A graded loading experimental device for dynamic load effects in roadways of soft coal seams

Abstract

This utility model discloses a graded loading experimental device for dynamic load effects in roadways of soft coal seams, belonging to the technical field of roadway support experimental devices. This graded loading experimental device for dynamic load effects in roadways of soft coal seams limits energy dissipation at the front and rear ends of the model, ensuring the roadway surrounding rock is under triaxial stress. It enables graded loading, allowing for direct observation of crack propagation and deformation failure patterns in the roadway surrounding rock during loading, determining the extent of roadway surrounding rock failure, and more accurately reproducing the actual deformation of the roadway in the field. This provides a basis for determining roadway surrounding rock support parameters and offers an effective research method for addressing the problem of large deformations and difficulty in supporting roadways in soft coal seams.

Description

Technical Field

[0001] This utility model relates to the technical field of roadway support experimental devices, specifically a graded loading experimental device for dynamic load effects in roadways of soft coal seams. Background Technology

[0002] In the coal mining industry, the support effect of the working face and roadway directly affects mining efficiency and operational safety. The significant differences in geological conditions among different mines further increase the difficulty of researching roadway support technology. Physical similarity simulation experiments, as an important means of exploring the deformation law of the surrounding rock in roadways and optimizing support schemes, can obtain key technical indicators and parameters through precise simulation of rock strata characteristics, roadway support methods, and deformation and failure processes, providing reliable scientific basis for on-site production practices.

[0003] Currently, physical similarity simulation devices in laboratories are mainly divided into two categories: two-dimensional and three-dimensional. However, both have significant limitations in experimental applications.

[0004] The two-dimensional device is a plane stress model, which is convenient for experimental operation, but it has significant simulation defects: when simulating a roadway in a soft coal seam, the stress cannot be effectively transferred downward after loading at the top of the model. Due to the small size of the roadway, the front and rear sections of the model are free surfaces, which ultimately leads to the stress being released on the free surfaces at the front and rear of the model. It is impossible to accurately obtain the crack propagation and deformation law of the surrounding rock in the roadway, and it cannot provide effective parameter basis for the support scheme.

[0005] While three-dimensional simulation devices can more closely resemble the actual geological environment of coal seam mining, their models are usually large in size, resulting in drawbacks such as high cost, long cycle, high operation difficulty, and difficult dismantling. Especially for the mining roadways of soft coal seams, it is difficult to intuitively observe the real deformation process and laws of the surrounding rock in the middle of the roadway, leading to poor experimental results.

[0006] Therefore, in order to address the shortcomings of current experimental devices, a graded loading experimental device for dynamic load effects in roadways of three soft coal seams was invented, providing a basis for determining roadway support parameters. Utility Model Content

[0007] To address the shortcomings of existing technologies, this invention provides a graded loading experimental device for dynamic load effects in roadways of soft coal seams, thus solving the problems mentioned in the background section.

[0008] To achieve the above objectives, this utility model is implemented through the following technical solution: a graded loading experimental device for dynamic load effect in roadways of soft coal seams, comprising a physical similarity simulation experimental device, similarity simulation materials, a hydraulic loading device, and a data acquisition terminal;

[0009] The hydraulic loading device is installed on the physical similarity simulation experimental equipment, and the physical similarity simulation experimental equipment and the similarity simulation material are bonded together through friction connection.

[0010] Preferably, the physical similarity simulation experimental equipment includes an experimental steel frame, an acrylic plate, bolts, data monitoring points, and channel steel. The acrylic plate, data monitoring points, and reinforcing channel steel are fixed to the experimental steel frame using bolts.

[0011] Preferably, the experimental steel frame is a rectangular steel frame with a hydraulic loading device installed on top.

[0012] Preferably, the similar simulation materials include soft rock simulation materials, soft coal simulation materials, and conventional rock strata simulation materials. The acrylic plate and the soft rock simulation materials, soft coal simulation materials, and conventional rock strata simulation materials are bonded together through friction connection. Edible oil is coated on the contact surfaces of the soft rock simulation materials, soft coal simulation materials, and conventional rock strata simulation materials to adjust the coefficient of friction with the acrylic plate.

[0013] Preferably, the hydraulic loading device is a hydraulic loading cylinder and a cylinder loading controller.

[0014] Preferably, the data acquisition terminal is a total station data monitoring device.

[0015] Beneficial effects

[0016] This invention provides a graded loading experimental device for dynamic load effects in roadways of soft coal seams. Compared with existing technologies, it has the following advantages:

[0017] (1) The graded loading experimental device for dynamic load effect in roadway of soft coal seam is simple in structure, easy to operate and low in cost.

[0018] (2) The graded loading experimental device for dynamic load effect in roadway of soft coal seam reduces the error generated by the traditional plane stress model to simulate the free end face, restores the weak mechanical properties of soft rock itself, and has high experimental accuracy.

[0019] (3) The graded loading experimental device for dynamic load effect in roadways of soft coal seams can simulate the influence of dynamic load on roadways and their supports under mining operations by equipping them with graded loading equipment.

[0020] (4) The graded loading experimental device for dynamic load effect in roadways of soft coal seams limits the energy dissipation of the front and rear ends of the model, can satisfy the triaxial stress state of the roadway surrounding rock, and can realize graded loading. It can intuitively observe the crack propagation and deformation failure law of the roadway surrounding rock during the loading process, determine the range of roadway surrounding rock failure, and more accurately restore the actual situation of roadway deformation on site. This provides a basis for determining the roadway surrounding rock support parameters and provides an effective research method for the problem of large deformation and difficulty in support of roadways in soft coal seams. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the external structure of this utility model;

[0022] Figure 2 This is the left view of the present invention.

[0023] In the figure: 1-Experimental steel frame, 2-Hydraulic loading cylinder, 3-Acrylic plate, 4-Bolt, 5-Data monitoring point, 6-Soft rock simulation material, 7-Soft coal simulation material, 8-Conventional rock stratum simulation material, 9-Cylinder loading controller, 10-Channel steel, 11-Total station data monitoring device. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Example 1

[0026] Please see Figures 1-2 This utility model provides a technical solution: a graded loading experimental device for dynamic load effect in roadways of three soft coal seams, including an experimental steel frame 1, a hydraulic loading cylinder 2, an acrylic plate 3, bolts 4, data monitoring points 5, soft rock simulation material 6, soft coal simulation material 7, conventional rock strata simulation material 8, a cylinder loading controller 9, a channel steel 10, and a total station data monitoring device 11.

[0027] Among them, the acrylic plate 3 is bonded to the soft rock simulation material 6, soft coal simulation material 7, and conventional rock stratum simulation material 8 through friction connection. The contact surfaces of the soft rock simulation material 6, soft coal simulation material 7, and conventional rock stratum simulation material 8 are coated with edible oil to adjust the friction coefficient with the acrylic plate 3. The hydraulic cylinder 2 is in surface contact with the rock stratum simulation material 6.

[0028] Example 2

[0029] Please see Figures 1-2 The following are the specific steps for conducting similar simulation studies using this experimental setup:

[0030] Step 1: Preparation of experimental materials:

[0031] Physical similarity simulation experiment equipment: 1 experimental steel frame, 3 acrylic plates, 4 bolts, 10 channel steels;

[0032] Similar simulation materials: fly ash, river sand, gypsum powder, whiting, water, soybean oil;

[0033] Hydraulic loading device: hydraulic loading cylinder 2 and loading controller 9;

[0034] Data acquisition terminal: Total station data monitoring device 11.

[0035] Step 2: Laying out similar simulation materials and fixing the model:

[0036] In the experimental steel frame 1, similar simulated materials are laid layer by layer from bottom to top. Before laying, the proportions and thicknesses of various simulated materials need to be determined based on the actual geological conditions to be simulated. The specific layering settings are as follows:

[0037] The bottom of the model uses conventional rock strata simulation material 8, which is made of river sand, gypsum powder, white powder and water, mixed in a specific ratio.

[0038] The central part of the model is the roof and floor of the roadway and the soft coal area. This area uses targeted similar simulation materials: the soft coal similar material 7 is prepared by mixing river sand, gypsum, whiting, fly ash and soybean oil in proportion, and the soft rock similar material 6 for the roof and floor is prepared by mixing river sand, gypsum, whiting and soybean oil in proportion. Soybean oil is used to replace water in conventional simulation materials for both types of materials to adapt to the physical properties of soft rock and soft coal.

[0039] The upper part of the model also uses conventional rock strata simulation material 8.

[0040] During the laying of similar materials, channel steel 10 and bolts 4 should be used simultaneously, installed in a bottom-up order to assist in material laying and achieve model fixation. The thickness of the similar material laid in a single operation should be controlled between 1 and 1.5 cm. After laying, the material needs to be compacted, and simulated coal and rock joints should be delineated to restore the joint characteristics in real geological structures. The operation procedures on the front and back sides of experimental frame 1 should be consistent.

[0041] Step 3: Preparations before model loading:

[0042] After the model inside the experimental steel frame 1 in step one has been fully dried and shaped, the channel steel 10 is removed first, and then the data monitoring points 5 are arranged. A small amount of soybean oil is evenly applied to the surface of the acrylic plate 3 that contacts the experimental model, and then it is installed on the experimental steel frame 1 with bolts 4. To enhance stability, the acrylic plate 3 is further reinforced with channel steel 10. The reinforcement position can be flexibly adjusted according to the specific situation of the model. The operation process on the front and back sides of the experimental steel frame 1 is consistent.

[0043] Step 4: Hierarchical loading and data collection:

[0044] After the above assembly is completed, the hydraulic loading cylinder 2 is controlled by the cylinder loading controller 9 to apply load to the model to the original rock stress state of the roadway. Subsequently, graded loading can be implemented according to the mining influence coefficient. Then, the position of the total station data monitoring device 11 is adjusted and fixed so that it can monitor in real time during the model loading process. At this point, the graded loading experimental device for the three soft coal seam mining roadway is completed.

[0045] Example 3

[0046] Implementation Case:

[0047] The No. 5 coal seam in Chenghe Shanyang Coal Mine, Shaanxi Province, is the main mineable coal seam. The coal body f coefficient is about 0.6. The roof and floor of the coal seam have rheological and expansive properties. The roof is a composite roof composed of siltstone and No. 4 coal seam, with an f coefficient of about 1.6. The floor is mudstone with a clay content as high as about 70%. It softens when exposed to water, with an f coefficient of about 0.4. It is a typical three-soft coal seam.

[0048] The 1509 working face at Shanyang Coal Mine is an isolated working face. Influenced by the mining stress from the working faces on both sides and the pre-support stress of this working face, the roadway experiences large deformation around its perimeter. To investigate the mechanism of this large deformation in the mining roadway of the soft coal seam at Shanyang Coal Mine, a similar simulation study was conducted using this experimental setup. The specific implementation steps are as follows:

[0049] Step 1: Preparation of experimental materials:

[0050] Physical similarity simulation experiment equipment: 1 experimental steel frame, 3 acrylic plates, 4 bolts, 10 channel steels;

[0051] Similar simulation materials: fly ash, river sand, gypsum powder, whiting, water, soybean oil;

[0052] Hydraulic loading device: hydraulic loading cylinder 2 and loading controller 9;

[0053] Data acquisition terminal: Total station data monitoring device 11.

[0054] Step 2: Laying out similar simulation materials and fixing the model:

[0055] First, based on the lithology and physical and mechanical parameters of the simulated object, the proportions of various similar simulated materials were determined, and the materials were prepared according to the proportions. The specific layered materials and proportions are as follows:

[0056] The bottom of the model uses conventional rock strata simulation material 8, which is made by mixing river sand, gypsum, white powder, and water in a weight ratio of 7:0.2:0.8:0.7.

[0057] The central part of the model represents the roof and floor of the roadway and the soft coal area. The corresponding materials and proportions are as follows: Soft coal similar material 7 is prepared by mixing river sand, gypsum, whiting powder, fly ash, and soybean oil in a weight ratio of 20:1:5:20:4.1; soft rock similar material 6 for the roof is prepared by mixing river sand, gypsum, whiting powder, and soybean oil in a weight ratio of 9:0.2:0.8:0.9; soft rock similar material 6 for the floor is prepared by mixing river sand, gypsum, whiting powder, and soybean oil in a weight ratio of 9:0.1:0.9:0.9.

[0058] The upper and lower parts of the model are identical, using the same conventional rock strata simulation material 8.

[0059] After the material preparation is completed, the thickness of the similar simulated material for each rock layer is determined according to the actual geological borehole columnar section. The thickness of each layer is controlled at 1.5 cm. During laying, tools are used to fully compact the material to ensure density. Then, simulated joints are divided on the surface of each layer of material, with the joint direction perpendicular to the channel steel and the spacing between them being 5 cm.

[0060] Step 3: Preparations before model loading:

[0061] After the model is laid out, it is allowed to dry. During this process, the position of the hydraulic loading cylinder 2 needs to be adjusted in advance to ensure it is in contact with the model surface, preparing for subsequent loading. After the model has dried and solidified sufficiently, the channel steel 10 originally used for auxiliary laying is removed, and data monitoring points 5 are set up.

[0062] Subsequently, acrylic plate 3 is installed and reinforced. After the acrylic plate 3 is attached to the surface of the model, it is fixed to the experimental steel frame 1 with bolts 4. At the same time, channel steel 10 is added to further strengthen the fixation. The reinforcement position can be flexibly adjusted according to the size of the model. After the fixation is completed, the hydraulic loading cylinder 2 is operated to apply a load to the model until the original rock stress state of the tunnel is reached. Finally, the excavation and support simulation operation of the tunnel is carried out.

[0063] Step 4: Hierarchical loading and data collection:

[0064] Install the total station data monitoring device 11, adjust it to the optimal observation angle and fix it. Then, use the hydraulic loading cylinder 2 to perform graded loading on the model. The loading scheme is shown in Table 1.

[0065] Table 1 Graded Loading Scheme for Surrounding Rock of Tunnel

[0066]

[0067] During the model loading process, the total station data monitoring device 11 was used to record the entire process data of the roadway from initial deformation to complete destruction in real time, and photos were taken and saved for later analysis.

[0068] Based on this experiment, the deformation and failure characteristics of the mining roadway in the three soft coal seams are analyzed as follows:

[0069] After the hydraulic cylinder applied a load of 10.87 MPa (1 times the original rock stress) and the tunnel was excavated, cracks appeared on the inner surface of the tunnel and particles fell off.

[0070] After the roadway was supported by the original plan at a load of 11.96 MPa (1.1 times the original rock stress), cracks and fragment peeling appeared at the shoulder corners of the roadway, the sidewalls bent slightly, and the floor surface was damaged.

[0071] When the pressure was increased to 13.04 MPa (1.2 times the original rock stress), the stress of the surrounding rock was redistributed after the tunnel was excavated. Local damage occurred in the surrounding rock at the left shoulder corner, cracks appeared in the sidewall, and the floor began to bulge.

[0072] When the load was increased to 14.13 MPa (1.3 times the original rock stress), the rock blocks on the left shoulder of the tunnel loosened and fell off, the cracks on the right shoulder began to develop upwards, and the main crack in the sidewall was connected to form a large crack, showing an "X" shaped failure feature, with a crack depth of 1.58m.

[0073] When the load was increased to 15.22 MPa (1.4 times the original rock stress), the cracks on both shoulders of the roadway were connected, and the surrounding rock in the shallow part of the roof collapsed, forming a "collapse arch" with a height of 1.72 m. The roof anchor bolts were basically ineffective.

[0074] When the load was increased to 16.31 MPa (1.5 times the original rock stress), the rock mass inside the "fall arch" of the roadway roof fractured, causing bending and subsidence. The deep rock mass of the roof was displaced to a depth of 4.3 m. The coal seam cracks in the roadway sidewalls increased and bulged out to a maximum depth of 3.0 m. The maximum failure depth of the floor was 1.8 m, ultimately resulting in large deformation around the roadway.

[0075] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0076] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0077] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A graded loading experimental device for dynamic load effects in roadways of soft coal seams, characterized in that: This includes physical similarity simulation experimental equipment, similarity simulation materials, hydraulic loading devices, and data acquisition terminals; The hydraulic loading device is installed on the physical similarity simulation experimental equipment, and the physical similarity simulation experimental equipment and the similarity simulation material achieve interlayer bonding through friction connection; The similar simulation materials include soft rock simulation material (6), soft coal simulation material (7), and conventional rock stratum simulation material (8). The acrylic plate (3) and the soft rock simulation material (6), soft coal simulation material (7), and conventional rock stratum simulation material (8) are bonded together by friction. The contact surfaces of the soft rock simulation material (6), soft coal simulation material (7), and conventional rock stratum simulation material (8) are coated with edible oil to adjust the coefficient of friction with the acrylic plate (3).

2. The hierarchical loading experiment device for dynamic load effect of three-soft coal seam roadway according to claim 1, characterized in that: The physical similarity simulation experimental equipment includes an experimental steel frame (1), an acrylic plate (3), bolts (4), data monitoring points (5), and channel steel (10). The acrylic plate (3), data monitoring points (5), and reinforcing channel steel (10) are fixed to the experimental steel frame (1) using bolts (4).

3. The graded loading experimental device for dynamic load effects in roadways of three soft coal seams according to claim 2, characterized in that: The experimental steel frame (1) is a rectangular steel frame with a hydraulic loading device installed on top.

4. The hierarchical loading experiment device for dynamic load effect of three-soft coal seam roadway according to claim 1, characterized in that: The hydraulic loading device consists of a hydraulic loading cylinder (2) and a cylinder loading controller (9).

5. The hierarchical loading experiment device for dynamic load effect of three-soft coal seam roadway according to claim 1, characterized in that: The data acquisition terminal is a total station data monitoring device (11).

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