becoming increasingly important in mining, the more so after the less favorable reservoir has been dismantled and penetrates into areas with more complex geological-tectonic structure. To monitor primarily inclinometer and strain motor are used.

For mining, especially the low-loss mining in larger depths, the monitoring of the tectonic Sci.wächezonen the overburden is important because you can determine the current geomechanical behavior of Deckgebirgsausschnitten based on the obtained measurement information. According to KNOLL (Neue Bergbautechnik? [1981], p.384-389), two types of geomechanical behavior are distinguished.

In the first case, regardless of the potential weakness zones limiting it, the dock cliff responds as a normal component of a larger continuum (Behavior I). In the second case it behaves like a compact plate under the influence of its own weight between the now opened tectonic zones of weakness and on the still further, resulting from the basic state of tension of the mountains. Tensions act (Behavior II). The overburden clippings can change their geometric behavior abruptly from continuum behavior to plate behavior. This transition is associated with a local seismic event.

While in Behavior I in Deckgebirgsausschnitt relatively little Berugbaubedingte deformation energy is stored, it can lead to the accumulation of considerable amounts of energy in the decking slabs, especially in the edge zones, in the mode II. For example, the evaluation of the last tectonic rock strike in the Werra valley by KNOLL (1981) showed that more than 90% of the amount of energy of 10 ¹³ J was from the overburden, although this was not exactly known from the ground state of the mountains resulted. This rockfall, dated 23.6.1976, was associated with major changes in the degree of severity of the tectonic zones of weakness delimiting the overburden. But for the amount of mining-related deformation energy stored as a result of the transition to the geomechanical behavior Il in the overburden, it is ultimately irrelevant whether the corresponding Trennflächenerweiterungen done in a few large or in many small steps. The starting points for interfacial expansion of partially open perturbations or for the tearing up of potential tectonic weak zones are likely to be mainly in the vicinity of the storage horizon or near the daily surface. Underground this is the loosening zone in the vicinity of the mining cavities, over days it is the outgrowth of the tectonic zones of weakness, the latter from the time they reach the edge zone of Lehrmann's trough. With the well-known seismic mine monitoring system (MILITZER, SCHÖN, STÖTZNER: Engineering and Mining Geophysics, Leipzig [1986]), monitoring of the tectonic weak zones for interfacial expansion, especially near the reservoir, is hardly possible. This is due to the low positioning accuracy in the vertical detection direction. Seismic oeckgebirgsereignisso with vertical focal distances of 50-10Om from the mining base can not be identified as such and are therefore assigned a flat rate to the mining horizon. Better locating opportunities arise for the rarer events with herds near the surface of the day. In addition to the seismic monitoring systems, there are still a number of maritime mechanical or mountain mechanical measuring point networks in mining. Here are, for example, relative height changes by over and underground leveling, Abstandäsiderungen with Pfeilerquerdehnungs- and convergence knives, tensile or pressure changes with strain gauges, load cells with inductive or capacitive encoders, Meßstempeln, load cells, print cartridges (see GIMM: potash and salt mining, Leipzig 1968], or DREYER, rock mechanics in salt, Stuttgart [1974]), pressure pad (see Patent DE 3403521 KESSELS, FLENTGE, KOLDITZ [1985]) recorded in terms of area.

The achievable with the above methods of measurement resolution of 10 ~ ⁵ m in height and distance measurements and 10 ⁵ Pa in Druckmossungen is not sufficient to record the effects of all mountain mechanical essential local seismic events on the pillars with an economically acceptable Meßstellendichte metrologically. An in patent application WP E21 F 3,194,523 (SIMON, NEUMEYER [1988]) shows calculation example given that the corresponding Meßschwellen to 10 ^-9 m ² Pa or 10 must be decreased in order to achieve this object. This is achieved in the degradation horizon using a network of Klinometermeßstellen, the installed at each measuring point on both sides of a pillar clinometer as (iebirgsdruckmosser work and with the aid of pressure pad sensors are calibrated (Patent Application WP E21 F 3194523, SIMON, NEUMEYER [1988]).

For the task of determining the geomechanical behavior of overburden clippings, it is not sufficient to measure their movements only in one level (degradation horizon). A second measuring point must be unstabilized near the surface of the day, which detects the movements of the overburden that are taking place there and also includes the tectonic weak zones in the marginal zone of the Lehmann trough above the uncircumcised.

Object of the invention

The aim of the invention is to eliminate the shortcomings of the known mine monitoring systems with regard to the detection of the current geomechanical behavior of tailings cutouts by monitoring the tectonic zones of weakness in the overburden. The measurement effort should be kept as low as possible taking into account the local mountain mechanical situation and the geological-tfiktonischen conditions while ensuring full mining safety.

Explanation of the essence of the invention

The invention is based on the object of devising an arrangement for monitoring tectonic weak zones in the overburden in such a way that the changes in the degree of separation of this sulfur zone are associated with local seismic events in order to determine the current geomechanical behavior of the monitored dockyard segments.

A monitoring based only on the evaluation eroignisbodingtor effects provides the measurement information sporadically, d. H. not the pre-Hoisagbaron tormins of onorgiereichoron local seismic events. It is therefore an object of the present invention to devise a method which allows, at any arbitrary date, the monitored zones of weakness in the dockyard of underground cavities for changes in their degree of separation

check. According to the invention, the first partial task is achieved by means of two networks of fault monitoring measuring stations (FuM), one of which, according to FIG. H. 1.5-2 m below the surface of the earth, the second one will be installed underground on a mining base.

An upper network FMS is realized by a pair of long base registering level variometers 10 measuring between reference points 11 over the scratches and those on both banks of tectonic weaknesses 13. By measuring points of this surface network also tectonic weakness zones are monitored over the Unrrritzten in the region of the heavily loaded edge zone of the Lehmann trough.

To a FuM of the underground network include two of the known, consisting of two inclinometers 8 and a pressure pad sensor 9. Arrangements for measuring abrupt changes in pier load pressure. They are installed on both sides of the weak zone at closely adjacent pillars in the manner as Fig. 3 explains. That is, between the two so-called Meßpfeilcrn located approximately in the region of the weak zone, a meter-free third pillar, the shock can be folded down to produce the required for calibration drastic change in the pillar load pressure.

Of the four joints of the square measuring pillars, three are occupied by the sensors 8 and 9. The sensor-free fourth Meßpfeilerstöße lie opposite the center pillar. As in the known arrangement for measuring abrupt changes in the pillar loading pressure, the sensors 8 and 9 are installed in vertical planes which run approximately in the center of the measuring pillars parallel to the sensor-free joints.

To ensure a comprehensive monitoring of the overburden, the above and below ground FuM are installed on measuring profiles, ie. H. Vertical planes 15 which are perpendicular to the middle strike of the overburden cut-outs and are equidistant from each other in the latter direction (see Fig. 2).

The thresholds of the sensors of the FüM network are chosen so small that in addition to the effects of local seismic events and gas salt outbreaks on the vertical movements of the earth's surface caused by switching on and off the main pit fan and sudden changes in the pillar load pressure are detected by measurement. The latter have the advantage that in the entire pit field with comparable large amplitudes occur, are reversible and repeatable, which facilitates their identification.

As with other monitoring systems, both continuous and event triggered can be registered. The signals are pre-amplified at the points of need and fed via cable to a central control room. Here, the data is evaluated by means of a microcomputer.

The method according to the invention is based either on the evaluation of the load effects caused by pit ventilator circuits (process variant A) or the direct effects of local seismic events and larger gas-salt outbreaks (variant B).

Variant A allows a control of the monitored weakness zones of any changes in their degree of separation, which can be chosen at any time. The required comparative values are provided by the once a week maintenance muffler shutdowns.

By variant B, a short time after a local seismic event or gas-salt outbreak corresponding measurement information is supplied at least for the part of the surveillance area in which dec event-induced measurement effect is sufficiently large.

In case of disturbances of registrations during the event, eg. As by overdrive or by Neizausfaii, the desired information on the event-related changes of the Durchgennungsgranes the weakness zones can be obtained subsequently to variant A by means of mine ventilation circuits.

Regardless of the type of sudden ^{1 '} ' mountain movements, ie independent of the variant of the method, the information given is obtained from the measured data in four process steps:

In the first method step, in the same way as in the known method for measuring abrupt changes of the pillar loading pressure with an iteration method using the LECOLAZET jump test, the event-related (erratic) components are separated from the non-event (smooth) pitch components and geo-related noise components by comparison of the registrations of adjacent measurement sites eliminated the waveform.

In the second method step, the sudden changes in the pillar loading pressure or relative vertical movements of the daily surface are determined by comparing the event-related inclination variations with the corresponding calibration signals.

In the third method step, the quotients of the amounts of the effects measured on both sides of the weak zones are determined and thus comparable parameters for the results of the above and below-ground measurements are introduced.

In the fourth method step, the changes which have occurred in the degree of separation of the zones of weakness are determined by comparing the quotients obtained with the corresponding results of previous measurements and then incorporating the results in the current covering mountain model. On the basis of the deck mountain model one determines the current geomechanischc behavior of deck mountain cutouts.

embodiment

In succession, the invention will be explained in more detail with reference to an exemplary embodiment by means of the drawing. Describe in the accompanying drawings:

Fig. 1: oin Untortägigos Hnhlraumsystom (elevation) with over and underground networks of Faultüberwachungsmeßstellen Fig. 2: gogehondo to Fig. 1 network of surface Faultüborwachungsmeßstellen Fig. 3: the arrangement of the Sonsoron at an underground Faultüberwachungsmeßstelle. Two pressure sensors 9 and two or four inclinometers 8 are used.

To monitor the overburden via hollow. systems of relatively small horizontal extent, e.g. As in the case of the installed mainly in salt deposits final deposits of nuclear fuel, the solution shown in plan view in Fig. 1 in elevation and Fig. 2 in plan is preferred. The above-mentioned Faultüberwachungsmeßstellen (FüM) by pairs of langbasigen Niveauvariomatern 10 are realized. The latter measure between reference points 11 over the scratches outside of the edge zone 14 and those on both shafts of the tectonic weakness zones 13 (reference points 4 and 5).

To monitor the overburden over extensive minefields, a solution is preferred with regard to the day-to-day life, which compromises between economic and metrological requirements. To reduce the installation effort, the reference points 11 of only one of the weakness zone 13 monitoring level variometer 10 in the area above the Unrritzten beyond the Randzon «presents. At the other fuses of the same zone of weakness one installs three short-basal level-variometers (pausing length 20-25m), one of which measures across the weak zone, while the comparison instruments register the tilting movements of the two banks of the weak zone.

All level variometers used in the same weak zone register in the same azimuth. For the sake of signal identification and SNR enhancement, the pair of long-baseline level vari- ables can not be dispensed with.

As a preferred solution for the realization of the underground FüM applies an arrangement of two inclinometers 8 and two pressure pad sensors 9. They are installed on both sides of the weak zone to closely adjacent pillars in the manner as Fig. 3 explains. That is, between the two so-called Meßpfeilern located approximately in the region of the weak zone a meter-free third pillar, the shock can be folded down to produce the required for calibration drastic change in the pillar load pressure.

The preferred solution for the standard underground daytime model differs from that described in the previous section by the reduced number of inclinometers used (two instead of four) for cost reasons. As indicated in Fig. 3, the two inclinometers have been omitted from meter butt joints which are diagonally opposite each other.

This ensures that the stress-related inclination components are received with opposite signs in the registrations. By contrast, the regional inclination components are registered by the azimuth-measuring inclinometers with the same sign.

To ensure a comprehensive monitoring of the overburden, a solution is preferred in which the over- and underground-FüM in vertical planes (measuring profiles) 15 are installed, which are perpendicular to the middle strike the Ueckgebirgsausschnitte and have the same distance from each other in the latter direction.

Variant A is preferred by the described variants of the method because it enables a determination of changes in the degree of separation of the monitored tectonic weak zones to arbitrary dates. The latter does not rule out that according to variant B with eventual high-energy local seismic events or gas-salt outbreaks event-triggered registered and evaluated.

For event-triggered commissioning of the registration devices and for the evaluation of the measurement data, underground air pressure registrations as well as the measurement information of the seismic mine monitoring system about the duration of the hearth, the way and magnitude of the local seismic events and the like are required.

In order to enable the application of process variant A also in nuclear fuel repositories, one or more fans must be installed within the closed cavity system, which generate zones with increased or reduced air pressure when switched on in the underground cavity system.

For compressing a wide-meshed network of rooms, in whose interstices no tectonic areas were mapped, the preferred solution provides for the establishment of additional measuring points with simpler sensor equipment. An overlying additional measuring point is realized by a single long-base level variometer 10. Underground, the sensor equipment of such a measuring point is reduced to two inclinometer 8 and a pressure pad sensor. 9

The solution preferred here differs in terms of performance from an underground monitoring system for nuclear fuel repositories consisting only of pressure pad sensors according to DE 3403521 in the following points:

the measurement threshold which is lower by several orders of magnitude enables the early detection and follow-up of possible stepwise changes in the severity of the monitored weak zones long before the pressure pad sensors respond,

- the tectonic Schwijche zones in the zone Bt-Jasteten due to mining-related tensions edge zone 14

- Equipment effects due to the radiation-induced heating of the mountains are excluded at least in the daytime measuring devices,

- The current state of the monitored weak zones can be checked at regular intervals or at any time.

Claims (10)

1. Arrangement for monitoring tectonic weak zones in the overburden of underground cavities, using long-base inclinometers (level variometers) and pressure pad sensors, characterized in that: - in each case a network of Fault Monitoring Measuring Points (FüM) is installed at a depth of one to two meters below the surface of the earth and underground on at least one sole, - a füM of the upper (surface) network du ^r ch a pair of langbasigen registering level variometers (10) is realized, two subassemblies of two inclinometers (8) and one pressure pad sensor (9) for measuring abrupt changes in pier pressure applied to either side of the weakness zone on closely adjacent piers, - the inclinometers of the underground pipes are working as rock driers and calibrated with the help of the pressure pad sensor, - there is a measuring device-free third pillar between the two measuring pillars of the underground floor, the joint of which can be folded down to produce the drastic change in the pillar loading pressure on both measuring pillars required for the calibration, - Of the four joints of a square Meßpfeilers three with the sensors (8) and (9) are fitted, while the sensor-free fourth Meßpfeilerstoß the center pillar opposite. 2. Arrangement according to claim 1, characterized in that the above-ground network also includes measuring points that allow monitoring of tectonic weakness zones over the Unrrritzten in the region of the heavily loaded edge zone of the Lehmann trough. 3. Arrangement according to claim 1 or 2, characterized in that to ensure a nationwide monitoring of the overburden, the over- and underground FüM on measuring profiles (15) are installed, which are perpendicular to the middle sweeping the decking mountain cuttings and in the last direction equal distances from each other to have. 4. Arrangement according to claim 1 to 3, characterized in that the measured on the above and underground FüM metrologically detected vertical movements of the earth's surface and changes in Pfeilerbe'estungsdruckes continuously or event-triggered and pre-amplified the corresponding signals at the measuring points and fed via cable to a Meßwertauswertezentrale become. 5. Arrangement according to claim 1 to 4, characterized in that at each of the underground FüM only a pair of inclinometer (8) and a pair of pressure pad sensors (9) measure and that the two inclinometers installed in the same azimuth, but at different collisions of the two Meßpfeiler , whereby it is achieved that the regional inclination components of both devices with the same sign, the load-related inclination variations, however, are registered with opposite signs. 6. Arrangement according to claim 1 to 5, characterized in that on a mapped over days tectonic zone of weakness only one FüM is realized in the usual way with a pair of langbasigen Niveuavariometern and on all other FüM this weakness zone arrangements of three short-basic (20- 25 m) level variometers are used, one of which measures across the weak zone, while the comparison instruments register the tilting movements of the two shores of the weak zone, with the level-variometers installed on all above-ground feet of the weak zone in the same azimuth. 7. Arrangement according to claim 1 to 6, characterized in that for more accurate monitoring of the deck mountain movements over extensive cavity systems without mapped tectonic weaknesses or in large-scale testing for mountain mechanical model calculations the corresponding wide-meshed FüM network is compacted by Zusatzmeßstellen with simpler Sersorausstattung that a überägige Zusatzmeßstelle with only a langbasigen level variometer and a Untertertägige Zusatzmeßstelle with only one arrangement of two inclinometers (8) and a pressure pad sensor (9) are equipped. 8. A method for monitoring tectonic weak zones in the overburden of underground cavities using over and under day subsurface pressure recordings and using seismic mine monitoring system gauge information on hearth time, hearth location and magnitude of local seismic events, characterized in that - In the first step, reversible or irreversible additional loads of the Ps ^ kgebirge generated and the corre sponding vertical movements of the earth's surface or changes in the piercing pressure are meßiechnisch detected, in the second method step, the event-related (erratic) components are separated from the non-event-conditioned (smooth) components and device-related interference components are eliminated by comparing the registrations of adjacent measuring points with respect to the signal shape, in the third method step, by comparing the event-related inclination variations with the corresponding calibration signals, the event-related changes in the column overload pressure or the corresponding relative vertical movements of the daily surface are determined, in the fourth method step, the quotients of the amounts of the effects measured on both sides of the weak zones are determined and thus comparable parameters for the results of the above and below-ground measurements are introduced, in the fifth method step, by comparison of the obtained quotients with the corresponding results of previous measurements, the changes in the degree of separation of the monitored zones of weakness are determined and these changes incorporated into the current capping model, thus finally determining the current geomechanical behavior of the monitored overburden sections. 9. The method according to claim 8, characterized in that instead of the z. B. generated by switching on and off the main pit ventilator changes in the tailgating load caused by local seismic events, gas salt outbreaks or explosive events sudden additional loads of the overburden. 10. The method according to claim 8 to 9, characterized in that in underground cavity systems with closed weather cycle, z. As in underground landfills for the final disposal of nuclear fuel, one or more fans are installed, the defined changes of the underground air pressure in all areas of the cavity system and thus allow the determination of occurred changes in Durchtrenni ngsgrad the monitored weaknesses to arbitrary appointments.