A stable water pressure loading device for rock mechanics indoor experiments

Abstract

The present invention discloses a stable water pressure loading device for indoor rock mechanics experiments, and relates to the technical field of rock mechanics test equipment. The present invention comprises an installation platform, a test model, a water outlet pipe, a water outlet valve, a rod-type piston, a water pressure gauge, a water injection valve, a water injection pipe, a piston rod and a pulley loading system; the test model, the rod-type piston and the pulley loading system are arranged on the installation platform; the test model, the water outlet pipe, the water outlet valve, the rod-type piston, the piston rod and the pulley loading system are connected in sequence; the water pressure gauge, the water injection valve and the water injection pipe are arranged in sequence at the lower part of the outer wall of the rod-type piston. The fracture water pressure of the present invention is output through the rod-type piston, and the piston rod provides tension through a directional weight and is subjected to axial force, which can ensure the stability of water pressure during the fracture expansion process; it adopts pure mechanical loading, has sensitive response and no noise; it has a simple principle, is easy to operate, has good safety, and has a low cost; it is suitable for stable water pressure loading in indoor rock mechanics hydraulic coupling experiments.

Description

Technical Field

[0001] The invention relates to the technical field of rock mechanics test equipment, and in particular to a stable water pressure loading device for rock mechanics indoor tests. Background Art

[0002] As the buried depth of tunnels (tunnels and chambers) in transportation, water conservancy and mining engineering gradually increases, the strata they pass through also become more complex. Under the action of excavation disturbance stress and fissure water, water inrush disasters occur frequently, causing serious construction delays and economic losses. In order to reveal the fracture and instability mechanism of deeply buried rock mass under the action of fissure water pressure, domestic and foreign scholars have carried out a large number of indoor hydraulic coupling test studies on fractured specimens. Due to the wide distribution range of underground aquifers, the fracture water pressure remains basically stable with the expansion of rock mass cracks during excavation. Stable fracture water pressure is the main factor causing rock mass fracture and instability and inducing water inrush disasters. The current indoor test research mainly uses servo pumps for hydraulic loading, which can maintain the stability of fracture water pressure in the early stage of fracture expansion. However, when the crack enters the unstable expansion stage, the crack expands very rapidly, resulting in a large expansion in a very short time. The servo pump is unable to provide an equal volume of high-pressure water, resulting in a rapid decrease in fracture water pressure. In addition, when the fracture water pressure drops to the servo pump response threshold, the servo pump cannot accurately increase the water pressure in a small range, and it is easy to exceed the set value during the pressure increase process to produce a shock effect. Therefore, the crack expansion using the traditional servo water pressure loading method is completed under the action of unstable fracture water pressure, which is inconsistent with the actual engineering situation. In order to solve the problem of stable water pressure loading, some scholars use high-pressure gas sources to assist in applying stable water pressure, but the generation and storage of high-pressure gas poses a safety hazard, and it is also difficult to replenish pressure when long-term stable high water pressure output is required.

[0003] In summary, there is still a problem in the current rock hydraulic coupling test research that water pressure is difficult to load stably. Summary of the invention

[0004] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art and to provide a stable water pressure loading device for rock mechanics indoor experiments.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] Specifically, the device includes a mounting platform, a test model, a water outlet pipe, a water outlet valve, a pull rod type piston, a water pressure gauge, a water injection valve, a water injection pipe, a piston pull rod and a pulley loading system;

[0007] The connection relationship is:

[0008] A test model, a tie rod type piston and a pulley loading system are arranged on the mounting platform;

[0009] The test model, the water outlet pipe, the water outlet valve, the tie rod type piston, the piston tie rod and the pulley loading system are connected in sequence;

[0010] A water pressure gauge, a water injection valve and a water injection pipe are sequentially connected to the lower part of the outer wall of the pull rod type piston.

[0011] The present invention has the following advantages and positive effects:

[0012] ① The fracture water pressure is output through the pull rod piston. The piston pull rod provides tension through the directional weight and the axial force is applied, which can ensure the stability of the water pressure during the fracture expansion process;

[0013] ② It adopts pure mechanical loading, which is sensitive and noiseless. It is more energy-saving and environmentally friendly than the electric drive servo pump. It does not need to consider the impact of power failure during long-term testing (such as creep test) and has high stability.

[0014] ③Simple principle, easy operation, good safety and low cost.

[0015] ④ Suitable for stable water pressure loading in indoor rock mechanics hydraulic coupling experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention;

[0017] Figure 2 It is a vertical cross-sectional view of the pull rod type piston 4 in the present invention;

[0018] Figure 3 It is a schematic diagram of the structure of the weight 95 in the present invention.

[0019] In the figure:

[0020] 0—Installation platform,

[0021] 01—the first installation platform, 02—the second installation platform, 03—the third installation platform.

[0022] 1—Test model.

[0023] 2—Water outlet pipe.

[0024] 3—Water outlet valve.

[0025] 4—Piercing rod piston,

[0026] 41—vent hole, 42—sealing ring, 43—piston chamber, 44—water outlet, 45—water inlet, 46—sealing ring.

[0027] 5—Water pressure gauge.

[0028] 6—Water filling valve.

[0029] 7—Water injection pipe.

[0030] 8—Piston tie rod.

[0031] 9—Pulley loading system,

[0032] 90—beam;

[0033] 91—fixed pulley, 911—first fixed pulley, 912—second fixed pulley, 913—third fixed pulley,

[0034] 914—4th fixed pulley;

[0035] 92—wire rope, 921—first wire rope, 922—second wire rope;

[0036] 93—movable pulley;

[0037] 94—brake;

[0038] 95 - weights,

[0039] 951—left weight block, 952—right weight block, 953—guide hole, 954—through hole;

[0040] 96—guide bracket;

[0041] 97—Pallet;

[0042] 98—cushion;

[0043] 99—Guide support. DETAILED DESCRIPTION

[0044] The following is a detailed description with reference to the embodiments and drawings.

[0045] 1. Structure of the device

[0046] 1. Overall

[0047] like Figure 1 , 2 3. The device includes a mounting platform 0, a test model 1, a water outlet pipe 2, a water outlet valve 3, a pull rod piston 4, a water pressure gauge 5, a water injection valve 6, a water injection pipe 7, a piston pull rod 8 and a pulley loading system 9;

[0048] The connection relationship is:

[0049] A test model 1, a pull rod piston 4 and a pulley loading system 9 are arranged on a mounting platform 0;

[0050] The test model 1, the water outlet pipe 2, the water outlet valve 3, the pull rod type piston 4, the piston pull rod 8 and the pulley loading system 9 are connected in sequence;

[0051] A water pressure gauge 5, a water injection valve 6 and a water injection pipe 7 are sequentially connected to the lower part of the outer wall of the pull rod type piston 4.

[0052] Its working mechanism is:

[0053] The pulley loading system 9 applies a pulling force to the piston rod 8, and the piston rod 8 acts on the water in the rod-type piston 4, converting the pulling force of the piston rod 8 into the output water pressure of the water outlet pipe 2. The output pulling force of the pulley loading system 9 can be adjusted to obtain stable water pressures of different sizes. During the loading process, the output pulling force of the pulley loading system 9 is stable and the axial center of the piston rod 8 is pulled, so a stable water pressure can be output to the experimental model 1.

[0054] 2. Functional components

[0055] like Figure 1 , 2 , as shown in Figure 3.

[0056] 0) Installation platform 0

[0057] The mounting platform 0 is a support frame, including the first mounting platform 01, the second mounting platform 02 and the third mounting platform 03, which respectively fix and support the test model 1, the first fixed pulley 911, the second fixed pulley 912, the pull rod piston 4, and the brake 94, the third fixed pulley 913, and the fourth fixed pulley 914.

[0058] 1) Test model 1

[0059] The material specimen to be tested is rock or rock-like material containing cracks.

[0060] 2) Water outlet pipe 2

[0061] For commonly used parts.

[0062] 3) Water outlet valve 3

[0063] For commonly used parts.

[0064] 4) Tie rod piston 4

[0065] like Figure 2 The pull rod piston 4 is composed of a vent hole 41, a sealing ring 42, a piston chamber 43, a water outlet 44, a water injection port 45 and a sealing ring 46;

[0066] Its main body is a cylindrical cavity, namely the piston cavity 43; a vent hole 41 is arranged at the top of the piston cavity 43, and a sealing ring 42 and a sealing ring 46 are respectively arranged at the upper part and the bottom of the piston cavity 43, which are dynamically connected to the top of the piston rod 8 and the outlet of the piston rod 8 respectively; a water outlet 44 and a water injection port 45 are respectively arranged at the lower part of the piston cavity 43.

[0067] Its working mechanism is:

[0068] The pull rod type piston 4 is a force transmission mechanism, used in conjunction with the piston pull rod 8. The piston cavity 43 is filled with water, and the top of the piston pull rod 8 acts on the water in the piston cavity 43. When the piston pull rod 8 is pulled, the pulling force is converted into the output water pressure of the water outlet 44.

[0069] 5) Water pressure gauge 5

[0070] For commonly used parts.

[0071] 6) Water injection valve 6

[0072] For commonly used parts.

[0073] 7) Water injection pipe 7

[0074] For commonly used parts.

[0075] 8) Piston rod 8

[0076] It is a commonly used item and is a long pole.

[0077] 9) Pulley loading system 9

[0078] like Figure 1 , the pulley loading system 9 includes a crossbeam 90, a fixed pulley 91, a wire rope 92, a movable pulley 93, a brake 94, a weight 95, a guide bracket 96, a tray 97, a buffer pad 98 and a guide support 99;

[0079] (0) Beam 90

[0080] It is a commonly used part, that is, a cross bar, used to support the guide bracket 96, and the center opening of the cross beam 90 is used for the wire rope 92 to pass vertically.

[0081] (1) Fixed pulley 91

[0082] The fixed pulleys 91 include a first fixed pulley 911 , a second fixed pulley 912 , a third fixed pulley 913 and a fourth fixed pulley 914 , which are commonly used parts.

[0083] (2) Wire rope 92

[0084] The steel wire rope 92 includes a first steel wire rope 921 and a second steel wire rope 922 , which are commonly used.

[0085] (3) movable pulley 93;

[0086] For commonly used parts.

[0087] (4) Brake 94

[0088] It is a commonly used part and is an electric clamp used to clamp the wire rope 92.

[0089] (5) Weight 95

[0090] like Figure 3, the weight 95 includes a left weight block 951 and a right weight block 952;

[0091] A guide hole 953 is provided at the center of the left weight block 951 and the right weight block 952;

[0092] A through hole 954 is provided on the right side of the left weight block 951 , and a through hole 954 is provided on the left side of the right weight block 952 .

[0093] (6) Guide bracket 96

[0094] It is a commonly used part, including two cylindrical vertical rods on the left and right.

[0095] (7) Tray 97

[0096] It is a commonly used part, namely a round plate.

[0097] (8) cushion 98;

[0098] It is a commonly used item, i.e. a cushion.

[0099] (9) Guide support 99.

[0100] It is a commonly used piece, that is, a square block.

[0101] Its location and connection relationship are:

[0102] On the first installation platform 01, the test model 1, the first fixed pulley 911, the second fixed pulley 912 and the guide support 99 are arranged from left to right in sequence; under the third installation platform 03, the third fixed pulley 913, the brake 94 and the fourth fixed pulley 914 are arranged from left to right in sequence; the bottom of the piston pull rod 8 is connected to the first steel wire rope 921, and the first steel wire rope 921 passes through the first fixed pulley 911 and the second fixed pulley 912 and is connected to the movable pulley 93; the second steel wire rope 922, the head end of which is fixed to the leftmost side under the third installation platform 03, passes through the movable pulley 93, the third fixed pulley 913, the brake 94 and the fourth fixed pulley 914 in sequence, and the tail end of which is connected to the tray 97;

[0103] With the connection between the tail end of the second steel wire rope 922 and the tray 97 as the vertical center line, a crossbeam 90, a guide bracket 96, a buffer pad (98) and a guide support 99 are arranged in sequence from top to bottom to form a loading mechanism; a weight 95 is loaded on the tray 97 to obtain different loading forces.

[0104] Its working mechanism is:

[0105] Different mass weights 95 are loaded on the tray 97 to obtain different loading forces; the first fixed pulley 911, the second fixed pulley 912, the third fixed pulley 913 and the fourth fixed pulley 914 are used to change the direction of loading force transmission, and the movable pulley 93 amplifies the loading force by 2 times for output; the guide bracket 96 passes through the guide hole 953 of the weight 95, and the second steel wire rope 922 passes through the central through hole 954 of the weight 95 to ensure stable output of the loading force.

[0106] 2. Embodiment of the device

[0107] This embodiment provides a stable water pressure loading device for rock mechanics indoor test, such as Figure 1 , 2 As shown in , 3, it includes an installation platform 0, a test model 1, a water outlet pipe 2, a water outlet valve 3, a pull rod type piston 4, a water pressure gauge 5, a water injection valve 6, a water injection pipe 7, a piston pull rod 8 and a pulley loading system 9.

[0108] The tie rod type piston 4 is arranged on the second mounting platform 02, and is composed of a vent hole 41, a sealing ring 42, a piston cavity 43, a water outlet 44, a water injection port 45 and a sealing ring 46; the piston cavity 43 and the piston tie rod 8 are cylindrical; the tie rod type piston 4 and the piston tie rod 8 are made of high-strength stainless steel; the tie rod type piston 4 is designed to have a maximum stable output water pressure of 20 MPa; the diameter of the piston tie rod 8 is 0.5 cm; one end of the piston tie rod 8 acts on the water in the piston cavity 43, and the other end is connected to the pulley loading system 9; the wall thickness of the tie rod type piston 4 is 5 cm, ensuring that the piston wall can withstand 20 MPa water pressure during loading; the diameter of the piston cavity 43 is 1.23 cm; the cross-sectional water area of ​​the piston cavity 43 (cross-sectional area of ​​the piston cavity 43 - cross-sectional area of ​​the piston tie rod 8) is 1 cm 2 ; A sealing ring 42 is provided at one end of the piston rod 8 located inside the rod-type piston 4; when the piston rod 8 moves to the maximum stroke, the water injection port 45 and the water outlet 44 are still located below the upper edge of the sealing ring 42; a sealing ring 46 is provided at the extending portion of the piston rod 8 at the lower end of the rod-type piston 4; the pressure resistance design values ​​of the sealing ring 42 and the sealing ring 46 are both greater than 20MPa; a vent hole 41 is provided at the top of the piston cavity 43 to prevent vacuum negative pressure from being generated between the piston cavity wall above the piston rod 8 and the piston rod 8 during the downward movement of the piston rod 8, a water injection port 45 is provided on the right side and is connected to the water injection pipe 7, and a water outlet 44 is provided on the left side and is connected to the test model 1 through the water outlet pipe 2; the test model 1 is a test piece of rock or rock-like material containing fractures to be tested; a water outlet valve 3 is provided at the connection between the water outlet pipe 2 and the water outlet 44; a water pressure gauge 5 and a water injection valve 6 are installed on the water injection pipe 7; the maximum range of the water pressure gauge 5, the water injection valve 6 and the water outlet valve 3 are all designed to withstand pressures greater than 20MPa;

[0109] The pulley loading system 9 is composed of a crossbeam 90, a first fixed pulley 911, a second fixed pulley 912, a third fixed pulley 913, a fourth fixed pulley 914, a first steel wire rope 921, a second steel wire rope 922, a movable pulley 93, a brake 94, a weight 95, a tray 97, a guide bracket 96, a buffer pad 98 and a guide support 96; the first fixed pulley 911, the second fixed pulley 912 and the guide support 96 are fixed on the first mounting platform 01; the third fixed pulley 913, the fourth fixed pulley 914 and the brake 94 are fixed on the third mounting platform 03; one end of the first steel wire rope 921 is connected to the piston rod 8 and The first fixed pulley 911 and the second fixed pulley 912 are connected to the movable pulley 93; the connection section between the first wire rope 921 and the piston rod 8 above the first fixed pulley 911 and the axis of the piston rod 8 are located on the same vertical line to ensure that the piston rod 8 is subjected to axial force; the length of the connection section between the first wire rope 921 and the piston rod 8 above the first fixed pulley 911 is greater than the maximum stroke of the piston rod 8 to prevent the piston rod 8 from hitting the first fixed pulley 911 below due to the rapid decrease in water pressure after the rock specimen is broken; one end of the second wire rope 922 is fixed on the third mounting platform 03, and the other end passes through the movable pulley 93, the third fixed pulley 912 in sequence. The wheel 913, the brake 94, the fourth fixed pulley 914, the crossbeam 90 are connected to the tray 97; the second steel wire rope 922 sections on both sides of the movable pulley 93 are placed vertically; the connecting section of the second steel wire rope 922 and the tray 19 is placed vertically; the guide bracket 96 is fixed on the guide support 99, the crossbeam 90 above the guide bracket 96 can be disassembled, and the center of the crossbeam 90 is opened for the second steel wire rope 922 to pass through; the guide bracket 96 is a cylindrical smooth steel pipe; a buffer pad 98 is provided on the guide support 99; the weights 95 are suspended on the tray 97; each weight 95 is composed of a symmetrical left weight block 951 and a right weight block 952, A through hole 954 is provided in the center for the second steel wire rope 922 to pass through; two symmetrical guide holes 953 are provided on the central axis of the weight 95, and the guide holes 953 are polished and smooth. The size and spacing of the guide holes 953 are respectively consistent with the diameter and spacing of the guide bracket 96. The weight 95 can slide up and down through the guide bracket 96 to ensure stable loading; the weight 95 has multiple sizes to ensure that the output water pressure accuracy reaches 0.1MPa; the distance between the lower end of the tray 97 and the buffer pad 98 should be less than twice the maximum stroke of the piston rod 8 to avoid the rapid decrease in water pressure after the rock specimen is broken, causing the piston rod 8 to impact the bottom of the rod-type piston 4.

[0110] 3. Based on the above structural design, the specific implementation steps of the device provided by the present invention are as follows:

[0111] 1. Water filling: keep the pulley loading system 9 unloaded before water filling. If there are weights 95 hanging on the tray 97, remove the crossbeam 90 and take out the weights 95 from the guide bracket 96. When filling water, first open the water filling valve 6 and the water outlet valve 3, connect the water filling pipe 7 to the water pump, discharge the air in the pull rod type piston 4 and the water outlet pipe 2, close the water outlet valve 3, push the piston pull rod 8 back to the top of the pull rod type piston 4 by the water pressure of the water pump, close the water filling valve 6, and turn off the water pump.

[0112] 2. Loading: Start the brake 94 to clamp the second steel wire rope 922, remove the crossbeam 90, and hang the weight 95 corresponding to the set water pressure value on the tray 97 through the guide bracket 96. The conversion formula between the set water pressure value p and the weight mass m is as follows:

[0113] p=2mg / (s1-s2) (1)

[0114] In the formula, g is the acceleration due to gravity, s1 is the cross-sectional area of ​​the piston chamber 43, and s2 is the cross-sectional area of ​​the piston rod 8. The multiplication factor 2 is because the movable pulley 93 amplifies the pulling force of the first steel wire rope 921 to twice the weight of the weight 95. In this embodiment, s1-s2=1cm 2 , take the acceleration due to gravity g = 9.8m / s 2 When the pull rod type piston 4 outputs a water pressure of 20 MPa, the corresponding mass of the weight 95 is 102.041 kg.

[0115] Close the brake 94 and observe the value of the water pressure gauge 5. Since there is inevitably a certain amount of resistance in the load transfer process, the actual water pressure value will be smaller than the theoretical calculated value. It is necessary to add additional weights to make the water pressure gauge 5 reach the set water pressure value. If the water pressure gauge 5 reading cannot be stable, it means that the connection between the pull rod piston 4 and the piston pull rod 8 is not sealed well and needs to be repaired. When the water pressure gauge 5 reading reaches the set water pressure value and remains stable, open the water outlet valve 3 to complete the stable water pressure loading.

[0116] 3. Start the test: Turn on the rock mechanics testing machine and conduct uniaxial, biaxial, triaxial and creep tests on test model 1.

[0117] 4. Unloading: turn off the rock mechanics testing machine, remove the water pump, disassemble the crossbeam 90, take out the weight 95 from the guide bracket 96, and install the crossbeam 90; open the water injection valve 6, drain the water inside the pull rod piston 4, and end this test.

[0118] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A stable water pressure loading device for rock mechanics indoor test, characterized by: It comprises an installation platform (0), a test model (1), a water outlet pipe (2), a water outlet valve (3), a pull rod type piston (4), a water pressure gauge (5), a water injection valve (6), a water injection pipe (7), a piston pull rod (8) and a pulley loading system (9); The connection relationship is: A test model (1), a pull rod piston (4) and a pulley loading system (9) are arranged on a mounting platform (0); The test model (1), the water outlet pipe (2), the water outlet valve (3), the pull rod type piston (4), the piston pull rod (8) and the pulley loading system (9) are connected in sequence; A water pressure gauge (5), a water injection valve (6) and a water injection pipe (7) are sequentially connected to the lower part of the outer wall of the pull rod type piston (4); The pull rod type piston (4) is composed of a vent hole (41), a sealing ring (42), a piston cavity (43), a water outlet (44), a water injection port (45) and a sealing ring (46); The main body is a cylindrical cavity, namely a piston cavity (43); a vent hole (41) is arranged at the top of the piston cavity (43); a sealing ring (42) and a sealing ring (46) are arranged at the top and bottom of the piston cavity (43), respectively, which are dynamically connected to the top of the piston rod (8) and the outlet of the piston rod (8); a water outlet (44) and a water injection port (45) are arranged at the bottom of the piston cavity (43); The pulley loading system (9) comprises a crossbeam (90), a fixed pulley (91), a steel wire rope (92), a movable pulley (93), a brake (94), a weight (95), a guide bracket (96), a tray (97), a buffer pad (98) and a guide support (99); The weight (95) comprises a left weight block (951) and a right weight block (952), wherein the centers of the left weight block (951) and the right weight block (952) are provided with guide holes (953); the right side of the left weight block (951) is provided with a through hole (954), and the left side of the right weight block (952) is provided with a through hole (954); Its location and connection relationship are: On the first installation platform (01), the test model (1), the first fixed pulley (911), the second fixed pulley (912) and the guide support (99) are arranged in sequence from left to right; under the third installation platform (03), the third fixed pulley (913), the brake (94) and the fourth fixed pulley (914) are arranged in sequence from left to right; the bottom of the piston pull rod (8) is connected to the first steel wire rope (921), and the first steel wire rope (921) passes through the first fixed pulley (911) and the second fixed pulley (912) and is connected to the movable pulley (93); the second steel wire rope (922), the head end of which is fixed to the leftmost side under the third installation platform (03), passes through the movable pulley (93), the third fixed pulley (913), the brake (94) and the fourth fixed pulley (914) in sequence, and the tail end of which is connected to the tray (97); With the connection point between the tail end of the second steel wire rope (922) and the tray (97) as the vertical center line, a crossbeam (90), a guide bracket (96), a buffer pad (98) and a guide support (99) are arranged in sequence from top to bottom to form a loading mechanism; a weight (95) is loaded on the tray (97) to obtain different loading forces.

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