A method for analyzing a freezing wall of a vertical shaft in deep and strong water-permeable fractured and weak rock stratum

Abstract

The present application relates to mine freezing construction technical field, specifically is a kind of deep strong water permeable fissure soft rock stratum shaft freezing wall analysis method, comprising: collecting the freezing point reaching freezing temperature, fitting as freezing temperature field;Based on the position of each freezing point in freezing temperature field, with the time point that freezing point reaches freezing temperature, divide freezing area, and form freezing boundary according to the morphological characteristics of freezing area;With the position of freezing boundary in multiple time periods, deduce the position point at freezing boundary, with the interval distance and interval temperature gradient between position point, view the advancing trend of freezing boundary;Based on the advancing trend of current freezing boundary, set boundary condition under advancing trend;Freezing temperature field is segmented into multiple evaluation temperature surfaces using the boundary condition of current freezing boundary, to evaluate temperature surface to freezing temperature field iteration, correct freezing boundary;Realize the accuracy of freezing boundary identification, improve the safety and efficiency of freezing construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mine freezing construction, in particular to a deep strong water permeable fissure soft rock stratum shaft freezing wall analysis method. BACKGROUND

[0002] When implementing shaft freezing construction in deep strong water permeable fissure soft rock stratum, the formation and stability of the freezing wall are the core problems to ensure the safety of the project. The traditional freezing wall analysis method mainly relies on temperature measurement hole data, empirical formula or static numerical simulation. However, when identifying the freezing temperature field, it is difficult to capture the continuous distribution characteristics of the temperature field, resulting in reduced accuracy of identifying the evolution trend of the freezing boundary and affecting the analysis effect of the freezing boundary.

[0003] For example, Chinese patent publication No. CN110847955A discloses a method for freezing room column type residual mining area water accumulation to recover empty coal seam, which belongs to the field of coal mining. Based on the feasibility of uphole mining of empty coal seam, the distribution of column group and empty area group in the room column type residual mining area, the amount and range of water accumulation in the residual mining area, the artificial refrigeration technology is used to freeze the water in the goaf, so that the liquid water becomes ice with certain bearing capacity, filling the empty area of the room column type residual mining area, and the collapsed roof stones and residual coal pillars in the goaf are also frozen into ice blocks. The entire goaf is filled with huge ice blocks frozen by water, and at the same time, the huge ice blocks and the top and bottom plates of the residual mining area, the coal pillars and the goaf boundary rock collectively form a whole with certain bearing capacity. Then, a special mining method is used to mine the overlying empty coal seam.

[0004] For example, Chinese patent publication No. CN112761729A discloses a mine shaft temperature-displacement field coupling physical simulation experiment device and method based on freezing method construction, which comprises a model frame, a simulation shaft, a liquid carbon dioxide steel bottle, a liquid inlet pipe, a stainless steel freezing pipe, a pipe temperature sensor, and an optical fiber temperature sensor. The rock and soil samples are fixedly arranged in the model frame; the simulation shaft is inserted into the middle part of the rock and soil samples; and the stainless steel freezing pipe is fixedly provided with a liquid return pipe. The present application has strict and scientific layout and high intelligence degree, replaces the operation mode of separate construction monitoring hole and temperature sensor arrangement, realizes multi-point temperature sampling of rock and soil layer, shaft wall and pipe by means of temperature monitoring system composed of pipe temperature sensor and optical fiber temperature sensor, realizes statistics of three-dimensional deformation amount of rock and soil layer and shaft wall by means of strain gauge sensing, and realizes mine shaft temperature-displacement field coupling physical simulation based on freezing method construction.

[0005] The prior art describes how to perform the freezing process and points out that the displacement law under the strain is obtained to identify the current freezing construction process; however, such processing cannot timely track the advancing process of the freezing boundary under the current freezing construction, resulting in the inability to identify local abnormalities of the freezing boundary, thereby reducing the overall construction efficiency. SUMMARY

[0006] To solve the above technical problems, the technical scheme adopted by the present application is: a deep strong water permeable fracture soft rock stratum shaft freezing wall analysis method, comprising: S1, reading the temperature value at the temperature measuring hole, collecting the freezing point reaching the freezing temperature, and fitting the freezing temperature field by numerical fitting.

[0007] S2, based on the position of each freezing point in the freezing temperature field, the time point at which 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, with the position of the freezing boundary in multiple time periods, the position point of the freezing boundary is derived, and the interval distance and interval temperature gradient between the position points are used to view the advancing trend of the freezing boundary.

[0009] S4, based on the advancing trend of the current freezing boundary, the trend analysis of the freezing boundary is performed, and the boundary condition under the advancing trend is set according to the fitness of the freezing boundary.

[0010] S5, the freezing temperature field is divided into multiple evaluation temperature surfaces using the boundary condition of the current freezing boundary, the freezing temperature field is iterated using the evaluation temperature surface, and the freezing boundary is corrected according to the temperature value after iteration.

[0011] The present application has the following advantages: first, the present application converts the discrete temperature points into continuous freezing field temperature by fitting the data measured by the temperature measuring hole, and explains the data of the corresponding position freezing boundary under the freezing construction; and the morphological characteristics of the freezing boundary are associated with the corresponding time of the freezing boundary using time difference and temperature gradient analysis, thereby improving the accuracy of freezing boundary identification.

[0012] Second, the present application tracks the advancing trend of the current freezing boundary by using the distance value of multiple position points at the freezing boundary in the advancing process, using the maximum distance and minimum distance, correcting the position point displacement value obtained in the form of a time threshold to reduce data processing abnormalities, and then comparing the advancing direction of the freezing boundary with the temperature gradient direction by mapping the projection area of each position point in multiple time periods, determining the change of the current freezing boundary in temperature consistency, and completing the tracking of multiple positions on the freezing boundary.

[0013] Thirdly, the application constructs the fitness of the frozen boundary through the indexes of local freezing rate, thickness change, etc., and in combination with the frozen boundary update speed, the data identified on the frozen boundary is updated in the form of mirror image, the frozen boundary which has not completed the loop is viewed, and in the form of multi-directional optimization processing, the adaptive adjustment of the boundary condition of the frozen boundary is realized, the problem of single strategy in the identification of the frozen boundary is corrected, and the accuracy of the frozen boundary tracking is improved. BRIEF DESCRIPTION OF DRAWINGS

[0014] The application will be further described below in combination with the drawings and embodiments.

[0015] Figure 1 It is a flowchart of a deep strong water permeable fissure soft rock stratum vertical shaft frozen wall analysis method.

[0016] Figure 2 It is a specific implementation mode schematic diagram of step S2 of the application.

[0017] Figure 3 It is a specific implementation mode schematic diagram of step S3 of the application.

[0018] Figure 4 It is a specific implementation mode schematic diagram of step S4 of the application.

[0019] Figure 5 It is a specific implementation mode schematic diagram of step S5 of the application. DETAILED DESCRIPTION

[0020] The embodiments of the application will be described in detail below. The embodiments described below are exemplary and are only used to explain the application and cannot be understood as a limitation of the application. If the specific technology or condition is not indicated in the embodiments, the technology or condition described in the literature in the art or according to the product instruction is used.

[0021] Reference Figure 1 A deep strong water permeable fissure soft rock stratum vertical shaft frozen wall analysis method comprises the following steps: S1, reading the temperature value at the temperature measuring hole, collecting the frozen point reaching the frozen temperature, and fitting the frozen temperature field in a numerical fitting manner.

[0022] S2, based on the position of each frozen point in the frozen temperature field, dividing the frozen area according to the time point at which the frozen point reaches the frozen temperature, and forming the frozen boundary according to the morphological characteristics of the frozen area.

[0023] S3, deducing the position point at the frozen boundary based on the position of the frozen boundary in a plurality of time periods, and viewing the advancing trend of the frozen boundary according to the interval distance and interval temperature gradient between the position 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 an embodiment of the present application, in step S2, the freezing boundary of the current freezing temperature field needs to be identified, which generally needs to obtain a plurality of points below 0°C, for example, based on -1°C, a plurality of freezing points in the current freezing temperature field are connected, and the line segment connected at 0°C represents the freezing front entering the freezing state, the position at the freezing front represents the direction in which the freezing boundary is likely to advance, which is relatively unstable and needs to be monitored in time to find out whether the current formed freezing boundary will be affected by the strong permeability of the rock stratum water flow or other scenarios, and finally output a freezing boundary that will change stably over time.

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

[0033] S22, using the probability distribution area of the freezing point, importing the radial gradient of each freezing point in the freezing temperature field, and performing temperature field error identification.

[0034] S23, using the freezing temperature field after error identification, performing area judgment on the freezing area in the freezing temperature field, and obtaining the morphological characteristics of the freezing area.

[0035] S24, using the morphological characteristics of the freezing area as a guide, importing the constraint conditions of each freezing point, performing multi-time period difference identification using the constraint conditions, and using the boundary after difference as the output freezing 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 indicate the time window of the currently identified freezing point. After calculating the probability distribution of each freezing point in the time window, the probability distribution area of each freezing point is formed to indicate its distribution form in the data space.

[0037] When using each freezing point to identify the temperature field error, the distance between each freezing point and the center of the freezing pipe is marked from the position of the freezing pipe. The distance values are traversed from small to large to judge the temperature gradient value at the position of the current freezing point and check whether there is an error value between the temperature gradient at the position and the theoretical temperature gradient. Mark a plurality of regions with errors to judge whether there are intermittent regions, finger-shaped protruding regions and other regions with obvious temperature gradient distribution abnormalities in the current temperature field. These regions will represent whether there is strong permeability in the current rock stratum and whether there are cracks and other situations. These rock stratum structures will affect the freezing effect of the rock stratum and need to be identified and processed separately, and the time and trend of forming the freezing boundary at the corresponding position are tracked.

[0038] When the frozen temperature field is regionally judged in step S23, the following is included: when the region is judged to be an intermittent region, the area of the region in which the frozen region is intermittently distributed is taken as the morphological feature of the frozen region; when the region is judged to be a ring-distributed region, the flow direction of the ring-distributed region is taken as the morphological feature of the frozen region; and when the region is judged to be a finger-shaped protruding region, the local convex temperature gradient and the mutation direction are taken as the morphological feature of the frozen region.

[0039] At this time, when the region is identified as a ring-distributed region, it indicates that the temperature contour is in the form of concentric circles, and it indicates that the current frozen region is evenly distributed. The thickness of the current frozen boundary can be directly calculated to identify the boundary thickness. If it is an intermittent region, it indicates that there may be cracks, fissures and other distribution forms of rock strata at the corresponding position, resulting in discontinuous jumps or fractures of the contour when the rock stratum is frozen. At this time, it indicates that the corresponding position is prone to seepage risk, and the current soil freezing trend and efficiency are affected, and need to be marked to assist subsequent adjustment of the freezing strength. For the finger-shaped protruding region, it indicates that the temperature contour has a directional mutation phenomenon, which represents a local anomaly of the current freezing trend, which may lead to an increase in overall freezing consumption and abnormal development of the freezing trend. The seepage direction of the corresponding position and the constraint condition of the freezing point corresponding position are associated to determine the position at which a stable frozen boundary can be formed.

[0040] The constraint condition described in step S24 will select different condition values according to different regions. For example, the minimum frozen thickness, the maximum allowable loop time and the maximum supplemental cold value are mainly identified for the intermittent region. For the ring-distributed region, the closure degree of the frozen wall is used to determine whether it is completely closed, and the radial thickness fluctuation is used to identify whether it is uniformly frozen. For the finger-shaped protruding region, the advancing speed of the frozen front is used. These contents are used as the current constraint condition.

[0041] Then, using the time period, the displacement amount, the thickness change amount and the constraint condition difference value of the described frozen position are used to verify whether the current frozen boundary is in a stable form.

[0042] The implementation of step S24 further includes: performing multi-objective differential queries on the frozen region by using the boundary displacement amount and the thickness change rate of each frozen region in adjacent time periods to determine the frozen boundary that satisfies the constraint condition.

[0043] At this time, when the constraint condition is satisfied, the change rate of the boundary displacement amount and the thickness change rate relative to the target value is the smallest. Then, the constraint condition of the current frozen region is checked, and when the mapped constraint conditions are consistent after being identified in multiple time periods, the boundary part with consistent mapping and the smallest change rate is taken as the output frozen boundary.

[0044] The preferred boundary displacement amount is calculated by freezing the boundary line of the region, calculating the position value of each point, dividing the average value of the displacement value under normal freezing, and obtaining the change rate relative to the target value. For the thickness change rate, the distance from the center of the frozen region to the boundary is divided by the average value of the distance from the center of the frozen region to the boundary under normal freezing, and the thickness change rate is obtained. When both values are minimized and the constraints mapped by the current frozen region in multiple time periods are consistent, it is determined that the boundary part of the current frozen region is stable and can be output as a frozen boundary.

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

[0046] Preferably, the number of cycles is set to represent the frequency of current frozen temperature field measurement, to indicate the change of the current frozen position in multiple time periods.

[0047] In an embodiment of the present application, when viewing the advancing trend of the frozen boundary, relative identification processing of the seepage field is also required, such as energy conservation equation verification of the relative heat change of the current frozen boundary when advancing.

[0048] ; wherein, represents the thermal conductivity of the rock stratum, which is obtained by directly measuring the rock stratum currently subjected to artificial freezing; 、 respectively represent the density and specific heat capacity of water; represents the seepage velocity vector, which is verified by inferring the water flow velocity under the current rock stratum with respect to the temperature gradient, or by verifying the seepage velocity vector with respect to the currently identified temperature gradient; represents the temperature gradient, which represents the temperature gradient of the current frozen temperature field at the frozen boundary; the first term on the left side of the above formula represents heat conduction, and the second term represents heat convection caused by seepage, which is used to explain the part of heat carried away. Thus, it is explained whether the current rock stratum conforms to the normal law when the frozen temperature field advances the frozen boundary in the presence of water seepage.

[0049] Then the temperature field is identified, such as being analyzed, identifying the part reaching the frozen boundary, and identifying the frozen radius of the frozen boundary, to identify the size of the frozen region at the current freezing pipe, so as to further judge the freezing condition of the frozen wall of the shaft of the current rock stratum.

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

[0051] ; wherein, represents the temperature at the radial distance r; represents the frozen pipe wall temperature, which is obtained by directly measuring the temperature of the frozen pipe; represents the temperature of the undisturbed formation far away, which indicates the temperature of the 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, , the calculated value of which tends to infinity, at which time the temperature field tends to be concentric, if Pe is greater than 0, then there is seepage, the temperature field is stretched, forming an asymmetric distribution, and the denominator part is used to indicate the normalization, so that when the radial distance r is the same as the radius of the frozen pipe, the temperature of the frozen pipe wall and the temperature at the radial distance r are the same in calculation; represents the Peclet number, which represents the competition between seepage and heat conduction, , wherein represents the radial velocity, which can be solved by the energy conservation equation to determine the current Peclet number; represents the radius of the frozen pipe; represents the radial coordinate, i.e. the distance from the center of the frozen pipe to a certain point. After identifying multiple temperatures at the radial distance, the measured temperature at the current temperature hole can be compared to identify the temperature at multiple positions in the current frozen temperature field. The implementation of the above calculation formula is mainly used to identify the variation law of the temperature at multiple positions in the current frozen temperature field to assist in determining the current frozen frozen radius, for example, the solving method of the frozen radius is: ; by solving the form of x, the corresponding x value is known to describe its frozen radius, which is a dimensionless parameter, which is essentially a variable that normalizes the actual frozen radius with the radius of the frozen pipe and the Peclet number. The frozen boundary is represented as: ; the final frozen radius, which represents the distance from the center of the current frozen pipe to the frozen front, determines the thickness of the frozen wall, and the frozen radius is used to judge whether the frozen wall can smoothly close the circle, whether it meets the pressure resistance requirements, etc.

[0052] The above formula is used to check multiple frozen points at the current frozen boundary to identify whether the trend and value of the frozen point meet the normal freezing rules, and then the verification of the advancing trend of the checked frozen boundary is identified to identify whether the current shaft frozen wall meets the standard.

[0053] As 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 application, as shown in Figure 4 The implementation of step S4 includes: S41, based on the advancing trend of the frozen boundary, taking the local freezing rate and thickness change value of the frozen boundary as the fitness of the corresponding frozen boundary.

[0073] S42, with the fitness of the frozen boundary, checking the optimal advancing position of the frozen boundary, judging whether the current frozen boundary forms a closed ring-shaped area, if so, determining the boundary condition of the current frozen boundary at the time point when the frozen boundary completes the ring.

[0074] S43, if not, according to the update speed of the fitness of the frozen boundary, mirror updating the optimal advancing position, and constructing a multi-attribute decision matrix.

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

[0076] Preferably, the fitness of the frozen boundary can be used as the basis for sorting the freezing rate and thickness change of multiple local positions of the frozen boundary. If the freezing rate is the same, the thickness change is used for sorting, or the freezing rate and thickness change are normalized, and the weighted value is used as the basis for sorting. The weighted weight can be selected in the form of 0.5, 0.5.

[0077] Preferably, when checking the optimal advancing position of the frozen boundary, the local freezing rate and thickness change value are sorted, and the weight of the sorted position is the largest or the sorted position satisfies the consistency of the temperature gradient direction, and the local position with the largest weight or the most forward position in the sorted position is taken as the optimal advancing position. Whether the optimal advancing position is formed when the optimal advancing position is obtained is judged.

[0078] As for mirror updating the optimal advancing position, mirror transforming the optimal advancing position to generate a symmetric advancing point, then according to the symmetric advancing point, a multi-attribute decision matrix is constructed, which includes local freezing rate, thickness change value, position coordinates, and the direction of the current advancing trend. Then, according to the value 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 ring is not completed, and the boundary condition related to the current freezing rate and freezing efficiency is obtained.

[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 records the temperature of the current frozen temperature field, the mechanical boundary verifies the stress of the current frozen wall, the fluid boundary verifies the velocity of the current seepage, the time boundary marks the time of completing freezing, and the control boundary indicates whether to input cold quantity and the like, so as to complete the setting of the boundary conditions of the freezing boundary.

[0080] If the completion is not completed, the boundary conditions record the freezing rate, the thickness change, the temperature value, whether there is seepage disturbance, the time of data update and the like, and these data are taken as the output boundary conditions.

[0081] In an embodiment of the present application, as shown in Figure 5 The implementation mode of step S5 includes: S51, using the equivalent identification mode, processing the freezing boundary at the circumferential, radial and axial directions of each evaluation temperature surface, and sequentially identifying the freezing boundary and the corresponding freezing radius in multiple directions.

[0082] S52, correcting the current freezing boundary by using the advancing value of the freezing radius in each direction, and determining the equivalent thickness of the freezing boundary in each direction by using the positioning size of the freezing radius in three directions.

[0083] S53, jointly analyzing the frozen temperature field by using the equivalent thickness of the freezing boundary at each position and the control cluster of the temperature value, and optimizing the freezing boundary at multiple positions according to the joint analysis result, to complete the correction of the freezing boundary.

[0084] Preferably, when the frozen temperature field is jointly analyzed, the current identified equivalent thickness and the control cluster of the temperature value are processed, each control cluster represents a group of similar and consistent freezing behavior regions, these regions have consistent temperature gradient and consistent freezing rate, then the temperature and freezing rate of the freezing boundary at each position are recorded and marked, to determine the correction mode of the freezing boundary at multiple positions, such as increasing the cold quantity input for the slow advancing cluster, inhibiting the sudden advancing region by using the control mode such as increasing the brine temperature, reinforcing the weak region by using the mode such as grouting and local cooling, reinforcing the partial weak freezing region, so that the finally completed freezing region can maintain a certain structural strength, and the combination mode of the related boundary conditions of the freezing boundary is updated.

[0085] Preferably, when identifying the equivalent thickness, the identification is performed in the circumferential direction, the radial direction and the axial direction in sequence. In the circumferential direction, whether the frozen boundary is completed or not and the thickness of the completed frozen boundary are observed. In the radial direction, the thickness of the frozen boundary radiating outward from the frozen pipe is observed, and the value of the outward diffusion boundary is observed. In the axial direction, whether the part parallel to the axis of the frozen pipe is completed or not is observed. The frozen thickness can be observed by observing the temperature value of the region reaching the freezing temperature in multiple time periods, and the frozen boundary thickness in the corresponding position can be obtained by using methods such as ground penetrating radar, resistivity imaging, ultrasonic detection, etc. The equivalent thickness is used to indicate the thickness value identified in the same region in the three directions. The value is combined into a data pair or a vector in the three directions to represent the thickness value in a region where the freezing is completed, to indicate the advancement of the frozen boundary. After these values are used as boundary conditions for the correction of the frozen boundary, they are output to the external control terminal, and the current freezing mode is adjusted according to the data of the external control terminal.

[0086] Preferably, when the joint analysis result is used to optimize the frozen boundary in multiple positions, the implementation further includes: checking whether the boundary condition corresponding to the frozen boundary before and after optimization exceeds the historical data range, if yes, based on the time point of the current boundary condition correction, using the moving average of the boundary condition to correct the frozen boundary; if no, outputting the optimized boundary condition to the corresponding frozen boundary.

[0087] At this time, whether the boundary condition exceeds the historical data range is mainly processed for the frozen boundary that has not completed the loop, and the updated frozen rate value needs to be compared with the historical data to check whether the current set boundary condition is reasonable. When the historical data range is exceeded, it means that the current data setting is too large or too small, and the boundary condition needs to be corrected by using the moving average of the continuous time period to complete the relative correction of the frozen boundary. If not, the correction is completed.

[0088] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application, which are still covered by the protection scope of the present application.

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 in deep, highly permeable, fractured, and weak rock formations according to claim 1, wherein: 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, and weak rock formations of a vertical shaft 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, weak rock formations 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 combined analysis results are used to optimize the frozen boundary at multiple locations, 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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