Monitoring and forewarning method for coal-rock dynamic disasters based on electromagnetic radiation and earth sound

Abstract

A monitoring and forewarning method for coal-rock dynamic disasters based on an electromagnetic radiation and an earth-sound monitoring includes the following steps: (1) calculating the weighted average value of research parameter P(t) during a time period according to the monitoring data collected by the electromagnetic radiation and the earth-sound monitoring system in real time; (2) calculating D(t), the deviation value of P(t); (3) calculating |D(t)| as the deviation threshold value, the average value of |D(t)| during period of normal mining of the working surface; (4) calculating D.sub.S, the number of times that D(t) is greater than |D(t)| in one day; (5) normalizing D.sub.S to obtain the monitoring and forewarning index ; (6) forewarning the hazard state of dynamic disaster of the working surface in real time according to and forewarning method, determining hazard level.

Claims

1. A monitoring and forewarning method for coal-rock dynamic disasters based on an electromagnetic radiation and an earth sound, wherein an electromagnetic radiation sensor and an earth-sound sensor are respectively arranged on a coal body or a rock body for collecting an energy and a pulse number of the electromagnetic radiation, and an energy and a frequency of an earth-sound signal in real time as original data; the method comprises the following steps: step (1), calculating P(t), wherein the P(t) is a weighted average value of a research parameter in a time period, and the P(t) is calculated according to monitoring data collected by an electromagnetic radiation and an earth-sound monitoring system; step (2), calculating D(t), wherein the D(t) is a deviation value of the P(t); step (3), calculating |D(t)|, wherein the |D(t)| is an average value of the |D(t)|, and the |D(t)| is an absolute value of the D(t) during a period of normal mining of a working surface, and using the |D(t)| as a deviation threshold value; step (4), calculating D.sub.S, wherein the D.sub.S is a number of times that the deviation value D(t) is greater than the deviation threshold value |D(t)| in one day; step (5), normalizing the D.sub.S to obtain a monitoring and forewarning index ; step (6), forewarning a hazard state of a dynamic disaster of the working surface in real time according to the and a forewarning method, and determining a hazard level of the dynamic disaster, wherein, in the step (1), the research parameter is one or more of an electromagnetic radiation energy, an electromagnetic radiation pulse number, an earth-sound energy, or an earth-sound frequency, and the weighted average value of the research parameter P(t) is a result of a cumulative sum of the research parameter divided by a time window length during the time period, the monitoring and forewarning index in the step (5) is calculated by the following formula: $\mathrm{.Math.}=\frac{D_S-D_{S\text{-}\min }}{D_{S\text{-}\max }-D_{S\text{-}\min }},$ wherein D.sub.S-max is a maximum value of the D.sub.S during the time period, and D.sub.S-min is a minimum value of the D.sub.S during the time period, and the hazard level in the step (6) includes no hazard, a low hazard, a medium hazard and a high hazard; and the hazard level is determined as follows: when <0.5, no hazard exists, when 0.5<0.65, the low hazard exists, when 0.65<0.8, the medium hazard exists, and when 0.8, the high hazard exists.

2. The monitoring and forewarning method of claim 1, wherein, the time period is 10 minutes.

3. The monitoring and forewarning method of claim 1, wherein, the deviation value D(t) in the step (2) is calculated by the following formula: $D\left(t\right)=\frac{P\left(t\right)-\stackrel{\_}{P\left(T_t\right)}}{\stackrel{\_}{P\left(T_t\right)}};$ wherein, $\stackrel{\_}{P\left(T_t\right)}=\frac{1}{n}\underset{i=1}{\overset{n}{.Math.}}{P}_i\left(T_t\right),T_t$ represents a time interval related to time t, and is the time interval from a time point before the time t to the time t, and n is a number of the P(t), the weighted average value of the research parameter, in the time interval of T.sub.t.

4. The monitoring and forewarning method of claim 3, wherein, the time interval is 24 hours.

5. The monitoring and forewarning method of claim 1, wherein, the period of normal mining of the working surface in the step (3) is a period in which the working surface is not affected by geological structures including faults and folds and there is no abnormal situation in the working surface including a roof weighting and a dynamic pressure behavior, and the period is one or multiple months.

6. The monitoring and forewarning method of claim 1, wherein, the time period is from a time point that a previous dynamic pressure behavior occurs to a present time point.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flowchart of the present invention;

(2) FIG. 2 is a weighted average value P.sub.dE(t) during a time period calculated by an earth-sound energy in accordance with one embodiment of the present invention;

(3) FIG. 3 is a deviation value D.sub.dE(t) calculated by an earth-sound energy in accordance with one embodiment of the present invention;

(4) FIG. 4 is a number of times D.sub.SdE that a deviation value calculated by an earth-sound energy is greater than a deviation threshold value in one day in accordance with one embodiment of the present invention; and

(5) FIG. 5 is a normalized monitoring and forewarning index calculated by an earth-sound energy in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

(6) The technical solution in the embodiment of the present invention will be described clearly and definitely with reference to the accompanying drawings of the embodiments of the present invention. Apparently, the described embodiments are merely a part of embodiments of the present invention, rather than all embodiments. All other embodiments made by those skilled in the art without creative work belong to the protective scope of the present invention.

(7) Referring to FIG. 1-FIG. 5, the technical solution of the present invention is as follows. A monitoring and forewarning method for coal-rock dynamic disasters based on an electromagnetic radiation and an earth-sound monitoring is provided. For the method, an electromagnetic radiation sensor and an earth-sound sensor are respectively arranged on a coal body or a rock body for collecting an energy and a pulse number of the electromagnetic radiation, and an energy and a frequency of an earth-sound signal in real time as original data. The method includes the following steps:

(8) step (1), P(t), the weighted average value of research parameter in a time period, is calculated according to the monitoring data collected in real time by the electromagnetic radiation and earth-sound monitoring system. The research parameter is one or more of the electromagnetic radiation energy, the electromagnetic radiation pulse number, the earth-sound energy, or the earth-sound frequency; and the weighted average value of the research parameter P(t) is defined as the result of the cumulative sum of research parameter divided by the time window length during the time period, for example, the time period may be 10 minutes.

(9) step (2), D(t), the deviation value of P(t), is calculated. The deviation value D(t) is calculated by the following formula:

(10) $D\left(t\right)=\frac{P\left(t\right)-\stackrel{\_}{P\left(T_t\right)}}{\stackrel{\_}{P\left(T_t\right)}};$

(11) where,

(12) $\stackrel{\_}{P\left(T_t\right)}=\frac{1}{n}\underset{i=1}{\overset{n}{.Math.}}{P}_i\left(T_t\right),T_t$
represents the time interval related to the time t, and is the time interval from a time point before the time t to the time t, and n is the number of P(t) in the time interval T.sub.t.

(13) step (3), |D(t)|, the average value of |D(t)| which is the absolute value of D(t) during the period of normal mining of the working surface, is calculated, and the |D(t)| is used as the deviation threshold value. The period of normal mining refers to the period in which the working surface is not affected by geological structures including faults and folds and there is no abnormal situation including roof weighting and dynamic pressure behavior. The period of normal mining may be one or multiple months.

(14) step (4), D.sub.S, the number of times that the deviation value D(t) is greater than the deviation threshold value |D(t)| in one day, is calculated.

(15) step (5), D.sub.S is normalized to obtain the monitoring and forewarning index . The monitoring and forewarning index is calculated by the following formula:

(16) $\mathrm{.Math.}=\frac{D_S-D_{S\text{-}\min }}{D_{S\text{-}\max }-D_{S\text{-}\min }},$

(17) where, D.sub.S-max is d the maximum value of D.sub.S during a time period (generally, the time period is a period from a time point when the dynamic pressure behavior occurs to the present time point), and D.sub.S-min is the minimum value of D.sub.S during the time period (generally, the time period is a period from a time point when the dynamic pressure behavior occurs to the present time point).

(18) step (6), according to the monitoring and forewarning index and the forewarning method, the hazard state of dynamic disaster of the working surface is forewarned in real time, and the hazard level of the dynamic disaster is determined. The hazard level includes no hazard, low hazard, medium hazard and high hazard. The hazard level is determined as follows. When <0.5, no hazard exists, when 0.5<0.65, low hazard exists, when 0.65<0.8, medium hazard exists, and when 0.8 high hazard exists.

(19) One embodiment of the present invention is further described below with reference to drawings.

(20) In the present embodiment, the earth-sound energies collected from Aug. 8, 2016 to Jan. 25, 2017 by the earth-sound monitoring system within the hazardous working surface under the mine pressure bump are used as the initial data. The initial data is processed and analyzed by the method of the present invention to obtain the monitoring and forewarning index of the present invention. The forewarning method is used to determine the hazard state of the working face, thus explaining the implement of the present invention.

(21) The earth-sound energy is taken as a research parameter. Each time interval of 10 minutes, P.sub.dE(t), the weighted average value of the earth-sound energy, is calculated, and the results are shown in FIG. 2.

(22) The D.sub.dE(t), the deviation value of P.sub.dE(t), is calculated based on the following formula:

(23) $D_{\mathrm{dE}}\left(t\right)=\frac{P_{\mathrm{dE}}\left(t\right)-\stackrel{\_}{P_{\mathrm{dE}}\left(T_t\right)}}{\stackrel{\_}{P_{\mathrm{dE}}\left(T_t\right)}},$

(24) where

(25) $\stackrel{\_}{P_{\mathrm{dE}}\left(T_t\right)}=\frac{1}{n}\underset{i=1}{\overset{n}{.Math.}}{P}_{\mathrm{dE}\text{-}i}\left(T_t\right),T_t$
represents the time interval, and the time interval is 24 hours, n is the number of the weighted average value of the earth-sound energy within the time interval of T.sub.t. The results of D.sub.dE(t) calculated based on the results in FIG. 2 are shown in FIG. 3.

(26) |D.sub.dE(t)|, the average value of absolute values of deviation values collected during the mining period without abnormal situation on working surface (from Aug. 8, 2016 to Sep. 8, 2016), is calculated. The result of |D.sub.dE(t)| is 0.62, which is used as the deviation threshold value.

(27) D.sub.SdE, the number of times that the deviation value |D.sub.dE(t)| is greater than the deviation threshold value |D.sub.dE(t)| in a day, is calculated, and the results are shown in FIG. 4.

(28) A time window after Nov. 24, 2016 (the day when a coal burst occurs) from FIG. 4 is selected to be normalized. The monitoring and forewarning index .sub.dE is calculated through the formula

(29) ${\mathrm{.Math.}}_{\mathrm{dE}}=\frac{D_{\mathrm{SdE}}-D_{\mathrm{SdE}\text{-}\min }}{D_{\mathrm{SdE}\text{-}\max }-D_{\mathrm{SdE}\text{-}\min }},$
and the calculation results are shown in FIG. 5.

(30) Finally, the hazard level is determined according to the monitoring and forewarning index .sub.dE and the determination criteria of bursting hazard. When <0.5, no hazard exists, when 0.5<0.65, low hazard exists, when 0.65<0.8, medium hazard exists, and when 0.8, high hazard exists. The hazard level of the coal working surface between Nov. 24, 2016 and Jan. 25, 2017 is shown in FIG. 5.

(31) Although preferred embodiments of the present invention have been described in detail, it should be understood by those skilled in the art that various changes, modifications and substitutions can be made to the embodiments without departing from the principle and spirit of the present invention, the scope of the present invention is defined by the appended claims and the equivalents thereof.