Method, material and device for manufacturing tunnel models with different tunnel shapes and structural surfaces under pressure

Abstract

The invention relates to a method, a material and a device for manufacturing tunnel models with different tunnel shapes and structural surfaces under pressure. The device comprises a front side plate, a rear side plate, a left side plate, a right side plate, a soft contact bottom plate, a prefabricated tunnel model column, a ballast top plate and a structural surface manufacturing mold and sliding objective table integrated loading frame, and the size design of the side plates and the ballast top plate is carried out through an established size design method; the tunnel model selects a rock similar material through a similarity theory; the manufacturing method comprises the steps of installing a mold, adjusting the angle of a model column, smearing mold oil, establishing a function relation of the thickness of the model, forming pressure and the quality of the rock similar material, calculating the quality of the similar material, pouring the material, applying pressure, removing the mold, injecting fine grinding slurry and maintaining the model. According to the method, the tunnel physical model with different ground stress, different tunnel shapes and any occurrence structural plane is manufactured, the physical characteristics of the tunnel physical model are similar to those of protolith, and a physical foundation is laid for researching a tunnel catastrophe geologic structure and the three-dimensional stress coupling effect.

Description

Technical Field

[0001] The invention belongs to the technical field of rock mechanics, and in particular relates to a device and a method for making tunnel models with different hole shapes, angles and structural surfaces under pressure conditions. Background Art

[0002] Excavation disturbance induces high ground stress disasters in deep buried engineering, which is a common type of underground disaster. However, the geological structure, ground stress, and environment of deep buried tunnels are very complex, and the construction conditions such as blasting and mechanical excavation are different, with many variation factors. At the same time, tunnel disasters are sudden and difficult to monitor in time on site. The process and damage mechanism of deep buried tunnel disasters induced by excavation disturbance are still unclear. Therefore, physical model experiments, as an important means to reveal the evolution mechanism of disasters, are of great significance for interpreting and regulating the process of disaster breeding in deep buried engineering excavation.

[0003] At present, there are several problems in tunnel model making:

[0004] 1. Currently, the production of tunnel physical models mostly adopts dense vibration or short-term mechanical compaction, without considering the diagenetic stress environment of the surrounding rock. At the same time, there is a lack of calculation indicators for the design size of the mold under high pressure environment;

[0005] 2. The three-dimensional geostress environment is complex, and the relationship between the principal stress direction and the tunnel space is complex. At the same time, the tunnel morphology in actual projects varies. At present, the tunnel physical model making device is often targeted at a certain special working condition, and the installation is not convenient, resulting in low production efficiency and high time cost. In addition, for complex and different working conditions, it is necessary to specially make different tunnel model molds corresponding to different working conditions, which greatly increases the test cost. A low-cost, easy-to-install and easy-to-operate tunnel model making device that can simultaneously adapt to the study of tunnel morphology and the relationship with the principal stress space is needed;

[0006] 3. The tunnel surrounding rock contains complex thin-layer hard structural surfaces. The distance, position and occurrence of the structural surface from the free surface play a certain role in controlling tunnel disasters. However, the current tunnel physical model production method is difficult to produce thin-layer structural surfaces, and it is also difficult to control the occurrence and position of the structural surface;

[0007] 4. When making a tunnel physical model, the composition of the selected rock-like material will affect its mechanical properties. After forming and curing, the thickness of the tunnel physical model will be affected by the pressure applied during the forming process and the quality of the rock-like material, making it difficult to achieve the expected thickness.

[0008] Therefore, there is an urgent need to invent a tunnel model manufacturing method, material and device that can solve the above problems. Summary of the invention

[0009] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method, material and device for making tunnel models with different hole shapes and structural surfaces under pressure, so as to solve a series of problems existing in the above-mentioned background technology, such as the lack of calculation indicators for mold design dimensions, inconvenient installation of model molds, inability to provide different diagenetic pressures, difficulty in accurately controlling the shape and angle of the tunnel, difficulty in making thin-layer structural surfaces of the tunnel surrounding rock, and difficulty in determining rock-similar materials for the tunnel physical model and the quality of casting materials.

[0010] In order to achieve the above object, the technical solution of the present invention is as follows:

[0011] The device for making tunnel physical models with different hole shapes and angles under pressure conditions comprises a front side plate, a rear side plate, a left side plate, a right side plate, a soft contact bottom plate provided with a screw positioning blind hole, a prefabricated tunnel model column with a variable hole shape and angle, and a ballast top plate with a tunnel hole; a thin rubber layer consistent with the cross-sectional shape and size of the ballast top plate is arranged at the lower part of the ballast top plate, and the thin rubber layer plays a role in preventing the leakage of the pouring slurry during the pouring and pressurizing of the tunnel physical model; a rotating disc for a tunnel hole with a variable angle and shape is arranged in the middle of the ballast top plate; the rotating disc for the tunnel hole with a variable angle and shape is arranged with angle scale lines, angle locking parts and variable angle and shaped tunnel holes, which are suitable for precise adjustment of specific angles of prefabricated tunnel model columns of different hole shapes; the variable angle and shape tunnel holes are consistent with the shape and size of the prefabricated tunnel model columns of the variable hole shape and angle, and the two are movably connected by setting a sealing ring, which also plays a role in preventing the casting slurry from leaking during the casting and pressurization of the tunnel physical model; a thin rubber layer consistent with the cross-sectional size of the ballast top plate is set on the upper part of the soft contact bottom plate, a threaded positioning blind hole is set in the center of the soft contact bottom plate, and the soft contact bottom plate is connected with the front side plate, the rear side plate, the left side plate, and the right side plate through the side plate fixing bolt holes to form a tunnel model cavity;

[0012] The method for determining the size, forming pressure and grouting material of the tunnel physical model is as follows:

[0013] The physical model of the tunnel should maintain similar geometric shapes and dimensions to the prototype, and the corresponding angles should be equal, that is, any corresponding linear length of the prototype and the model should maintain a certain proportional relationship. The ratio of the prototype and the model is represented by λ, and the side length of the model section should meet the length ratio:

[0014] Where L P is the side length of the prototype section, L M is the cross-sectional side length of the tunnel physical model;

[0015] The equivalent diameter d of the tunnel physical model M The calculation formula is as follows:

[0016] Where d P is the equivalent diameter of the prototype tunnel. The equivalent diameter is the diameter of each type of tunnel when it is converted into a circular tunnel of equal area. The equivalent diameter d P The calculation formula is as follows:

[0017] Where S P is the cross-sectional area of ​​the prototype tunnel;

[0018] In order to ignore the boundary effect, the edge length a of the tunnel physical model must satisfy the following formula:

[0019] The calculation formula of the forming pressure F0 of the tunnel physical model is as follows: q0=γh+q g (5) F0=q0a 2 (6)

[0020] Where γ is the original rock density, h is the tunnel depth, q1 is the tunnel ground stress, q g is tectonic stress;

[0021] The selection of aggregates for rock-similar materials used for casting should consider the mineral composition and particle grading characteristics of the original rock. The selection of cementing materials should consider the strength and brittleness of the original rock. The selection of conditioning agents should consider the density and porosity of the original rock. By adjusting the types and proportions of aggregates, cementing materials, and conditioning agents, the mechanical properties of the cast rock-similar materials of the tunnel physical model are similar to those of the original rock. The similar mechanical properties include brittleness, dynamic properties, and critical perturbation strength. The quantitative index of the brittleness index is the ductility-brittleness index I controlled by the comprehensive index of pre-peak and post-peak properties. BD Determine, ductility and brittleness index I BD The calculation formula is as follows: I BD =B n (E-H) / H (7)

[0022] Where B n is a constant parameter, E is the elastic modulus before the rock peak, H is the modulus after the rock peak, and the value of the modulus after the rock peak is equal to the slope of the post-peak curve;

[0023] Brittleness similarity scale between tunnel physical model and original rock Need to meet:

[0024] Where I BDP is the prototype ductility and brittleness index, IBDM is the ductility-brittleness index of the tunnel physical model;

[0025] Dynamic elastic modulus E d and dynamic Poisson's ratio μ d As an important indicator of rock dynamic properties, the dynamic elastic modulus similarity scale Similarity ratio to dynamic Poisson's ratio Satisfy the following formula:

[0026] Where λ σ is the stress similarity scale; λ ρ is the density similarity scale, λ h is the similarity scale of tunnel depth, λ ε is the strain similarity scale, strain is a dimensionless physical quantity, then λ ε =1;

[0027] The quantitative index of the critical intensity of disturbance is the critical coefficient η cs Determine the critical perturbation coefficient η cs The calculation formula is as follows:

[0028] Where σ cs is the perturbation critical stress, σ p is the peak intensity;

[0029] From formula (11), we can know that the critical disturbance coefficient η cs is a dimensionless physical quantity, then the perturbation critical coefficient similarity scale Satisfy the following formula:

[0030] Where η csP is the prototype disturbance critical coefficient, η csM is the critical coefficient of disturbance of the tunnel physical model;

[0031] The method for determining the design dimensions of the side plates and the pressure top plate is as follows:

[0032] The side plate is simplified into a T-shaped beam-column combination model, in which both ends of the beam are fixed, the bottom of the column is fixed, and the joint between the beam and the column is hinged. According to the preset forming pressure of the tunnel model, the equivalent linear load q acting on the beam is calculated. E , the equivalent linear load q E Equivalent to concentrated force F, equivalent to linear load q E The calculation formula of the concentrated force F is as follows: F=q E a (15)

[0033] Where q is the uniformly distributed surface force preset in the tunnel model; A0 is the cross-sectional area of ​​the tunnel;

[0034] Calculate the equivalent linear load q acting on the column C , the calculation formula is as follows:

[0035] Where, β is the lateral force coefficient;

[0036] The concentrated force F is applied to the beam-column hinge point A, and the equivalent linear load q C Act on the column and calculate the deflection ω of the beam-column hinge point A. The calculation formula is as follows:

[0037] Where E is the elastic modulus of the side plate, I is the moment of inertia of the beam-column section, the deflection ω of point A must satisfy ω<0.02mm, and the height H and width B of the side plate must satisfy the formula:

[0038] Finally, the thickness D of each plate is determined according to the size of the tunnel physical model. The plate thickness D must satisfy the plate thickness safety factor K. sa <1, the thickness safety factor K is satisfied sa The calculation formula is as follows:

[0039] Where t is the material coefficient of the physical model plate, and E is the elastic modulus of the physical model plate;

[0040] The size of the side plate and the size of the tunnel physical model are calculated according to the above formula, and the size of the pressure top plate is finally determined, so that the pressure top plate, the side plate and the soft contact bottom plate form a closed tunnel physical model mold frame;

[0041] The method for determining the design size of the prefabricated tunnel model column is as follows:

[0042] The equivalent diameter d of the tunnel physical model is obtained based on the similarity ratio between the tunnel model and the prototype tunnel. M Calculate the tunnel cross-sectional area S of the physical model M , the calculation formula is as follows:

[0043] The tunnel cross-sectional area S of the physical model Mand the preset tunnel shape, determine the tunnel outline size of the physical model, and then determine the cross-sectional size of the prefabricated tunnel model column; then determine the length l of the prefabricated tunnel model column according to the thickness d of the tunnel physical model, and thus determine the design size of the prefabricated tunnel model column;

[0044] A threaded positioning blind hole of the same specification as the soft contact bottom plate is arranged at the center of the prefabricated tunnel model column with variable hole shape and angle, and a positioning screw penetrates through the threaded positioning blind hole of the soft contact bottom plate and the prefabricated tunnel model column with variable hole shape and angle to closely connect the two;

[0045] The structural surface manufacturing mold of different occurrences and positions includes an electromagnetic fixed support, a telescopic movable rod with adjustable length, a spherical connector with adjustable angle, and a replaceable thin-layer structural surface mold. The replaceable thin-layer structural surface mold is a stainless steel sheet wrapped with hot-melt plastic. The various parts are connected by a spherical connector with adjustable angles. The structural surface manufacturing mold is installed on the side wall of the prefabricated tunnel model column with variable hole shape and angle through the electromagnetic fixed support;

[0046] The sliding stage integrated loading frame is assembled from a pressure top plate, an electro-hydraulic servo actuator, a double-line slide rail, a model stage and a support;

[0047] A method for making tunnel models with different hole shapes, angles and structural surfaces under pressure conditions, using a device for making tunnel models with different hole shapes, angles and structural surfaces under pressure conditions, comprising the following steps:

[0048] Step 1: After the front side plate, rear side plate, left side plate, right side plate and soft contact bottom plate in the tunnel physical model manufacturing mold are installed and fixed through the side plate fixing bolt holes, the prefabricated tunnel model column is placed on the soft contact bottom plate, and the tunnel hole rotating disk with the tunnel angle alignment line and the ballast top plate with the angle scale line are used to adjust the tunnel model angle, and the rotation angle of the disk is fixed by the angle locking piece on the disk, and the prefabricated tunnel model column is fixed to the threaded positioning blind hole of the soft contact bottom plate by the positioning bolts;

[0049] Step 2: Install the thin-layer structural surface mold on the side wall of the prefabricated tunnel model column with an electromagnetic fixed support. Adjust the angle and position of the thin-layer structural surface mold by adjusting the angle of the spherical connector and the length of the telescopic movable rod, and turn on the switch on the electromagnetic fixed support to fix the length of the telescopic movable rod on the thin-layer structural surface mold and the angle of the spherical connector. Use a small brush to evenly apply a layer of release oil on the inner wall of each plate, the side wall of the prefabricated tunnel model column, and the structural surface support mold;

[0050] Step 3: Establish the mapping relationship between the thickness of the tunnel physical model, the forming pressure, and the mass of the rock-similar material to determine the mass of the rock-similar material used for casting;

[0051] Step 3.1: inject a certain mass of rock-like material into the tunnel physical model making mold, apply a certain molding pressure, and after the tunnel physical model is formed and cured, measure the thickness of the tunnel physical model;

[0052] Step 3.2: Replace the rock-like materials with different masses for casting, apply different molding pressures, and after the curing is completed, measure the thickness of the tunnel physical model; repeat the above steps to obtain the rock-like material mass, the applied molding pressure and the tunnel physical model thickness data of each group of models, and establish the functional relationship between the tunnel physical model thickness, molding pressure and rock-like material mass:

[0053] Where d is the thickness of the physical model of the tunnel after forming, m is the mass of the rock-similar material during grouting, ρ is the density of the rock-similar material, E is the elastic modulus of the rock-similar material, and κ is the material compression correction coefficient.

[0054] Step 3.3: Calculate the mass of the rock-similar material used for pouring according to the thickness of the tunnel physical model, the forming pressure, the mass functional relationship of the rock-similar material, the preset forming pressure and the thickness of the tunnel physical model;

[0055] Step 4: Pour the evenly mixed rock-like material into the tunnel physical model making mold to the predetermined position, vibrate and compact it, and smooth the surface;

[0056] Step 5: After the pouring is completed, a ballast top plate with preset holes is placed on the top of the tunnel physical model mold so that the prefabricated tunnel model column can smoothly pass through the holes of the ballast top plate;

[0057] Step 6: Place the assembled sample production mold on the model stage of the sliding stage integrated loading frame, and push the model stage to the center position of the electro-hydraulic servo actuator of the loading frame through the double-line slide rail, lift the electro-hydraulic servo actuator to make the ballast top plate contact with the pressure top plate of the loading frame, start pressurizing to a predetermined pressure value, and maintain the pressure state for a preset number of days;

[0058] Step 7: After maintaining the pressure state for the preset number of days, the mold is removed, and the plastic wrapped around the thin-layer structural surface mold is melted by electricity. The structural surface mold is pulled out, and the natural original structural surface fine-ground slurry is injected under pressure to seal the preset thin-layer structural surface. The prefabricated tunnel model column in the middle of the model is then taken out and naturally cured for the preset number of days. The tunnel model with a certain hole shape, angle and structural surface is completed under pressure conditions.

[0059] The beneficial effects of the present invention are mainly manifested in:

[0060] 1. The rock-like material used in the present invention is always under stress conditions from molding to final setting, simulating the rock diagenetic stress environment, greatly improving the similarity of rock samples, and providing a method for determining the design size of a tunnel physical model manufacturing mold, thereby ensuring the safety and reliability of the mold;

[0061] 2. The present invention is convenient and fast to operate, highly efficient and practical. It only needs to change the tunnel model and use the holes of the pressure plate with angle alignment lines to complete the production of physical models with different tunnel shapes and angles, which greatly reduces the test cost. The present invention also provides a tunnel angle fixing device and an angle calibration scale to achieve precise control of geometric features such as tunnel shape and angle, and realizes the production of tunnel models with low cost and convenient installation and operation, which is suitable for studying tunnel morphology and spatial relationship with principal stress.

[0062] 3. The present invention can adjust the angle and position of the thin-layer structural surface mold in the tunnel physical model at will, taking into account the influence of the distance, position and occurrence of the structural surface from the free surface on the tunnel disaster process and destruction mechanism;

[0063] 4. The present invention provides a method for selecting rock-like materials required for making a tunnel physical model by using similarity theory, so as to ensure that the model is similar to the prototype tunnel in mechanical properties. At the same time, a functional relationship between the thickness of the tunnel physical model, the molding pressure and the mass of the rock-like materials is established, so as to ensure that the model can reach a preset thickness after pressurized molding and curing. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 Schematic diagram of the device structure for making tunnel models with different hole shapes, angles and structural surfaces under pressure conditions;

[0065] Figure 2 This is a structural diagram of the integrated loading frame of the sliding stage;

[0066] Figure 3 Create an exploded view of the mold structure for the tunnel physical model;

[0067] Figure 4 Make mold structure drawings for structural surfaces;

[0068] Figure 5 Rotating disk diagram for tunnel hole;

[0069] Figure 6 Produce mold ballast top plate diagram for tunnel physical model;

[0070] Figure 7 Produce front and rear side panels of the mold for the tunnel physical model;

[0071] Figure 8 Make left and right side panels of the mold for the tunnel physical model;

[0072] Fig. 9 Produce mold soft contact base plate map for tunnel physical model;

[0073] Fig.10 This is the T-beam-column combination model diagram;

[0074] Fig.11 Casting diagram for rock-like materials;

[0075] Fig.12 Pressurized diagram for the tunnel physical model;

[0076] Fig.13 This is a physical picture of the circular tunnel physical model;

[0077] Fig.14 This is a physical picture of the city gate tunnel (0°) physical model;

[0078] Fig.15 This is a physical model of a city gate-shaped (45°) tunnel;

[0079] Fig.16 This is a physical model of a city gate-shaped (90°) tunnel;

[0080] In the figure: 1- sliding stage integrated loading frame, 101- pressure top plate, 102- electro-hydraulic servo actuator, 103- double-line slide rail, 104- model stage, 105- support, 2- tunnel physical model production mold, 201- prefabricated tunnel model column, 201-1- circular prefabricated tunnel model column, 201-2- horseshoe-shaped prefabricated tunnel model column, 201-3- city gate-shaped prefabricated tunnel model column, 202- tunnel hole rotating disk, 202-1- circular tunnel hole rotating disk, 202-2- horseshoe-shaped tunnel hole rotating disk, 202-3- city gate shaped tunnel hole rotating disc, 203-ballast top plate, 204-soft contact bottom plate, 205-rear side plate, 206-right side plate, 207-front side plate, 208-left side plate, 209-threaded positioning blind hole, 210-positioning screw, 211-ballast top plate thin rubber layer, 212-side plate fixing bolt hole, 213-bottom plate thin rubber layer, 214-angle locking piece, 215-variable angle and shape tunnel hole, 3-structural surface manufacturing mold, 301-thin layer structural surface mold, 302-telescopic movable rod, 303-spherical connector, 304-electromagnetic fixed support. DETAILED DESCRIPTION

[0081] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0082] like Figures 1 to 16As shown, a device for making a tunnel physical model with different hole shapes and angles under pressure conditions comprises a front side plate 207, a rear side plate 205, a left side plate 208, a right side plate 206, a soft contact bottom plate 204 provided with a screw positioning blind hole 209, a prefabricated tunnel model column 201 with a variable hole shape and angle, and a ballast top plate 203 with a tunnel hole; a thin rubber layer 211 consistent with its cross-sectional shape and size is arranged at the lower part of the ballast top plate 203, and the thin rubber layer 211 plays a role in preventing the casting slurry from leaking during the casting and pressure application process of the tunnel physical model; a variable angle and shape tunnel hole rotating disk 202 is arranged in the middle of the ballast top plate 203; the variable angle and shape tunnel hole rotating disk 202 is arranged with angle scale lines, angle locking parts 214 and The variable angle and shape tunnel hole 215 is suitable for precise adjustment of specific angles of prefabricated tunnel model columns 201 of different hole shapes; the variable angle and shape tunnel hole 215 is consistent with the shape and size of the prefabricated tunnel model column 201 of the variable hole shape and angle, and the two are movably connected by setting a sealing ring, which also plays a role in preventing the casting slurry from leaking during the casting and pressure application process of the tunnel physical model; a thin rubber layer 213 consistent with the cross-sectional size of the ballast top plate is set on the upper part of the soft contact bottom plate 204, and a threaded positioning blind hole 209 is set in the center of the soft contact bottom plate 204. The soft contact bottom plate 204 is connected to the front side plate 207, the rear side plate 206, the left side plate 208, and the right side plate 206 through the side plate fixing bolt holes 212 to form a tunnel model cavity;

[0083] The size, forming pressure and grouting rock similar material of the tunnel physical model are determined as follows:

[0084] The physical model of the tunnel should maintain similar geometric shapes and dimensions to the prototype, and the corresponding angles should be equal, that is, any corresponding linear length of the prototype and the model should maintain a certain proportional relationship. λ is used to represent the scale of the prototype and the model. The side length of the prototype section L is taken as P =25000mm, the cross-sectional side length L of the tunnel physical model M =250mm, the length scale of the side length of the model section can be calculated:

[0085] Cross-sectional area S of the prototype tunnel P =19.635m 2 , the equivalent diameter of the prototype tunnel can be calculated:

[0086] The equivalent diameter d of the tunnel physical model M The calculation formula is as follows:

[0087] Take the tunnel physical model edge length a = L M =250mm, the edge length a of the tunnel physical model must satisfy the following formula:

[0088] According to the calculation results, it can be known that the formula is satisfied Boundary effects may not be considered;

[0089] Original rock density γ=28000N / m 3 , tunnel depth h = 203m, structural stress q g =1.3MPa, the forming pressure F0 of the tunnel physical model can be calculated: q0=γh+q g =28000×203×10 -6 +1.3=6.984MPa (5) F0=q0a 2 =6.984×250 2 ×10 -3 =436.5kN (6)

[0090] The selection of aggregates of rock-similar materials used for casting should consider the mineral composition, particle grading and other characteristics of the original rock. The selection of cementing materials should consider the strength and brittleness of the original rock. The selection of conditioning agents should consider the density and porosity of the original rock. By adjusting the types and proportions of aggregates, cementing materials and conditioning agents, the mechanical properties of the cast rock-similar materials of the tunnel physical model are similar to those of the original rock. The similar mechanical properties include brittleness, dynamic properties, and critical strength of disturbance. The quantitative index of the brittleness index is the ductility-brittleness index I controlled by the comprehensive index of pre-peak and post-peak characteristics. BD Determine, ductility and brittleness index I BD The calculation formula is as follows: I BD =B n (E-H) / H (7)

[0091] Due to the ductility-brittleness index I BD is a dimensionless physical quantity, then the brittleness similarity scale between the tunnel physical model and the original rock is Need to meet:

[0092] Dynamic elastic modulus E d and dynamic Poisson's ratio μ d As an important indicator of rock dynamic properties, the dynamic elastic modulus similarity scale Similarity ratio to dynamic Poisson's ratio Satisfies the following formula, where strain is a dimensionless physical quantity, then λ ε =1; density similarity scale λ ρ=2.5, when calculating tunnel geostress, the buried depth of the tunnel physical model is the same as that of the prototype tunnel, then the tunnel buried depth similarity ratio λ h =1;

[0093] The quantitative index of the critical intensity of disturbance is the critical coefficient η cs Determine the critical perturbation coefficient η cs The calculation formula is as follows:

[0094] Where σ cs is the perturbation critical stress, σ p is the peak intensity;

[0095] From formula (11), we can know that the critical disturbance coefficient η cs is a dimensionless physical quantity, then the perturbation critical coefficient similarity scale Satisfy the following formula:

[0096] Where η csP is the prototype disturbance critical coefficient, η csM is the critical coefficient of disturbance of the tunnel physical model;

[0097] According to the requirements that the above-mentioned rock-similar materials need to meet, the materials for making the tunnel physical model are determined. Quartz sand and feldspar sand are selected as aggregates, and their gradation is consistent with the gradation of granite mineral particles. Cement and gypsum are used as binders, borax is used as a retarder, polycarboxylic acid water reducer, and nano-silica are used as regulators.

[0098] The method for determining the design dimensions of the side plates and the pressure top plate 203 is as follows:

[0099] The side plate is simplified into a T-beam-column combination model (such as Fig.10 As shown in the figure, the two ends of the beam are fixed, the bottom of the column is fixed, and the joint between the beam and the column is hinged. The hinge point is called point A. According to the preset forming pressure of the tunnel model, the equivalent linear load q acting on the beam is calculated. E , the equivalent linear load q E Equivalent to concentrated force F, equivalent to linear load q E The calculation formula of the concentrated force F is as follows, where the cross-sectional area of ​​the tunnel A0 = 2481.75 mm 2 F=q Ea=908.75×250×10 -3 =227.19kN (15)

[0100] Where q is the uniform surface force preset in the tunnel model;

[0101] Calculate the equivalent linear load q acting on the column C , the calculation formula is as follows, where the lateral force coefficient β = 0.25

[0102] The concentrated force F is applied to the beam-column hinge point A, and the equivalent linear load q C Act on the column and calculate the deflection ω of the beam-column hinge point A. The calculation formula is as follows, where the elastic modulus of the side plate E = 206 GPa, the moment of inertia of the beam-column section I = 3.125×10 -5 m 4

[0103] The deflection ω of point A satisfies ω<0.02mm, and the height H=280mm and width B=262mm of the side plate satisfy the formula:

[0104] The thickness of each plate is D = 23mm, and the plate thickness D must satisfy the plate thickness safety factor K sa <1, the thickness safety factor K is satisfied sa The calculation formula is as follows, where the material coefficient of the mold for making the tunnel physical model is t = 4.1, σ e is the unit stress;

[0105] The plate thickness D=23mm satisfies the safety factor requirement. In summary, in this example, the height H of each side plate is 280mm, the width B is 262mm, and the thickness D is 23mm. The height and width of the ballast top plate 203 are both 250mm, and the thickness D is 23mm.

[0106] The method for determining the design dimensions of the prefabricated tunnel model column 201 is as follows:

[0107] The equivalent diameter d of the tunnel physical model is obtained based on the similarity ratio between the tunnel model and the prototype tunnel. M Calculate the tunnel cross-sectional area S of the physical model M , the calculation formula is as follows:

[0108] The tunnel cross-sectional area S of the physical model M=1963.50mm 2 The preset tunnel shape is a city gate shape, and the tunnel cross-sectional dimensions of the physical model are determined to be a bottom plate length of 50 mm, a side wall height of 20 mm, and a dome as a semicircle with a diameter of 50 mm; then, according to the thickness d=250 mm of the tunnel physical model, the length l=250 mm of the prefabricated tunnel model column 201 is determined, thereby determining the design dimensions of the prefabricated tunnel model column to be a length l=250 mm, a cross-sectional dimension of a bottom plate length of 50 mm, a side wall height of 20 mm, and a dome as a semicircle with a diameter of 50 mm;

[0109] A threaded positioning blind hole 209 of the same specification as the soft contact bottom plate is arranged at the center of the prefabricated tunnel model column 201 with variable hole shape and angle, and a positioning screw 210 penetrates the threaded positioning blind hole 209 of the soft contact bottom plate 204 and the prefabricated tunnel model column 201 with variable hole shape and angle to closely connect the two;

[0110] The structural surface manufacturing mold 3 of different occurrences and positions includes an electromagnetic fixed support 304, a telescopic movable rod 302 of adjustable length, a spherical connector 303 of adjustable angle, and a replaceable thin-layer structural surface mold 301. The replaceable thin-layer structural surface mold 301 is a stainless steel sheet wrapped with hot-melt plastic, and each part is connected by a spherical connector 303 of which the angle can be adjusted at will. The structural surface manufacturing mold 3 is installed on the side wall of the prefabricated tunnel model column 201 with variable hole shape and angle through the electromagnetic fixed support 304;

[0111] The sliding stage integrated loading frame 1 is assembled from a pressure top plate 101 , an electro-hydraulic servo actuator 102 , a double-line slide rail 103 , a model stage 104 and a support 105 .

[0112] In this embodiment:

[0113] Take the tunnel model making method with the size of 250mm×250mm×250mm, the tunnel profile is a city gate shape, the front side plate is at a 90° angle with the tunnel horizontal line, the hard structure surface is 40mm away from the tunnel free surface, and the inclination angle is 45° as an example;

[0114] A method for making tunnel models with different hole shapes, angles and structural surfaces under pressure conditions, using a device for making tunnel models with different hole shapes, angles and structural surfaces under pressure conditions, comprising the following steps:

[0115] Step 1: After the front side plate 207, the rear side plate 205, the left side plate 208, the right side plate 206, and the soft contact bottom plate 204 in the tunnel physical model manufacturing mold 2 are installed and fixed through the side plate fixing bolt holes 212, the city gate-shaped prefabricated tunnel model column 201-3 is placed on the soft contact bottom plate 204, and the tunnel model angle is adjusted to 90° using the city gate-shaped tunnel hole rotating disk 202-3 with the tunnel angle alignment line and the ballast top plate 203 with the angle scale line, and the rotation angle of the city gate-shaped tunnel hole rotating disk 202-3 is fixed by the angle locking piece 214 on the disk 202, and the city gate-shaped prefabricated tunnel model column 201-3 is fixed to the threaded positioning blind hole 209 of the soft contact bottom plate 204 by the positioning bolt 210;

[0116] Step 2: Install the thin-layer structural surface production mold 301 on the side wall of the city gate-shaped prefabricated tunnel model column 201-3 using an electromagnetic fixed support 304. Adjust the angle of the spherical connector 303 and the length of the telescopic movable rod 302 so that the distance between the thin-layer structural surface production mold 301 and the free surface of the tunnel is 40 mm. Adjust the angle of the thin-layer structural surface production mold 301 so that the inclination angle of the thin-layer structural surface production mold 301 is 45°. Turn on the switch on the electromagnetic fixed support 304 to fix the length of the telescopic movable rod 302 on the thin-layer structural surface mold and the angle of the spherical connector 303. Use a small brush to evenly apply a layer of release oil on the inner wall of each plate, the side wall of the city gate-shaped prefabricated tunnel model column 201-3 and the structural surface support mold 3;

[0117] Step 3: Establish the mapping relationship between the thickness of the tunnel physical model, the forming pressure, and the mass of the rock-similar material to determine the mass of the rock-similar material used for casting;

[0118] Step 3.1: inject a certain mass of rock-like material into the tunnel physical model making mold 2, apply a certain molding pressure, and after the tunnel physical model is formed and cured, measure the thickness of the tunnel physical model;

[0119] Step 3.2: Replace the rock-like materials with different masses for casting, apply different molding pressures, and after the curing is completed, measure the thickness of the tunnel physical model; repeat the above steps to obtain the rock-like material mass, the applied molding pressure and the tunnel physical model thickness data of each group of models, and establish the functional relationship between the tunnel physical model thickness, molding pressure and rock-like material mass:

[0120] Where d is the thickness of the physical model of the tunnel after forming, m is the mass of the rock-similar material during grouting, ρ is the density of the rock-similar material, E is the elastic modulus of the rock-similar material, and κ is the material compression correction coefficient.

[0121] Step 3.3: Calculate the mass of the rock-similar material used for pouring according to the thickness of the tunnel physical model, the forming pressure, the mass function of the rock-similar material, the preset forming pressure and the thickness of the tunnel physical model. The calculation process is as follows:

[0122] The thickness of the tunnel physical model after forming in this example is d = 250 mm, and the density of the rock-like material is ρ = 1.80 g / cm 3 , the elastic modulus of rock-like materials E = 4.62 GPa, the material compression correction coefficient κ = 1.40, and the required grouting rock material mass m = 28.185 kg obtained by functional relationship (22);

[0123] Step 4: Pour the mixed and stirred rock-like material into the tunnel physical model production mold 2 to the predetermined position, vibrate and compact it, and smooth the surface;

[0124] Step 5: After the pouring is completed, a ballast top plate 203 with preset holes is covered on the top of the tunnel physical model manufacturing mold 2, so that the gate-shaped prefabricated tunnel model column 201-3 can smoothly pass through the hole of the ballast top plate 203;

[0125] Step 6: Place the assembled sample production mold on the model stage 104 of the sliding stage integrated loading frame 1, and push the model stage 104 to the center of the electro-hydraulic servo actuator 102 of the loading frame through the double-line slide rail 103, lift the electro-hydraulic servo actuator 102 to make the ballast top plate 203 contact with the pressure top plate 101 of the loading frame, start pressurizing to a predetermined pressure value, and maintain the pressure state for a preset number of days;

[0126] Step 7: After maintaining the pressure state for a preset number of days, the mold is removed, and the plastic wrapped around the thin-layer structural surface mold 301 is melted by electricity, and the structural surface mold 3 is pulled out. The natural original structural surface fine-ground slurry is injected under pressure to seal the preset thin-layer structural surface, and then the gate-shaped prefabricated tunnel model column 201-3 in the middle of the model is taken out. Natural curing is carried out for a preset number of days, and a tunnel model with a certain hole shape, angle and structural surface is completed under pressure conditions.

[0127] Matters not covered by the present invention are known technologies.

[0128] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for making tunnel models with different shapes and structural surfaces under pressure, characterized by: It includes a sliding stage integrated loading frame, tunnel physical model production molds with different hole shapes and angles, structural surface production molds with different occurrences and positions, and tunnel physical model specimens; The mold for making tunnel physical models with different hole shapes and angles under pressure conditions comprises a front side plate, a rear side plate, a left side plate, a right side plate, a soft contact bottom plate provided with a screw positioning blind hole, a prefabricated tunnel model column with a variable hole shape and angle, and a ballast top plate with a tunnel hole; a thin rubber layer consistent with the cross-sectional shape and size of the ballast top plate is provided at the bottom of the ballast top plate, a rotating disc of a tunnel hole with a variable angle and shape is provided in the middle of the ballast top plate, the rotating disc of the tunnel hole with a variable angle and shape is arranged with an angle scale line, an angle locking piece and a tunnel hole with a variable angle and shape, and the tunnel hole with a variable angle and shape is connected to the prefabricated tunnel hole with a variable hole shape and angle. The shape and size of the tunnel model column are consistent, and the two are movably connected by setting a sealing ring; a thin rubber layer consistent with the cross-sectional shape and size of the ballast top plate is set on the upper part of the soft contact bottom plate, a threaded positioning blind hole is set at the center of the screw positioning soft contact bottom plate, and a threaded positioning blind hole of the same specification as the soft contact bottom plate is set at the center of the prefabricated tunnel model column with variable hole shape and angle. The positioning screw penetrates the threaded positioning blind holes of the soft contact bottom plate and the prefabricated tunnel model column with variable hole shape and angle to tightly connect the two, and the soft contact bottom plate is connected with the front side plate, the rear side plate, the left side plate, and the right side plate through the side plate fixing bolt holes to form a tunnel model cavity; The structural surface manufacturing mold with different shapes and positions includes an electromagnetic fixed support, a telescopic movable rod with adjustable length, a spherical connector with adjustable angle, and a replaceable thin-layer structural surface mold. The various parts are connected by a spherical connector with adjustable angle. The structural surface manufacturing mold is installed on the side wall of the prefabricated tunnel model column with variable hole shape and angle through the electromagnetic fixed support.

2. A device for making tunnel models with different shapes and structural surfaces under pressure according to claim 1, characterized in that: The tunnel physical model specimen and the prototype must maintain similar geometric shapes and dimensions, and the corresponding angles must be equal, that is, any corresponding linear length of the prototype and the model must maintain a certain proportional relationship, and the ratio of the prototype quantity and the model quantity is represented by λ. The side length of the model section must meet the length ratio: Where L P is the side length of the prototype section, L M is the cross-sectional side length of the tunnel physical model; The equivalent diameter d of the tunnel physical model M The calculation formula is as follows: Where d P is the equivalent diameter of the prototype tunnel. The equivalent diameter is the diameter of each type of tunnel when it is converted into a circular tunnel of equal area. The equivalent diameter d P The calculation formula is as follows: Where S P is the cross-sectional area of ​​the prototype tunnel; In order to ignore the boundary effect, the edge length a of the tunnel physical model must satisfy the following formula: The calculation formula of the forming pressure F0 of the tunnel physical model is as follows: q0=γh+q g (5) F0=q0a 2 (6) Where γ is the original rock density, h is the tunnel depth, q1 is the tunnel ground stress, q g is tectonic stress; The materials for making the tunnel physical model sample are selected from aggregates with the same mineral types, component ratios, particle grading, and microscopic mineral structure characteristics as the original rock of the prototype tunnel. The strength and brittleness of the original rock should be considered in the selection of cementing materials, and the density and porosity of the original rock should be considered in the selection of conditioning agents. By adjusting the types and proportions of aggregates, cementing materials, and conditioning agents, the tunnel physical model sample can achieve mechanical properties similar to those of the prototype tunnel. The similar mechanical properties include brittleness, dynamic properties, and perturbation critical strength. The quantitative index of the brittleness index is the ductility-brittleness index I controlled by the comprehensive index of pre-peak and post-peak properties. BD Determine, ductility and brittleness index I BD The calculation formula is as follows: I BD =B n (E-H) / H (7) Where B is a constant parameter, E is the elastic modulus before the rock peak, H is the modulus after the rock peak, and the value of the modulus after the rock peak is equal to the slope of the post-peak curve; Brittleness similarity scale between tunnel physical model and original rock Need to meet: Where I BDP is the prototype ductility and brittleness index, I BDM is the ductility-brittleness index of the tunnel physical model; Dynamic elastic modulus E d and dynamic Poisson's ratio μ d As an important indicator of rock dynamic properties, the dynamic elastic modulus similarity scale Similarity ratio to dynamic Poisson's ratio Satisfy the following formula: Where λ σ is the stress similarity scale; λ ρ is the density similarity scale, λ h is the similarity scale of tunnel depth, λ ε is the strain similarity scale, strain is a dimensionless physical quantity, then λ ε =1; The quantitative index of the critical intensity of disturbance is the critical coefficient η cs Determine the critical perturbation coefficient η cs The calculation formula is as follows: Where σ cs is the perturbation critical stress, σ p is the peak intensity; From formula (11), we can know that the critical disturbance coefficient η cs is a dimensionless physical quantity, then the perturbation critical coefficient similarity scale Satisfy the following formula: Where η csP is the prototype disturbance critical coefficient, η csM is the critical coefficient of disturbance of the tunnel physical model.

3. A device for making tunnel models with different shapes and structural surfaces under pressure according to claim 1, characterized in that: The method for determining the design dimensions of the side plates and the pressure top plate is as follows: The side plate is simplified into a T-shaped beam-column combination model, in which both ends of the beam are fixed, the bottom of the column is fixed, and the joint between the beam and the column is hinged. According to the preset forming pressure F0 of the tunnel model, the equivalent linear load q acting on the beam is calculated. E , the equivalent linear load q E Equivalent to concentrated force F, equivalent to linear load q E The calculation formula of the concentrated force F is as follows: F=q E a (15) Where q is the uniformly distributed surface force preset in the tunnel model; A0 is the cross-sectional area of ​​the tunnel; Calculate the equivalent linear load q acting on the column C , the calculation formula is as follows: Where, β is the lateral force coefficient; The concentrated force F is applied to the beam-column hinge point A, and the equivalent linear load q C Act on the column and calculate the deflection ω of the beam-column hinge point A. The calculation formula is as follows: Where E is the elastic modulus of the side plate, I is the moment of inertia of the beam-column section, the deflection ω of point A must satisfy ω<0.02mm, and the height H and width B of the side plate must satisfy the formula: Finally, the thickness D of each plate is determined according to the size of the tunnel physical model. The plate thickness D must satisfy the plate thickness safety factor K. sa <1, the thickness safety factor K is satisfied sa The calculation formula is as follows: Where t is the material coefficient of the physical model plate, and E is the elastic modulus of the physical model plate; The size of the side plate and the size of the tunnel physical model are calculated according to the above formula, and the size of the pressure top plate is finally determined, so that the pressure top plate, the side plate and the soft contact bottom plate form a closed tunnel physical model mold frame; The method for determining the design size of the prefabricated tunnel model column is as follows: The equivalent diameter d of the tunnel physical model is obtained based on the similarity ratio between the tunnel model and the prototype tunnel. M Calculate the tunnel cross-sectional area S of the physical model M , the calculation formula is as follows: The tunnel cross-sectional area S of the physical model M And the preset tunnel shape is used to determine the tunnel outline size of the physical model, and then the cross-sectional size of the prefabricated tunnel model column is determined; then the length l of the prefabricated tunnel model column is determined according to the thickness d of the tunnel physical model, thereby determining the design size of the prefabricated tunnel model column.

4. A device for making tunnel models with different shapes and structural surfaces under pressure according to claim 1, characterized in that: The sliding stage integrated loading frame is assembled from a pressure top plate, an electro-hydraulic servo actuator, a double-line slide rail, a model stage and a support.

5. A device for making tunnel models with different shapes and structural surfaces under pressure according to claim 1, characterized in that: The molds for making the tunnel physical models with different hole shapes and angles and the molds for making the structural surfaces with different occurrences and positions are made of stainless steel, and the replaceable thin-layer structural surface mold is a stainless steel sheet wrapped with hot-melt plastic.

6. A device for making tunnel models with different shapes and structural surfaces under pressure according to claim 1, characterized in that: After adjusting the rotation angle of the spherical connector and the length of the telescopic movable rod, the mold for making structural surfaces of different shapes and positions locks the spherical connector and the telescopic movable rod by turning on a switch on the electromagnetic fixing support.

7. A method for using a device for making tunnel models with different shapes and structural surfaces under pressure according to claims 1 to 6, characterized in that: The following steps are involved: Step 1: After the front side plate, rear side plate, left side plate, right side plate and soft contact bottom plate in the tunnel physical model manufacturing mold are installed and fixed through the side plate fixing bolt holes, the prefabricated tunnel model column is placed on the soft contact bottom plate, and the tunnel hole rotating disk with the tunnel angle alignment line and the ballast top plate with the angle scale line are used to adjust the tunnel model angle, and the rotation angle of the disk is fixed by the angle locking piece on the disk, and the prefabricated tunnel model column is fixed to the threaded positioning blind hole of the soft contact bottom plate by the positioning bolts; Step 2: On the side wall of the prefabricated tunnel model column, use an electromagnetic fixed support to install a thin layer structural surface production mold; adjust the angle and position of the thin layer structural surface mold by adjusting the angle of the spherical connector and the length of the telescopic movable rod, turn on the switch on the electromagnetic fixed support to fix the length of the telescopic movable rod on the thin layer structural surface mold and the angle of the spherical connector; use a small brush to evenly apply a layer of demoulding oil on the inner wall of each plate, the side wall of the prefabricated tunnel model column and the structural surface support mold; Step 3: Establish the mapping relationship between the thickness of the tunnel physical model, the forming pressure, and the mass of the rock-similar material to determine the mass of the rock-similar material used for casting; Step 3.1: inject a certain mass of rock-like material into the tunnel physical model making mold, apply a certain molding pressure, and after the tunnel physical model is formed and cured, measure the thickness of the tunnel physical model; Step 3.2: Replace the rock-like materials with different masses for casting, apply different molding pressures, and after the curing is completed, measure the thickness of the tunnel physical model; repeat the above steps to obtain the rock-like material mass, the applied molding pressure and the tunnel physical model thickness data of each group of models, and establish the functional relationship between the tunnel physical model thickness, molding pressure and rock-like material mass: Where d is the thickness of the physical model of the tunnel after forming, m is the mass of the rock-similar material during grouting, ρ is the density of the rock-similar material, E is the elastic modulus of the rock-similar material, and κ is the material compression correction factor; Step 3.3: Calculate the mass of the rock-similar material used for pouring according to the thickness of the tunnel physical model, the forming pressure, the mass functional relationship of the rock-similar material, the preset forming pressure and the thickness of the tunnel physical model; Step 4: Pour the evenly mixed rock-like material into the tunnel physical model making mold to the predetermined position, vibrate and compact it, and smooth the surface; Step 5: After the pouring is completed, a ballast top plate with preset holes is placed on the top of the tunnel physical model mold so that the prefabricated tunnel model column can smoothly pass through the holes of the ballast top plate; Step 6: Place the assembled sample production mold on the model stage of the sliding stage integrated loading frame, and push the model stage to the center position of the electro-hydraulic servo actuator of the loading frame through the double-line slide rail, lift the electro-hydraulic servo actuator to make the ballast top plate contact with the pressure top plate of the loading frame, start pressurizing to a predetermined pressure value, and maintain the pressure state for a preset number of days; Step 7: After maintaining the pressure state for the preset number of days, the mold is removed, and the plastic wrapped around the thin-layer structural surface mold is melted by electricity. The structural surface mold is pulled out, and the natural original structural surface fine-ground slurry is injected under pressure to seal the preset thin-layer structural surface. The prefabricated tunnel model column in the middle of the model is then taken out and naturally cured for the preset number of days. The tunnel model with a certain hole shape, angle and structural surface is completed under pressure conditions.

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