A method for preparing a rock mass model containing complex structural surfaces

Abstract

The present invention discloses a method for preparing a similar model of a rock mass containing a complex structural surface. The method comprises mixing cement mortar according to a required formula to obtain a main material, and uniformly pouring the model of the part without a structural surface; in the part with a structural surface, using sugar as a structural surface filling material to print the first section of the structural surface part with a three-dimensional structure; then pouring the main material in the first section of the printed structural surface; repeating the above process to continue printing the next section until the model is printed, and after curing, heating and water washing are performed to make the sugars in the filling part of all the structural surfaces completely flow out or be dissolved, and then the preparation of the rock mass model containing a complex three-dimensional structural surface is completed. Compared with the traditional method, the present invention has a higher preparation accuracy in the structural surface part of the model; the use of sugars can completely remove it without affecting the main structure; and except for the structural surface part, the main materials of other parts do not need to be finely arranged, and only need to be simply poured, and the printing speed is faster.

Description

Technical Field

[0001] The invention belongs to the field of rock and soil testing, and in particular relates to a method for preparing a rock mass model containing a complex structural surface. Background Art

[0002] The rock mass scale model experiment can simulate the stress, deformation and failure characteristics of the prototype rock and soil structure in a small-scale model experiment, which is convenient for studying the disaster mechanism of large-scale rock and soil bodies and further proposing corresponding disaster prevention measures. Among them, the most critical link is how to prepare a qualified scale model so that it is strictly geometrically similar to the prototype rock and soil body containing artificial structures and natural structural surfaces. At present, the most commonly used rock mass similarity model is prepared by layered pouring of cement-based materials. Since cement-based materials are fluid when not solidified, support materials must be used for artificial structures, structural surfaces and cracks to prevent cement from blocking the structure, structural surfaces and cracks. For artificial structures such as caverns and underground tunnels in the model, rubber bags and other methods can be used to assist in preparation; for structural surfaces such as cracks and joints, support materials must be pre-placed at the structural surface position. The existing technology mostly uses methods such as sprinkling prefabricated paper sheets and plastic sheets to prepare. However, this method is only applicable to the preparation of regular structural surfaces with simple two-dimensional structures, and it is difficult to prepare structural surfaces such as faults, cracks, joints, etc. with complex three-dimensional structures. Summary of the invention

[0003] The purpose of the present invention is to propose a method for preparing a rock mass similarity model containing complex structural surfaces in view of the above-mentioned problems existing in the prior art.

[0004] The object of the present invention is achieved through the following technical scheme: a method for preparing a similar model of a rock mass containing a complex structural surface, the method comprising the following steps:

[0005] Step 1: Mix cement mortar according to the required formula to obtain the main material, and evenly cast the model of the non-structured surface;

[0006] Step 2: When pouring reaches the part with structural surface, stop pouring, use a three-degree-of-freedom manipulator with heating function, use sugar as the structural surface filling material, and start printing the first section of the structural surface filling model with a three-dimensional complex structure;

[0007] The first section of the structural surface filling model is prepared by layered printing. The allowable printing height h of the single section structural surface filling model is determined according to the material tensile strength t, the structural surface opening d, and the main material density ρ:

[0008]

[0009] Where g is the acceleration due to gravity;

[0010] Step 4: After the structural surface filling model is printed, a detailed three-dimensional digital model of the structural surface filling model is established by laser scanning;

[0011] Step 5: Pour the main material in step 1 into the first section of the printed structural surface filling model;

[0012] Step 6: Continue printing the next section of the structural surface filling model in the same way as the previous section;

[0013] Step 7: Repeat steps 5-6 until all the main parts of the model and the filling parts of the structural surface are printed:

[0014] Step 8: After all printing is completed, cure the cement mortar until it is completely solidified;

[0015] Step 9: By heating and water flushing, the sugars in the filling parts of all structural surfaces are completely flowed out or dissolved, and the rock model containing complex three-dimensional structural surfaces is prepared.

[0016] Furthermore, the main material obtained in step 1 is continuously stirred before use, and an accelerating setting agent is mixed into the main material during use to make it initially set as soon as possible.

[0017] Furthermore, fructose is selected as the structural surface filling material.

[0018] Furthermore, in step 5, when pouring the main material of a section, ensure that the structural surface filling model of the section is slightly higher than the main material, and the height difference should be more than 1 mm to prevent the structural surface filling model of the next section from being unable to connect with the previous section.

[0019] Furthermore, in step 6, when continuing to print the next section of the structural surface filling model, if the bottom of a certain part of the structural surface of this section is not continuous with the top of the previous section, it can also be printed directly on the main material of the previous section.

[0020] Furthermore, in step 6, it is necessary to additionally print the connecting filling part between the discontinuous structural surface and the continuous structural surface of the structural surface filling model so as to discharge the sugars in the discontinuous structural surface part during the subsequent heating and dissolving process.

[0021] The main advantages of the present invention over the prior art are:

[0022] 1. Compared with the previous method of preparing two-dimensional structural surfaces with prefabricated paper sheets and plastic sheets, the present invention uses temperature-sensitive fructose as a 3D printing substrate to print support materials in layers, making it possible to prepare structural surfaces with complex three-dimensional structures such as cracks, joints, and faults; and the present invention adopts a section printing + casting method. Since the previous section has been cast when the next section is printed, the structural surface is better protected, and more complex structural surfaces can be printed;

[0023] 2. According to the calculation formula of the allowable printing height of a single layer, the maximum opening of the structural surface is positively correlated with the printing height. Therefore, by reducing the segment height, a structural surface with a smaller maximum opening, that is, a finer structure, can be prepared. When the segment height is about 1 cm, the width of the structural surface can be less than 0.3 mm;

[0024] 3. Compared with the more expensive special water-soluble support materials in the traditional resin 3D printing industry, the present invention innovatively proposes to use extremely common fructose as the structural surface support material, which greatly reduces the cost and the waste liquid after flushing has less pollution to the environment. In addition, the melting point of fructose is 96 degrees, which is more feasible.

[0025] 4. Compared with the traditional method of fine printing for both structural surfaces and main material parts, in the present invention, except for the structural surface part, the main material of other parts does not need fine printing, but only needs simple casting. The overall preparation speed is much faster than the previous method. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 Schematic diagram of a rock mass similarity model with complex structural surfaces during the printing process;

[0028] Figure 2 This is a schematic diagram of a printed rock mass similarity model with complex structural surfaces.

[0029] In the figure, 1-similar model without structural surface part, 2-first section of structural surface filling model, 3-main material cast on both sides of structural surface filling model, 4-main material part of the model, 5-continuous structural surface filling part of the model, 6-discontinuous structural surface filling part of the model, 7-connection filling part between discontinuous structural surface and continuous structural surface of the model; DETAILED DESCRIPTION

[0030] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0031] like Figure 1 and Figure 2 As shown, the present invention provides a method for preparing a rock mass similarity model containing a complex structural surface. The method comprises the following steps:

[0032] Step 1: Main materials: 525 cement + 40-70 mesh quartz sand are mixed in a mass ratio of 1:1, and the water: solid weight ratio is 1:2. Oscillate and stir evenly. Before pouring, mix in an accelerator with sodium aluminate as the main component at a cement mass ratio of 2%.

[0033] Step 2: The overall model is 1m square, of which the bottom 30cm part is part 1 without structural surface, and this part is evenly poured with the main material.

[0034] Step 3: When pouring reaches the part with structural surface, stop pouring, and start printing the first section of structural surface filling model 2 with three-dimensional complex structure with structural surface filling material. Use a three-degree-of-freedom manipulator with heating function and micro-outlet; the structural surface filling material must meet the requirements of low melting point, high strength after solidification, and good solubility (preferably soluble in water). In the present invention, fructose is used as the structural surface filling material, which is cheap, has low melting point, and is pollution-free; this section of the structural surface filling model is prepared by layered printing; the printing height h of a single section of the structural surface filling model cannot be too high, otherwise the structural surface filling material may break during the next step of pouring and leveling. The calculation basis for the allowable printing height h of a single layer: the tensile strength of the material is about 10MPa, the structural surface opening is 1mm, and the density of the main material is 2500kg / m 3 According to the following formula, h is about 0.06m; to ensure safety, the safety factor is 2, so h is 0.03m

[0035]

[0036] According to the formula designed in the present invention, it can be ensured that during pouring, the printed structural surface is prevented from being broken and damaged due to the pouring operation.

[0037] Step 4: After the structural surface filling model is printed, a detailed three-dimensional digital model of the structural surface filling model is established by laser scanning.

[0038] Step 5: Pour the main material 3 in the first section of the printed structural surface filling model. It should be noted that the height of the main material is slightly lower than the structural surface filling model of this section. The height difference should be more than 1mm to prevent the next section of the structural surface filling model from being unable to connect with the previous section.

[0039] Step 6: Continue to print the next section of the structural surface filling model in the same way as the previous section. If the bottom of a certain part of the structural surface of this section is not connected to the top of the previous section, as shown in the figure Figure 1 The non-continuous structural surface filling part 6 of the model can also be directly printed on the main material 3 in the previous section; and the connecting filling part 7 between the non-continuous structural surface and the continuous structural surface of the model needs to be additionally printed to discharge the filling material of the non-continuous structural surface part during the subsequent heating and dissolving process.

[0040] Step 7: Repeat steps 5-6 until the main material part 4 of the model, the continuous structural surface filling part 5 of the model, the discontinuous structural surface filling part 6 of the model, and the connection filling part 7 between the discontinuous structural surface and the continuous structural surface of the model are all printed.

[0041] Step 8: After all printing is completed, cure the cement mortar until it is completely solidified.

[0042] Step 9: By heating + water flushing, the filling part of the structural surface is completely flowed out or dissolved, and the preparation of the rock model containing a complex three-dimensional structural surface is completed.

[0043] Personnel in the technical field can easily make various changes and modifications based on the text description, drawings and claims provided by the present invention without departing from the concept and scope of the present invention defined by the claims. Any modification or equivalent change made to the above embodiments based on the technical concept and essence of the present invention shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a similar model of a rock mass containing a complex structural surface, characterized in that: The method comprises the following steps: Step 1: Mix cement mortar according to the required formula to obtain the main material, and evenly cast the model of the non-structured surface; Step 2: When pouring reaches the part with structural surface, stop pouring, use a three-degree-of-freedom manipulator with heating function, use fructose as the structural surface filling material, and start printing the first section of the structural surface filling model with a three-dimensional complex structure; The structural surface filling model is prepared by layered printing. The allowable printing height h of a single-section structural surface filling model is determined according to the material tensile strength t, the structural surface opening d, and the main material density ρ: Where g is the acceleration due to gravity; Step 4: After the structural surface filling model is printed, a detailed three-dimensional digital model of the structural surface filling model is established by laser scanning; Step 5: Pour the main material in step 1 in the first section of the printed structural surface filling model; when pouring the main material of a section, ensure that the structural surface filling model of that section is slightly higher than the main material, and the height difference should be more than 1mm to prevent the next section of the structural surface filling model from being unable to connect with the previous section; Step 6: Continue to print the next section of the structural surface filling model in the same way as the previous section of the structural surface filling model; when continuing to print the next section of the structural surface filling model, if the bottom of a certain part of the structural surface of this section is not connected with the top of the previous section, it can also be printed directly on the main material of the previous section; it is necessary to additionally print the connecting filling part between the discontinuous structural surface and the continuous structural surface of the structural surface filling model, so as to discharge the fructose in the discontinuous structural surface part during the subsequent heating and dissolving process; Step 7: Repeat steps 5-6 until all the main parts of the model and the filling parts of the structural surface are printed: Step 8: After all printing is completed, cure the cement mortar until it is completely solidified; Step 9: By heating and water flushing, the fructose in the filling part of all the structural surfaces is completely flowed out or dissolved, and the preparation of the rock model containing complex three-dimensional structural surfaces is completed.

2. The method for preparing a similar model of a rock mass containing a complex structural surface according to claim 1, characterized in that: The main material obtained in step 1 is continuously stirred before use, and an accelerating setting agent is mixed into the main material during use to make it initially set as soon as possible.

Images