Method for predicting spatio-temporal evolution law of sandstone temperature field under laser action

Abstract

The present application relates to the technical field of laser rock breaking, and discloses a method for predicting the spatio-temporal evolution law of the temperature field of sandstone under laser action, which can accurately predict the evolution law of the temperature field of rock under laser action without relying on complex rock parameters, thereby improving the accuracy and precision of the laser rock breaking process. The present application scheme comprises: establishing a laser beam energy density distribution equation subject to Gaussian distribution, and constructing a rock surface temperature field expression; measuring rock surface temperature data under different experimental conditions through laser irradiation experiments, and establishing a relationship between model parameters and spot diameter and a relationship between model parameters and laser power and irradiation time through data fitting, respectively; obtaining a rock surface temperature field spatio-temporal evolution model under laser action by simultaneously solving the rock surface temperature field expression, the relationship between model parameters and spot diameter, and the relationship between model parameters and laser power and irradiation time, and predicting the distribution law of the sandstone surface temperature under laser action.

Description

Technical Field

[0001] This invention relates to the field of laser rock breaking technology, specifically to a method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation. Background Technology

[0002] Laser rock breaking technology, with its core advantages of high energy density and strong directionality, has become an emerging key technology in the field of deep, hard rock fracturing. It has great application potential in safe, low-disturbance, and efficient excavation of deep hard rock and in the prevention and control of rockbursts in deep, high-stress areas. Its core principle is to concentrate high-density energy on a small, localized area of ​​rock to achieve precise and efficient hard rock fracturing, while minimizing disturbance to the surrounding deep rock mass. This effectively solves the problems of large disturbance to the surrounding rock mass and low fracturing efficiency of traditional rock breaking technologies.

[0003] However, the practical application of laser rock breaking technology still faces key technical bottlenecks. Existing research mainly focuses on describing macroscopic phenomena, lacking in-depth and clear understanding of the multi-scale damage response mechanism of rocks under laser action and the intrinsic mechanism of laser-induced fracturing of hard rocks, making it difficult to accurately control the laser rock breaking process.

[0004] In the core technical aspect of temperature field prediction, existing rock temperature models under laser irradiation have certain limitations: these models are derived based on the law of conservation of energy and the heat conduction equation, involving numerous rock parameters. Not only is the model structure complex, but the process of obtaining rock parameters is also difficult. Especially in on-site construction scenarios, due to limitations such as environmental conditions and testing equipment, the timeliness and accuracy of parameter acquisition are difficult to guarantee. This directly leads to poor applicability of existing models, which cannot meet the needs of accurate prediction of the evolution of rock temperature field under laser irradiation in actual engineering.

[0005] Therefore, developing a method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation that is highly applicable, easy to use, and does not rely on complex rock parameters is key to promoting the engineering application of laser rock breaking technology and is of great significance for improving the accuracy, safety, and efficiency of the laser rock breaking process. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation, which can accurately predict the evolution of rock temperature field under laser irradiation without relying on complex rock parameters, thereby improving the precision and accuracy of the laser rock breaking process.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0008] A method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation includes the following steps:

[0009] S1. Establish the energy density distribution equation of the laser beam that follows a Gaussian distribution;

[0010] S2. Based on the laser beam energy density distribution equation that follows a Gaussian distribution, construct an expression for the temperature field on the rock surface;

[0011] S3. Design multiple sets of laser irradiation experiments, and measure the rock surface temperature data under different experimental conditions by changing the spot diameter, laser power and irradiation time parameters.

[0012] S4. Based on the results of the multiple laser irradiation experiments, establish the relationship between model parameters and spot diameter, and the relationship between model parameters and laser power and irradiation time through data fitting;

[0013] S5. By combining the above expressions for the rock surface temperature field, the relationship between model parameters and spot diameter, and the relationship between model parameters and laser power and irradiation time, a spatiotemporal evolution model of the rock surface temperature field under laser action is obtained.

[0014] S6. Using the spatiotemporal evolution model of the rock surface temperature field under laser irradiation, the temperature distribution law of sandstone surface under laser irradiation is predicted.

[0015] Furthermore, in step S1, the equation for the energy density distribution of the laser beam, which follows a Gaussian distribution, is:

[0016] ;

[0017] in, Laser power, unit: ; The laser spot radius is expressed in units of 1 / 2. ; The coordinates of the center of the light spot; The coordinates of the laser thermally affected area; Laser beam energy density, in units of Its sensitivity to laser power and laser spot radius Control.

[0018] Furthermore, step S1 also includes: obtaining the laser beam energy density distribution curve and the absolute value curve of the slope of the laser beam energy density curve, and verifying the rationality of the laser beam energy density distribution equation by combining the morphological characteristics of the two curves with the physical laws of laser beam energy propagation.

[0019] Furthermore, the method for obtaining the laser beam energy density distribution curve includes:

[0020] Determine the laser power and spot radius parameters, take the coordinates of discrete points within the laser heat-affected zone, substitute them into the laser beam energy density distribution equation, calculate the energy density value corresponding to each point, and plot a curve with the radial position as the abscissa and the corresponding energy density as the ordinate.

[0021] Furthermore, the method for obtaining the absolute value curve of the slope of the laser beam energy density curve includes:

[0022] Differentiating the energy density distribution equation with respect to the laser spot radius r yields the slope expression;

[0023] Substitute the coordinates of discrete location points into the slope expression to calculate the corresponding slope value. After taking the absolute value, plot the curve with the radial position as the abscissa and the corresponding absolute slope value as the ordinate.

[0024] Furthermore, in step S2, based on the laser beam energy density distribution equation that follows a Gaussian distribution, an expression for the rock surface temperature field is constructed, including:

[0025] make , The energy density distribution equation of the laser beam, which follows a Gaussian distribution, can be transformed into the following form:

[0026] ;

[0027] Projecting the transformed laser beam energy density distribution equation onto Based on the positive correlation between energy density and temperature, an expression for the temperature field on the rock surface is established:

[0028] ;

[0029] in, and All are model parameters; The surface temperature of the rock; The laser spot radius;

[0030] The A plane is defined as a plane with the center of the laser spot as the origin, the radial distance along the x-axis of the rock surface as the abscissa, and the laser beam energy density as the ordinate.

[0031] Furthermore, in step S4, the relationship between the established model parameters and the spot diameter is as follows:

[0032] ;

[0033] in, The diameter of the laser spot;

[0034] The established model parameters are related to laser power and irradiation time as follows:

[0035] ;

[0036] in, Laser power; This refers to the irradiation time.

[0037] Furthermore, in step S5, by combining the expression for the rock surface temperature field, the relationship between the model parameters and the spot diameter, and the relationship between the model parameters and the laser power and irradiation time, a spatiotemporal evolution model of the rock surface temperature field under laser irradiation is obtained, including:

[0038] By combining the expressions for the rock surface temperature field, the relationship between the model parameters and the spot diameter, and the relationship between the model parameters and the laser power and irradiation time, a simplified model of the rock surface temperature field under laser irradiation is obtained: ;

[0039] This simplified model is a one-dimensional spatiotemporal evolution model focusing on the x-axis direction, based on the axisymmetric characteristics of the temperature field on the rock surface.

[0040] Next, based on the axisymmetric characteristics of the rock surface temperature field, the simplified model of the rock surface temperature field under laser irradiation is extended to a complete form covering x and y variables, resulting in the final spatiotemporal evolution model of the rock surface temperature field under laser irradiation:

[0041] ;

[0042] in, The x-coordinate of the laser spot center is... The vertical coordinate is the center of the laser spot.

[0043] The beneficial effects of this invention are:

[0044] (1) Lower the application threshold and improve applicability and convenience:

[0045] This invention breaks through the dependence of existing temperature models on complex rock parameters. It eliminates the need to obtain difficult-to-measure rock parameters and can establish a prediction model using only laser parameters (spot diameter, laser power) and time parameters (irradiation time). This greatly simplifies the operation process and is especially suitable for complex working conditions where parameter acquisition is limited, such as on-site construction, significantly enhancing the engineering application value of the technology.

[0046] (2) Improve the accuracy of temperature field prediction:

[0047] Based on the energy density of a Gaussian distributed laser beam, this invention constructs a spatiotemporal evolution model by fitting the expression of the temperature field on the rock surface and establishing a quantitative relationship between model parameters and key laser parameters. This model can capture the dynamic changes in the surface temperature of sandstone under laser irradiation in real time, clearly revealing the evolution law of the temperature field with the spot diameter, laser power, and irradiation time. It has high prediction accuracy and provides data support for precise temperature control during laser rock breaking. Attached Figure Description

[0048] Figure 1 This is a flowchart of the method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation in an embodiment of the present invention.

[0049] Figure 2 This is a schematic diagram of the laser beam energy density curve in an embodiment of the present invention.

[0050] Figure 3 This is a schematic diagram of the absolute value of the slope of the laser beam energy density curve in an embodiment of the present invention.

[0051] Figure 4 This is a schematic diagram of the fitting curve of radial temperature data of the sample surface in an embodiment of the present invention.

[0052] Figure 5 Model parameters in the embodiments of the present invention A schematic diagram illustrating the effect of changes on the temperature distribution curve.

[0053] Figure 6 Model parameters in the embodiments of the present invention A schematic diagram illustrating the effect of changes on the temperature distribution curve.

[0054] Figure 7 This is a schematic diagram illustrating the effect of the spot diameter on the laser beam energy density in an embodiment of the present invention.

[0055] Figure 8 This is a schematic diagram illustrating the effect of laser power on laser beam energy density in an embodiment of the present invention.

[0056] Figure 9 Model parameters in the embodiments of the present invention A schematic diagram showing the changes in spot diameter and irradiation time.

[0057] Figure 10 Model parameters in the embodiments of the present invention A schematic diagram showing the relationship between the light spot diameter and the light spot diameter.

[0058] Figure 11 Model parameters in the embodiments of the present invention A schematic diagram showing the relationship between laser power and irradiation time.

[0059] Figure 12This is a schematic diagram of the fitted surface of model parameter b in an embodiment of the present invention. Detailed Implementation

[0060] This invention aims to provide a method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation. This method accurately predicts the evolution of rock temperature field under laser irradiation without relying on complex rock parameters, thereby improving the precision and accuracy of the laser rock-breaking process. The core idea is to address the problems of existing laser-based rock temperature field prediction models relying on complex and difficult-to-obtain rock parameters, having poor applicability, and being difficult to precisely control the laser rock-breaking process. The core approach focuses on simplifying parameter dependence, focusing on key laser variables, and constructing a precise spatiotemporal model. Taking the strong similarity between the Gaussian distribution laser beam energy density and the rock surface temperature field as a starting point, the laser beam energy density distribution equation is first established, and an expression for the rock surface temperature field is constructed. Then, quantitative correlations are established between the model parameters and easily obtainable key laser parameters (spot diameter, laser power) and time parameters (irradiation time), avoiding dependence on the rock's own parameters. Subsequently, the spatiotemporal evolution model of the temperature field under laser irradiation is constructed by combining these relationships, achieving accurate prediction of the spatiotemporal evolution of sandstone temperature field. This solves the practicality problem of existing models and provides core technical support for the precise control and mechanism research of the laser rock-breaking process.

[0061] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0062] This embodiment provides a method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation. (See also...) Figure 1 It includes the following implementation process:

[0063] S1. Establish the energy density distribution equation of the laser beam that follows a Gaussian distribution;

[0064] In this step, the energy of the laser beam is the source of the temperature rise in the rock sample; therefore, the energy density distribution characteristics of the laser beam directly affect the temperature field distribution characteristics of the sample. The temperature distribution curve of the sample surface and the energy density distribution curve of the laser beam show a high degree of consistency. Since the energy density of the laser beam in industrial applications generally follows a Gaussian distribution (energy gradually decreases from the center of the spot to the edge, which matches the output characteristics of actual laser equipment), this embodiment establishes the laser beam energy density distribution equation based on the Gaussian distribution:

[0065] ;

[0066] in, Laser beam energy density, in units of Its sensitivity to laser power and laser spot radius Control; Laser power, unit: ; The laser spot radius is expressed in units of 1 / 2. ; The coordinates of the center of the light spot; The coordinates are those of the laser-affected zone.

[0067] To further verify the rationality of the laser beam energy density distribution, this embodiment, after establishing the above equation, also obtains the laser beam energy density distribution curve and the absolute value curve of the slope of the laser beam energy density curve. Combining the morphological characteristics of the two curves with the physical laws of laser beam energy propagation, the rationality of the laser beam energy density distribution equation is verified.

[0068] The methods for obtaining the laser beam energy density distribution curve include:

[0069] Determine the laser power and spot radius parameters, take the coordinates of discrete points within the laser heat-affected zone, substitute them into the laser beam energy density distribution equation, calculate the energy density value corresponding to each point, and plot a curve with the radial position as the abscissa and the corresponding energy density as the ordinate.

[0070] Methods for obtaining the absolute value of the slope curve of the laser beam energy density curve include:

[0071] Differentiating the energy density distribution equation with respect to the laser spot radius r yields the slope expression;

[0072] Substitute the coordinates of discrete location points into the slope expression to calculate the corresponding slope value. After taking the absolute value, plot the curve with the radial position as the abscissa and the corresponding absolute slope value as the ordinate.

[0073] In one exemplary embodiment, the obtained laser beam energy density distribution curve is as follows: Figure 2 As shown, the curve exhibits a single-peak shape with "low at the edge and high at the center". The energy density at the edge of the light spot is close to zero but not zero. Along the radial direction of the light spot outward, the energy density gradually decreases to zero from the edge. Along the radial direction of the light spot inward, the energy density gradually increases from the edge and reaches its peak at the center of the light spot, which fully conforms to the physical law of Gaussian distribution of "concentration at the center and decay at the edge".

[0074] The absolute value of the slope of the obtained laser beam energy density curve is as follows: Figure 3 As shown, the curve exhibits a trend of "first increasing and then decreasing". The absolute value of the slope is zero at the edge of the sample. As the slope approaches the outer edge of the light spot, the absolute value gradually increases from zero. When moving radially inward along the light spot to a certain specific position, the absolute value of the slope reaches its peak (this position corresponds to the region where the energy density changes most drastically). Continuing to move towards the center of the light spot, the absolute value of the slope gradually decreases until it drops to zero at the center of the light spot (at which point the energy density reaches its peak and the rate of change is zero), which perfectly matches the physical change law of energy density distribution.

[0075] S2. Based on the laser beam energy density distribution equation that follows a Gaussian distribution, construct an expression for the temperature field on the rock surface;

[0076] In this step, since the change in rock surface temperature is directly driven by laser energy density, and the two have strong similarity in spatial distribution (the temperature is high in areas with high energy density, and the temperature changes synchronously in areas with gradually changing energy density), this embodiment constructs the expression for the rock surface temperature field based on the above-mentioned Gaussian distribution energy density equation by means of variable substitution, dimensional simplification and constant correction.

[0077] Specifically, two model parameters were first set. and Using the theoretical assumptions based on the Gaussian distribution, let , To simplify the complex laser beam energy density distribution equation, the transformation is as follows:

[0078] ;

[0079] Next, considering that the temperature field on the rock surface under laser irradiation is axisymmetrically distributed (with the center of the laser spot as the origin, the temperature is the same on the same radius circle), this embodiment projects the above-described transformed equation onto... Plane. Wherein, The plane refers to a plane with the center of the laser spot as the origin, the radial distance from the rock surface along the x-axis as the abscissa, and the laser beam energy density as the ordinate. After projection, the equations can be simplified, eliminating the need to consider the influence of the y-axis coordinate, and only considering the influence of the radial distance from the center of the laser spot on the temperature field.

[0080] In addition, considering that the rock surface temperature is the same as the ambient temperature in the initial stage of laser irradiation, and the temperature field calculation needs to be based on the actual initial temperature to avoid the theoretical model from deviating from the actual working conditions, it is also necessary to introduce a constant term into the rock surface temperature field expression. This constant term corresponds to the ambient room temperature (e.g., 25℃, which can also be flexibly adjusted according to the ambient temperature of the actual application scenario).

[0081] Finally, since the distribution characteristics of rock surface temperature and laser energy density are highly similar, then... The expression for the temperature field on the rock surface can be obtained as follows:

[0082] ;

[0083] in, and All are model parameters; The surface temperature of the rock; The radius of the laser spot is denoted as .

[0084] To verify the fitting accuracy of this expression, this embodiment uses ORIGIN software to construct the above temperature field expression and fits it to the experimentally measured radial temperature data of the sandstone surface. See [link to documentation]. Figure 4 The fitted curve almost completely overlaps with the experimental data points. The calculated coefficient of determination and the corrected coefficient of determination are 0.99948 and 0.99946, respectively, indicating that the temperature model shown in the expression of the rock surface temperature field is reasonable and has a high goodness of fit.

[0085] S3. Design multiple sets of laser irradiation experiments, and measure the rock surface temperature data under different experimental conditions by changing the spot diameter, laser power and irradiation time parameters.

[0086] In this step, sandstone samples were irradiated using multiple sets of laser irradiation experiments, with variations in the laser spot diameter, laser power, and irradiation time. For each set of experiments, radial temperature data of the rock surface was measured using an infrared thermal imager, resulting in multiple sets of measurement results. Each set of results includes the laser spot diameter, laser power, and irradiation time parameters used, as well as the measured rock surface temperature data. It is understandable that, to obtain more accurate temperature data, multiple measurements at the same location can be taken and the average value calculated. These measurement results will serve as the basis for subsequent modeling and fitting.

[0087] S4. Based on the results of the multiple laser irradiation experiments, establish the relationship between model parameters and spot diameter, and the relationship between model parameters and laser power and irradiation time through data fitting;

[0088] In this step, based on the results of multiple laser irradiation experiments, data fitting is used to adjust the model parameters. and model parameters By fitting the data, a quantitative relationship between the laser and key laser parameters is established, thus laying the foundation for the subsequent establishment of a spatiotemporal evolution model of the temperature field on the rock surface under laser action.

[0089] To investigate parameters and parameters The influence on rock surface temperature distribution was investigated by using the aforementioned expression for the rock surface temperature field, fixing one parameter while adjusting the value of the other to calculate different rock surface temperature data, and then plotting the curves. (See also...) Figure 5 The horizontal axis represents the radial distance from the sample surface, and the vertical axis represents the rock surface temperature at the corresponding location. Each curve in the figure corresponds to a different parameter. The possible values ​​of . See also Figure 6 The horizontal axis represents the radial distance from the sample surface, and the vertical axis represents the rock surface temperature at the corresponding location. Each curve in the graph corresponds to a different parameter. The value of .

[0090] And in order to know the parameters and parameters To determine which specific laser key parameters are related, it is necessary to investigate the influence mechanism of different laser key parameters on the rock surface temperature distribution. Since the rock surface temperature distribution is consistent with the laser beam energy density distribution, a relationship curve between the laser key parameters and the laser beam energy density can be established to reveal this influence mechanism. (See also...) Figure 7 This figure visually demonstrates the impact of the laser spot diameter, a laser parameter, on the laser beam energy density distribution. The horizontal axis represents the radial distance of the spot, and the vertical axis represents the laser beam energy density at the corresponding location. Each curve in the figure corresponds to a different spot diameter. See also... Figure 8 It intuitively demonstrates the influence of laser power, a laser parameter, on the distribution of laser beam energy density. The horizontal axis of the figure represents the radial distance of the laser spot, and the vertical axis represents the laser beam energy density at the corresponding location. Each curve in the figure corresponds to a different laser power.

[0091] contrast Figures 5-8 It can be seen that the parameters Increasing the value of (decreasing the absolute value) generally lowers the temperature but increases the heat-affected zone; increasing the spot diameter generally lowers the laser beam energy density and temperature but increases the laser beam energy density and temperature distribution range. Similarly, the parameters An increase in absolute value leads to an overall increase in temperature, and an increase in laser power similarly leads to an overall increase in both laser power density and temperature. These results demonstrate that the above expression for the temperature field on the rock surface is reasonable, and the parameters... The mechanism by which the light spot diameter affects temperature distribution is basically the same as that of the parameters. The mechanism by which laser power affects temperature distribution is basically the same. Based on this, parameters will be further established based on experimental results. and The relationship between laser parameters and laser parameters.

[0092] Depend on Figure 5 and Figure 7 It can be seen that the parameters The effect on temperature is similar to that of the laser spot diameter, and increasing the laser irradiation time also leads to an increase in the heat-affected zone. Therefore, in terms of parameters... The relationship between the light spot diameter and the illumination time should be considered to determine whether the irradiation time parameter needs to be included. Figure 9 It can be seen that the parameters The model parameters are strongly correlated with the spot diameter, but not significantly correlated with the illumination time. Therefore, the model parameters... It is the diameter of the light spot. The function is represented as:

[0093] ;

[0094] in, The influence of spot diameter on model parameters The sensitivity coefficient is mainly used to determine With the diameter of the light spot The magnitude of the change Model parameters The basic correction term is mainly used to compensate for the deviation between the theoretical model and the actual experimental conditions, and to ensure the rationality of the model under extreme conditions.

[0095] Based on the above formula, the parameters are fitted using the experimental results of the laser irradiation experiment. The relationship between the light spot diameter and the data points and the fitting function can be found in [reference needed]. Figure 10 After fitting, the following formula is obtained:

[0096] ;

[0097] Calculations showed that the coefficient of determination and the corrected coefficient of determination for this relationship were 0.93569 and 0.91962, respectively, indicating a high goodness of fit and accurate description of the parameters. The relationship between the light spot diameter and the light spot diameter.

[0098] In addition, in comparison Figure 6 and Figure 8 It can be seen that the parameters An increase in absolute value raises the overall temperature value; similarly, an increase in laser power also raises the temperature value, i.e., the parameter... The effect of laser power on temperature is similar to that of laser irradiation time. Considering that increasing laser irradiation time also increases the temperature, and combining this with the expression for the temperature field on the rock surface, then the parameters... It should be laser power. and irradiation time The function is represented as:

[0099] ;

[0100] See Figure 11 It displays the parameters. The relationship between the parameters and laser power and irradiation time shows that... The laser power and irradiation time showed a strong correlation and regularity. Therefore, a parameter was established with laser power and irradiation time as independent variables. The multivariate polynomial regression model, obtained through nonlinear fitting using the experimental results of laser irradiation experiments, yields the following equation:

[0101] ;

[0102] parameter See the fitted surface. Figure 12 The fitted surface closely matches the discrete data points, and the calculated coefficient of determination and correction coefficient of determination for this model are 0.91387 and 0.91054, respectively, indicating a high goodness of fit and accurate characterization of the parameters. The relationship between laser power and irradiation time.

[0103] S5. By combining the above expressions for the rock surface temperature field, the relationship between model parameters and spot diameter, and the relationship between model parameters and laser power and irradiation time, a spatiotemporal evolution model of the rock surface temperature field under laser action is obtained.

[0104] In this step, by combining the expressions for the rock surface temperature field after projection, the relationship between the model parameters and the laser spot diameter, and the relationship between the model parameters and the laser power and irradiation time, a spatiotemporal evolution model of the rock surface temperature field under laser irradiation can be obtained. This model considers in detail the laser parameters including the spot radius and laser power, the time parameter (laser irradiation time), and the spatial parameter (coordinates of the laser-affected zone). The model form is as follows:

[0105] ;

[0106] Understandably, this model is a one-dimensional spatiotemporal evolution model focusing on the x-axis direction, based on the axisymmetric characteristics of the rock surface temperature field. Therefore, it is necessary to restore the dimension based on the axisymmetric characteristics of the rock surface temperature field to obtain the final spatiotemporal evolution model of the rock surface temperature field under laser irradiation.

[0107] ;

[0108] in, The x-coordinate of the laser spot center is... The vertical coordinate is the center of the laser spot.

[0109] S6. Using the spatiotemporal evolution model of the rock surface temperature field under laser irradiation, the temperature distribution law of sandstone surface under laser irradiation is predicted.

[0110] In this step, after obtaining the spatiotemporal evolution model of the rock surface temperature field under laser irradiation, it can be deployed in practical application scenarios. After clarifying key laser parameters such as laser spot diameter, laser power, and irradiation time, the coordinates of the location to be predicted can be input to obtain the predicted rock surface temperature at that location. This provides data support for precise temperature control during laser rock breaking.

[0111] Although embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, and all such changes and alterations shall not depart from the protection scope of the present invention.

Claims

1. A method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation, characterized in that, Includes the following steps: S1. Establish the equation for the energy density distribution of a laser beam that follows a Gaussian distribution: ； in, Laser power, unit: ; The laser spot radius is expressed in units of 1 / 2. ; The coordinates of the center of the light spot; The coordinates of the laser thermally affected area; Laser beam energy density, in units of Its sensitivity to laser power and laser spot radius Control; S2. Based on the Gaussian distribution equation for the laser beam energy density, the expression for the rock surface temperature field is constructed as follows: make , The energy density distribution equation of the laser beam, which follows a Gaussian distribution, can be transformed into the following form: ； Projecting the transformed laser beam energy density distribution equation onto Based on the positive correlation between energy density and temperature, an expression for the temperature field on the rock surface is established: ； in, and All are model parameters; The surface temperature of the rock; The laser spot radius; The A plane is defined as a plane with the center of the laser spot as the origin, the radial distance along the x-axis of the rock surface as the abscissa, and the laser beam energy density as the ordinate. S3. Design multiple sets of laser irradiation experiments, and measure the rock surface temperature data under different experimental conditions by changing the spot diameter, laser power and irradiation time parameters. S4. Based on the results of the multiple laser irradiation experiments, establish the relationship between model parameters and spot diameter, and the relationship between model parameters and laser power and irradiation time through data fitting; S5. By combining the above expressions for the rock surface temperature field, the relationship between model parameters and spot diameter, and the relationship between model parameters and laser power and irradiation time, a spatiotemporal evolution model of the rock surface temperature field under laser action is obtained. S6. Using the spatiotemporal evolution model of the rock surface temperature field under laser irradiation, the temperature distribution law of sandstone surface under laser irradiation is predicted.

2. The method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation as described in claim 1, characterized in that, Step S1 also includes: obtaining the laser beam energy density distribution curve and the absolute value curve of the slope of the laser beam energy density curve, and verifying the rationality of the laser beam energy density distribution equation by combining the morphological characteristics of the two curves with the physical laws of laser beam energy propagation.

3. The method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation as described in claim 2, characterized in that, The methods for obtaining the laser beam energy density distribution curve include: Determine the laser power and spot radius parameters, take the coordinates of discrete points within the laser heat-affected zone, substitute them into the laser beam energy density distribution equation, calculate the energy density value corresponding to each point, and plot a curve with the radial position as the abscissa and the corresponding energy density as the ordinate.

4. The method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation as described in claim 2, characterized in that, The methods for obtaining the absolute value curve of the slope of the laser beam energy density curve include: Differentiating the energy density distribution equation with respect to the laser spot radius r yields the slope expression; Substitute the coordinates of discrete location points into the slope expression to calculate the corresponding slope value. After taking the absolute value, plot the curve with the radial position as the abscissa and the corresponding absolute slope value as the ordinate.

5. The method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation as described in claim 1, characterized in that, In step S4, the relationship between the established model parameters and the spot diameter is as follows: ； in, The diameter of the laser spot; The established model parameters are related to laser power and irradiation time as follows: ； in, Laser power; This refers to the irradiation time.

6. The method for predicting the spatiotemporal evolution of sandstone temperature field under laser irradiation as described in claim 5, characterized in that, In step S5, by combining the expression for the rock surface temperature field, the relationship between the model parameters and the spot diameter, and the relationship between the model parameters and the laser power and irradiation time, a spatiotemporal evolution model of the rock surface temperature field under laser irradiation is obtained, including: By combining the expressions for the rock surface temperature field, the relationship between the model parameters and the spot diameter, and the relationship between the model parameters and the laser power and irradiation time, a simplified model of the rock surface temperature field under laser irradiation is obtained: ； This simplified model is a one-dimensional spatiotemporal evolution model focusing on the x-axis direction, based on the axisymmetric characteristics of the temperature field on the rock surface. Next, based on the axisymmetric characteristics of the rock surface temperature field, the simplified model of the rock surface temperature field under laser irradiation is extended to a complete form covering x and y variables, resulting in the final spatiotemporal evolution model of the rock surface temperature field under laser irradiation: ； in, The x-coordinate of the laser spot center is... The vertical coordinate is the center of the laser spot.

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