A model experiment house foundation deformation loading method based on ground fissure morphological change

Abstract

The application discloses a model experiment house foundation deformation loading method based on ground fissure morphological change, collects information related to the model experiment, calculates the geometric similarity ratio and the kinematic similarity ratio of the model experiment, investigates the ground fissure at the house position in the field, determines the spatial overlapping relationship and the fissure morphological change stage, determines the initial position of the platform support column and the moving loading mode in combination with the fissure morphological change and the spatial overlapping relationship, and calculates the loading time and the loading rate of the model house foundation deformation. The spatial overlapping relationship between the fissure and the house is comprehensively considered, the simulation experiment result precision of the house deformation damage under the ground fissure is higher, the platform support column moving loading mode is scientifically and comprehensively reflected, and a solid foundation is laid for the subsequent development of the house foundation deformation loading experiment.

Description

Technical Field

[0001] This invention relates to the field of foundation deformation calculation technology for model experimental houses. Specifically, it is a method for loading deformation of the foundation of model experimental houses based on changes in the morphology of ground fissures. Background Technology

[0002] Large-scale coal mining inevitably leads to large-scale surface subsidence, damaging surface buildings, roads, and farmland. Currently, scholars have conducted extensive research on surface deformation and building deformation in mining areas, primarily covering theoretical analysis, numerical simulation, and physical simulation. Theoretical analysis mainly uses probability integral methods to predict surface deformation at the location of buildings in mining areas and roughly determine the damage level of buildings. Numerical simulation in building deformation research oversimplifies foundation stress, deformation loading, and building structure, while also exhibiting significant uncertainties in model constitutive methods and parameter selection. Physical simulation has certain advantages, directly loading surface deformation and visually displaying the characteristics of building deformation and damage. Patent CN109686214A discloses a surface movement deformation simulation experimental platform, which uses an automated mechanical control device to generate (simulate) three-dimensional surface movement deformation. A building model is built according to a design scale, placed and fixed on the experimental platform, and movement deformations of different natures and magnitudes are applied to the foundation of the building model to study the deformation and damage characteristics of buildings affected by surface movement deformation. However, the experimental platform did not provide a scientific and comprehensive loading method and procedure when simulating the deformation of the building foundation.

[0003] Surface fissures are a common type of geological hazard in coal mining subsidence areas, resulting from uneven subsidence and horizontal movement of the regional surface. Related studies indicate that under geological mining conditions with shallowly buried thick coal seams (depth ratio H / M < 30), surface deformation is severe and concentrated, easily leading to surface fissures that threaten the safety of buildings. Furthermore, surface movement affected by fissures is often uneven and discontinuous, frequently manifesting as block movement, and its impact and damage patterns on surface buildings are unique. However, quantitative research on the extent of damage to buildings caused by mining-induced surface fissures is currently scarce. Existing technologies establish foundation soil models and building models, rationally coupling them to create different surface movement and deformation conditions, facilitating the study of the relationship between surface deformation and building movement and deformation. However, in studies of model building deformation in mining areas, while the relationship between surface deformation and model building deformation can be obtained by artificially assigning a movement amount, the impact characteristics of fissures—discontinuous surface deformation—on building damage are not considered, and the scientific calculation methods for the loading mode, loading time, and rate of foundation deformation under surface fissure action are not explored. Summary of the Invention

[0004] Therefore, the technical problem to be solved by this invention is to propose a model experimental building foundation deformation loading method based on the morphological changes of ground fissures, which can lay an experimental foundation for the study of the deformation damage of buildings (structures) under the influence of ground fissures in mining subsidence areas.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A model experimental method for foundation deformation loading of houses based on ground fissure morphology changes includes the following steps:

[0007] (1) Collect relevant data on the working face of the mining area, the simulated village houses, the model houses and the basic deformation test platform, and calculate the geometric similarity ratio and kinematic similarity ratio of the model experiment;

[0008] (2) Conduct on-site investigation of surface cracks at the location of the house to determine the spatial overlap between the two, and determine the crack type and morphological change stage based on the crack morphological change characteristics;

[0009] (3) Determine the initial position and moving loading method of the platform support column based on the shape changes of the crack and its overlapping relationship with the building;

[0010] (4) Based on the geometric similarity theory, calculate the three-dimensional movement of the platform support column corresponding to the different morphological change stages of the two types of cracks;

[0011] (5) Based on the kinematic similarity theory, calculate the deformation loading time and loading rate of the foundation of the model house at different stages of morphological change.

[0012] In step (1) of the above-mentioned model experiment house foundation deformation loading method based on ground fissure morphology changes, the data collected includes:

[0013] Mining geological parameters: Strike length of working face D e Average advance speed of the working face v , tendency length D c The relative position parameters of the simulated village houses are: the actual size of the village houses and their planar position relative to the working surface.

[0014] The geometric dimensions of simulated village houses l h and the geometric dimensions of the model house l m ; Dimensions of the basic deformation test platform and horizontal spacing between adjacent support columns d Its three-dimensional movable range.

[0015] The aforementioned method for model experiment building foundation deformation loading based on ground fissure morphology changes calculates the geometric similarity ratio of the model experiment based on collected data. a l Similarity to exercise time a t ;

[0016] Geometric similarity ratio a l Geometric similarity requires that the model and the prototype house have similar geometric shapes, and that their dimensions maintain a certain proportion, that is: (1);

[0017] In equation (1), l m The dimensions of the model house include length, width, and height, in meters (m). l h The actual dimensions of the village houses are in meters; for house model experiments, a l Use a ratio of 1:10 to 1:30;

[0018] Similarity ratio of exercise time a t Kinematic similarity requires that the motion of all corresponding points in the model and the prototype be similar, and that the motion time maintains a certain proportion, that is: (2);

[0019] In equation (2), a t The similarity ratio of motion time; T Loading time for the experimental platform; t The time of surface movement and deformation;

[0020] Based on Newton's laws and the method for deriving similarity criteria for mining subsidence, and combined with the kinematic similarity of similar material model experiments, the relationship between the motion time similarity ratio and the geometric similarity ratio is obtained as follows: (3).

[0021] In step (2) of the above-mentioned model experimental house foundation deformation loading method based on ground fissure morphology changes,

[0022] (2-1) Determining the spatial overlap relationship between cracks and houses: Conduct on-site investigations of surface cracks at the locations of houses in the simulated village, record the locations where cracks intersect with the walls on both sides of the houses, and determine the spatial overlap relationship between cracks and houses; when recording, use the major and minor axes of the houses as references, and summarize the overlap relationship between cracks and houses as follows: cracks are parallel to the major axis of the house, cracks are parallel to the minor axis of the house, cracks are oblique to the major axis of the house, cracks are oblique to the minor axis of the house, and cracks are oblique to both the major and minor axes of the house; the acute angle between the direction of the crack's extension and the direction of the house's major axis is denoted as... fAnd use a measuring tape to measure the horizontal distance of the crack from the nearest corner of the roof. d 1 and d 2 This allows the support columns to be moved to the crack location in advance;

[0023] (2-2) Acquisition of crack morphology parameters: The crack morphology parameters, i.e., the opening width, are determined by on-site measurement, model prediction, or artificially prescribed methods. w and step height h ;

[0024] (2-3) Determination of crack type and morphological change stages:

[0025] Crack types: The geometric morphological changes of surface cracks at the center and edge of the goaf are different, and they are divided into two types: permanent opening type and dynamic change type. The morphology of permanent opening type cracks will go through the process of "opening-stabilization"; the morphology of dynamic change type cracks includes the process of "opening-expansion-closure".

[0026] Crack morphology change stages: Combining the morphological characteristics of the two types of cracks, the crack morphology change stages are divided into three stages: opening stage, expansion stage, and closing stage.

[0027] Stage 1: Opening Stage: Both permanently opening and dynamically changing fractures undergo an opening stage. During this stage, the morphological changes of the ground fractures are characterized by sudden changes; the opening width and step height of the fractures can rapidly increase to the initial opening width within a short period. w 0 and initial step height h 0;

[0028] Phase 2: The expansion phase is when dynamically changing cracks undergo expansion. During this phase, the crack's opening width and step height increase, reaching their maximum opening width when the working face is positioned directly below or slightly behind the crack. w max Maximum step height h max ;

[0029] Stage 3 Closure Stage: Dynamically changing cracks will go through a closure stage; in this stage, as the working face moves further away, the surface at the crack location changes from tensile deformation to compressive deformation, the crack gradually closes, and its opening width and step height will eventually change to 0.

[0030] In step (2-2) of the above-mentioned model experiment house foundation deformation loading method based on ground fissure morphology changes:

[0031] a. Obtain the morphological parameters of the cracks through on-site measurements: When there are sufficient on-site observation conditions in the target mining area, surveyors use steel rulers or tape measures to obtain the initial opening width of the cracks. w 0 and initial step height h 0, and continuous observation was conducted during the working face advance, recording the changes in crack width and height over time, and measuring the maximum opening width and maximum step height of crack development, respectively. w max , h max ;

[0032] b. Obtain the morphological parameters of the fracture through model prediction: Using the surface fracture morphology prediction formula and combining it with the geological mining conditions of the target mine, calculate and determine the initial opening width of the fracture. w 0. Initial step height h 0 and maximum opening width w max Maximum step height h max ;

[0033] Maximum opening width w max :

[0034] ;

[0035] ;

[0036] ;

[0037] ;

[0038] ;

[0039] In the formula, S 0 represents the maximum surface subsidence; tan β The main influencing angle is tangent; H For the working face mining depth; H z The depth of the crack; l s The periodic breakage distance of the top plate of the working face; e 0 represents the critical horizontal deformation value of the ground fissure; c For the cohesion of the soil, ϕ For the internal friction angle of soil, R m The ultimate tensile strength of the soil, c The bulk density of the soil; M For coal seam thick mining, q For the surface subsidence coefficient, iThe dip angle of the coal seam; n e , n c This is the mining activity coefficient, with a value range of [0,1]. If the calculated result is greater than 1, it is taken as 1. D e The length of the working face. D c The working face dip length; f The lithology coefficient for overburden is 0.9 for soft rock, 0.8 for medium-hard rock, and 0.7 for hard rock.

[0040] Initial opening width w 0:

[0041] For dynamically changing cracks, the initial opening width ;

[0042] In the formula, k The ratio of the initial crack opening width is 0.4 to 0.8, and its value is mainly related to the mining depth of the working face and the mechanical properties of the overlying rock and soil.

[0043] For permanently open cracks, the crack width is also related to the location where the crack forms.

[0044] Initial opening width ;

[0045] In the formula, x This refers to the horizontal distance between the crack and the coal face at the working face; l b The size and distribution range of cracks in the outer edge region of the working face. l b = H / tan d ,in H For the working face mining depth, d The angle of the surface crack;

[0046] Crack step height h :

[0047] In the formula, A This represents the proportionality coefficient, with values ​​ranging from 1 to 4; [The remaining text appears to be incomplete and requires further context.] w 0、 w max Substitute into the above equation and solve. h 0 and h max ;

[0048] c. Artificially prescribed method: Applying equal increments to the opening width and step height helps to determine the critical deformation amount of the corresponding crack when the house is damaged.

[0049] In step (3) of the above-mentioned model experiment house foundation deformation loading method based on ground fissure morphology changes,

[0050] (3-1) Initial position of platform support columns: When simulating the effect of cracks on the damage of the house, firstly, four support columns are set up at the four corners of the model house for fixation; secondly, according to the overlap between the cracks and the house wall, four more support columns are added to accurately simulate the position of the cracks, so as to carry out the model house loading experiment of ground crack deformation; when the house is affected by multiple cracks, four more support columns are added for each additional crack, and they are moved in advance to the actual position of the crack.

[0051] (3-2) Platform support column moving loading method: When simulating surface cracks, both permanent opening type and dynamic change type cracks should keep the support column on one side of the crack stationary at different stages of morphological change, so that the support column on the side closer to the coal wall of the working face or the advancing position can move vertically or horizontally synchronously, and the direction of movement of the support column should be consistent with the actual movement direction of the surface point at the crack.

[0052] Vertical movement loading of support columns: The vertical movement of support columns is not affected by the overlapping relationship between the building and the crack space. During the different stages of crack opening, expansion and closing, different movement modes such as sinking and lifting will occur.

[0053] Horizontal movement loading of support columns: During model experiments, it is stipulated that the major and minor axes of the model house should be consistent with the major axis (X-axis) and minor axis (Y-axis) of the platform.

[0054] A. Horizontal movement direction: The horizontal movement direction of the support column on the adjustment side should be perpendicular to the crack extension direction and move towards the goaf side of the working face;

[0055] B. Horizontal movement method:

[0056] When the crack is parallel to the long or short axis of the house, the support column on the adjustment side can be moved along the X or Y axis.

[0057] When the crack is not parallel to the long or short axis of the house, since the platform support column can only move along the X or Y axis, the adjustment side support column adopts a "step-like" movement method during loading, gradually reaching the position of the maximum opening width in n steps; when the crack is closing, the support column should move in the opposite "step-like" manner.

[0058] In step (4) of the above-mentioned model experiment building foundation deformation loading method based on ground fissure morphology changes, the morphology change stage of the permanent opening type crack is mainly the initial opening stage, and the crack morphology will no longer change afterward, so the loading stage of the experiment is the opening stage; while under the action of the dynamic change type crack, the loading of the model experiment includes the opening stage, the expansion stage and the closing stage.

[0059] (4-1) Calculation of vertical movement of platform support columns: The simulation of crack step height is achieved by keeping the height of the support columns on one side of the model house constant and changing the height of the support columns on the other side, thus realizing the influence of crack step height on the house; based on the step height change Δ at different stages of the crack... h i Calculate the vertical movement Δ of the adjustable side support column of the model house. H i :

[0060] (4);

[0061] In equation (4), i The first change in crack morphology i The process is divided into three stages: the first stage is the opening stage, the second stage is the expansion stage, and the third stage is the closing stage. a l The geometric similarity ratio of the model experiment;

[0062] During the opening phase, the support column sinks rapidly, and the vertical movement of the support column... ,in , h 0 represents the initial step height of the crack.

[0063] During the expansion phase, the support columns sink and gradually increase to their maximum value, representing the vertical movement of the support columns. ,in ;

[0064] During the closing phase, the support column rises and gradually returns to its initial height, with the vertical movement of the support column being... ,in ;

[0065] (4-2) Calculation of horizontal movement of platform support columns: The simulation of crack opening width is achieved by keeping the position of the support column on one side of the building unchanged and adjusting the horizontal position of the support column on the other side of the building to realize the tensile deformation of the building caused by the crack; the calculation of the horizontal movement of the support column should consider the influence of the spatial overlap between the crack and the building, and the acute angle between the crack extension direction and the long axis of the building is denoted as... f The acute angle between the model house and the X-axis of the coordinate system represents the horizontal movement Δ of the support column on the adjusting side. W :

[0066] (5);

[0067] In equation (5), , The first i The horizontal movement of the stage adjustment side support column along the X and Y axes, in mm; a l The geometric similarity ratio of the model experiment; Δ w i For the crack i The change in opening width during the stage;

[0068] During the opening phase, the support columns move rapidly horizontally along the X and Y axes, respectively, with a movement amount... , ,in , w 0 represents the initial opening width of the crack;

[0069] During the expansion phase, the horizontal movement of the support column gradually increases to its maximum value. , ,in , w max This represents the maximum opening width of the crack.

[0070] During the closing phase, the support column moves horizontally in the opposite direction and gradually returns to its initial position. The horizontal movement of the support column... , ,in .

[0071] In step (5) of the above-mentioned model experimental house foundation deformation loading method based on ground fissure morphology changes, the calculation method for the deformation loading time of the model house foundation under different morphological change stages for permanently open cracks and dynamically changing cracks is as follows:

[0072] Stage 1: Opening Stage: In the initial opening stage of both permanently opening and dynamically changing cracks, the morphological changes of the cracks are characterized by suddenness; the deformation loading process in this stage should be completed instantaneously, i.e., the loading time... T 1≈0;

[0073] Stage 2, Expansion Stage: Dynamically changing cracks, after advancing a certain length of the working face, arise on the surface ahead of the working face at certain intervals, and reach their maximum development above or behind the working face at a certain distance. If the advancing distance of the working face during this process is L2, then L2 is:

[0074] (6);

[0075] In equation (6),H For the working face mining depth; α 1 represents the leading angle of crack formation, with measured values ​​ranging from 70° to 85°. The value is related to the lithology of the overlying strata; the harder the lithology, the larger the angle, and vice versa. α 2 represents the hysteresis angle of the maximum deformation of the crack, which is 80°-90°; α 1. α 2. Determined by analogy with measured values ​​from mines with similar geological conditions or adjacent mines;

[0076] Its loading time T 2 is:

[0077] (7);

[0078] In the formula, v The average advancing speed of the working face is expressed in m / d.

[0079] Combining formulas (3), (6), and (7), we get:

[0080] (8);

[0081] Phase 3: Closure Phase. The closure phase is when the dynamically changing fracture changes from its maximum morphological parameter to zero. During this period, the mining face gradually moves away from the fracture, and the surface deformation at the fracture site changes from tensile deformation to compressive deformation until it has no effect on the fracture. The advancing distance of the working face during this process is... L 3, then L 3 is:

[0082] (9);

[0083] In the formula, d 0 represents the boundary angle of the impact of surface mining, with a value ranging from 45° to 65°;

[0084] Loading time T 3 is:

[0085] (10);

[0086] In the formula, v The average advancing speed of the working face, in m / d. a t The similarity ratio of motion time;

[0087] Combining formulas (3), (9), and (10), we get:

[0088] (11).

[0089] The above-mentioned model experimental house foundation deformation loading method based on the morphological changes of ground fissures has the following loading rates: permanent opening cracks only have deformation loading during the opening stage, while dynamic changing cracks also have deformation loading during the expansion and closure stages.

[0090] When the model house is subjected to loading for crack deformation, the horizontal and vertical displacements of the platform support columns at different stages of morphological change are as follows: , The platform loading time corresponding to this stage is The loading rate of the model house is calculated using the following formula:

[0091] (12);

[0092] (13);

[0093] In the formula, , , The platform support columns are located along the horizontal X、Y Direction and vertical Z The loading rate of directional movement, mm / s; For the first i The amount of subsidence of the stage support column; For the first i Stage support column along X The horizontal displacement in the direction; For the first i Stage support column along Y The horizontal displacement in the direction; For the first i The time it takes for the platform support columns to move during the phase, among which T 1≈0; i When =1, it is the opening stage. i When the value is 2, it is the expansion phase. i =3 indicates the closure stage; regardless of whether it is a permanently opening crack or a dynamically changing crack, during the opening stage... T 1≈0, meaning that the loading of the crack opening width and the step height are completed instantaneously, and the loading rate is relatively fast.

[0094] The technical solution of the present invention achieves the following beneficial technical effects:

[0095] 1. This invention proposes a model experimental method for loading deformation of building foundations based on the morphological changes of ground fissures, in order to conduct more scientific and comprehensive simulation experiments on the deformation and damage of buildings in mining areas. The key technical points are: based on the morphological changes of ground fissures and their spatial overlap with the building, the stages of fissure morphological changes are divided, and the loading method of moving the platform support columns is determined; and combined with similarity theory, the loading time and loading rate of the building foundation deformation at each stage are calculated.

[0096] 2. Based on the morphological changes of ground fissures and their overlapping relationship with the building space, three stages of fissure morphological changes were identified, and the moving loading method of the platform support columns was determined. This summary and classification not only considers the changing characteristics of the fissures themselves, but also the interaction between the fissures and the building space, and is scientifically and comprehensively reflected in the moving loading method of the platform support columns, which can lay a solid foundation for subsequent building foundation deformation loading experiments.

[0097] 3. Based on similarity theory, the loading time and loading rate of the foundation of the model house in different stages of crack morphological change were calculated. This dynamic loading conforms to the general law of crack development and also takes into account the spatial overlap between cracks and the house, which will make the simulation results of house deformation damage under the action of surface cracks more accurate. Attached Figure Description

[0098] Figure 1 The present invention provides a schematic diagram of the spatial overlap between ground fissures and buildings; a) shows the fissures intersecting the minor axes of the buildings on both sides; b) shows the fissures intersecting both the major and minor axes of the buildings on both sides; c) shows the fissures intersecting the major axes of the buildings on both sides; d) shows the fissures parallel to the major axis of the buildings; e) shows the fissures parallel to the minor axis of the buildings; f) is a top view showing the fissures intersecting both the major and minor axes of the buildings on both sides.

[0099] Figure 2 A schematic diagram showing the morphological characteristics and distribution of surface cracks in a certain mine.

[0100] Figure 3 A schematic diagram of the moving loading method of the support column of the house model test platform under the action of cracks; a is a top view of the model test platform, b is a schematic diagram of the moving loading of the support column at section AA' in the top view, and c is a schematic diagram of the moving loading of the support column at section BB' in the top view.

[0101] Figure 4 Schematic diagram of the horizontal movement of the platform support columns during different stages of morphological change; Figure 5 A schematic diagram showing the change in the movement of the platform support columns over time during different stages of morphological change. Detailed Implementation

[0102] This application proposes a model experimental building foundation deformation loading method based on ground fissure morphology changes, so as to conduct more scientific and comprehensive simulation experiments on building deformation damage in mining areas.

[0103] The simulation experiment on deformation and damage of houses in mining areas utilizes an existing experimental platform (patent CN109686214A) and conducts loading studies on continuous / discontinuous deformation based on similarity theory.

[0104] Step 1: Collect relevant data on the working face of the mining area, simulated village houses, model houses and experimental platforms, and calculate the geometric similarity ratio and kinematic similarity ratio of the model experiment.

[0105] During the experiment, information such as working face mining parameters, village and model house dimensions, and experimental platform parameters are typically involved.

[0106] Before conducting the experiment, it is necessary to collect relevant data on the deformation loading of the model experimental house foundation, including: ① Mining and location parameters of the working face in the mining area, including the length of the working face. D e Tendency to be long D c Average advance speed of the working face v ① The relative positions of the houses in the simulated village to the houses in the model village; ② The geometric dimensions of the houses in the simulated village and the model houses. l h , l m ③ Dimensions of the basic deformation test platform and horizontal spacing between adjacent support columns d Its three-dimensional movable range. Based on relevant information, the geometric similarity ratio and kinematic similarity ratio of the model experiment were calculated.

[0107] (1) Geometric similarity ratio

[0108] Geometric similarity requires that the model and the prototype house have similar geometric shapes, and that their dimensions maintain a certain proportion, i.e.:

[0109] (1)

[0110] In the formula, l m The dimensions of the model house include length, width, and height, in meters (m). l h The actual dimensions of the village houses are in meters (m). For house model experiments, the geometric similarity ratio is generally taken as 1:10 to 1:30.

[0111] (2) Similarity ratio of movement time

[0112] Motion time similarity requires that the motion of all corresponding points in the model and the prototype be similar, and that the motion time maintains a certain proportion, that is:

[0113] (2)

[0114] In the formula, The similarity ratio of motion time; T Loading time for the experimental platform; t This represents the time of surface movement and deformation.

[0115] Based on Newton's laws and the method for deriving similarity criteria for mining subsidence, and combined with the kinematic similarity of similar material model experiments, the relationship between the kinematic time similarity ratio and the geometric similarity ratio can be obtained as follows:

[0116] (3)

[0117] In the formula, is the geometric similarity ratio.

[0118] Step 2: Conduct an on-site investigation of the surface cracks at the location of the house to determine the spatial overlap between the cracks and the surface cracks. Based on the morphological change characteristics of the cracks, determine the crack type and the stage of morphological change.

[0119] During the on-site investigation, the main focus was on the spatial overlap between the cracks and the building, as well as the acquisition of crack morphology parameters.

[0120] (1) Determining the relationship between cracks and the building space

[0121] A field investigation was conducted on the surface cracks at the location of the house, recording the locations where the cracks intersected with the walls on both sides of the house to determine the spatial overlap relationship between the cracks and the house. The loading method of the model experimental platform varied depending on the spatial overlap relationship between the cracks and the house. This application uses the long and short axes of the house as references, and the overlap relationships can be summarized as follows: cracks parallel to the long axis of the house, cracks parallel to the short axis of the house, cracks obliquely intersecting the long axis of the house, cracks obliquely intersecting the short axis of the house, and cracks obliquely intersecting both the long and short axes of the house. Figure 1 As shown, the acute angle between the direction of the crack's extension and the long axis of the building is denoted as . f And use a measuring tape to measure the horizontal distance of the crack from the nearest corner of the roof. d 1 and d 2. This allows the support column to be moved to the crack location in advance.

[0122] (2) Obtaining crack morphology parameters

[0123] The generation and development of surface cracks are related to factors such as working face parameters, geological conditions, and topographical features. During mining, they are affected by mechanical forces such as tension, compression, and shear, exhibiting different geometric morphological changes. However, regardless of the crack's variation, two key morphological parameters exist: opening width and crack width. w and step height h When conducting model experiments, different methods can be used to obtain the crack opening width and step height, depending on the site conditions and research objectives.

[0124] ① Obtain the morphological parameters of the cracks through on-site measurements. When there are sufficient on-site observation conditions in the target mining area, surveyors can use a steel ruler or tape measure to obtain the initial opening width of the cracks. w 0 and initial step height h 0, and continuous observation was conducted during the working face advance, recording the changes in crack width and height over time, and measuring the maximum opening width and maximum step height of crack development, respectively. w max , h max .

[0125] ② Obtain the morphological parameters of the cracks through model prediction. In the absence of sufficient on-site measurement conditions or before the working face is mined, if you wish to conduct a simulation experiment on the damage of surface cracks to buildings, you can calculate and determine the initial crack opening width based on the prediction formula for surface crack morphology and the geological mining conditions of the target mine. w 0. Initial step height h 0 and maximum opening width w max Maximum step height h max .

[0126] The specific prediction method is as follows:

[0127] Maximum opening width w max :

[0128] ;

[0129] ;

[0130] ;

[0131] ;

[0132] ;

[0133] In the formula, S 0 represents the maximum surface subsidence; tanβ The main influencing angle is tangent; H For the working face mining depth; H z The depth of the crack; l s The periodic breakage distance of the top plate of the working face; e 0 represents the critical horizontal deformation value of the ground fissure; c For the cohesion of the soil, ϕ For the internal friction angle of soil, R m The ultimate tensile strength of the soil, c The bulk density of the soil; M For coal seam thick mining, q For the surface subsidence coefficient, i The dip angle of the coal seam; n e , n c This is the mining activity coefficient, with a value range of [0,1]. If the calculated result is greater than 1, it is taken as 1. D e The length of the working face. D c The working face dip length; f The lithology coefficient for overburden is 0.9 for soft rock, 0.8 for medium-hard rock, and 0.7 for hard rock.

[0134] Initial opening width w 0:

[0135] For dynamically changing cracks, the initial opening width ;

[0136] In the formula, k The ratio of the initial crack opening width is 0.4 to 0.8, and its value is mainly related to the mining depth of the working face and the mechanical properties of the overlying rock and soil.

[0137] For permanently open cracks, the crack width is also related to the location where the crack forms.

[0138] Initial opening width ;

[0139] In the formula, x This refers to the horizontal distance between the crack and the coal face at the working face; l b The size and distribution range of cracks in the outer edge region of the working face. l b = H / tan d ,in H For the working face mining depth, d The angle of the surface crack;

[0140] Crack step height h :

[0141] In the formula, A This represents the proportionality coefficient, with values ​​ranging from 1 to 4; [The remaining text appears to be incomplete and requires further context.] w 0、 w max Substitute into the above equation and solve. h 0 and h max .

[0142] ③ Determine the morphological parameters of the cracks through artificially defined methods. When conducting model experiments to study relevant patterns, analyze the quantitative relationship between changes in crack parameters and building damage and deformation. This can be done by artificially setting the crack opening width and step height.

[0143] Generally, the load can be increased incrementally in equal increments. For example, the crack width can be increased sequentially by 0mm, 10mm, 20mm, 30mm, ..., and the crack step height can be increased sequentially by 0mm, 10mm, 20mm, 30mm, ... This regular change in width and height helps to determine the critical deformation amount of the corresponding crack when the building is damaged.

[0144] When obtaining the morphological parameters of surface cracks, in addition to steel tape measurement, on-site measurement methods such as UAV photogrammetry and foundation Lidar scanning can also be used, as well as numerical simulation software such as PFC particle flow for simulation calculation.

[0145] (3) Determination of crack type and morphological change stage

[0146] Surface cracks do not form immediately upon mining; rather, they develop when the working face reaches a certain size. The initial morphological changes are abrupt, followed by different continuous variations. Previous studies have shown that the geometric morphological changes of surface cracks at the center and edges of the goaf differ, classifying them into two types: permanently opening cracks and dynamically changing cracks. Figure 2 As shown. The morphology of permanently open cracks undergoes a "opening-stabilization" process, while the morphology of dynamically changing cracks includes a "opening-expansion-closure" process. Therefore, based on the morphological characteristics of both types of cracks, the stages of crack morphological change can be divided into three stages: opening, expansion, and closure.

[0147] Stage 1 (Opening Stage): Both permanently opening and dynamically changing fractures undergo an opening stage. During this stage, the morphological changes of the ground fractures are characterized by sudden changes; the opening width and step height of the fractures can rapidly increase to the initial opening width within a short period.w 0 and initial step height h 0.

[0148] Phase 2 (Expansion Phase): Dynamically changing cracks will undergo an expansion phase. During this phase, the crack's opening width and step height will increase, reaching maximum opening width when the working face advances to a position directly below or slightly behind the crack. w max Maximum step height h max .

[0149] Stage 3 (Closure Stage): Dynamically changing cracks will undergo a closure stage. In this stage, as the working face advances further away, the surface at the crack location changes from tensile deformation to compressive deformation, and the crack gradually closes. Its opening width and step height will eventually change to 0.

[0150] Step 3: Determine the initial position of the platform support column and the method of moving and loading based on the shape changes of the crack and its overlapping relationship with the building.

[0151] Ground fissures are a type of discontinuous deformation of the Earth's surface, primarily caused by uneven and inconsistent movement of the surface on either side of the fissure. During model building experiments, this phenomenon can be simulated by keeping the support columns on one side of the fissure stationary while adjusting the support columns on the other side. During the model experiment, the position and loading method of the platform support columns are adjusted according to the stages of fissure morphological change and their overlap with the building's spatial dimensions.

[0152] (1) Initial position of platform support column

[0153] As an important component of the experimental platform, the support columns directly act on the foundation of the building, providing forces and deformations to the structure. When simulating the effect of cracks on building damage, four support columns need to be installed at the four corners of the model building for initial fixation. Additionally, four more support columns are needed to accurately simulate the location of the cracks, based on the overlap between the cracks and the building walls, in order to conduct loading experiments on the model building to simulate surface crack deformation.

[0154] It is foreseeable that when a building is affected by multiple cracks, the number of platform support columns will need to be increased. Four support columns will be needed for each additional crack, and these columns should be moved in advance to the location where the crack will actually affect the building. For ease of description, this simulation will use a single crack as an example.

[0155] (2) Platform support column moving loading method

[0156] Surface movement caused by coal mining all points towards the center of the goaf. When the subsidence and horizontal movement of adjacent surface points are inconsistent and exceed a certain critical value, surface cracks will occur. When simulating surface cracks, for both types of cracks at different stages of morphological change, the support columns on one side of the crack must remain stationary. The support columns closer to the coal face or the advancing position (i.e., the adjusting side) must then undergo synchronous vertical or horizontal movement. Furthermore, the direction of movement of the support columns should be consistent with the actual movement direction of the surface points at the crack. Figure 3 As shown.

[0157] 1) Vertical movement loading of support columns. The vertical movement of support columns is not affected by the overlapping relationship between the building and the crack space, but different movement modes such as sinking and lifting will occur at different stages of crack opening, expansion and closing.

[0158] 2) Horizontal Movement Loading of Support Columns. For ease of loading during model experiments, it is usually stipulated that the major and minor axes of the model house are aligned with the major axis (X-axis) and minor axis (Y-axis) of the platform. ① Horizontal Movement Direction: The horizontal movement direction of the support column on the adjustment side should be perpendicular to the crack extension direction and move towards the goaf side of the working face. ② Horizontal Movement Method: When the crack is parallel to the major or minor axis of the house, the support column on the adjustment side can move along the X-axis or Y-axis; when the crack is not parallel to the major or minor axis of the house, since the platform support column can only move along the X-axis or Y-axis, the support column on the adjustment side can adopt a "stepped" movement method during loading, gradually reaching the position of the maximum opening width in n steps, such as... Figure 4 As shown, similarly, during the crack closure stage, the support column should move in a reverse "stepped" manner.

[0159] It is worth noting that the value of n should be as large as possible during the experiment, and the support column should be moved along the shorter side first to avoid aggravating the dynamic damage to the building and causing the simulation results to have a larger error.

[0160] Step 4: Based on the geometric similarity theory, calculate the three-dimensional movement of the platform support columns corresponding to different stages of morphological change in the model house.

[0161] The experimental platform simulates the morphological characteristics of ground fissures by controlling the three-dimensional movement of the platform's support columns. The support columns serve as the moving points for simulating surface fissures. These moving points generate horizontal or vertical displacements to simulate the opening width and step height of the fissures. Simultaneously, the support columns apply tensile and shear stresses to the foundation of the building above, simulating the discontinuous surface deformation of ground fissures acting on the building foundation.

[0162] When loading the deformation of the building foundation in the model experiment, it is necessary to calculate the three-dimensional movement of the platform support column corresponding to the two types of cracks at different stages of morphological change, based on the geometric morphological parameters of the cracks on the ground surface (building foundation) and the geometric similarity ratio of the model experiment.

[0163] The morphological change of a permanently open crack mainly occurs in the initial opening stage, after which the crack morphology no longer changes. Therefore, the loading stage in the experiment is the opening stage. In contrast, the loading of a dynamically changing crack in the model experiment includes the opening, propagation, and closure stages.

[0164] (1) Calculation of vertical movement of platform support columns

[0165] The simulation of the crack step height is achieved by keeping the height of the support column on one side of the model house constant while changing the height of the support column on the other side, thus realizing the effect of the crack step height on the house. Figure 3 As shown. Based on the variation in step height at different stages of the crack. Calculate the vertical movement of the adjustable side support columns of the model house. :

[0166] (4)

[0167] In the formula, i The first change in crack morphology i The process is divided into three stages: the first stage is the opening stage, the second stage is the expansion stage, and the third stage is the closing stage. a l This represents the geometric similarity ratio of the model experiment.

[0168] ① During the opening phase, the support column sinks rapidly, and the vertical movement of the support column... ,in , h 0 represents the initial step height of the crack.

[0169] ② During the expansion phase, the support column sinks and gradually increases to its maximum value, and the vertical movement of the support column... ,in .

[0170] ③ During the closing phase, the support column rises and gradually returns to its initial height, and the vertical movement of the support column... ,in .

[0171] (2) Calculation of horizontal movement of platform support columns

[0172] The simulation of crack opening width is achieved by keeping the position of the support column on one side of the house unchanged and adjusting the horizontal position of the support column on the other side to simulate the tensile deformation of the house caused by the crack. Figure 3 As shown. The calculation of the horizontal movement of the support column needs to consider the influence of the overlap between the crack and the building space. The acute angle between the crack's extension direction and the building's major axis (i.e., the X-axis of the coordinate system) is denoted as... fThe horizontal movement of the adjustment side support column of the model house :

[0173] (5)

[0174] In the formula, , The first i The horizontal movement of the stage adjustment side support column along the X and Y axes, in mm; The geometric similarity ratio of the model experiment; Δ w i For the crack i The change in opening width during the stage.

[0175] ① During the opening phase, the support columns move rapidly horizontally along the X-axis and Y-axis respectively, with the amount of movement... , ,in , w 0 represents the initial opening width of the crack.

[0176] ② During the expansion phase, the horizontal movement of the support column gradually increases to its maximum value. , ,in , w max This represents the maximum opening width of the crack.

[0177] ③ During the closing phase, the support column moves horizontally in the opposite direction and gradually returns to its initial position. The horizontal movement of the support column... , ,in .

[0178] Step 5: Based on the kinematic similarity theory, calculate the deformation loading time and loading rate of the model house at different stages of morphological change.

[0179] The morphological change stage of permanently opening cracks is mainly the initial opening stage, after which the crack morphology hardly changes, and its loading stage is the opening stage. However, under the action of dynamically changing cracks, the loading process in the model experiment includes an opening stage, a propagation stage, and a closing stage. The calculation methods for the deformation loading time of the model building foundation under different morphological change stages for both types of cracks are as follows:

[0180] ① Opening stage

[0181] In the initial opening stage of both permanently opening and dynamically changing cracks, the morphological changes are characterized by sudden changes. Based on this characteristic, the loading process for deformation in this stage should be instantaneous, i.e., the loading time... T 1≈0.

[0182] ② Expansion Phase

[0183] The propagation stage is the period from the formation of dynamically changing cracks to the morphological parameters reaching their maximum value. This process is related to the advancing position of the working face. After the working face advances to a certain length, dynamically changing cracks generate on the surface ahead of the working face at certain intervals, and reach their maximum value above or behind the working face at a certain distance. The advancing distance of the working face during this process is... L 2, then L 2 is:

[0184] (6)

[0185] In the formula, H For the working face mining depth; α 1 represents the leading angle of crack formation. The measured value is generally 70°~85°. Its value is mainly related to the lithology of the overlying strata. The harder the lithology, the larger the angle, and vice versa. α 2 is the hysteresis angle of the maximum deformation of the crack, which is generally 80°~90°. α 1. α 2. The angular parameters can be determined by analogy with measured values ​​from mines with similar geological conditions or adjacent mines.

[0186] Its loading time T 2 is:

[0187] (7)

[0188] In the formula, v The average advancing speed of the working face is expressed in m / d.

[0189] Combining formulas (3), (6), and (7), we get:

[0190] (8).

[0191] ③ Closure phase

[0192] The closure phase is the stage where a dynamically changing fracture changes from its maximum morphological parameter to zero. During this period, the mining face gradually moves away from the fracture, and the surface deformation at the fracture site changes from tensile deformation to compressive deformation until it has no effect on the fracture. The advancing distance of the working face during this process is... L 3, then L 3 is:

[0193] (9)

[0194] In the formula, d 0 represents the boundary angle of the impact of surface mining, and its value is generally between 45° and 65°.

[0195] Loading time T3 is:

[0196] (10)

[0197] In the formula, v The average advancing speed of the working face is expressed in m / d.

[0198] Combining formulas (3), (9), and (10), we get:

[0199] (11)

[0200] (2) Loading rate of model house

[0201] Permanently open cracks only require deformation loading during the opening stage, while dynamically changing cracks require deformation loading during both the expansion and closure stages.

[0202] When the model house is subjected to loading for crack deformation, the movement of the platform support columns at different stages of morphological change is: , The platform loading time corresponding to this stage is ,like Figure 5 As shown. The loading rate of the model house can be calculated using the following formula:

[0203] (12)

[0204] (13)

[0205] In the formula, The platform support columns are located along the horizontal X、Y Direction and vertical Z The loading rate of directional movement, mm / s; For the first i The amount of subsidence of the stage support column; For the first i Stage support column along X The horizontal displacement in the direction; For the first i Stage support column along Y The horizontal displacement in the direction; For the first i The time it takes for the platform support columns to move during the phase, among which T 1≈0; i When =1, it is the opening stage. i When the value is 2, it is the expansion phase. i =3 indicates the closure stage. It is worth noting that, regardless of whether it is a permanently opening crack or a dynamically changing crack, during the opening stage... T 1≈0, meaning that the loading of the crack width and height is completed instantaneously, and the loading rate is relatively fast.

[0206] This invention proposes a model house foundation deformation loading method based on ground fissure morphology changes. The key technical point is that, based on the morphological changes of ground fissures and their overlapping relationship with the house space, the crack morphology change stages are divided, and the platform support column moving loading method is determined; and, combined with similarity theory, the loading time and loading rate of the house foundation deformation in each stage are calculated.

[0207] The protection points are: (1) the moving loading method of the support column of the model experimental platform based on the morphological changes of ground fissures and their overlapping relationship with the building space; (2) the calculation method of the loading time and rate of the model building foundation deformation at different morphological change stages.

[0208] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A model experimental method for foundation deformation loading of houses based on ground fissure morphological changes, characterized in that, Includes the following steps: (1) Collect relevant data on the working face of the mining area, the simulated village houses, the model houses and the basic deformation test platform, and calculate the geometric similarity ratio and kinematic similarity ratio of the model experiment; (2) Conduct on-site investigation of surface cracks at the location of the house to determine the spatial overlap between the two, and determine the crack type and morphological change stage based on the crack morphological change characteristics; (3) Determine the initial position and moving loading method of the platform support column based on the shape changes of the crack and its overlapping relationship with the building; (4) Based on the geometric similarity theory, calculate the three-dimensional movement of the platform support column corresponding to the different morphological change stages of the two types of cracks; (5) Based on the kinematic similarity theory, calculate the deformation loading time and loading rate of the model house foundation at different stages of morphological change; In step (2), (2-1) Determining the spatial overlap relationship between cracks and houses: Conduct on-site investigations of surface cracks at the locations of houses in the simulated village, record the locations where cracks intersect with the walls on both sides of the houses, and determine the spatial overlap relationship between cracks and houses; when recording, use the major and minor axes of the houses as references, and summarize the overlap relationship between cracks and houses as follows: cracks are parallel to the major axis of the house, cracks are parallel to the minor axis of the house, cracks are oblique to the major axis of the house, cracks are oblique to the minor axis of the house, and cracks are oblique to both the major and minor axes of the house; the acute angle between the direction of the crack's extension and the direction of the house's major axis is denoted as... φ And use a measuring tape to measure the horizontal distance of the crack from the nearest corner of the roof. d 1 and d 2 This allows the support columns to be moved to the crack location in advance; (2-2) Obtaining crack morphology parameters: The crack morphology parameters, i.e., the opening width, are determined through on-site measurements, model prediction, or artificially defined methods. w and step height h ; (2-3) Determination of crack type and morphological change stages: Crack types: The geometric morphological changes of surface cracks at the center and edge of the goaf are different, and they are divided into two types: permanent opening type and dynamic change type. The morphology of permanent opening type cracks will go through the process of "opening-stabilization"; the morphology of dynamic change type cracks includes the process of "opening-expansion-closure". Crack morphology change stages: Combining the morphological characteristics of the two types of cracks, the crack morphology change stages are divided into three stages: opening stage, expansion stage, and closing stage. Stage 1: Opening Stage: Both permanently opening and dynamically changing fractures undergo an opening stage. During this stage, the morphological changes of the ground fractures are characterized by sudden changes; the opening width and step height of the fractures can rapidly increase to the initial opening width within a short period. w 0 and initial step height h 0; Phase 2: The expansion phase is when dynamically changing cracks undergo expansion. During this phase, the crack's opening width and step height increase, reaching their maximum opening width when the working face is positioned directly below or slightly behind the crack. w max Maximum step height h max ; Stage 3 Closure Stage: Dynamically changing cracks will go through a closure stage; in this stage, as the working face moves further away, the surface at the crack location changes from tensile deformation to compressive deformation, the crack gradually closes, and its opening width and step height will eventually change to 0. In step (2-2): a. Obtain the morphological parameters of the cracks through on-site measurements: When there are sufficient on-site observation conditions in the target mining area, surveyors use steel rulers or tape measures to obtain the initial opening width of the cracks. w 0 and initial step height h 0, and continuous observation was conducted during the working face advance, recording the changes in crack width and height over time, and measuring the maximum opening width and maximum step height of crack development, respectively. w max , h max ; b. Obtain the morphological parameters of the fracture through model prediction: Using the surface fracture morphology prediction formula and combining it with the geological mining conditions of the target mine, calculate and determine the initial opening width of the fracture. w 0. Initial step height h 0 and maximum opening width w max Maximum step height h max ; Maximum opening width w max : ； ； ； ； ； In the formula, S 0 represents the maximum surface subsidence; tan β The main influencing angle is tangent; H For the working face mining depth; H z The depth of the crack; l s The periodic breakage distance of the top plate of the working face; ε 0 represents the critical horizontal deformation value of the ground fissure; c For the cohesion of the soil, ϕ For the internal friction angle of soil, R m The ultimate tensile strength of the soil, γ The bulk density of the soil; M For coal seam thick mining, q For the surface subsidence coefficient, θ The dip angle of the coal seam; n e , n c This is the mining activity coefficient, with a value range of [0,1]. If the calculated result is greater than 1, it is taken as 1. D e The length of the working face. D c The working face dip length; f The lithology coefficient for overburden is 0.9 for soft rock, 0.8 for medium-hard rock, and 0.7 for hard rock. Initial opening width w 0: For dynamically changing cracks, the initial opening width ; In the formula, k The ratio of the initial crack opening width is 0.4 to 0.8, and its value is mainly related to the mining depth of the working face and the mechanical properties of the overlying rock and soil. For permanently open cracks, the crack width is also related to the location where the crack forms; Initial opening width ; In the formula, x This refers to the horizontal distance between the crack and the coal face at the working face; l b The size and distribution range of cracks in the outer edge region of the working face. l b = H / tan δ ,in H For the working face mining depth, δ The angle of the surface crack; Crack step height h : In the formula, A This represents the proportionality coefficient, with values ​​ranging from 1 to 4; [The remaining text appears to be incomplete and requires further context.] w 0、 w max Substitute into the above equation and solve. h 0 and h max ; c. Artificially prescribed method: Applying equal increments to the opening width and step height helps to determine the critical deformation amount of the corresponding crack when the house is damaged; In step (3), (3-1) Initial position of platform support columns: When simulating the relationship between cracks and damage to houses, firstly, four support columns are set up at the four corners of the model house for fixation; secondly, according to the overlap between cracks and the house wall, four more support columns are added to accurately simulate the position of cracks so as to carry out loading experiments on the model house of ground crack deformation. When a house is affected by multiple cracks, four additional support columns should be added for each additional crack, and these columns should be moved in advance to the location where the cracks are actually affecting the house. (3-2) Platform support column moving loading method: When simulating surface cracks, both permanent opening type and dynamic change type cracks should keep the support column on one side of the crack stationary at different stages of morphological change, so that the support column on the side closer to the coal wall of the working face or the advancing position can move vertically or horizontally synchronously, and the direction of movement of the support column should be consistent with the actual movement direction of the surface point at the crack. Vertical movement loading of support columns: The vertical movement of support columns is not affected by the overlapping relationship between the building and the crack space. During the different stages of crack opening, expansion and closing, different movement modes such as sinking and lifting will occur. Horizontal movement loading of support columns: During model experiments, it is stipulated that the major and minor axes of the model house should be consistent with the major axis (X-axis) and minor axis (Y-axis) of the platform. A. Horizontal movement direction: The horizontal movement direction of the support column on the adjustment side should be perpendicular to the crack extension direction and move towards the goaf side of the working face; B. Horizontal movement method: When the crack is parallel to the long or short axis of the house, the support column on the adjustment side can be moved along the X or Y axis. When the crack is not parallel to the long or short axis of the house, since the platform support column can only move along the X or Y axis, the adjustment side support column adopts a "step-like" movement method during loading, gradually reaching the position of the maximum opening width in n steps; when the crack is closing, the support column should move in the opposite "step-like" manner.

2. The method for model experimental house foundation deformation loading based on ground fissure morphological changes according to claim 1, characterized in that, In step (1), data collection includes: Mining area geological parameters: working face strike length D e Average advance speed of the working face v , tendency length D c The relative position parameters of the simulated village houses are: the actual size of the village houses and their planar position relative to the working surface. The geometric dimensions of simulated village houses l h and the geometric dimensions of the model house l m ; Dimensions of the basic deformation test platform and horizontal spacing between adjacent support columns d Its three-dimensional movable range.

3. The method for model experimental house foundation deformation loading based on ground fissure morphological changes according to claim 2, characterized in that, Based on the collected data, the geometric similarity ratio of the model experiment was calculated. a l Similarity to exercise time a t ; Geometric similarity ratio a l Geometric similarity requires that the model and the prototype house have similar geometric shapes, and that their dimensions maintain a certain proportion, that is: (1); In equation (1), l m The dimensions of the model house include length, width, and height, in meters (m). l h The actual dimensions of the village houses are in meters. For house model experiments a l Use a ratio of 1:10 to 1:30; Similarity ratio of exercise time a t Kinematic similarity requires that the motion of all corresponding points in the model and the prototype be similar, and that the motion time maintains a certain proportion, that is: (2); In equation (2), a t The similarity ratio of motion time; T Loading time for the experimental platform; t The time of surface movement and deformation; Based on Newton's laws and the method for deriving similarity criteria for mining subsidence, and combined with the kinematic similarity of similar material model experiments, the relationship between the motion time similarity ratio and the geometric similarity ratio is obtained as follows: (3).

4. The method for model experimental house foundation deformation loading based on ground fissure morphological changes according to claim 3, characterized in that, In step (4), the morphological change stage of the permanently open crack is mainly the initial opening stage, and the crack morphology will no longer change afterward, so the loading stage of the experiment is the opening stage; while under the action of the dynamically changing crack, the loading of the model experiment includes the opening stage, the expansion stage and the closing stage. (4-1) Calculation of vertical movement of platform support columns: The simulation of crack step height is achieved by keeping the height of the support columns on one side of the model house constant and changing the height of the support columns on the other side, thus realizing the influence of crack step height on the house; based on the step height change Δ at different stages of the crack... h i Calculate the vertical movement Δ of the adjustable side support column of the model house. H i : （4）； In equation (4), i The first change in crack morphology i The process is divided into three stages: the first stage is the opening stage, the second stage is the expansion stage, and the third stage is the closing stage. a l The geometric similarity ratio of the model experiment; During the opening phase, the support column sinks rapidly, and the vertical movement of the support column... ,in , h 0 represents the initial step height of the crack. During the expansion phase, the support columns sink and gradually increase to their maximum value, representing the vertical movement of the support columns. ,in ; During the closing phase, the support column rises and gradually returns to its initial height, with the vertical movement of the support column being... ,in ; (4-2) Calculation of horizontal movement of platform support columns: The simulation of crack opening width is achieved by keeping the position of the support column on one side of the building unchanged and adjusting the horizontal position of the support column on the other side of the building to realize the tensile deformation of the building caused by the crack; the calculation of the horizontal movement of the support column should consider the influence of the spatial overlap between the crack and the building, and the acute angle between the crack extension direction and the long axis of the building is denoted as... φ The acute angle between the model house and the X-axis of the coordinate system represents the horizontal movement Δ of the support column on the adjusting side. W : （5）； In equation (5), , The first i The horizontal movement of the stage adjustment side support column along the X and Y axes, in mm; a l The geometric similarity ratio of the model experiment; Δ w i For the crack i The change in opening width during the stage; During the opening phase, the support columns move rapidly horizontally along the X and Y axes, respectively, with a movement amount... , ,in , w 0 represents the initial opening width of the crack; During the expansion phase, the horizontal movement of the support column gradually increases to its maximum value. , ,in , w max This represents the maximum opening width of the crack. During the closing phase, the support column moves horizontally in the opposite direction and gradually returns to its initial position. The horizontal movement of the support column... , ,in .

5. The method for model experimental house foundation deformation loading based on ground fissure morphological changes according to claim 3, characterized in that, In step (5), the calculation method for the deformation loading time of the model house foundation under different morphological change stages of permanent opening cracks and dynamic change cracks is as follows: Stage 1: Opening Stage: In the initial opening stage of both permanently opening and dynamically changing cracks, the morphological changes of the cracks are characterized by suddenness; the deformation loading process in this stage should be completed instantaneously, i.e., the loading time... T 1≈0; Stage 2, Expansion Stage: Dynamically changing cracks, after advancing a certain length of the working face, arise on the surface ahead of the working face at certain intervals, and reach their maximum development above or behind the working face at a certain distance. If the advancing distance of the working face during this process is L2, then L2 is: （6）； In equation (6), H For the working face mining depth; α 1 represents the leading angle of crack formation, with measured values ​​ranging from 70° to 85°. The value is related to the lithology of the overlying strata; the harder the lithology, the larger the angle, and vice versa. α 2 represents the hysteresis angle of the maximum deformation of the crack, which is 80°-90°; α 1. α 2. Determined by analogy with measured values ​​from mines with similar geological conditions or adjacent mines; Its loading time T 2 is: （7）； In the formula, v The average advancing speed of the working face is expressed in m / d. Combining formulas (3), (6), and (7), we get: （8）； Phase 3: Closure Phase. The closure phase is when the dynamically changing fracture changes from its maximum morphological parameter to zero. During this period, the mining face gradually moves away from the fracture, and the surface deformation at the fracture site changes from tensile deformation to compressive deformation until it has no effect on the fracture. The advancing distance of the working face during this process is... L 3, then L 3 is: （9）； In the formula, δ 0 represents the boundary angle of the impact of surface mining, with a value ranging from 45° to 65°; Loading time T 3 is: （10）； In the formula, v The average advancing speed of the working face, in m / d. a t The similarity ratio of motion time; Combining formulas (3), (9), and (10), we get: （11）。 6. The method for model experimental house foundation deformation loading based on ground fissure morphological changes according to claim 5, characterized in that, Model house loading rate: Permanently opening cracks only undergo deformation loading during the opening stage, while dynamically changing cracks also undergo deformation loading during the expansion and closure stages. When the model house is subjected to loading for crack deformation, the horizontal and vertical displacements of the platform support columns at different stages of morphological change are as follows: , The platform loading time corresponding to this stage is The loading rate of the model house is calculated using the following formula: （12）； （13）； In the formula, , , The platform support columns are located along the horizontal X, Y Direction and vertical Z The loading rate of directional movement, mm / s; For the first i The amount of subsidence of the stage support column; For the first i Stage support column along X The horizontal displacement in the direction; For the first i Stage support column along Y The horizontal displacement in the direction; For the first i The time it takes for the platform support columns to move during the phase, among which T 1≈0; i When =1, it is the opening stage. i When the value is 2, it is the expansion phase. i When the value is 3, it is the closed phase; Whether it is a permanently opening crack or a dynamically changing crack, during the opening stage T 1≈0, meaning that the loading of the crack opening width and the step height are completed instantaneously, and the loading rate is relatively fast.

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