Underground caverns layered excavation physical model chain filling device and design method thereof

Abstract

The application discloses a physical model chain filling device for layered excavation of underground caverns and a design method thereof. The device comprises a filling block unit. A plurality of filling block units are sequentially spliced in the direction of excavation depth at each excavation layer. The filling block unit comprises a center block and a peripheral block which is movably connected around the center block. The center block and the peripheral block are assembled to form the filling block unit. When the center block of the first filling block unit is pulled out, the peripheral block is pulled out as a whole, and the filling block units in the direction of excavation depth are pulled out in a chain connection state synchronously. The application can be used for testing the influence of multi-stage layered excavation of underground caverns on the safety of surrounding rock and obtaining safety monitoring data of surrounding rock with less excavation disturbance, so as to further accurately analyze the failure mechanism and mode of surrounding rock.

Description

Technical Field

[0001] This application relates to the field of underground cavern group model testing technology, and in particular to a chain filling device for a physical model of layered excavation of underground caverns and its design method. Background Technology

[0002] Affected by various complex natural factors, the construction of large underground cavern groups in water conservancy and hydropower is the most complex system engineering in underground engineering today. In order to ensure the safety of underground cavern group construction, multi-stage layered excavation is often adopted. Physical model tests can reflect the stress characteristics of natural rock masses of underground cavern groups at different excavation depths and times in a relatively intuitive, qualitative or quantitative way, and observe and study the deformation and failure phenomena in the surrounding rock.

[0003] Existing methods for physical model testing of underground caverns generally employ manual excavation and prefabricated integral models for pushing and pulling. Excavation is carried out after load is applied, which can easily lead to problems such as the filling blocks getting stuck, disintegrating, or being unable to be removed normally. At the same time, the excavation depth, time, and range cannot be effectively controlled, failing to truly reflect the actual excavation process. Consequently, the nature and mechanism of the damage to the surrounding rock are not entirely consistent with reality, affecting the guiding significance of the test results. Therefore, there is an urgent need for a chain-type filling device and method for physical model testing of layered excavation of underground caverns. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a chain-type filling device and its design method for a physical model of layered excavation of underground caverns. This device is used to experimentally simulate the impact of multi-stage, layered excavation of underground cavern groups on the safety of the surrounding rock. The technical solution is as follows:

[0005] The first aspect of this application provides a chain-type filling device for a physical model of layered excavation of underground caverns, including filling block units. Several filling block units are sequentially spliced ​​together in each excavation layer along the excavation depth direction. Each filling block unit includes a central block and peripheral blocks surrounding the central block and movably connected to it. The central block and the peripheral blocks are assembled to form the filling block unit, so that when the central block of the first filling block unit is pulled out, the peripheral blocks are pulled out as a whole, and the filling block units along the excavation depth direction are pulled out in a chain-connected state.

[0006] For example, in the chain-type filling device of the physical model for layered excavation of underground caverns provided in one embodiment, the central block has a first surface and a second surface corresponding to the center of the first surface along the excavation depth direction. The area of ​​the second surface is smaller than that of the first surface, so that each side connecting the first surface and the second surface forms an inclined surface. The peripheral blocks that fit into the inclined sides are respectively connected to the inclined sides around the central block, so that the central block and the peripheral blocks are assembled to form a cuboid structure.

[0007] For example, in the chain-type filling device for the physical model of the layered excavation of the underground cavern provided in one embodiment, the outer block includes a first wedge-shaped block attached to the top inclined side of the central block, a second wedge-shaped block attached to the bottom inclined side of the central block, a third wedge-shaped block attached to one side inclined side of the central block along the excavation width direction, a fourth wedge-shaped block attached to the other side inclined side of the central block along the excavation width direction, and a fifth and a sixth block extending to both sides along the excavation width direction and respectively attached to and connected to the outer walls of the third and fourth wedge-shaped blocks. The first, second, third, and fourth wedge-shaped blocks are connected by tenon and mortise joints and surround the central block, while the fifth and sixth blocks are movably connected to the central block by connecting components.

[0008] For example, in the chain-type filling device for the physical model of the layered excavation of underground caverns provided in one embodiment, the connecting component includes a connecting rod, a chute, and a limiting hole. One end of the connecting rod extends into the interior of the fifth / sixth block and is abutted by a spring, while the other end is a free end that passes through the third / fourth wedge block and abuts against the outer wall of the central block. A chute is provided on the side wall of the central block near the third and fourth wedge blocks for the free end of the connecting rod to slide. A limiting hole is provided at the end of the chute near the second surface to limit the movement of the free end of the connecting rod. When the central block is pulled out by force, the free end of the connecting rod moves in the chute and is limited and fixed by the limiting hole when it moves to the limiting hole, thereby driving the outer blocks to be pulled out synchronously.

[0009] For example, in the chain filling device of the physical model of the layered excavation of the underground cavern provided in one embodiment, a perforation is provided at the center of the central block along the excavation depth direction, and a connecting sleeve is provided in the perforation. Several filling block units arranged sequentially along the excavation depth direction are linked sequentially through the connecting sleeve.

[0010] For example, in the chain filling device of the physical model of the layered excavation of the underground cavern provided in one embodiment, a barrier plate is provided between the filling block units that are sequentially spliced ​​along the excavation depth direction, and the barrier plate is sleeved on the end of the connecting sleeve that is exposed in the central block.

[0011] For example, in the chain filling device of the physical model for layered excavation of underground caverns provided in one embodiment, the connecting sleeve before the last filling block unit includes a sleeve body, a connecting bolt is provided at one end of the sleeve body, an internal thread for secondary connection is provided at the other end of the sleeve body, and a blocking ring is provided at that end; the connecting sleeve inside the last filling block unit includes a sleeve body, connecting bolts are provided at both ends of the sleeve body, and a blocking ring is provided at the end of the sleeve body.

[0012] The second aspect of this application provides a design method for a chain-type filling device for a physical model of layered excavation of underground caverns, applied to the aforementioned chain-type filling device for a physical model of layered excavation of underground caverns, comprising the following steps:

[0013] S1 determines the research content, geometric similarity ratio, and model specimen size of the model test;

[0014] S2 calculates parameters such as surrounding rock type, ground stress, underground cavern group size, number of excavation layers, and excavation depth based on actual engineering parameters using geometric similarity ratio;

[0015] S3 design involves layered excavation and filling of block unit structures to determine the dimensions of internal connecting components;

[0016] S4 precast cavern group PC model, infill block specimen mold, and layered excavation cavern model specimen;

[0017] S5 applies layered excavation and filling block specimens;

[0018] S6 applies a stabilizing load;

[0019] S7 performs layered excavation simulation until excavation is completed;

[0020] The S8 monitors the stress and deformation of the surrounding rock and each cavern, records stress and strain data, the damage status of the surrounding rock in each cavern, and analyzes the failure mechanism and nature of the surrounding rock during the layered excavation process.

[0021] For example, in the design method of the chain filling device for the physical model of the layered excavation of underground caverns provided in one embodiment, in step S1, the research content of the model test is determined to be the stability test of the surrounding rock of the layered excavation cavern group, and the geometric similarity ratio is achieved by reducing or enlarging the dimensions of each part of the model and the actual project by the same proportion using the following formula:

[0022]

[0023] Where l1 is the actual engineering dimension, l2 is the model specimen dimension, and C l This represents the geometric similarity ratio.

[0024] For example, in the design method of the chain filling device for the physical model of the layered excavation of underground caverns provided in one embodiment, in step S2, based on the elastic modulus E, internal friction angle Φ, unit weight γ, cohesion c, and Poisson's ratio ε of the actual surrounding rock in the project as the main reference mechanical parameters, the target mechanical parameters of the surrounding rock similar material are obtained by converting the geometric similarity ratio. The composition and proportion of the similar material are investigated, the proportion range of coarse and fine aggregates, binders and other regulators is determined, multiple sets of similar material preparation work are carried out, and a large number of direct shear tests and uniaxial compression tests are conducted to determine the proportion of similar materials. The load value is designed according to the measured ground stress, and the load is applied on the boundary of the specimen through the test equipment. The main powerhouse, main transformer room and tail-end control room of the underground cavern group of the water conservancy and hydropower project are converted into parameters of the length, width, height and number of excavation layers and excavation depth of the three major cavern groups through geometric similarity ratio.

[0025] The beneficial effects of the chain-type filling device and its design method for a physical model of layered excavation of underground caverns provided in some embodiments of this application are as follows: This application can fix the excavation depth of the specimen, and the filling block unit can be removed in a chain-like manner through the connection of connecting rods and connecting sleeves, which has a certain degree of overall convenience. It can also prevent the filling block from disintegrating and losing its support after excavation. At the same time, the internal components of the filling block can be reused, which is economical. Furthermore, it can obtain safety monitoring data of the surrounding rock with less excavation disturbance, and further accurately analyze the failure mechanism and mode of the surrounding rock. The device and test method of this application are feasible, simple to operate, and highly flexible in testing, and can more realistically simulate the layered excavation conditions of underground cavern engineering. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the infill block unit in this application;

[0028] Figure 2 This is an exploded view of the filled block element of this application;

[0029] Figure 3 This is a schematic diagram of the connection state structure of the infill block unit in this application;

[0030] Figure 4 This is a schematic diagram of a connecting sleeve structure according to an embodiment of this application;

[0031] Figure 5 This is a schematic diagram of the connecting sleeve structure according to another embodiment of this application;

[0032] Figure 6 This is a schematic diagram of the state structure for experimental simulation using the filled block unit of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0035] The first aspect of this application provides a chain-type filling device for a physical model of layered excavation of underground caverns, such as... Figure 1-6 As shown, the model includes filling block units 100, which are layered and filled within the porous model specimen 200. Several filling block units 100 are sequentially spliced ​​together along the excavation depth direction in each excavation layer. Each filling block unit 110 includes a central block 110 and peripheral blocks 120 surrounding and movably connected to the central block 110. The central block 110 and the peripheral blocks 120 are assembled to form the filling block unit 100, so that when the central block 110 of the first filling block unit 100 is pulled out, the peripheral blocks 120 are pulled out as a whole, and the filling block units 100 along the excavation depth direction are pulled out in a chain-like connection.

[0036] For example, in the chain-type filling device of the physical model for layered excavation of underground caverns provided in one embodiment, such as Figure 2 As shown, the central block 110 has a first surface 111 and a second surface 112 corresponding to the center of the first surface 111 along the excavation depth direction. The area of ​​the second surface 112 is smaller than that of the first surface 111, so that each side connecting the first surface 111 and the second surface 112 forms an inclined surface. The peripheral blocks 120 that fit into the inclined sides are respectively connected to the inclined sides around the central block 110, so that the central block 110 and the peripheral blocks 120 are assembled to form a cuboid structure.

[0037] For example, in the chain-type filling device of the physical model for layered excavation of underground caverns provided in one embodiment, such as Figure 1-3 As shown, the peripheral block 120 includes a first wedge-shaped block 121 attached to the top inclined side of the central block 110, a second wedge-shaped block 122 attached to the bottom inclined side of the central block 110, a third wedge-shaped block 123 attached to one side inclined side of the central block 110 along the excavation width direction, a fourth wedge-shaped block 124 attached to the other side inclined side of the central block 110 along the excavation width direction, and extends to both sides along the excavation width direction. A fifth block 125 and a sixth block 126 are respectively attached to the outer walls of the third wedge block 123 and the fourth wedge block 124. The first wedge block 121, the second wedge block 122, the third wedge block 123 and the fourth wedge block 124 are connected by tenons and mortise and tenons and surround the central block 110. The fifth block 125 and the sixth block 126 are respectively movably connected to the central block 110 through connecting components 130.

[0038] Specifically, such as Figure 2 As shown, the first wedge-shaped block 121 at the top and the second wedge-shaped block 122 at the bottom of the central block 110 provide support for the central block 110. The first wedge-shaped block 121 and the second wedge-shaped block 122 are provided with mortise grooves 141, and the third wedge-shaped block 123 and the fourth wedge-shaped block 124 are provided with tenons 142 that are adapted to the mortise grooves 141. The first wedge-shaped block 121, the second wedge-shaped block 122, the third wedge-shaped block 123 and the fourth wedge-shaped block 124 are connected by mortise and tenon joints to surround the central block 110.

[0039] For example, in the chain-type filling device of the physical model for layered excavation of underground caverns provided in one embodiment, such as Figure 1-4As shown, the connecting assembly 130 includes a connecting rod 131, a sliding groove 132, and a limiting hole 133. One end of the connecting rod 131 extends into the interior of the fifth block 125 / sixth block 126 and is abutted by a spring 134. The other end is a free end that passes through the third wedge-shaped block 123 / fourth wedge-shaped block 124 and abuts against the outer wall of the central block 110. The central block 110 is located near the third wedge-shaped block 123 and the fourth wedge-shaped block 124. The sidewalls are respectively provided with sliding grooves 132 for the free end of the connecting rod 131 to slide; the end of the sliding groove 132 near the second surface 112 is provided with a limiting hole 133 for limiting the movement of the free end of the connecting rod 131; wherein, when the central block 110 is pulled out by force, the free end of the connecting rod 131 moves in the sliding groove 132, and when it moves to the limiting hole 133, it is limited and fixed by the limiting hole 133 and drives the peripheral block 120 to be pulled out synchronously.

[0040] Specifically, blind holes 135 along the excavation width direction are provided inside the fifth block 125 and the sixth block 126, and through holes 136 corresponding to the blind holes 135 are provided on the third wedge-shaped block 123 and the fourth wedge-shaped block 124. One end of the connecting rod 131 extends into the blind hole 135 and is abutted by the spring 134, and the other end passes through the through hole 136 and abuts against the groove 132 on the side wall of the central block 110. The spring 134 is a return spring. The connecting rod 131 compresses the spring 134, so that the spring 134 is in a compressed state. When the central block 110 is pulled out, the connecting rod 131... The free end moves within the slide groove 132. When it moves to the limiting hole 133, the return spring 134, which is in a compressed state, rebounds and resets, locking the connecting rod 131 within the limiting hole 133. As the central block 110 continues to be pulled out, it drives the third wedge block 123, the fourth wedge block 124, the fifth block 125, and the sixth block 126 to be pulled out synchronously. Since the first wedge block 121, the second wedge block 122 are fixedly connected to the third wedge block 123 and the fourth wedge block 124 through tenons and mortise, they are also pulled out synchronously, thus causing the outer block 120 to be pulled out as a whole along with the central block 110.

[0041] The limiting hole 133 is a variable diameter hole with a large diameter at the front and a small diameter at the rear, which forms a stepped surface inside the limiting hole 133. By designing the limiting hole 133 with a large diameter at the front, it can ensure that the connecting rod 131 can fall into the limiting hole 133. Furthermore, as the central block 110 pulls out the connecting rod 131, it extends into the small diameter at the rear, which plays a transition and safety role, ensuring that the connecting rods 131 on both sides extend into the limiting hole 133 to form an effective connection.

[0042] For example, in the chain-type filling device of the physical model for layered excavation of underground caverns provided in one embodiment, such as Figure 1-3 As shown, a perforation 113 is provided at the center of the central block 110 along the excavation depth direction, and a connecting sleeve 140 is provided in the perforation 113. Several filling block units 100 arranged sequentially along the excavation depth direction are connected sequentially through the connecting sleeve 140.

[0043] For example, in the chain-type filling device of the physical model for layered excavation of underground caverns provided in one embodiment, such as Figure 4 As shown, the connecting sleeve 140 before the last filling block unit includes a sleeve body 141, a connecting bolt 142 is provided at one end of the sleeve body 141, and an internal thread 143 for secondary connection is provided at the other end of the sleeve body 141, with a retaining ring 144 at that end; as Figure 5 As shown, the connecting sleeve 140 in the last filling block unit includes a sleeve body 141, with connecting bolts 142 at both ends of the sleeve body 141, and a blocking ring 144 at the end of the sleeve body 141.

[0044] According to the above embodiments, by setting connecting bolts 142 and internal threads 143 at both ends of the connecting sleeve 140 before the last filling block unit, adjacent filling block units 100 are connected by inserting the connecting bolts 142 into the internal threads 143 to form a continuous and stable connecting chain. When the center block 110 of the first filling block unit 100 is pulled out, the filling block units 100 along the excavation depth direction are pulled out in a chain connection state. In this application, the filling block units 100 are easy to install and disassemble. By setting a blocking ring 144 at the rear end of the connecting sleeve 140, the diameter of the blocking ring 144 is larger than the diameter of the sleeve body 141, increasing the cross-sectional area and strength, and preventing the connecting sleeve 140 from coming out of the through hole 113.

[0045] The connecting sleeve 140 is made of high-strength metal material, and its length is designed according to the size of the filler block.

[0046]

[0047] The diameter d1 of the sleeve body 141 is obtained according to:

[0048]

[0049] The diameter d2 of the connecting bolt 142 is obtained, where F is the axial pressure on the filler block, T is the torque on the connecting sleeve, K is the torque coefficient, and σ is the stress on the filler block.

[0050] For example, in the chain-type filling device of the physical model for layered excavation of underground caverns provided in one embodiment, such as Figure 3As shown, a barrier plate 150 is provided between the filling block units 100 that are sequentially spliced ​​along the excavation depth direction. The barrier plate 150 is sleeved on the end of the connecting sleeve 140 that is exposed above the center block 110.

[0051] Specifically, a hole is provided in the center of the barrier plate 150. The hole in the center of the barrier plate 150 is fitted onto the connecting bolt 142 at the end of the connecting sleeve 140 and fixed by the nut 151. The length of the barrier plate 150 along the excavation width direction is at least greater than the length of the central block 110, thereby limiting whether each chain-connected filling block unit 100 along the excavation depth direction needs to be pulled out. When it is necessary to pull out the filling block unit 100 before a certain excavation depth, the barrier plate 150 at that depth is removed, and the subsequent filling block units 100 remain stationary.

[0052] According to the above embodiment, by setting a barrier plate 150 between two adjacent filling block units 100, the connecting sleeve 140 is blocked and prevented from loosening, thereby preventing the connecting chain of the connecting sleeve 140 from loosening during the layered excavation process when the excavated block disintegrates, splashes out, and twists.

[0053] The second aspect of this application provides a design method for a chain-type filling device for a physical model of layered excavation of underground caverns, applied to the aforementioned chain-type filling device for a physical model of layered excavation of underground caverns, comprising the following steps:

[0054] S1 determines the research content, geometric similarity ratio, and model specimen size of the model test;

[0055] In S1, the research content of the model test is determined to be the stability test of the surrounding rock of the layered excavation tunnel group. The geometric similarity ratio is achieved by scaling down or enlarging the dimensions of each part of the model and the actual project in the same proportion using the following formula:

[0056]

[0057] Where l1 is the actual engineering dimension, l2 is the model specimen dimension, and C l This represents the geometric similarity ratio.

[0058] S2 calculates parameters such as surrounding rock type, ground stress, underground cavern group size, number of excavation layers, and excavation depth based on actual engineering parameters using geometric similarity ratio;

[0059] In S2, the target mechanical parameters of the surrounding rock are obtained by converting the geometric similarity ratio based on the elastic modulus E, internal friction angle Φ, unit weight γ, cohesion c, and Poisson's ratio ε of the actual surrounding rock. The composition and proportion of the similar materials are investigated, the proportion range of coarse and fine aggregates, cementitious agents and other modifiers is determined, multiple sets of similar materials are prepared, and a large number of direct shear tests and uniaxial compression tests are carried out to determine the proportion of similar materials.

[0060] The load value is designed based on the measured ground stress, and the load is applied on the specimen boundary using test equipment.

[0061] The underground cavern complex of water conservancy and hydropower projects mainly consists of the main powerhouse, main transformer room, and tailrace control room. The length, width, height, number of excavation layers, and excavation depth of the three major cavern complexes are calculated by geometric similarity ratio.

[0062] S3 design involves layered excavation and filling of block unit structures to determine the dimensions of internal connecting components;

[0063] Based on the length × width × height of the underground cavern group obtained in S2, as well as the number of excavation layers and the excavation depth, the structure and size of the filling block unit are designed. For example, if the underground cavern group has a length × width × height of 50cm × 12cm × 15cm, the number of excavation layers is three, and the excavation depth is 5cm at a time, the length × width × height of the filling block unit is 5cm × 4cm × 3cm. The fifth block 125 and the sixth block 126 on both sides are designed according to the outline of the cavern group.

[0064] S4 precast cavern group PC model, infill block specimen mold, and layered excavation cavern model specimen;

[0065] Based on the dimensions of the underground cavern group calculated from S2, a prefabricated PC cavern group outline model was constructed. Simultaneously, based on the layered block structure, a silicone mold was made, and similar materials were used to cast the layered excavation and filling blocks. Combining the PC cavern group outline model with similar materials to the surrounding rock in S2, a rough cavern model specimen was cast and excavated in layers.

[0066] S5 applies layered excavation and filling block specimens;

[0067] like Figure 3As shown, the prefabricated filling blocks are assembled with the internal connecting components. First, the connecting sleeve 140 is placed in the through hole 113 in the central block 110. Simultaneously, according to the mortise and tenon structure, the first wedge-shaped block 121, the second wedge-shaped block 122, the third wedge-shaped block 123, and the fourth wedge-shaped block 124 are spliced ​​around the central block 110. Then, the spring 134 is placed in the blind holes 135 in the fifth block 125 and the sixth block 126. Next, the connecting rods 134 on both sides are placed in the blind holes 135. The free ends of the connecting rods 134 on both sides pass through the pre-drilled through holes 136 on the third wedge-shaped block 123 and the fourth wedge-shaped block 124 and abut against the sliding groove 132 on the side wall of the central block 110. Finally, the assembled filling block units 100 are sequentially connected along the excavation depth direction, as shown in the diagram. Figure 6 As shown, the assembled chain-type filling block unit 100 is further placed in the layered excavation hole model specimen 200, and strain gauges are simultaneously attached to the outside of the hole surrounding rock.

[0068] S6 applies a stabilizing load;

[0069] Based on the design load value in S2, a loading device was selected to apply the load to the specimen to simulate the environment of the underground cavern group.

[0070] S7 performs layered excavation simulation until excavation is completed;

[0071] According to the layered excavation sequence and excavation depth, the fixing nut 151 on the barrier plate 150 at the front of the corresponding filling block unit 100 is turned to remove the barrier plate 150. The central block 110 is then slowly pulled out through the connecting sleeve 140. The central block 110 and the outer blocks 120 slide in the groove 132 of the central block 110 along with the connecting rods 131 on both sides, and are pushed into the limiting hole 133 by the elastic force generated by the spring 134 and fixed. This allows several filling block units 100 connected along the excavation depth direction to be pulled out in a chain-like manner. Due to the first wedge block 121 and the second wedge block 12 2 is connected to the third wedge block 123 and the fourth wedge block 124 with a mortise and tenon structure, so the first wedge block 121 and the second wedge block 122 are simultaneously brought out by the third wedge block 123 and the fourth wedge block 124; simulating the same excavation advance condition, and at the same time, depending on the research content, the nut 151 can be fixed again to the connecting bolt 142 of the connecting sleeve 140 of the rear filling block unit 100 to observe the surrounding rock condition after different excavation times. Repeat the above steps to complete the single-layer excavation, and then repeat the above operation on the remaining layered excavation blocks until the layered excavation test is completed, simulating the actual layered excavation condition of underground caverns.

[0072] The S8 monitors the stress and deformation of the surrounding rock and each cavern, records stress and strain data, the damage status of the surrounding rock in each cavern, and analyzes the failure mechanism and nature of the surrounding rock during the layered excavation process.

[0073] The chain-type filling device for the physical model of layered excavation of underground caverns proposed in this application can fix the excavation depth of the specimen. The filling block units can be removed as a whole through the connection of connecting rods and connecting sleeves, which has a certain degree of overall convenience. It can also prevent the filling blocks from disintegrating and losing their support after excavation. At the same time, the internal components of the filling blocks can be reused, which is economical. Furthermore, it can obtain safety monitoring data of the surrounding rock with less excavation disturbance, and more accurately analyze the failure mechanism and mode of the surrounding rock. The device and test method proposed in this application are feasible, simple to operate, and highly flexible in testing, and can more realistically simulate the layered excavation conditions of underground cavern engineering.

[0074] Although the embodiments of this application have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this application. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this application is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A chain-type filling device for a physical model of layered excavation of underground caverns, characterized in that, The system includes filler block units, several of which are sequentially linked along the excavation depth in each excavation layer. Each filler block unit includes a central block and peripheral blocks surrounding and movably connected to the central block. The central block and the peripheral blocks are assembled to form the filler block unit, so that when the central block of the first filler block unit is pulled out, the peripheral blocks are pulled out as a whole, and the filler block units along the excavation depth are pulled out in a chain-like connection. The central block has a first surface and a second surface corresponding to the center of the first surface along the excavation depth direction. The area of ​​the second surface is smaller than that of the first surface, so that each side connecting the first surface and the second surface forms an inclined surface. The peripheral blocks that fit into the inclined sides are respectively connected to the inclined sides around the central block, so that the central block and the peripheral blocks are assembled to form a cuboid structure. The peripheral blocks include a first wedge-shaped block attached to the top inclined side of the central block, a second wedge-shaped block attached to the bottom inclined side of the central block, a third wedge-shaped block attached to one inclined side of the central block along the excavation width direction, a fourth wedge-shaped block attached to the other inclined side of the central block along the excavation width direction, and a fifth and a sixth block extending to both sides along the excavation width direction and respectively attached to the outer walls of the third and fourth wedge-shaped blocks. The first, second, third, and fourth wedge-shaped blocks are connected by tenons and mortise and tenons and surround the central block. The fifth and sixth blocks are movably connected to the central block by connecting components.

2. The chain-type filling device for the physical model of layered excavation of underground caverns according to claim 1, characterized in that, The connection component includes: A connecting rod, one end of which extends into the interior of the fifth / sixth block and is abutted by a spring, and the other end is a free end that passes through the third / fourth wedge block and abuts against the outer wall of the central block; The central block has sliding grooves on its sidewalls near the third and fourth wedge blocks, respectively, for the free end of the connecting rod to slide. A limiting hole is provided at the end of the slide near the second surface to limit the movement of the free end of the connecting rod; When the central block is pulled out, the free end of the connecting rod moves within the groove and is fixed by the limiting hole when it reaches the limiting hole, which in turn pulls out the outer block synchronously.

3. The chain-type filling device for the physical model of layered excavation of underground caverns according to claim 2, characterized in that, A perforation is provided at the center of the central block along the excavation depth direction, and a connecting sleeve is provided in the perforation. Several filling block units arranged sequentially along the excavation depth direction are connected sequentially through the connecting sleeve.

4. The chain-type filling device for the physical model of layered excavation of underground caverns according to claim 3, characterized in that, A barrier plate is provided between the filling block units that are sequentially spliced ​​along the excavation depth direction, and the barrier plate is sleeved on the end of the connecting sleeve that is exposed in the central block.

5. The chain-type filling device for the physical model of layered excavation of underground caverns according to claim 4, characterized in that, The connecting sleeve before the last filling block unit includes a sleeve body, a connecting bolt at one end of the sleeve body, an internal thread for secondary connection at the other end of the sleeve body, and a blocking ring at that end; the connecting sleeve inside the last filling block unit includes a sleeve body, connecting bolts at both ends of the sleeve body, and a blocking ring at the end of the sleeve body.

6. A design method for a chain-type filling device for a physical model of layered excavation of underground caverns, applied to the chain-type filling device for a physical model of layered excavation of underground caverns as described in any one of claims 1-5, characterized in that, Includes the following steps: S1 determines the research content, geometric similarity ratio, and model specimen size of the model test; S2 calculates parameters such as surrounding rock type, ground stress, underground cavern group size, number of excavation layers, and excavation depth based on actual engineering parameters using geometric similarity ratio; S3 design involves layered excavation and filling of block unit structures to determine the dimensions of internal connecting components; S4 precast cavern group PC model, infill block specimen mold, and layered excavation cavern model specimen; S5 applies layered excavation and filling block specimens; S6 applies a stabilizing load; S7 performs layered excavation simulation until excavation is completed; The S8 monitors the stress and deformation of the surrounding rock and each cavern, records stress and strain data, the damage status of the surrounding rock in each cavern, and analyzes the failure mechanism and nature of the surrounding rock during the layered excavation process.

7. The design method of the chain-type filling device for the physical model of layered excavation of underground caverns according to claim 6, characterized in that, In S1, the research content of the model test is determined to be the stability test of the surrounding rock of the layered excavation tunnel group. The geometric similarity ratio is achieved by scaling down or enlarging the dimensions of each part of the model and the actual project in the same proportion using the following formula: ； in, For actual engineering dimensions, For the dimensions of the model specimen, C l This represents the geometric similarity ratio.

8. The design method of the chain-type filling device for the physical model of layered excavation of underground caverns according to claim 6, characterized in that, In S2, based on the elastic modulus E, internal friction angle Φ, unit weight γ, cohesion c, and Poisson's ratio ε of the actual surrounding rock in the engineering project, the target mechanical parameters of the surrounding rock similar material are obtained by converting the geometric similarity ratio. The composition and proportion of the similar material are investigated, the proportion range of coarse and fine aggregates, cementitious agents and other regulators is determined, multiple sets of similar material preparation work are carried out, and direct shear test and uniaxial compression test are conducted to determine the proportion of the similar material. The load value is designed based on the measured ground stress, and the load is applied on the specimen boundary using test equipment. The main powerhouse, main transformer room, and tailrace control room of the underground cavern group of the water conservancy and hydropower project were converted into parameters such as length, width, height, number of excavation layers, and excavation depth by geometric similarity ratio.

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