CN116877197A - Microseismic monitoring and early warning method for mine shaft stability - Google Patents

Abstract

The invention belongs to the field of mining technology, and in particular relates to a microseismic monitoring and early warning method for mine shaft stability, which is characterized by including the following steps: Step 1. Establishment of a wellbore stability microseismic monitoring system; Step 2. Microseismic signal identification; Step 3. Data Statistical analysis and early warning. The microseismic monitoring and early warning method for mine shaft stability of the present invention adopts microseismic monitoring technology and realizes real-time and three-dimensional monitoring of the stability of the mine shaft by optimizing the arrangement of sensors in the monitoring area, collecting data and analyzing the data, and can realize the stability of the mine shaft. Real-time online, all-round three-dimensional and remote monitoring can provide timely monitoring and early warning of potential damage to the wellbore.

Description

Microseismic monitoring and early warning method for mine shaft stability

Technical field

The invention belongs to the field of mining technology, and in particular relates to a microseismic monitoring and early warning method for the stability of mine shafts.

Background technique

The mine shaft is an important tunnel project in the mine. Many large-scale mines ore are discharged from the mine shaft. Therefore, the normal operation of the mine shaft is related to whether the mine output can be successfully completed. Classified from the damage mechanism, the damage to the mine shaft can be roughly divided into two types. One is due to the long-term impact of the ore during the ore process, resulting in continuous damage to the shaft wall; the other is the mine shaft is affected by mining activities and poor engineering. Affected by geological and other factors, the rock mass inside the shaft continues to fracture during long-term service, which in turn leads to damage to the mine shaft.

At present, the damage monitoring of mine shafts mainly focuses on the first type. Laser sensors are generally used to measure and image the walls of the mine shafts to determine whether damage has occurred and the extent of the damage. At present, there is little monitoring of the damage caused by the second type of mine slipping. The second type of damage caused by the mine slipping is often more common. If the rock mass inside the shaft is not discovered in time and effective measures are not taken, the scope of damage will continue. Expansion eventually led to the failure of the mine shaft to operate normally. Therefore, how to timely detect the rock mass damage inside the mine shaft is particularly critical. In response to this situation, a method for monitoring and early warning the stability of the mine shaft was invented to achieve the goal of timely monitoring and early warning of shaft damage.

Contents of the invention

The purpose of the present invention is to provide a microseismic monitoring and early warning method for the stability of mine shafts, which uses microseismic monitoring technology to achieve real-time and three-dimensional monitoring of the stability of mine shafts by optimizing the arrangement of sensors in the monitoring area, collecting data, and analyzing the data. Achieve the goal of timely monitoring and early warning of wellbore damage.

The purpose of the present invention is achieved through the following technical solutions:

The microseismic monitoring and early warning method for the stability of mine shaft slides of the present invention is characterized by including the following steps:

Step 1. Establish a wellbore stability microseismic monitoring system;

(1) Construct four vertical boreholes distributed in four directions 10m to 15m around the monitoring target wellbore;

(2) The sensor is installed in the borehole, and the distance between the sensors is 10m to 15m. After the sensor is installed at the designated position, the borehole is filled with cement mortar;

(3) Connect the sensor cable to the microseismic data acquisition instrument, and the data acquisition instrument is connected to the computer in the monitoring room through an optical cable, thus completing the establishment of the wellbore microseismic monitoring system;

Step 2. Microseismic signal identification;

Identify the waveform characteristics of useful signals, denoise and identify the collected microseismic signals, and extract the useful signals, namely rock fracture microseismic signals;

Step 3. Data statistical analysis and early warning;

(1) Statistical analysis of non-positioned events

Non-located events are one of the wellbore stability monitoring and early warning indicators. In order to count the level of non-located events, the non-located event rate a is introduced, that is, the number of non-located events per unit time is counted:

In the formula: N is the number of non-positioning events; T is the unit time, usually days or hours;

The monitoring and early warning threshold of the non-located event rate a is related to the surrounding rock of the wellbore and its stress state. After a period of monitoring, the event level value under normal conditions is found out, and then the appropriate early warning value is determined on this basis;

(2) Statistical analysis of positioning events

Analyze the spatial aggregation degree of positioning events. The more the positioning events are spatially aggregated, the greater the possibility of macroscopic damage to the potential rupture surface. The spatial aggregation ellipsoid rate of microseismic events is introduced to spatially distribute the positioning events on the plane. Construct an ellipse, and then calculate the ellipsoid rate e through the major and minor axes of the ellipse. The larger e is, the higher the spatial aggregation of positioning events. The expression is:

Among them, e is the ellipsoid ellipsoid rate; ɑ and b are the lengths of the major axis and minor axis of the ellipse respectively. Set the monitoring and early warning condition for microseismic positioning events to e≥0.8. When the early warning condition is triggered, the monitoring and early warning information will be issued immediately.

In the waveform feature identification of useful signals in step 2, the rock fracture microseismic signal has its obvious waveform features: the waveform identification duration is short, generally 10ms to 30ms; it has an obvious rise time, generally 2ms to 5ms; The frequency is generally between 1000Hz and 3000Hz.

Advantages of the invention:

The microseismic monitoring and early warning method of the mine shaft stability of the present invention adopts microseismic monitoring technology and realizes real-time and three-dimensional monitoring of the stability of the mine shaft by optimizing the arrangement of sensors in the monitoring area, collecting data and analyzing the data, and can realize the stability of the mine shaft. Real-time online, all-round three-dimensional and remote monitoring can provide timely monitoring and early warning of potential damage to the wellbore.

Description of the drawings

Figure 1 is a schematic structural diagram of the wellbore microseismic monitoring system of the present invention.

Figure 2 is a top view of Figure 1 of the present invention.

Figure 3 is a schematic diagram of a typical rock fracture signal of the present invention.

Detailed ways

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

As shown in Figures 1, 2 and 3, the mine shaft stability microseismic monitoring and early warning method of the present invention is characterized by including the following steps:

Step 1. Establish a wellbore stability microseismic monitoring system;

(1) Construct four vertical boreholes 2 distributed in four directions of 10m to 15m around the monitoring target wellbore 5;

(2) Sensor 1 is installed in borehole 2. The distance between sensors 1 is 10m to 15m. After sensor 1 is installed at the designated position, cement mortar is used to fill borehole 2;

(3) Connect the sensor cable to the microseismic data acquisition instrument 3, and the data acquisition instrument 3 is connected to the monitoring room computer 4 through an optical cable, thus completing the establishment of the wellbore microseismic monitoring system;

Step 2. Microseismic signal identification;

Since there are a large number of noise signals in and around wellbore 5, which directly affects the collection and analysis of rock fracture signals, it is necessary to identify the waveform characteristics of useful signals, denoise and identify the collected microseismic signals, and extract useful signals, that is, rock fracture microseismic signals. ; Rock fracture microseismic signals have obvious waveform characteristics: the waveform identification duration is short, generally 10ms to 30ms; there is an obvious rise time, generally 2ms to 5ms; the waveform frequency is generally 1000Hz to 3000Hz.

Step 3. Data statistical analysis and early warning;

The statistical analysis of microseismic monitoring data is divided into two categories. One is non-positioning events. This type of event has relatively small energy and cannot be received by multiple sensors 1 at the same time and cannot be positioned; the other is positioning events. This type of event has relatively large energy and can be Received by multiple sensors 1 at the same time.

(1) Statistical analysis of non-positioned events

Although non-located events cannot be located due to their relatively small energy and cannot be received by multiple sensors 1 at the same time, the level of non-located events indicates the activity of local rock mass fractures. The higher the event level, the more likely local damage will occur. The higher the stability, therefore, non-positioning events can be used as one of the wellbore 5 stability monitoring and early warning indicators. In order to count the level of non-positioned events, the non-positioned event rate a is introduced, that is, the number of non-positioned events per unit time is counted:

In the formula: N is the number of non-positioned events; T is the unit time, usually days or hours.

The monitoring and early warning threshold of the non-located event rate a is related to the surrounding rock of the wellbore 5 and its stress state. Generally, after a period of monitoring, the event level value under normal conditions is found out, and then the appropriate early warning value is determined on this basis.

(2) Statistical analysis of positioning events

It mainly analyzes the degree of spatial aggregation of positioning events. The more spatial aggregation of positioning events, the greater the possibility of macroscopic damage to the potential rupture surface. The concept of spatial aggregation ellipsoid rate of microseismic events is introduced, and the spatial distribution of positioning events is constructed into an ellipse on a plane. Then the ellipsoid rate e is calculated through the long and short axes of the ellipse. The larger e is, the higher the spatial aggregation degree of positioning events. Its expression is:

Among them, e is the ellipsoid ellipsoid rate; ɑ and b are the lengths of the major axis and minor axis of the ellipse respectively. Set the monitoring and early warning condition for microseismic positioning events to e≥0.8. When the early warning condition is triggered, the monitoring and early warning information will be issued immediately.

The microseismic monitoring and early warning method for mine shaft stability of the present invention adopts microseismic monitoring technology, and realizes real-time and three-dimensional monitoring of the stability of the mine shaft 5 by optimizing the arrangement of sensors 1 in the monitoring area, collecting data, and analyzing the data. Real-time online, all-round three-dimensional and remote monitoring of stability provides timely monitoring and early warning of potential damage to the wellbore 5.

Claims (2)

1. A microseismic monitoring and early warning method for stability of a mine drop shaft is characterized by comprising the following steps:

step 1, establishing a shaft stability microseismic monitoring system;

(1) Four vertical drilling holes are distributed and constructed in four directions of 10 m-15 m around the monitored target shaft;

(2) The sensors are arranged in the drill holes, the distance between the sensors is preferably 10-15 m, and after the sensors are arranged at the set positions, cement mortar is adopted to pour the drill holes;

(3) Connecting a sensor cable to a microseismic data acquisition instrument, and connecting the data acquisition instrument to a monitoring room computer through an optical cable, so that the establishment of a shaft microseismic monitoring system is completed;

step 2, identifying the microseismic signals;

carrying out waveform characteristic identification on the useful signals, denoising and identifying the acquired microseismic signals, and extracting the useful signals, namely rock fracture microseismic signals;

step 3, data statistical analysis and early warning;

(1) Non-localized event statistical analysis

The non-positioning event is used as one of the monitoring and early warning indexes of the stability of the shaft, and a non-positioning event rate a is introduced for counting the level of the non-positioning event, namely the number of the non-positioning events in unit time is counted:

wherein: n is the number of non-positioning events; t is a unit time, typically days or hours;

the monitoring and early warning threshold value of the non-positioning event rate a is related to the surrounding rock of the shaft and the stress state of the surrounding rock of the shaft, and is that after monitoring for a period of time, the event level value under normal conditions is found out, and then a proper early warning value is determined on the basis;

(2) Statistical analysis of localization events

Analyzing the aggregation degree of the positioning events in space, wherein the more the positioning events are aggregated in space, the greater the possibility of macroscopic damage of the potential fracture surface is; introducing the spatial aggregation ellipsoid ratio of microseismic events, constructing ellipses on a plane by the spatial distribution of positioning events, and then calculating the ellipsoid ratio e through the long and short axes of the ellipses, wherein the larger the e is, the higher the spatial aggregation degree of the positioning events is, and the expression is as follows:

wherein e is the ellipsoidal rate of ellipses; the lengths of the major axis and the minor axis of the ellipse are alpha and b, respectively. Setting the monitoring and early-warning condition of the microseismic positioning event as e not less than 0.8, and immediately sending out monitoring and early-warning information after triggering the early-warning condition.

2. The mine drop shaft stability microseismic monitoring and early warning method according to claim 1, wherein in the step 2 of carrying out waveform characteristic identification on useful signals, the rock breaking microseismic signals have obvious waveform characteristics: the waveform identification duration is short, generally 10 ms-30 ms; has obvious rising time, which is generally 2 ms-5 ms; the waveform frequency is generally 1000 Hz-3000 Hz.