The deformation and cracking of the rock will transmit sound waves. The evolution of rocks and the expansion of the companion will transmit sound waves. The rock acoustic emission and propagation process has a linear relationship with the change of rock. By analyzing the emission source and signal strength of rock sound, the driving factors of rock structure can be obtained. The evolution degree of rock structure can be obtained by analyzing the signal strength of rock sound. Therefore, it is the key to realize the localization and emission monitoring of rock students. The evolution of rock structure will lead to the imbalance of the internal energy of the rock. Constructing the structure of the internal imbalance of rock is by monitoring the sound of rock.
Three rock groups of different structures are shown in Fig. 1; a block of rock, a cylinder of rock, a piece of stone. The evolution of rock structure caused the interaction of the three rocks with each other. Parameter Y indicates the direction of the rectangular rock force. The parameter x indicates the direction of the force of the cylinder. α is the angle between the acoustic emission direction of the rectangular rock and the trapezoidal rock. β indicates the angle between the acoustic emission direction of the cylinder rock and the trapezoid rock.
The acoustic wave force field in the evolution process of rock group is shown in formula (1).
$$ \left\{\begin{array}{l}{\delta}_x\\ {}{\delta}_y\\ {}\sqrt{\delta_x+{\delta}_y}\end{array}\right\}=\frac{ \cos \alpha }{\pi \sqrt{ \sin \beta }}\left\{\begin{array}{l}1-y \sin \alpha \sqrt{\left|{x}^2-{y}^2\right|}\\ {}1+y \cos \alpha \sqrt{\left|{x}^2-{y}^2\right|}\\ {}y \cos \frac{\beta }{2} \sin \alpha \sqrt{\left|{x}^2-{y}^2\right|}\end{array}\right\} $$
(1)
Here, δ
x
denotes the rock s sound wave stress field from the cuboid cylindrical rock. δ
y
denotes the rectangular rock acoustic force field from cylinder rock and trapezoidal rock.
Internal energy evolution of rock group is shown in formula (2).
$$ \left\{\begin{array}{l}{\eta}_1\\ {}{\eta}_2\\ {}{\eta}_3\end{array}\right\}=\frac{\sqrt{\left|{x}^2-{y}^2\right|}}{\pi \sqrt{ \cos \beta }}\left\{\begin{array}{l} \cos \left({\alpha}^2-{\beta}^2\right)\mu \\ {}{\left|x-y\right|}^{\mu } \cos \alpha \\ {}\mu \sin \frac{\alpha }{2} \cos \frac{\beta }{2}\end{array}\right\} $$
(2)
Here, the energy intensity of the rectangular rock is expressed by η
1. Energy field strength of cylinder rocks is denoted by η
2. Energy intensity of the trapezoidal rock is denoted by η
3. Energy loss weight is denoted by μ.
The structure of the rock group deformation and acoustic propagation direction is shown in Fig. 2. Here, γ is the angle between weakening of energy and acoustic emission in evolution of the cylinder rock. The angle between the acoustic propagation direction of structure deformation and the direction of energy weakening in the direction of sound propagation and the direction of energy weakening is w. Therefore, the displacement caused by the structural deformation of the rock group is shown in the formula (3).
$$ \left\{\begin{array}{l}\varDelta x\\ {}\varDelta y\end{array}\right\}=\frac{\mu }{\sqrt{2\pi }}\left\{\begin{array}{l}\frac{1}{2} \cos \alpha \cos \gamma \\ {}\frac{1}{2} \sin \omega \cos \frac{1}{2}\beta \end{array}\right\} $$
(3)
The moving distance of rock group structure deformation \( \sqrt{\varDelta {x}^2+\varDelta {y}^2} \) can be obtained. The rock acoustic energy A
U
could be obtained by formula (4).
$$ {A}_U=\left\{\begin{array}{l}\frac{2}{\mu}\left|\sqrt{\varDelta {x}^2+\varDelta {y}^2}-{\delta}_x{\delta}_y\right| \sin \omega, \sqrt{\varDelta {x}^2+\varDelta {y}^2}>\sqrt{\left|{x}^2-{y}^2\right|}\\ {}\frac{\pi }{2}\sqrt{\left|{x}^2-{y}^2\right|} \cos \gamma, \sqrt{\varDelta {x}^2+\varDelta {y}^2}\le \sqrt{\left|{x}^2-{y}^2\right|}\end{array}\right. $$
(4)
In order to better monitor the acoustic emission of rock or large rock groups, we designed a wireless rock sound source monitoring network based on swarm intelligence. The network has the following functions:
-
(1)
Monitoring and convergence of rock acoustic emission signals
-
(2)
The reason and classification of rock acoustic emission
-
(3)
The structure and location of the rock sound source
-
(4)
The location of the rock or rock group
Based on the rock mechanical field, acoustic emission and energy field, the three-dimensional space of the sound source localization sensor based on the group wise perception is established, which is shown in Fig. 3. Here, Z
1, Z
2, Z
3, Z
4 are the rock acoustic emission signals perceived by the swarm intelligence sensors, which belong to the reverse direction of Y in the three bit space. In order to facilitate the sound source localization, they are mapped to the Y forward. In Fig. 3, we found that there are two perceptual points Z
2
' on the positive and the positive direction of the X and Z
μ
. This two-point is mapped to Z
2 point. This is because the characteristic of the formula (5) is shown when the rock acoustic emission is perceived by the swarm intelligence sensor.
$$ {Z}_2=\left\{\begin{array}{l}\frac{1}{2} \cos \alpha \sin \omega, \varDelta x>{x}_2\\ {}\frac{1}{2\pi } \sin \beta cso\gamma, {\mu}_2>\varDelta \mu \end{array}\right. $$
(5)
Rock sound source crowd positioning algorithm workflow is shown below:
-
(1)
Monitoring the acoustic emission energy of each rock group
-
(2)
Determination of rock structure
-
(3)
Calculate the displacement vector of rock structure
-
(4)
Crowd sensors to perceive the three force and harmonic propagation process of rock group
-
(5)
Mapping all the swarm intelligence to forward space of y
-
(6)
To connect the y to the space of the crowd perception points to 1 closed loop, to achieve the sound source localization
