Deep strong permeable fracture soft rock stratum vertical shaft frozen wall analysis method

Abstract

The invention relates to the technical field of mine freezing construction, in particular to a deep strong permeable fracture soft rock stratum vertical shaft frozen wall analysis method which comprises the steps that freezing points reaching the freezing temperature are collected and fitted into a freezing temperature field; dividing a freezing area according to the position of each freezing point in the freezing temperature field and the time point when the freezing point reaches the freezing temperature, and forming a freezing boundary according to the morphological characteristics of the freezing area; deriving position points at the frozen boundary according to the positions of the frozen boundary in a plurality of time periods, and checking the advancing trend of the frozen boundary according to the spacing distance and the spacing temperature gradient between the position points; based on the advancing trend of the current frozen boundary, setting a boundary condition under the advancing trend; dividing the freezing temperature field into a plurality of evaluation temperature surfaces by using the boundary condition of the current freezing boundary, iterating the freezing temperature field by using the evaluation temperature surfaces, and correcting the freezing boundary; the accuracy of freezing boundary identification is realized, and the safety and efficiency of freezing construction are improved.

Description

Technical Field

[0001] The invention relates to the technical field of mine freezing construction, in particular to a method for analyzing the frozen wall of a vertical shaft in a deep, highly permeable, fissured and weak rock stratum. Background Art

[0002] When implementing vertical shaft freezing in deep, highly permeable, fractured, and weak rock formations, the formation and stability of the frozen wall are key issues for ensuring project safety. Traditional frozen wall analysis methods rely primarily on temperature-gauging hole data, empirical formulas, or static numerical simulations. However, these methods struggle to capture the continuous distribution of the frozen temperature field, reducing the accuracy of identifying the frozen boundary's evolutionary trends and impacting the effectiveness of frozen boundary analysis.

[0003] For example, Chinese patent publication number CN110847955A discloses a method for freezing water in a room-and-pillar residual mining area and re-mining a hollow coal seam, which belongs to the field of coal mining. The present invention, based on determining the feasibility of upward mining of a hollow coal seam, exploring the distribution of coal pillar groups and void groups in the room-and-pillar residual mining area, and the amount and range of water accumulation in the residual mining area, utilizes artificial refrigeration technology to freeze the water in the goaf, turning the liquid water into ice with a certain bearing capacity, filling the void of the room-and-pillar residual mining area, and freezing the collapsed roof stones and remaining coal pillars in the goaf into ice blocks. The entire goaf is filled with a huge ice block frozen from the accumulated water. At the same time, this huge ice block, together with the roof and floor plates of the residual mining area, the coal pillars, and the surrounding rocks at the boundary of the goaf, forms a whole with a certain bearing capacity, and then a special mining method for mining the overlying hollow coal seam is carried out.

[0004] For example, Chinese Patent Publication No. CN112761729A discloses a device and method for a coupled physical simulation experiment of the temperature and displacement field of a mine shaft constructed using a freezing method. The device comprises a model frame, a simulated shaft, a liquid carbon dioxide cylinder, a liquid inlet pipe, a stainless steel freezing pipe, a pipeline temperature sensor, and an optical fiber temperature sensor. Rock and soil samples are fixedly arranged in layers within the model frame. A simulated shaft is inserted into the middle of the rock and soil samples. A liquid return pipe is fixedly installed on the upper portion of the stainless steel freezing pipe. This device features a rigorous, scientific, and highly intelligent layout. Instead of constructing individual monitoring holes and deploying temperature sensors, it utilizes a temperature monitoring system composed of pipeline temperature sensors and optical fiber temperature sensors to achieve multi-point temperature sampling of the rock and soil layer, shaft wall, and pipeline. Strain gauge sensing enables statistical analysis of the three-dimensional deformation of the rock and soil layer and shaft wall, thus achieving a coupled physical simulation of the temperature and displacement field of a mine shaft constructed using the freezing method.

[0005] The existing technology describes how to perform freezing processing and points out that the displacement law under strain can be obtained to identify the current freezing construction process; however, this processing cannot timely track the advancement process of the freezing boundary under the current freezing construction, resulting in the inability to identify local anomalies of the freezing boundary, which reduces the overall construction efficiency. Summary of the Invention

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for analyzing the frozen wall of a vertical shaft in a deep, highly permeable, fractured and weak rock formation, including: S1, reading the temperature value at the temperature measuring hole, collecting the freezing point that reaches the freezing temperature, and fitting it into a freezing temperature field using a numerical fitting method.

[0007] S2, based on the position of each freezing point in the freezing temperature field and the time point when the freezing point reaches the freezing temperature, the freezing area is divided, and the freezing boundary is formed according to the morphological characteristics of the freezing area.

[0008] S3, using the position of the freezing boundary in multiple time periods, deduce the location points at the freezing boundary, and check the advancement trend of the freezing boundary based on the interval distance and interval temperature gradient between the location points.

[0009] S4, based on the advancement trend of the current frozen boundary, the trend analysis of the frozen boundary is performed, and the boundary conditions under the advancement trend are set according to the fitness of the frozen boundary.

[0010] S5, using the boundary conditions of the current freezing boundary to divide the freezing temperature field into multiple evaluation temperature surfaces, iterating the freezing temperature field with the evaluation temperature surfaces, and correcting the freezing boundary with the iterated temperature values.

[0011] The beneficial effects of the present invention are: 1. The present invention converts the data measured by the temperature measuring holes into continuous freezing field temperature with discrete temperature points to illustrate the data of the freezing boundary at the corresponding position under freezing construction; and uses time difference and temperature gradient analysis to associate the morphological characteristics of the freezing boundary with the corresponding time of the freezing boundary, thereby improving the accuracy of freezing boundary identification.

[0012] 2. The present invention tracks the advancement trend of the current frozen boundary by using the distance values ​​of multiple position points at the frozen boundary during the advancement process, with their maximum distance and minimum distance, and corrects the obtained position point displacement values ​​in the form of time thresholds to reduce anomalies during data processing; then, the projected area of ​​each position point is mapped under multiple time periods, and the advancement direction of the frozen boundary is compared with the temperature gradient direction to determine the changes in the temperature consistency of the current frozen boundary, thereby completing the tracking of multiple positions on the frozen boundary.

[0013] 3. The present invention constructs the adaptability of the frozen boundary through indicators such as local freezing rate and thickness change, and combines the frozen boundary update speed to perform mirror update on the data identified on the frozen boundary, check the frozen boundary that has not completed the intersection, and realize adaptive adjustment of the boundary conditions of the frozen boundary in the form of multi-directional optimization processing, correct the problem of single strategy in frozen boundary identification, and improve the accuracy of frozen boundary tracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below with reference to the accompanying drawings and examples.

[0015] Figure 1 The present invention is a flowchart of a method for analyzing the frozen wall of a vertical shaft in a deep, highly permeable, fractured, and weak rock formation.

[0016] Figure 2 It is a schematic diagram of a specific implementation method of step S2 of the present invention.

[0017] Figure 3 It is a schematic diagram of a specific implementation method of step S3 of the present invention.

[0018] Figure 4 It is a schematic diagram of a specific implementation method of step S4 of the present invention.

[0019] Figure 5 It is a schematic diagram of a specific implementation method of step S5 of the present invention. DETAILED DESCRIPTION

[0020] The following embodiments of the present invention are described in detail. The embodiments described below are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in the art or in the product specifications shall be followed.

[0021] See Figure 1 A method for analyzing the frozen wall of a vertical shaft in a deep, highly permeable, fractured, and weak rock formation comprises: S1, reading the temperature value at a temperature measuring hole, collecting the freezing points that reach the freezing temperature, and fitting them into a freezing temperature field using a numerical fitting method.

[0022] S2, based on the position of each freezing point in the freezing temperature field and the time point when the freezing point reaches the freezing temperature, the freezing area is divided, and the freezing boundary is formed according to the morphological characteristics of the freezing area.

[0023] S3, using the position of the freezing boundary in multiple time periods, deduce the location points at the freezing boundary, and check the advancement trend of the freezing boundary based on the interval distance and interval temperature gradient between the location points.

[0024] S4, based on the advancement trend of the current frozen boundary, the trend analysis of the frozen boundary is performed, and the boundary conditions under the advancement trend are set according to the fitness of the frozen boundary.

[0025] S5, using the boundary conditions of the current freezing boundary to divide the freezing temperature field into multiple evaluation temperature surfaces, iterating the freezing temperature field with the evaluation temperature surfaces, and correcting the freezing boundary with the iterated temperature values.

[0026] In step S1, the temperature value identified at the temperature measuring hole is mainly identified to identify the current position that can be at 0°C; at the same time, the temperature measuring hole is configured at the freezing pipe set at the current rock formation. In addition to identifying the position where the freezing temperature is reached, it is also necessary to check the temperature of other areas and the temperature of the rock formation far away from the temperature measuring hole to identify the range covered by the currently configured freezing temperature field, and further identify the advancement of the freezing temperature field in multiple time dimensions.

[0027] Therefore, when fitting the freezing temperature field, step S1 is implemented in such a way as to further include: identifying the current temperature measurement frequency by the temperature values ​​of the temperature measuring holes at multiple positions, defining multiple temperature units by the distance between two adjacent freezing points at the temperature measurement frequency, each temperature unit representing a segmented area, and recording the temperature value at each temperature measurement and the positions of multiple freezing points that reach the freezing temperature in each area.

[0028] Orthogonal decomposition is performed based on the temperature value of each temperature unit, and the decomposed data is fitted as the output frozen temperature field.

[0029] As for the distance between two adjacent freezing points under the temperature measurement frequency, it is used to illustrate the distance between the freezing points that reach the freezing temperature each time the temperature is measured under the current temperature measurement frequency, to illustrate the relative position and advancement distance of the freezing when the rock layer is frozen, and to decompose these continuously frozen data into a temperature vector as the current output freezing temperature field.

[0030] Preferably, the freezing temperature is described as 0°C, and the freezing point will use spatial interpolation to form a temperature line in the current freezing temperature field to illustrate the temperature value and temperature gradient of the freezing temperature field. At the same time, in addition to the freezing point, the freezing temperature field also includes multiple other temperatures that are cooling down or away from the freezing point to illustrate the size of the freezing area and the relative temperature gradient.

[0031] In one embodiment of the present invention, in step S2, it is necessary to identify the freezing boundary of the current freezing temperature field. The freezing boundary generally requires obtaining multiple points below 0°C. For example, based on -1°C, multiple freezing points in the current freezing temperature field are connected. The line segment connected by 0°C will represent the freezing front entering the freezing state. The position of the freezing front will represent the direction in which the freezing boundary may advance. This position will be relatively unstable and needs to be monitored in time to find out whether the currently formed freezing boundary will be affected by strong infiltration of rock water flow or other scenarios, and finally output a freezing boundary that will stably change with time period.

[0032] like Figure 2 As shown, the implementation of step S2 includes: S21, according to the number of cycles of temperature identification, using the time point and position of the freezing point, setting the probability distribution area of ​​each freezing point.

[0033] S22, based on the probability distribution area of ​​the freezing point, the radial gradient of each freezing point in the freezing temperature field is imported to perform temperature field error identification.

[0034] S23, performing regional judgment on the frozen area within the freezing temperature field using the frozen temperature field after error recognition, and obtaining morphological features of the frozen area.

[0035] S24, using the morphological features of the frozen area as a guide, importing the constraints of each frozen point, performing multi-time period differential recognition based on the constraints, and using the boundary after differentiation as the output frozen boundary.

[0036] When setting the probability distribution area of ​​the freezing point, the coordinates of the freezing point at the time of freezing are used as the basis, and the probability distribution of each freezing point reaching the freezing temperature is calculated using Gaussian distribution. The time point used is used to illustrate the time window for currently identifying the freezing point. The probability distribution of the freezing points appearing in the time window is calculated separately to form the probability distribution area of ​​each freezing point to illustrate its distribution form in the data space.

[0037] As for using each freezing point to identify temperature field errors, starting from the location of the freezing pipe, mark the distance between each freezing point and the center of the freezing pipe, and use the distance value to traverse the freezing points one by one from small to large, and judge the temperature gradient value at the current freezing point to see if there is an error between the temperature gradient at some locations and the theoretical temperature gradient, and mark multiple areas with errors to determine whether there are intermittent areas, finger-like protruding areas, and other areas with obvious abnormal temperature gradient distribution in the current temperature field. These areas will represent whether the current rock formation has strong permeability and cracks. These rock formation structures will affect the freezing effect of the rock formation and need to be identified and processed separately, and the time and trend of the formation of the freezing boundary at the corresponding position should be tracked.

[0038] When performing regional judgment on the freezing temperature field in step S23, it includes: when the area is judged to be an intermittent area, the area of ​​the intermittent distribution of the freezing area is used as the morphological feature of the freezing area; when the area is judged to be an annular distribution area, the flow direction of the annular distribution area is used as the morphological feature of the freezing area; when the area is judged to be a finger-like protruding area, the temperature gradient and mutation direction of the local protrusion are used as the morphological features of the freezing area.

[0039] If it is identified as a ring-shaped distribution area at this time, it means that the temperature contour lines are concentric circles, indicating that the current frozen area distribution is relatively even, and its thickness can be directly calculated to identify the boundary thickness of the current freezing boundary; if it is an intermittent area, it means that there may be various rock distribution forms such as cracks and fissures at the corresponding position, which will cause discontinuous jumps or breaks in the contour lines when the rock layer is frozen. This means that the corresponding position is prone to seepage risks, which affects the current trend and efficiency of soil freezing and needs to be marked to assist in the subsequent adjustment of the freezing intensity; for finger-like protruding areas, it means that the temperature contour lines have a sudden change in direction. This phenomenon will represent a local anomaly in the current freezing trend, which may lead to an increase in overall freezing consumption and abnormal development of the freezing trend. It is necessary to associate the seepage direction of the corresponding position with the constraint conditions of the corresponding position of the freezing point to determine the position where a stable freezing boundary can be formed.

[0040] The constraints described in step S24 will select different condition values ​​according to the different judgment areas. For example, the intermittent area mainly identifies the minimum freezing thickness, the maximum allowable circle time and the maximum supplementary cooling value; the annular distribution area uses the freezing wall closure to judge whether it is completely closed, and the radial thickness fluctuation to identify whether it is uniformly frozen; the finger-like protruding area uses the advancement speed of the freezing front; these contents are used as the currently used constraints.

[0041] Then, the frozen positions described are evaluated using displacement, thickness change, and constraint condition difference values ​​in the form of time periods to verify whether the current frozen boundary is in a stable form.

[0042] The implementation of step S24 further includes: performing a multi-target differential query on the frozen area based on the boundary displacement and thickness change rate of each frozen area in adjacent time periods to determine a frozen boundary that meets the constraint conditions.

[0043] At this time, when the constraints are met, the boundary displacement and thickness change rate relative to the target value must be minimized. Then, the constraints of the current frozen area are checked. When the constraints are mapped consistently after identification in multiple time periods, the boundary parts with consistent mappings and the smallest change rate are used as the output frozen boundaries.

[0044] Preferably, the above-mentioned boundary displacement is directly calculated by the position value of each point on the boundary line of the frozen area, and then divided by the average value of the displacement value under normal freezing to obtain the rate of change relative to the target value. For the thickness change rate, the ratio of the distance from the center of the frozen area to its boundary is divided by the average value of the distance from the center of the frozen area to the boundary under normal freezing to obtain the rate of change of the thickness change rate relative to the target value. When these two values ​​are both minimum and the constraints mapped by the current frozen area in multiple time periods are consistent, it means that the boundary portion of the current frozen area is stable and can be output as a frozen boundary.

[0045] Preferably, when performing constraint condition mapping, the temperature of the current frozen area is used to query the constraint condition from the database, and the shape features after the query are synchronized to each frozen area.

[0046] Preferably, the above-mentioned number of cycles represents the frequency of measuring the current freezing temperature field and is set to illustrate the change of the current freezing position in multiple time periods.

[0047] In one embodiment of the present invention, when checking the advancement trend of the frozen boundary, relative identification processing of the seepage field is also required, such as verifying the relative heat change of the current frozen boundary during advancement using the energy conservation equation.

[0048] ;in, Indicates the thermal conductivity of the rock layer. In this case, the thermal conductivity is obtained by directly measuring the rock layer currently being artificially frozen. 、 represent the density and specific heat capacity of water respectively; Represents the seepage velocity vector. At this time, the seepage velocity vector will verify its temperature gradient by inferring the water flow speed under the current rock layer, or verify its seepage velocity vector by the currently identified temperature gradient; represents the temperature gradient, which indicates the temperature gradient of the current freezing temperature field at the freezing boundary. The first term on the left side of the above formula represents heat conduction, and the second term represents the heat convection caused by seepage, which is used to explain the part that takes away heat. This shows whether the freezing temperature field of the current rock layer conforms to normal rules under the advancing freezing boundary in the presence of water seepage.

[0049] Then, its temperature field is identified, for example, its temperature field is analyzed, the part reaching the freezing boundary is identified, and the freezing radius of the freezing boundary is identified to identify the size of the freezing area where the freezing pipe is currently used, so as to further judge the freezing condition of the current rock formation vertical shaft freezing wall.

[0050] Assuming that the seepage flows uniformly in the radial direction and its velocity is constant, the analytical value of the temperature field is expressed as shown below.

[0051] ;in, represents the temperature at radial distance r; Indicates the freezing pipe wall temperature, which is obtained by directly measuring the freezing pipe temperature; It indicates that there is no disturbance of the formation temperature in the distance, that is, the temperature of the rock formation under normal conditions; represents the modified second-kind zero-order Bessel function, which represents the solution of the differential equation. When Pe is 0, , its calculated value approaches infinity, at this time the temperature field approaches concentric circles. If Pe is greater than 0, it means that there is seepage, the temperature field is stretched, and an asymmetric distribution is formed. As for the denominator, , is used to illustrate the normalization effect, so that when the radial distance r is the same as the freezing pipe radius, the temperature of the freezing pipe wall and the temperature at the radial distance r are the same value in the calculation; represents the Peclet number, which characterizes the competitive relationship between seepage and heat conduction. ,in represents the radial velocity, which can be solved by the energy conservation equation to determine the current Péclet number; Indicates the radius of the freezing pipe; Represents the radial coordinate, i.e., the distance from the center of the freezing tube to a certain point. After completing the identification of multiple temperatures at the radial distance, the temperatures measured by the current temperature measuring hole can be compared to identify the temperatures at multiple locations in the current freezing temperature field. The implementation of the above calculation formula is mainly used to identify the temperature variation pattern of multiple locations in the current freezing temperature field to assist in determining the current freezing radius. For example, the solution for the freezing radius is: By solving the form of x, we can know the corresponding x value and describe its freezing radius. This x is a dimensionless parameter, which is essentially the variable after the actual freezing radius is normalized by the freezing pipe radius and the Peclet number. Expressed as: The final freezing radius represents the distance from the current freezing pipe center to the freezing front. It determines the thickness of the frozen wall. The freezing radius is used to determine whether the frozen wall can be successfully closed and whether it meets the pressure resistance requirements.

[0052] The above formula is used to check multiple freezing points at the current freezing boundary to identify whether the trend of the freezing points and the value are in line with the normal freezing rules. Then the frozen boundary verification trend is promoted to identify whether the current shaft freezing wall meets the standards.

[0053] like Figure 3As shown, the implementation of step S3 further includes: S31, taking the frozen boundary connection as the fixed boundary, and checking the position points on the fixed boundary and the position points on the frozen boundary respectively.

[0054] S32, subtract the displacement values ​​with a fixed boundary, check the interval distances of multiple location points, map the projected area of ​​each location point with the maximum and minimum distances of the interval distances, and set the change trend of each location point with the differential area value of the projected area in continuous time periods.

[0055] S33, determining whether the change trend of the current position point is consistent with the direction of the interval temperature gradient. If consistent, outputting the corresponding change trend as the advancement trend of the freezing boundary.

[0056] If they are inconsistent, S34 checks the projected area of ​​each location point and sets the advancement trend of the freezing boundary according to the inclination angle of the projected area.

[0057] Preferably, the fixed boundary represents the portion of the frozen boundary that is determined to be unchanged in multiple time periods, usually located in an area that has been completely circled, has stable temperature and no longer expands; these portions of the frozen boundary that are no longer changing are used as a reference coordinate system to identify the expansion direction and rate of the current frozen boundary relative to the fixed area, and at this time, the area in the freezing temperature field that reaches the freezing temperature the earliest and forms a closed structure is selected; this area will appear as a circular closed surface, a line segment or a curve composed of multiple points.

[0058] Preferably, when subtracting displacement values ​​with a fixed boundary, a point that does not change at a certain time point is selected as a reference, and then the position points on the frozen boundary in subsequent time periods are compared, and then the interval distance of multiple position points is obtained. The interval distance is obtained by subtracting the position points as displacement vectors, and the modulus of the displacement is used as the interval distance.

[0059] Preferably, the maximum distance obtained is used to illustrate the farthest expansion distance of a certain point on the boundary, and the minimum distance indicates that there is almost no expansion or even contraction at a certain point on the boundary. At this time, it is necessary to judge the changing trend of the interval distance in multiple time periods according to the maximum distance and the minimum distance to verify the advancement of the current frozen boundary.

[0060] That is, step S32 also needs to check the limit value of the interval distance to determine the advancement trend of the frozen boundary relative to the fixed boundary under the advancement of the frozen boundary.

[0061] The implementation method of step S32 also includes: classifying the maximum distance and minimum distance of the interval distances between the position points according to multiple time periods to obtain displacement time series data. At this time, the maximum distance and minimum distance of the position points in different time periods are clustered, and then the values ​​of the maximum distance and minimum distance are used to update the displacement time series data of the current frozen boundary advancement.

[0062] It is determined whether the time interval between consecutive minimum distances is less than a first time threshold. If it is less than the first time threshold, the corresponding minimum distances are merged to correct the displacement time series data.

[0063] If it is greater than the first time interval, check whether the time interval of the continuous maximum distances is less than the second time threshold. If it is less than the second time threshold, delete the continuous maximum distances and select the middle value of the continuous maximum distances as the new maximum distance.

[0064] Preferably, the minimum distance described above refers to the minimum displacement value obtained by averaging the displacement relative to the freezing boundary in multiple time periods, and the same applies to the maximum distance; at this time, the identification of the maximum distance and the minimum distance is used to illustrate whether the freezing stagnation and local rapid advancement trends exist.

[0065] For example, the minimum distance can be expressed as ;in, Indicates the minimum distance, which is the minimum distance relative to multiple consecutive time periods. The distance value is calculated based on the local standard deviation method, and it is judged whether the minimum distance is less than the lower limit of the confidence interval of the displacement of the position point on the frozen boundary. If it is less than the lower limit, the calculated minimum distance is considered to be the minimum distance for the current judgment. Otherwise, the continuous minimum distance judgment is not performed. It should be noted that the confidence interval used adopts a 95% confidence level to identify whether the current position point is in a stagnant state. Represents the average displacement value of multiple time steps. The average displacement value is in the form of a moving average and is calculated based on multiple consecutive time periods. represents the standard deviation, which is obtained based on the time series of all displacement values ​​on the current frozen boundary; Represents a control coefficient, which controls the sensitivity of the current value and ranges from 1 to 2. Obtaining the minimum distance at this point indicates whether the frozen boundary is experiencing continuous stagnation, useful for assessing overall changes. The maximum distance is implemented in the same way as the minimum distance: it determines whether it exceeds the upper limit of the confidence interval for the displacement of the point on the frozen boundary. If so, a continuous maximum distance determination is performed, followed by identifying any rapidly advancing local locations. The direction of these locations is then combined to identify the advancing trend of the frozen boundary.

[0066] For example, if the minimum distance appears continuously and is less than the first time threshold, it is considered that the freezing and stagnation phenomenon may continue. If the maximum distance appears twice in a row and is less than the second time threshold, it is considered that there is a local rapid advance phenomenon. In this case, the first time threshold is greater than the second time threshold. The first time threshold is set based on the expected freezing circle time, and its value is one-fifth to one-tenth of the expected freezing circle time. The second time threshold represents the time for a single frozen boundary identification, that is, a single time period for checking the frozen boundary.

[0067] Preferably, the acquired position points are obtained on the freezing front of the current freezing boundary, and the distance value of the position points changing with time relative to the fixed and unchanging freezing boundary is identified to illustrate the advancement of the current freezing boundary and whether the freezing boundary can complete the freezing task.

[0068] Preferably, when mapping the projected area based on the maximum and minimum distances, each point is treated as a small area. For example, a scaling factor is multiplied by the distance value, and the product is used as the projected area at that time. The scaling factor can be set according to the frozen wall analysis scenario, or a fixed value such as 2 or 5 can be used to describe the projected area, thereby amplifying the distance value to visualize the current frozen boundary advancement speed. The difference in projected area between adjacent time points is then used to illustrate the change trend.

[0069] Preferably, when judging whether the changing trend of the current position point is consistent with the direction of the interval temperature gradient, the vector of the changing trend of the position point is compared with the direction of the interval temperature gradient, and the vectors of these two values ​​are judged whether their directions are consistent using the cosine value of the angle. At this time, the average value of the consistent direction is used as the threshold for judging whether the cosine value of the angle is in the same direction.

[0070] As for the interval temperature gradient, it is used to illustrate the direction of the current cold discharge. When the cold discharge direction is consistent with the advancement direction of the freezing boundary, it means that there is no abnormality at present. At this time, consistency analysis is mainly used to identify abnormal formation seepage or cold distribution, and to verify whether various areas such as finger-like protrusions and local stagnation areas exist at the current freezing boundary, so as to timely adjust the layout of the freezing pipes and the brine temperature to prevent the risk of freezing instability.

[0071] Preferably, when the directions are consistent, the local displacement direction of the current position point is expanded outward, and the local displacement direction of the current position point is fitted with multiple adjacent points, and the tangent direction of the fitted displacement vector is used as the output advancement trend of the frozen boundary; at this time, the direction obtained is biased towards the advancement trend of the local position, and this part of the trend is displayed in the form of a tangent to illustrate the advancement of the current frozen boundary at the local position.

[0072] In one embodiment of the present invention, Figure 4 As shown, the implementation of step S4 includes: S41, based on the advancement trend of the freezing boundary, taking the local freezing rate and thickness change value of the freezing boundary as the fitness of the corresponding freezing boundary.

[0073] S42, checking the optimal advancing position of the freezing boundary based on the fitness of the freezing boundary, and determining whether the current freezing boundary forms a closed circle area. If so, determining the boundary condition of the current freezing boundary based on the time point when the freezing boundary completes the circle.

[0074] S43, if it is not formed, then the optimal advancement position is updated in a mirror image according to the update speed of the fitness of the frozen boundary, and a multi-attribute decision matrix is ​​constructed.

[0075] S44, traversing the area covered by the freezing boundary according to the multi-attribute decision matrix of the freezing boundary, checking the missing position of each area, updating each area with the local freezing rate at the missing position, and setting the boundary conditions of the freezing boundary.

[0076] Preferably, the adaptability of the frozen boundary can be used as the basis for sorting the freezing rates and thickness changes of multiple local positions of the frozen boundary. First, sort by freezing rate. If the freezing rates are the same, sort by thickness change. Alternatively, after normalizing the freezing rate and thickness change, use their weighted values ​​as the basis for sorting. The weighted weights can be selected in the form of 0.5, 0.5.

[0077] Preferably, when checking the optimal advancement position of the freezing boundary, after sorting by local freezing rate and thickness change value, the local position with the largest weight or satisfying the consistency of temperature gradient direction after sorting, and the local position at the top of the sorting is used as the optimal advancement position, and it is determined whether a closed circle area is formed when the optimal advancement position is currently obtained.

[0078] As for the mirror update of the optimal advancing position, the optimal advancing position is mirrored to generate symmetrical advancing points. Then, according to the symmetrical advancing points, a set of data corresponding to the symmetrical advancing points, including local freezing rate, thickness change value, position coordinates, and the direction of the current advancing trend, are combined into a multi-attribute decision matrix. Then, according to the values ​​of the multi-attribute decision matrix in multiple time periods, the area where the current frozen boundary is located is traversed to obtain the freezing rate of the frozen boundary at the corresponding position when the circle is not completed, so as to obtain the boundary conditions that explain the relationship between the current freezing rate and freezing efficiency.

[0079] When the freezing boundary is completed, its boundary conditions include thermodynamic boundary, mechanical boundary, fluid boundary, time boundary and control boundary; for example, the thermodynamic boundary will record the temperature of the current freezing temperature field, the mechanical boundary will verify the stress of the current freezing wall, the fluid boundary will verify the current seepage speed, the time boundary will mark the time of completion of freezing, and the control boundary will indicate whether to input cooling amount, etc., so as to complete the boundary condition setting of the freezing boundary.

[0080] If the intersection is not completed, the boundary conditions will record information such as freezing rate, thickness change, temperature value, whether there is seepage disturbance, data update time, etc., and use these data as output boundary conditions.

[0081] In one embodiment of the present invention, Figure 5 As shown, the implementation method of step S5 includes: S51, using an equivalent identification method, processing the freezing boundaries at the circumferential, radial and axial directions of each evaluation temperature surface, and sequentially identifying the freezing boundaries in multiple directions and the freezing radius corresponding to the freezing boundaries.

[0082] S52, using the advancement value of the freezing radius in each direction, correcting the current freezing boundary, conditionally constraining the freezing boundary with the positioning size of the freezing radius in the three-dimensional direction, and determining the equivalent thickness of the freezing boundary in each direction.

[0083] S53, using the equivalent thickness of the frozen boundary at each position and the control cluster of the temperature value, jointly analyzes the frozen temperature field, optimizes the frozen boundary at multiple positions according to the joint analysis results, and completes the frozen boundary correction.

[0084] Preferably, when performing a joint analysis on the freezing temperature field, the control clusters of the currently identified equivalent thickness and temperature values ​​are used for processing. Each control cluster represents a group of similar areas with consistent freezing behaviors. These areas will have consistent temperature gradients and freezing rates. The temperature and freezing rate of the freezing boundary at each position are then marked to determine the correction method of the freezing boundary at multiple positions, such as increasing the cold input to the slowly advancing cluster; suppressing the advancing area by using control methods such as increasing the brine temperature; reinforcing the weak areas, such as grouting and local cooling, to reinforce some frozen weak areas; so that the area that is finally frozen can maintain a certain structural strength, and update the combination of relevant boundary conditions at the freezing boundary.

[0085] Preferably, when identifying the equivalent thickness, the identification is carried out in sequence in the circumferential, radial and axial directions respectively; when identifying in the circumferential direction, the main observation is whether the freezing boundary has completed the intersection and the thickness of the completed intersection part; in the radial direction, the main observation is the thickness of the freezing boundary radiating outward from the freezing tube as the center, and the value of the boundary that diffuses outward is observed; as for the axis, the part parallel to the axis of the freezing tube is observed to check whether this part has completed freezing. As for the freezing thickness, the area where the temperature value reaches the freezing temperature can be observed through multiple time periods, and methods such as geological radar, resistivity imaging, ultrasonic detection, etc. are used to obtain the thickness of the freezing boundary at the corresponding position. As for the equivalent thickness, it is used to illustrate the thickness value identified in the same area in three directions. The value will be combined into a data pair or a vector in the three directions to represent the thickness value in a certain frozen area to illustrate the advancement of the current freezing boundary. These values ​​are then used as boundary conditions for freezing boundary correction and output to the external control terminal, and the current freezing method is adjusted according to the data of the external control terminal.

[0086] Preferably, when the frozen boundary is optimized at multiple positions based on the joint analysis results, its implementation method also includes: finding whether the boundary conditions corresponding to the frozen boundary before and after optimization exceed the historical data range; if so, based on the time point of the current boundary condition correction, the frozen boundary is corrected using the moving average of the boundary conditions; if not, the optimized boundary conditions are output to the corresponding frozen boundary.

[0087] At this time, check whether the boundary conditions exceed the historical data range. This is mainly done for frozen boundaries that have not completed the circle. Compare the values ​​of the freezing rate that need to be configured after the update with the historical data to see whether the currently set boundary conditions are reasonable. If it exceeds the historical data range, it means that the current data setting is too large or too small. The boundary conditions need to be corrected with the moving average of continuous time periods to complete the relative correction of the frozen boundary. As for the situation that it does not exceed the range, just note that the correction is completed.

[0088] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention, which are still covered by the scope of protection of the present invention.

Claims

1. A method for analyzing the frozen wall of a deep, highly permeable, fractured, and weak rock formation vertical shaft, characterized by: include: S1, read the temperature value at the temperature measuring hole, collect the freezing point that reaches the freezing temperature, and use numerical fitting to fit it into the freezing temperature field; S2, based on the position of each freezing point in the freezing temperature field, the freezing area is divided according to the time point when the freezing point reaches the freezing temperature, and the freezing boundary is formed according to the morphological characteristics of the freezing area; S3, using the position of the freezing boundary in multiple time periods to deduce the location points at the freezing boundary, and using the interval distance and interval temperature gradient between the location points to check the advancement trend of the freezing boundary; S4, based on the advancement trend of the current frozen boundary, the trend analysis of the frozen boundary is performed, and the boundary conditions under the advancement trend are set according to the fitness of the frozen boundary; S5, using the boundary conditions of the current freezing boundary to divide the freezing temperature field into multiple evaluation temperature surfaces, iterating the freezing temperature field with the evaluation temperature surfaces, and correcting the freezing boundary with the iterated temperature values.

2. The method for analyzing frozen walls in deep, highly permeable, fractured, and weak rock formations of a vertical shaft according to claim 1, characterized in that: The implementation of step S1 further includes: The current temperature measurement frequency is identified by the temperature values ​​of the temperature measuring holes at multiple positions, and multiple temperature units are defined by the distance between two adjacent freezing points at the temperature measurement frequency; Orthogonal decomposition is performed based on the temperature value of each temperature unit, and the decomposed data is fitted as the output frozen temperature field.

3. The method for analyzing frozen walls in deep, highly permeable, fractured, and weak rock formations according to claim 1, wherein: That is, the implementation of step S2 includes: S21, according to the number of cycles of temperature identification, using the time point and position of the freezing point, setting the probability distribution area of ​​each freezing point; S22, using the probability distribution area of ​​the freezing point, importing the radial gradient of each freezing point in the freezing temperature field to perform temperature field error identification; S23, performing regional judgment on the frozen area within the freezing temperature field using the frozen temperature field after error recognition, and obtaining morphological features of the frozen area; S24, using the morphological features of the frozen area as a guide, importing the constraints of each frozen point, performing multi-time period differential recognition based on the constraints, and using the boundary after differentiation as the output frozen boundary.

4. The method for analyzing frozen walls in deep, highly permeable, fractured, and weak rock formations of a vertical shaft according to claim 3, wherein: When performing regional determination on the freezing temperature field in step S23, the implementation thereof includes: When the area is judged to be an intermittent area, the area of ​​the frozen area in the intermittent distribution is used as the morphological feature of the frozen area; when the area is judged to be an annular distribution area, the flow direction of the annular distribution area is used as the morphological feature of the frozen area; when the area is judged to be a finger-like protrusion area, the temperature gradient and mutation direction of the local protrusion are used as the morphological features of the frozen area.

5. The method for analyzing frozen walls of deep, highly permeable, fractured, and weak rock formations in vertical shafts according to claim 3, characterized in that: The implementation of step S24 further includes: Based on the boundary displacement and thickness change rate of each frozen area in adjacent time periods, a multi-objective differential query is performed on the frozen area to determine the frozen boundary that meets the constraint conditions.

6. The method for analyzing frozen walls of deep, highly permeable, fractured, and weak rock formations in a vertical shaft according to claim 1, characterized in that: The implementation of step S3 further includes: S31, taking the frozen boundary connection as the fixed boundary, checking the position points on the fixed boundary and the position points on the frozen boundary respectively; S32, subtracting displacement values ​​with a fixed boundary to check the distances between multiple locations, mapping the projected area of ​​each location using the maximum and minimum distances between them, and setting the change trend of each location using the differential area value of the projected area in consecutive time periods; S33, determining whether the change trend of the current position point is consistent with the direction of the interval temperature gradient; if consistent, outputting the corresponding change trend as the advancement trend of the freezing boundary; If they are inconsistent, S34 checks the projected area of ​​each location point and sets the advancement trend of the freezing boundary according to the inclination angle of the projected area.

7. The method for analyzing frozen walls in deep, highly permeable fractured, weak rock formations according to claim 6, characterized in that: The implementation of step S32 further includes: The maximum and minimum distances between the position points are classified according to multiple time periods to obtain displacement time series data; Determine whether the time interval between consecutive minimum distances is less than a first time threshold. If so, merge the corresponding minimum distances and correct the displacement time series data. If it is greater than the first time interval, check whether the time interval of the continuous maximum distances is less than the second time threshold. If it is less than the second time threshold, delete the continuous maximum distances and select the middle value of the continuous maximum distances as the new maximum distance.

8. The method for analyzing frozen walls of deep, highly permeable, fractured, and weak rock formations in a vertical shaft according to claim 1, characterized in that: The implementation of step S4 includes: S41, based on the freezing boundary advancement trend, the local freezing rate and thickness change value of the freezing boundary are used as the fitness of the corresponding freezing boundary; S42, checking the optimal advancing position of the freezing boundary based on the fitness of the freezing boundary, and determining whether the current freezing boundary forms a closed circle. If so, the boundary condition of the current freezing boundary is determined based on the time point when the freezing boundary completes the circle. S43, if it is not formed, then the optimal advancement position is updated in a mirror image according to the update speed of the fitness of the frozen boundary, and a multi-attribute decision matrix is ​​constructed; S44, traversing the area covered by the freezing boundary according to the multi-attribute decision matrix of the freezing boundary, checking the missing position of each area, updating each area with the local freezing rate at the missing position, and setting the boundary conditions of the freezing boundary.

9. The method for analyzing frozen walls in deep, highly permeable, fractured, and weak rock formations of a vertical shaft according to claim 1, characterized in that: The implementation of step S5 includes: S51, using an equivalent identification method, processing the freezing boundaries in the circumferential, radial, and axial directions of each evaluation temperature surface, and sequentially identifying the freezing boundaries in multiple directions and the freezing radii corresponding to the freezing boundaries; S52, using the advancement value of the freezing radius in each direction, correcting the current freezing boundary, constraining the freezing boundary with the positioning size of the freezing radius in the three-dimensional direction, and determining the equivalent thickness of the freezing boundary in each direction; S53, using the equivalent thickness of the frozen boundary at each position and the control cluster of the temperature value, jointly analyzes the frozen temperature field, optimizes the frozen boundary at multiple positions according to the joint analysis results, and completes the frozen boundary correction.

10. A method for analyzing frozen walls in deep, highly permeable fractured, weak rock formations in a vertical shaft according to claim 9, characterized in that: When the frozen boundary is optimized at multiple locations using the combined analysis results, the implementation method also includes: Check whether the boundary conditions corresponding to the frozen boundaries before and after optimization exceed the historical data range. If so, use the moving average of the boundary conditions to correct the frozen boundaries based on the time point of the current boundary condition correction. If not, output the optimized boundary conditions to the corresponding frozen boundaries.

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