CN115575232A

CN115575232A - Multipoint three-way coal rock mass stress meter and coal rock mass stress monitoring method

Info

Publication number: CN115575232A
Application number: CN202211135358.6A
Authority: CN
Inventors: 郑建伟; 李春元; 齐庆新; 何团; 张良; 石晓闪
Original assignee: General Coal Research Institute Co Ltd
Current assignee: General Coal Research Institute Co Ltd
Priority date: 2022-09-19
Filing date: 2022-09-19
Publication date: 2023-01-06

Abstract

The invention relates to the safety field of underground engineering such as coal rock mass, and provides a multipoint three-way coal rock mass stress meter and a coal rock mass stress monitoring method, wherein a one-way stress monitoring unit in the stress meter comprises piezoelectric ceramics, a lead, an upper protective layer and a lower protective layer which are respectively arranged on the upper surface and the lower surface of the piezoelectric ceramics; a plurality of skeletons include main skeleton and sub-skeleton, the helmet is connected to the one end of main skeleton, sub-skeleton is connected to the other end, the skeleton is the tubulose, the main skeleton be close to helmet side embedding have along the skeleton axial arrange one-way stress monitoring unit and along the radial two at least direction vertically one-way stress monitoring unit who arranges of skeleton, sub-skeleton be close to main skeleton side embedding have along the radial two at least direction vertically one-way stress monitoring unit who arranges of skeleton, along the outer wall coplane of the one-way stress monitoring unit's of radial arrangement piezoceramics and skeleton, the wire is arranged in the hollow pipeline in the skeleton. According to the stress meter disclosed by the invention, the precision of stress monitoring data can be improved.

Description

Multipoint three-way coal rock mass stress meter and coal rock mass stress monitoring method

Technical Field

The disclosure relates to the field of coal rock mass and underground engineering safety, in particular to a multipoint three-way coal rock mass stress meter and a coal rock mass stress monitoring method.

Background

The implementation of underground mineral resource mining, tunnel excavation or other geological engineering can change the original stress distribution state in coal rock mass, and different underground engineering has different requirements on project service life and deformation in the using process, for example, the service life of a mining roadway in a coal mine is usually not more than 3 years, and the service life of a central main roadway is basically the same as that of a mine; likewise, the stoping roadway only needs to ensure that production is not affected during stoping of a working face, a certain amount of roadway deformation convergence is allowed to occur, and projects such as tunnels have strict requirements on deformation, so that different underground projects have different requirements on deformation and service life for different purposes. The method mainly comprises three types of influencing the deformation of the underground engineering, namely safety, including mechanical characteristics of a rock stratum where the underground engineering is located, stress applied to the boundary of the underground engineering and manually applied support measures, wherein if the change condition of the stress applied to the boundary of the underground engineering can be monitored and sensed timely and for a long time, corresponding measures can be better taken to guarantee normal operation of the underground engineering, and health and safety of workers are guaranteed.

At present, a borehole stress meter or a geophysical method is usually adopted to monitor the stress occurrence and evolution conditions of surrounding rocks in different deep parts away from the surface of an underground engineering, and although the existing geophysical method represented by stress wave perception can realize abnormal monitoring in a certain range, the difference of conditions such as cavity, water, stress abnormity and the like in a monitored area cannot be well solved on the aspect of waveform analysis; borehole stressometers usually have types such as fluid pressure type, vibrating string formula, fiber grating formula, hollow inclusion, but existing stressometers all have certain not enough if the installation technology is complicated, data bulk is single in the practical application in-process at present, can't satisfy the higher precision and the abundanter requirement to stress monitoring data at present to a certain extent, consequently need to develop new borehole stressometers and better monitor the state of underground works rock mass stress urgently.

Disclosure of Invention

The present disclosure is directed to solving, at least in part, one of the technical problems in the related art.

Therefore, the first purpose of the present disclosure is to provide a multipoint three-way coal-rock mass stress meter to improve the accuracy of stress monitoring data.

The second purpose of the present disclosure is to provide a coal-rock mass stress monitoring method based on a multipoint three-way coal-rock mass stress meter.

In order to achieve the above purpose, an embodiment of a first aspect of the present disclosure provides a multipoint three-way coal-rock mass stress meter, including a plurality of unidirectional stress monitoring units, a plurality of frameworks, and a protective cap;

the unidirectional stress monitoring unit comprises piezoelectric ceramics, a lead connected with the piezoelectric ceramics, and an upper protective layer and a lower protective layer which are respectively arranged on the upper surface and the lower surface of the piezoelectric ceramics;

a plurality of skeletons include main skeleton and inferior skeleton, the one end of main skeleton is connected the helmet, inferior skeleton is connected to the other end of main skeleton, the skeleton is the tubulose, the embedding of main skeleton near the helmet side has one-way stress monitoring unit that is located the hollow pipeline and radially arranges two at least direction vertically one-way stress monitoring unit along the skeleton axial arrangement, the embedding of inferior skeleton near main skeleton side has two at least direction vertically one-way stress monitoring units along the radial arrangement of skeleton, wherein along the piezoceramics of the one-way stress monitoring unit who arranges with the outer wall coplane of skeleton, the wire is arranged in the hollow pipeline in the skeleton.

In one embodiment of the present disclosure, a diameter of the piezoelectric ceramic is at least eight times or more a thickness of the piezoelectric ceramic, and diameters of the upper protective layer and the lower protective layer are both equal to or larger than the diameter of the piezoelectric ceramic.

In one embodiment of the disclosure, the upper protective layer or the lower protective layer is formed by pouring target concrete, and the target concrete is obtained based on materials and proportions determined by basic physical and mechanical properties of rock samples of stress monitoring points of the coal rock mass on site.

In one embodiment of the present disclosure, a surface of the piezoelectric ceramic is coated with a silica gel layer.

In one embodiment of the present disclosure, a slurry outlet is provided on an outer wall of each framework, and the slurry outlet communicates with a hollow pipeline inside the framework and the outer wall.

In one embodiment of the present disclosure, the multipoint three-way coal-rock mass stress meter further comprises a joint through which each of the skeletons is connected.

In one embodiment of the present disclosure, the number of the sub-skeletons is plural.

In order to achieve the above object, an embodiment of the second aspect of the present disclosure provides a coal-rock mass stress monitoring method based on a multipoint three-way coal-rock mass stress meter, including:

determining the number of frameworks based on a plurality of stress monitoring points in the coal-rock body drilling hole on site;

acquiring a prefabricated unidirectional stress monitoring unit and a plurality of tubular frameworks, wherein the frameworks comprise a main framework and a secondary framework;

one end of the main framework is connected with a protective cap and then is placed in a drill hole, a unidirectional stress monitoring unit located in the hollow pipeline and at least two unidirectional stress monitoring units perpendicular to the direction are arranged on the side, close to the protective cap, of the main framework along the axial direction of the framework, and a lead of the unidirectional stress monitoring unit penetrates through the hollow pipeline in the framework and is led to the outside;

after the main framework and the secondary framework are connected through the joint, at least two unidirectional stress monitoring units which are vertical to each other in the radial direction of the framework are arranged on the side, close to the main framework, of the secondary framework, wherein piezoelectric ceramics of the unidirectional stress monitoring units which are arranged in the radial direction are coplanar with the outer wall of the framework;

after all the frameworks are arranged, sealing the hole openings of the frameworks, and grouting hollow pipelines in the frameworks to pour the multipoint three-way coal-rock body stressometers into the drill holes;

and monitoring the coal rock mass stress information in real time by using a multipoint three-way coal rock mass stress meter.

In one embodiment of the present disclosure, a manufacturing process of the unidirectional stress monitoring unit includes: configuring target concrete based on the physical and mechanical properties of the rock sample of the stress monitoring point of the coal rock mass on site; and selecting piezoelectric ceramics with preset diameters, and pouring the target concrete on the upper surface and the lower surface of the piezoelectric ceramics to form an upper protective layer and a lower protective layer which are larger than or equal to a preset radius, so as to obtain the unidirectional stress monitoring unit.

In one embodiment of the present disclosure, after the unidirectional stress monitoring unit is manufactured, maintenance and uniaxial compression experiments are performed on the unidirectional stress monitoring unit.

In one or more embodiments of the present disclosure, the multipoint three-way coal-rock mass stress meter includes a plurality of unidirectional stress monitoring units, a plurality of frameworks and a protective cap, where the unidirectional stress monitoring units include piezoelectric ceramics, wires connected with the piezoelectric ceramics, and an upper protective layer and a lower protective layer respectively disposed on upper and lower surfaces of the piezoelectric ceramics; a plurality of skeletons include main skeleton and sub-skeleton, the helmet is connected to the one end of main skeleton, sub-skeleton is connected to the other end, the skeleton is the tubulose, the main skeleton be close to helmet side embedding have along the skeleton axial arrange one-way stress monitoring unit and along the radial two at least direction vertically one-way stress monitoring unit who arranges of skeleton, sub-skeleton be close to main skeleton side embedding have along the radial two at least direction vertically one-way stress monitoring unit who arranges of skeleton, along the outer wall coplane of the one-way stress monitoring unit's of radial arrangement piezoceramics and skeleton, the wire is arranged in the hollow pipeline in the skeleton. Under the condition, the piezoelectric ceramics are arranged in the two protective layers to form the unidirectional stress monitoring unit, different unidirectional stress monitoring units are arranged according to the three-dimensional stress monitoring purpose to acquire three-dimensional stress information, and meanwhile, a plurality of frameworks are utilized to acquire multipoint stress information, so that the precision of stress monitoring data is improved.

Additional aspects and advantages of the disclosure will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosure.

Drawings

In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative efforts. The above and/or additional aspects and advantages of the present disclosure will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of a multipoint three-way coal-rock mass stress gauge provided in an embodiment of the present disclosure;

fig. 2 is a schematic perspective view of a unidirectional stress monitoring unit provided in an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of a main skeleton provided in an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of a sub-skeleton provided in an embodiment of the present disclosure;

FIG. 5 is a schematic cross-sectional view of the backbone within the borehole taken along the direction of dashed line A1-A2 of FIG. 3;

FIG. 6 is a schematic diagram of borehole azimuth coordinates provided by an embodiment of the present disclosure;

fig. 7 is a schematic flow diagram of a coal-rock mass stress monitoring method based on a multipoint three-way coal-rock mass stress meter according to an embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with embodiments of the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the disclosed embodiments, as detailed in the appended claims.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present disclosure, "plurality" means at least two, e.g., two, three, etc., unless explicitly defined otherwise. It should also be understood that the term "and/or" as used in this disclosure refers to and encompasses any and all possible combinations of one or more of the associated listed items.

Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are illustrative and intended to explain the present disclosure, and should not be construed as limiting the present disclosure.

The invention provides a multipoint three-way coal rock mass stress meter and a coal rock mass stress monitoring method, and mainly aims to improve the precision of stress monitoring data. The multipoint three-way coal rock mass stress meter can be called as a stress meter for short.

In a first embodiment, fig. 1 is a schematic structural diagram of a multipoint three-way coal rock mass stress gauge provided by an embodiment of the present disclosure. As shown in fig. 1, the multipoint three-way coal rock mass stress meter 1 comprises a plurality of one-way stress monitoring units 10, a plurality of skeletons 20 and a protective cap 30.

In the present embodiment, the unidirectional stress monitoring unit 10 is used to collect stress information in a single direction. The number of the unidirectional stress monitoring units 10 is multiple.

Fig. 2 is a schematic perspective view of a unidirectional stress monitoring unit according to an embodiment of the disclosure. In some embodiments, as shown in fig. 2, the unidirectional stress monitoring unit 10 includes a piezoelectric ceramic 11, an upper protective layer 12 and a lower protective layer 13 respectively disposed on the upper and lower surfaces of the piezoelectric ceramic, and a wire 14 connected to the piezoelectric ceramic 11.

In the present embodiment, the piezoelectric ceramic generates an electrical signal based on the load (i.e., stress) it receives. The electrical signal may be a voltage signal or a current signal.

In some embodiments, the electrical signal is a voltage signal, and the load (i.e., stress) borne by the piezoelectric ceramic and the output voltage signal are typically in a linear relationship, which satisfies the requirement

Wherein U represents the voltage signal output by the unidirectional stress monitoring unit,

and F represents the load born by the unidirectional stress monitoring unit.

In some embodiments, the shape of the piezoelectric ceramic may be square or circular. But the shape of the piezoelectric ceramic is not limited thereto in the embodiments of the present disclosure.

In the present embodiment, the length, width, or diameter of the piezoelectric ceramic is much larger than the thickness of the piezoelectric ceramic. Wherein the much larger is 8 times and more. For example, the ratio may be 8 times, 10 times, 15 times, or the like. In this case, only a load parallel to the direction of the piezoelectric ceramics (i.e., parallel to the normal direction of the piezoelectric ceramics) causes an electric signal to appear on the piezoelectric ceramics, thereby obtaining unidirectional stress information.

In some embodiments, if the upper and lower surfaces of the piezoelectric ceramic are circular, the diameter of the piezoelectric ceramic is at least eight times the thickness of the piezoelectric ceramic. If the upper and lower surfaces of the piezoelectric ceramics are square, the length and width of the piezoelectric ceramics are at least eight times the thickness of the piezoelectric ceramics, respectively.

In some embodiments, the surface of the piezoelectric ceramic is coated with a silicone layer. Specifically, piezoelectric ceramics with preset diameters are selected, the lead is welded on the piezoelectric ceramics, and then a silica gel layer with preset thickness is uniformly coated or poured on the surface of the piezoelectric ceramics so as to prevent water and protect the piezoelectric ceramics.

In some embodiments, the predetermined diameter is, for example, less than 1cm in diameter and the predetermined thickness is, for example, no more than 0.5cm in thickness.

In some embodiments, the silicone layer may be made of epoxy resin or the like.

In the present embodiment, the upper protective layer and the lower protective layer are used to protect the piezoelectric ceramics. The contact surface of the upper protection layer and the upper surface of the piezoelectric ceramic covers the upper surface of the piezoelectric ceramic, and the contact surface of the lower protection layer and the lower surface of the piezoelectric ceramic covers the lower surface of the piezoelectric ceramic.

In some embodiments, if the upper and lower protective layers are cylindrical, the diameters of the upper and lower protective layers are both equal to or greater than the diameter of the piezoelectric ceramic. If the upper protective layer and the lower protective layer are cuboids, the length and the width of the upper protective layer and the lower protective layer are respectively larger than or equal to the length and the width of the piezoelectric ceramics.

In some embodiments, if the diameter of the piezoelectric ceramic is less than 1cm, the upper and lower protective layers may be, for example, cylinders having a diameter of 1cm and a thickness of 1 cm.

In some embodiments, the upper or lower protective layer is cast from a target concrete that is derived from materials and proportions determined based on the fundamental physico-mechanical properties of the rock sample at the stress monitoring point of the in situ coal rock mass.

In some embodiments, after obtaining the upper protective layer or the lower protective layer, respectively, the upper protective layer or the lower protective layer is disposed on the upper surface and the lower surface of the electroceramic laminated and wrapped by the silica gel, respectively, so as to obtain the unidirectional stress monitoring unit.

In some embodiments, after a silica gel layer such as epoxy resin on the surface of the piezoelectric ceramic is solidified, the piezoelectric ceramic is placed in the middle of the interior of a model, a space for a lead is reserved in the middle of the model, and target concrete is poured into the model, so that an upper protective layer or a lower protective layer is integrally formed on the upper surface and the lower surface of the piezoelectric ceramic, and the unidirectional stress monitoring unit is obtained.

In some embodiments, after a silica gel layer such as epoxy resin on the surface of the piezoelectric ceramic is solidified, the piezoelectric ceramic is placed in the middle of the interior of a mold, a space for a conducting wire is left in the middle of the mold, a cylindrical lower protective layer is poured below the piezoelectric ceramic, and a cylindrical upper protective layer is poured above the piezoelectric ceramic, so that the unidirectional stress monitoring unit is obtained.

In some embodiments, the unidirectional stress monitoring unit 10 may also be cured before being disposed on the skeleton, wherein the curing time is different for different materials. Thereby enabling the unidirectional stress monitoring unit to have the required strength.

In some embodiments, before the nursing-completed unidirectional stress monitoring unit 10 is arranged on the skeleton, a uniaxial compression experiment can be performed on the unidirectional stress monitoring unit 10, so as to obtain the compressive strength and the equivalent piezoelectric coefficient of each unidirectional stress monitoring unit. Specifically, the unidirectional stress monitoring unit 10 is placed on an experimental model to perform a uniaxial compression experiment to obtain the compressive strength of each unidirectional stress monitoring unit, a rated resistor with a set resistance value is added in a circuit, a lead is connected with a signal amplifier, the generated voltage/current is amplified and recorded by the signal amplifier, the equivalent piezoelectric coefficient of the unidirectional stress monitoring unit is obtained through the output of the voltage/current under different pressures, and the calibration of the unidirectional stress monitoring unit is realized. Based on experiments, the equivalent piezoelectric coefficient has a direct relation with piezoelectric ceramics, materials of an upper protective layer or a lower protective layer, pouring materials and the like, and also has a direct relation with the precision and the fitting degree in the processing process.

In this embodiment, the frame 20 is used to carry a unidirectional stress monitoring unit. The number of the frameworks 20 is multiple, the frameworks are connected in sequence, and a plurality of one-way stress monitoring units are arranged in each framework.

In this embodiment, the skeleton is tubular. The tubular shape may be, for example, a circular tube or a square tube. The wall thickness of the scaffold is h (see fig. 5). In some embodiments, the skeleton may be, for example, an iron pipe.

In this embodiment, the outer wall of one end of the framework is provided with a plurality of through holes, and each through hole penetrates through the outer wall and the hollow pipeline of the framework. The axial direction of each through hole coincides with the radial direction of the frame. The axial directions of at least 2 through holes of the plurality of through holes are mutually perpendicular. And a unidirectional stress monitoring unit is arranged in each through hole. The upper surface of the piezoelectric ceramic of the unidirectional stress monitoring unit is coplanar with the outer wall of the framework around the through hole.

In this embodiment, the plurality of frames include a main frame and a sub-frame, and the helmet is connected to one end of the main frame, and the sub-frame is connected to the other end of the main frame. The main framework is embedded with a unidirectional stress monitoring unit which is arranged along the axial direction of the framework and is positioned in the hollow pipeline and at least two unidirectional stress monitoring units which are arranged along the radial direction of the framework and are vertical to each other in the direction, close to the protective cap side. The side of the secondary framework, which is close to the main framework, is embedded with at least two unidirectional stress monitoring units which are arranged along the radial direction of the framework and are vertical to each other in the direction, wherein the piezoelectric ceramics of the unidirectional stress monitoring units arranged along the radial direction are coplanar with the outer wall of the framework, and the lead is arranged in a hollow pipeline in the framework.

Fig. 3 is a schematic structural diagram of a main skeleton according to an embodiment of the present disclosure. Fig. 4 is a schematic structural diagram of a sub-skeleton provided in the embodiments of the present disclosure. FIG. 5 is a schematic cross-sectional view of the backbone within the borehole taken along the direction of dashed line A1-A2 of FIG. 3. Fig. 6 is a schematic diagram of borehole azimuth coordinates provided in an embodiment of the present disclosure.

In some embodiments, as shown in fig. 1, 3, 5 and 6, each of the frames is a circular tube, the plurality of frames 20 includes a main frame 20A and a sub-frame 20B, one end of the main frame 20A is connected to the cap 30, and the other end of the main frame 20A is connected to the sub-frame 20B. Four unidirectional stress monitoring units 10 arranged along the radial direction of the framework are embedded in the side, close to the helmet, of the main framework 20A. The directions of two adjacent unidirectional stress monitoring units in the four unidirectional stress monitoring units are mutually vertical.

Fig. 6 is a partial cross-sectional view perpendicular to the depth direction of the roadway with the boreholes in the side walls of the roadway, the locations, numbers, depths and diameters of the boreholes in fig. 6 being merely schematic. Taking XYZ three-dimensional coordinates as an example, the Z direction in fig. 6 is the depth direction of the borehole (i.e., the skeleton axial direction), and the X direction and the Y direction are two directions perpendicular to each other in a plane perpendicular to the depth direction, for example, the X direction is a horizontal direction, and the Y direction is a vertical direction. The four unidirectional stress monitoring units comprise two unidirectional stress monitoring units in the X direction and two unidirectional stress monitoring units in the Y direction.

In some embodiments, as shown in fig. 1 and 3, the main frame 20A is embedded with a unidirectional stress monitoring unit disposed along the axial direction (i.e., Z direction) of the frame and located in the hollow pipe 21.

In some embodiments, to better collect stress information, the diameter of the hollow pipe of the skeleton at the unidirectional stress monitoring units arranged axially along the skeleton is equal to the diameter of the upper or lower protective layer of the unidirectional stress monitoring units (see fig. 3).

In some embodiments, as shown in fig. 1 and 4, the side of the secondary frame 20B near the primary frame is embedded with four unidirectional stress monitoring units 10 arranged radially along the frame. The arrangement of the four unidirectional stress monitoring units 10 of the sub-skeleton 20B is identical to the arrangement of the four unidirectional stress monitoring units 10 of the main skeleton 20A.

In some embodiments, as shown in fig. 1, 3 and 4, the wires of the unidirectional stress monitoring unit 10 disposed in each skeleton extend from the hollow pipe 21 to the outside.

In some embodiments, as shown in fig. 1, 3 and 4, the outer wall of each framework is provided with a slurry outlet 22, and the slurry outlet 22 is communicated with the hollow pipeline 21 in the framework and the outer wall.

In some embodiments, the number of sub-skeletons is plural. The number of sub-skeletons may be determined based on the location and number of stress monitoring points. Therefore, the monitoring requirements of a plurality of stress monitoring points in one rotary hole can be met.

In some embodiments, the skeletons of the stress meter can be arranged according to the distance between stress monitoring points, so that the length between two skeletons can be freely adjusted to meet the actual requirement.

In this embodiment, the cap 30 serves to better transmit axial (i.e., Z-direction) forces and push debris in the borehole to the bottom of the hole.

In some embodiments, the multipoint three-way coal rock mass stress meter further comprises joints, and the skeletons are connected through the joints.

In some embodiments, in order to ensure the direction of the force measured by the stress monitoring point, the joint adopts a semi-rotary joint to realize quick connection between adjacent frameworks for higher installation requirements. In addition, in order to ensure that the direction of the stress meter is the direction of the measured force, the stress meter is directly pushed horizontally after connection is completed.

In some embodiments, as shown in fig. 1, 3 and 4, one end of the main frame 20A is provided with a joint through which the main frame 20A is connected to the sub-frame 20B. The sub-bobbin 20B has a first joint 41 and a second joint 42 arranged at both ends thereof. The sub-bobbin 20B is connected to the other bobbins in sequence through the first joint 41 and the second joint 42.

In this embodiment, the multipoint three-way coal rock mass strain gage may be disposed in a borehole drilled in an underground works whose borehole diameter is larger than the outer circumferential diameter of the skeleton, and further, as shown in fig. 5, concrete is disposed between the outer wall of the skeleton and the borehole wall. Therefore, the stress meter is automatically coupled according to the surrounding rock development condition, and the adaptability of the stress meter is enhanced.

In some embodiments, the leads of all the unidirectional stress monitoring units of all the skeletons are led out from the hollow pipeline to the outside to be connected with external equipment. External equipment such as a signal receiver, a signal amplifier, an oscilloscope and the like, so as to obtain corresponding stress information (a current signal or a voltage signal). In this case, the monitored electrical signal (i.e., stress information) is transmitted based on the piezoelectric ceramic under pressure, and is transmitted to an external device through a signal line (i.e., a lead) and a subsequent analysis is performed.

In the multipoint three-way coal-rock body stress meter of the embodiment of the disclosure, the multipoint three-way coal-rock body stress meter comprises a plurality of one-way stress monitoring units, a plurality of frameworks and a protective cap, wherein each one-way stress monitoring unit comprises piezoelectric ceramics, a lead connected with the piezoelectric ceramics, and an upper protective layer and a lower protective layer which are respectively arranged on the upper surface and the lower surface of the piezoelectric ceramics; a plurality of skeletons include main skeleton and sub-skeleton, the helmet is connected to the one end of main skeleton, the sub-skeleton is connected to the other end, the skeleton is the tubulose, the main skeleton be close to helmet side embedding have along the skeleton axial arrange one-way stress monitoring unit and along the radial two at least direction vertically one-way stress monitoring unit who arranges of skeleton, sub-skeleton be close to main skeleton side embedding have along the radial two at least direction vertically one-way stress monitoring unit who arranges of skeleton, along the piezoceramics of the one-way stress monitoring unit who arranges and the outer wall coplane of skeleton, the wire is arranged in hollow pipeline in the skeleton. Under the condition, the piezoelectric ceramics are arranged in the two protective layers to form the unidirectional stress monitoring unit, different unidirectional stress monitoring units are arranged according to the three-dimensional stress monitoring purpose to acquire three-dimensional stress information, and meanwhile, a plurality of frameworks are utilized to acquire multipoint stress information, so that the precision of stress monitoring data is improved. The stress meter can be installed in a drill hole in an underground engineering rock body to monitor one-hole multi-point three-way stress, so that the stress meter is a one-hole multi-point three-way coal rock body stress meter. The stress meter disclosed by the invention has the advantages of abundant monitoring data volume, high precision, good sensitivity, low cost, convenience in installation, portability, long-term monitoring and stable power saving.

The following are embodiments of the disclosed method, and refer to embodiments of the disclosed strain gauge for details not disclosed in the embodiments of the disclosed method. The embodiment of the method disclosed by the invention provides a coal-rock mass stress monitoring method based on a multipoint three-way coal-rock mass stress meter. The coal rock stress monitoring method based on the multipoint three-way coal rock stress meter carries out stress monitoring based on the multipoint three-way coal rock stress meter of the stress meter embodiment.

Fig. 7 is a schematic flow diagram of a coal-rock mass stress monitoring method based on a multipoint three-way coal-rock mass stress meter according to an embodiment of the present disclosure. As shown in fig. 7, the coal-rock mass stress monitoring method based on the multipoint three-way coal-rock mass stress meter includes the following steps:

and S11, determining the number of frameworks based on a plurality of stress monitoring points in the site coal and rock drilling.

And S12, acquiring a prefabricated unidirectional stress monitoring unit and a plurality of tubular frameworks, wherein the frameworks comprise a main framework and a secondary framework.

In step S12, the manufacturing process of the unidirectional stress monitoring unit includes: configuring target concrete based on the physical and mechanical characteristics of the rock sample of the stress monitoring point of the coal rock mass on site; and selecting piezoelectric ceramics with a preset diameter, and pouring target concrete on the upper surface and the lower surface of the piezoelectric ceramics to form an upper protective layer and a lower protective layer which are larger than or equal to a preset radius, so as to obtain the unidirectional stress monitoring unit.

In some embodiments, the method of obtaining the target concrete comprises: sampling at a stress monitoring point of the coal rock mass on site to obtain a rock sample; testing the rock sample to obtain the basic physical mechanical properties of the rock sample; determining the material and the proportion of an experimental accessory based on the basic physical and mechanical properties of the rock sample; and obtaining the target concrete based on the materials and the mixture ratio.

In some embodiments, sampling at a stress monitoring point of the coal rock mass on site to obtain a rock sample comprises: sampling at the stress monitoring point of the coal rock mass on site, and then processing into a columnar rock sample with a preset size. The preset size may be, for example, 50mm × 100mm (diameter × height), and the number of columnar rock samples is, for example, not less than 15 groups.

In some embodiments, testing the rock sample to obtain basic physical mechanical properties of the rock sample comprises: and carrying out physical mechanical test on the rock sample, carrying out ultrasonic wave velocity measurement and the like to obtain the basic physical mechanical characteristics of the rock sample.

In some embodiments, the determining the materials and the proportion of the experimental part based on the basic physical mechanical properties of the rock sample, and obtaining the target concrete based on the materials and the proportion comprise: based on the obtained physical and mechanical properties of the rock sample, determining the strength, material and proportion of a concrete filling agent, thereby obtaining the rapid solidification type concrete which is close to the rock sample in strength and mechanical properties and has self-expansion characteristics as much as possible, wherein the rapid solidification type concrete is the target concrete.

In step S12, after the unidirectional stress monitoring unit is manufactured, maintenance and uniaxial compression experiments are performed on the unidirectional stress monitoring unit.

In step S12, the outer circumferential diameters of the plurality of tubular skeletons are determined based on the hole diameters of the holes drilled where the underground works need to be stress monitored, the hole diameters being larger than the outer circumferential diameter of the skeleton.

And S13, connecting one end of the main framework with a protective cap, then placing the main framework into a drill hole, arranging a one-way stress monitoring unit positioned in the hollow pipeline along the axial direction of the framework and at least two one-way stress monitoring units vertical to the direction along the radial direction of the framework on the side, close to the protective cap, of the main framework, and leading a lead of the one-way stress monitoring unit to the outside through the hollow pipeline in the framework.

And S14, after the main framework and the secondary framework are connected through the joint, at least two unidirectional stress monitoring units which are vertical to each other in the radial direction are arranged on the side, close to the main framework, of the secondary framework along the framework, wherein the piezoelectric ceramics of the unidirectional stress monitoring units which are arranged in the radial direction are coplanar with the outer wall of the framework.

In step S14, before connecting the main frame and the sub-frame, all the wires of the main frame are passed through the hollow pipe of the sub-frame, thereby protecting the cable.

In some embodiments, the number of the sub-skeletons in step S14 may be multiple, and one sub-skeleton connection arrangement with the former skeleton is selected each time until the connection is completed.

And S15, after all the frameworks are arranged, sealing the hole openings of the frameworks, and grouting the hollow pipeline in the frameworks to pour the multipoint three-way coal-rock mass stress meter in the drill holes.

In some embodiments, after all the frameworks are arranged in step S15, all the wires are led out of the drill hole, and when the multipoint three-way coal rock mass stress gauge is poured in the drill hole, the hole can be sealed by air bags or yellow mud at the hole opening position (namely, the position closest to the frameworks at the hole opening of the drill hole), and then high-pressure grouting is performed through the hollow pipeline of the multipoint three-way coal rock mass stress gauge by using a grouting material with self-expansion characteristics. The grouting material is, for example, self-compacting concrete, a high-molecular quick-setting material, or the like. In addition, leave an air duct between stressometer and drilling wall before pouring the multiple spot three-dimensional coal rock mass stressometer, be convenient for exhaust, carry out the slip casting with whole drilling like this, realize the monolithic pouring to pour whole stressometer in the drilling. After pouring is completed, the stress transmission inside the whole drill hole is good, slurry in the drill hole can block cracks of the hole wall, and the whole drill hole plays a certain reinforcing role in the position of the stress monitoring point.

And S16, monitoring the coal rock stress information in real time by using a multipoint three-way coal rock stress meter.

In some embodiments, in step S16, the lead of the multipoint three-way coal and rock mass stress meter led out of the borehole is connected with an external device, and three-way stress values of the measuring points at different times and different positions are obtained through the external device.

In some embodiments, the external device is configured to record stress information, such as a voltage signal, reflected by the multipoint three-way coal-rock mass stress meter, and calculate a stress value based on a relationship between the voltage signal and a value of the load. And the external equipment is also used for supporting the analysis of the stress environment, the damage range and the damage degree of the surrounding rock by taking the obtained stress value as basic data.

In some embodiments, the external devices include, for example, signal receivers, signal amplifiers, oscilloscopes, voltage acquisition storage devices, and the like.

In some embodiments, in order to eliminate the temperature influence caused by the casting and improve the accuracy of the obtained stress value, the external device further comprises a temperature compensator, considering that the piezoelectric ceramic is very sensitive to the temperature and releases heat during the casting of the concrete.

In some embodiments, the external device may also include a display having a recorded voltage magnitude.

It should be noted that the explanation of the embodiment of the multipoint three-way coal rock mass stress meter is also applicable to the coal rock mass stress monitoring method of the embodiment, and is not repeated herein.

The above-mentioned serial numbers of the embodiments of the present disclosure are merely for description, and do not represent the advantages or disadvantages of the embodiments.

In the coal-rock body stress monitoring method based on the multipoint three-way coal-rock body stress meter, the number of frameworks is determined based on a plurality of stress monitoring points in an on-site coal-rock body drilling hole, a prefabricated one-way stress monitoring unit and a plurality of tubular frameworks are obtained, the plurality of frameworks comprise a main framework and a secondary framework, one end of the main framework is connected with a protective cap and then placed in the drilling hole, one-way stress monitoring unit located in a hollow rock body pipeline is axially arranged on the side, close to the protective cap, of the main framework, at least two one-way stress monitoring units perpendicular to the direction are radially arranged along the frameworks, a lead of the one-way stress monitoring unit penetrates through the hollow pipeline in the frameworks to be led to the outside, after the main framework and the secondary framework are connected through a connector, at least two one-way stress monitoring units perpendicular to the direction are radially arranged on the side, close to the main framework, of the secondary framework, the piezoelectric ceramics of the one-way stress monitoring units arranged along the direction are coplanar with the outer walls of the frameworks, after the arrangement of all the frameworks is completed, the hole opening positions of the frameworks are subjected to coal-rock body pipeline, coal-rock body stress monitoring hole sealing is performed, and coal-rock body stress monitoring is performed by injecting coal-rock body three-way coal-rock body stress monitoring hole sealing by utilizing the multipoint three-rock body stress meter. Under the condition, through the stressometer that sets up including a plurality of skeletons and one-way stress monitoring unit in the drilling, arrange different one-way stress monitoring unit according to three-dimensional stress monitoring purpose in the skeleton, go out and carry out subsequent analysis such as stress monitoring through the wire with the help of the signal of telecommunication that can monitor that piezoceramics received pressure transmission, can improve the precision of stress monitoring data from this. In addition, the unidirectional stress monitoring unit is obtained by arranging piezoelectric ceramics inside two protective layers with mechanical properties similar to those of a rock stratum based on a piezoelectric effect, and the thickness of the piezoelectric ceramics is far smaller than the diameter or length and width of the piezoelectric ceramics, so that an electric signal can be ensured to appear on the piezoelectric ceramics only when a load parallel to the direction of the piezoelectric ceramics. Therefore, the accuracy and the sensitivity of the piezoelectric ceramic can be improved, and the accuracy of the stress monitoring data can be further improved. The method disclosed by the invention has the advantages of high precision, long-term monitoring, high sensitivity, stability and power saving; the coupling can be automatically carried out according to the development condition of the surrounding rock, and the adaptability is strong; the device can be arranged in a multi-point array manner, and the content of monitoring the stress of the coal rock mass is further enriched; the strength of the surrounding rock of the roadway can be locally reinforced; the concrete column is utilized to realize coordinated deformation and enhance the external force resistance; the one-hole multi-point three-way stress monitoring can be carried out, and the data volume is rich; the active detection can be realized, and the analysis precision is improved.

It should be understood that various forms of the flows shown above may be used, with steps reordered, added, or deleted. For example, the steps described in the present disclosure may be executed in parallel or sequentially or in different orders, and the present disclosure is not limited thereto as long as the desired results of the technical solutions of the present disclosure can be achieved.

The above detailed description should not be construed as limiting the scope of the disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A multipoint three-way coal and rock mass stress meter is characterized by comprising a plurality of one-way stress monitoring units, a plurality of frameworks and a protective cap;

2. The multipoint three-way coal-rock mass stress gauge according to claim 1, wherein the diameter of said piezoelectric ceramic is at least eight times greater than the thickness of said piezoelectric ceramic, and the diameters of said upper and lower protective layers are both greater than or equal to the diameter of said piezoelectric ceramic.

3. The multipoint three-way coal-rock mass stress gauge according to claim 1, wherein the upper protective layer or the lower protective layer is formed by pouring target concrete, and the target concrete is obtained based on materials and proportions determined by basic physical and mechanical properties of rock samples of stress monitoring points of on-site coal rock masses.

4. The multipoint three-way coal and rock mass stress gauge according to claim 1, wherein a silica gel layer is coated on the surface of the piezoelectric ceramic.

5. The multi-point three-way coal-rock mass stress gauge of claim 1, wherein the outer wall of each framework is provided with a slurry outlet hole, and the slurry outlet holes are communicated with the hollow pipeline and the outer wall in the framework.

6. The multipoint three-way coal rock mass stress gauge according to claim 1, further comprising joints through which the skeletons are connected.

7. The multipoint three-way coal rock mass stress gauge according to claim 1 or 6, wherein the number of said sub-frames is plural.

8. A coal rock mass stress monitoring method based on a multipoint three-way coal rock mass stress meter is characterized by comprising the following steps:

after the main framework and the sub-framework are connected through the joint, at least two unidirectional stress monitoring units which are vertical to each other in the radial direction of the framework are arranged on the side, close to the main framework, of the sub-framework, wherein piezoelectric ceramics of the unidirectional stress monitoring units which are arranged in the radial direction are coplanar with the outer wall of the framework;

after the arrangement of all the frameworks is completed, hole sealing is carried out on the hole openings of the frameworks, and grouting is carried out on hollow pipelines in the frameworks so as to enable the multipoint three-way coal-rock mass stress meter to be poured in the drill holes;

9. The coal rock mass stress monitoring method based on the multipoint three-way coal rock mass stress meter according to claim 8, wherein the manufacturing process of the one-way stress monitoring unit comprises the following steps:

configuring target concrete based on the physical and mechanical properties of the rock sample of the stress monitoring point of the coal rock mass on site;

and selecting piezoelectric ceramics with preset diameters, and pouring the target concrete on the upper surface and the lower surface of the piezoelectric ceramics to form an upper protective layer and a lower protective layer which are larger than or equal to a preset radius, so as to obtain the unidirectional stress monitoring unit.

10. The coal rock mass stress monitoring method based on the multipoint three-way coal rock mass stress meter according to claim 9, wherein after the unidirectional stress monitoring unit is manufactured, maintenance and uniaxial compression experiments are carried out on the unidirectional stress monitoring unit.