A test device and method for simulating formation damage under extreme conditions

Abstract

The present application relates to a test device and method for simulating formation damage under extreme conditions, and relates to the field of geotechnical engineering technology. It includes an upper shell, a lower shell, a first piston, a second piston, a piston connector and a driving member. A first accommodating space is formed in the upper shell, a first connecting hole is provided at the top of the upper shell, and the first connecting hole is connected to the first accommodating space; the top of the lower shell is connected to the bottom of the upper shell, a second accommodating space is formed in the lower shell, the second accommodating space is connected to the first accommodating space, a second connecting hole is provided at the bottom of the lower shell, and the second connecting hole is connected to the second accommodating space; the first piston is slidably arranged in the first accommodating space; the second piston is slidably arranged in the second accommodating space, and the driving member is arranged on the side of the second piston away from the first piston. The present application adopts a double-section design of the upper shell and the lower shell, which solves the problem of poor bearing capacity of the existing test device for simulating formation damage.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a test device and method for simulating stratum damage under extreme conditions. Background Art

[0002] Stratum damage and soil deformation are key factors that must be considered in underground engineering. The process of tunnel excavation will inevitably disturb the soil, causing stratum loss, loosening the overlying soil of the tunnel, causing active damage, and generating active earth pressure on the tunnel. The uplift of the tunnel or other engineering actions will also squeeze the soil, causing passive damage to the soil, and generating passive earth pressure on the tunnel. Therefore, in underground engineering, it is extremely important to understand the deformation and damage laws of the stratum soil.

[0003] The movable gate device is a classic method for simulating stratum failure. However, the existing movable gate device cannot meet the needs of simulating stratum failure under some extreme conditions, such as deep earth, deep sea, sudden drop of groundwater, etc. Under these conditions, the bearing capacity and shear strength of the movable gate device will be greatly affected.

[0004] With respect to the above-mentioned related technologies, there is a problem that the existing test devices for simulating formation damage have poor bearing capacity. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a test device and method for simulating formation damage under extreme conditions, aiming to solve the problem of poor bearing capacity of existing test devices for simulating formation damage.

[0006] The present application provides a test device and method for simulating formation damage under extreme conditions, which adopts the following technical scheme: a test device for simulating formation damage under extreme conditions, comprising:

[0007] An upper shell, wherein a first accommodation space is formed therein, and a first communication hole is provided at the top of the upper shell, wherein the first communication hole is communicated with the first accommodation space;

[0008] A lower shell, the top of which is connected to the bottom of the upper shell, a second accommodating space is formed in the lower shell, the second accommodating space is communicated with the first accommodating space, and a second communicating hole is provided at the bottom of the lower shell, the second communicating hole is communicated with the second accommodating space;

[0009] A first piston is slidably disposed in the first accommodation space;

[0010] a second piston slidably disposed in the second accommodation space, the second piston abutting against the bottom wall of the upper shell;

[0011] a piston connector, one end of which is connected to the first piston, and the other end of which is connected to the second piston;

[0012] A driving member is arranged on a side of the second piston away from the first piston, and is used for driving the second piston to move.

[0013] Optionally, the upper shell and the lower shell are detachably connected;

[0014] A sealing member is arranged between the upper shell and the lower shell.

[0015] Optionally, a first sealing ring is provided on the first piston, and a second sealing ring is provided on the second piston.

[0016] Optionally, the test device for simulating formation damage under extreme conditions includes a middle control unit, and a soil pressure sensor is provided on the first piston. The soil pressure sensor is used to detect soil pressure information exerted on the first piston, and the soil pressure sensor is electrically connected to the middle control unit.

[0017] Optionally, a pore water sensor is provided on the first piston, and the pore water sensor is used to detect pore water pressure information in sand, and the pore water sensor is electrically connected to the central control unit.

[0018] Optionally, the test device for simulating formation damage under extreme conditions includes a drainage component, which is disposed on the first piston and is used to absorb water on the first piston and discharge it.

[0019] Optionally, the drainage assembly includes a water seepage member, a first drainage pipe and a water tank, the water seepage member is arranged on the first piston, one end of the first drainage pipe is connected to the water seepage member, and the other end of the first drainage pipe is connected to the water tank.

[0020] Optionally, a third accommodating space is formed between the first piston, the second piston and the piston connector, and a third communicating hole is provided on the second piston, and the third communicating hole is respectively connected with the third accommodating space and the second accommodating space;

[0021] The first drain pipe is located in the third accommodating space;

[0022] The second piston is provided with a fourth communicating hole, and the fourth communicating hole is respectively connected with the first accommodating space and the second accommodating space;

[0023] The test device for simulating formation damage under extreme conditions comprises a second drainage pipe, one end of which is arranged on the second piston and communicated with the second connecting hole, and the other end of which is connected to the water tank.

[0024] Optionally, the test device for simulating formation damage under extreme conditions includes a limit fitting and a limit member, the limit fitting is arranged on the side of the second piston away from the first piston, the limit fitting is provided with a first limit hole, the lower shell is provided with a second limit hole, the first limit hole is concentrically arranged with the second limit hole, and the limit member is screwed to the first limit hole and the second limit hole, respectively.

[0025] A method for simulating formation damage under extreme conditions, applied to any of the above test devices for simulating formation damage under extreme conditions, the test device for simulating formation damage under extreme conditions comprising a middle control, a soil pressure sensor and a pore water sensor are provided on the first piston, the soil pressure sensor is used to detect soil pressure information on the first piston, the soil pressure sensor is electrically connected to the middle control, the pore water sensor is used to detect pore water pressure information in sand, and the pore water sensor is electrically connected to the middle control;

[0026] The method comprises:

[0027] Filling sand and soil, and obtaining first soil pressure information and first pore water pressure information in real time;

[0028] The driving member is started to control the first piston to move downward, and the second soil pressure information and the second pore water pressure information are obtained in real time.

[0029] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0030] The first piston is connected to the second piston through a piston connector, so the driving member drives the first piston and the second piston to move simultaneously in the same direction.

[0031] The patent application adopts a double-section design of an upper shell and a lower shell, where two pistons rub against their corresponding inner walls of the shell, thereby increasing the overall friction and making it easier to withstand the high pressure from the upper soil under extreme conditions.

[0032] The invention solves the problem of poor bearing capacity of the existing test device for simulating stratum damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1It is a schematic diagram of the overall structure of a test device for simulating formation damage under extreme conditions in an embodiment of the present application;

[0035] Figure 2 is a top view of a test device for simulating formation damage under extreme conditions in an embodiment of the present application;

[0036] Figure 3 is a cross-sectional view of a test device for simulating formation damage under extreme conditions in an embodiment of the present application;

[0037] Figure 4 Schematic diagram of the internal structure of the upper shell and the lower shell of the test device for simulating formation damage under extreme conditions in the embodiment of the present application;

[0038] Figure 5 is a schematic structural diagram of the lower shell of a test device for simulating formation damage under extreme conditions in an embodiment of the present application;

[0039] Figure 6 It is a flow chart of a method for simulating formation damage under extreme conditions in an embodiment of the present application.

[0040] Description of reference numerals:

[0041] 1. Upper shell; 11. Upper shell body; 111. First connecting hole; 112. Anti-leakage frame; 113. Fixing piece; 12. First shell connecting piece; 2. Lower shell; 21. Lower shell body; 211. Second connecting hole; 212. Second limiting hole; 22. Second shell connecting piece; 3. First piston; 31. First sealing ring; 32. Soil pressure sensor; 33. Water seepage piece; 34. Pore water sensor; 35. First drain pipe; 4. Second piston; 41. Second sealing ring; 42. Second drain pipe; 43. Third connecting hole; 44. Fourth connecting hole; 5. Piston connecting piece; 6. Limit fitting piece; 61. First avoidance hole; 62. Drainage outlet hole; 63. First limiting hole; 7. Limiting piece; 71. Insertion pin. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The present application is further described in detail below in conjunction with the accompanying drawings.

[0044] The embodiments of the present application disclose a test device and method for simulating formation damage under extreme conditions.

[0045] like Figure 1 , Figure 3 and Figure 4 As shown, a test device for simulating formation damage under extreme conditions includes an upper shell 1, a lower shell 2, a first piston 3, a second piston 4, a piston connector 5 and a driving member. A first accommodating space is formed in the upper shell 1, a first connecting hole 111 is provided at the top of the upper shell 1, and the first connecting hole 111 is connected to the first accommodating space; the top of the lower shell 2 is connected to the bottom of the upper shell 1, a second accommodating space is formed in the lower shell 2, and the second accommodating space is connected to the first accommodating space, a second connecting hole 211 is provided at the bottom of the lower shell 2, and the second connecting hole 211 is connected to the second accommodating space; the first piston 3 is slidably arranged in the first accommodating space; the second piston 4 is slidably arranged in the second accommodating space, and the second piston 4 abuts against the bottom wall of the upper shell 1; one end of the piston connector 5 is connected to the first piston 3, and the other end is connected to the second piston 4; the driving member is arranged on the side of the second piston 4 away from the first piston 3, and the driving member is used to drive the second piston 4 to move.

[0046] The first piston 3 is connected to the second piston 4 via the piston connector 5, so the driving member drives the first piston 3 and the second piston 4 to move simultaneously in the same direction.

[0047] Since the patent application simulates the bottom layer damage under extreme conditions (such as deep sea, deep earth, sudden drop of groundwater layer, etc.), the top of the first piston 3 will be subjected to high pressure from the upper soil, and the patent application adopts a double-section design of upper shell 1 and lower shell 2. There are two pistons rubbing against the corresponding inner walls of the shell, thereby increasing the overall friction force and making it easier to withstand the high pressure from the upper soil under extreme conditions.

[0048] The invention solves the problem of poor bearing capacity of the existing test device for simulating stratum damage.

[0049] like Figure 1 , Figure 3 and Figure 4 As shown, the upper shell 1 and the lower shell 2 are detachably connected; a sealing member is provided between the upper shell 1 and the lower shell 2.

[0050] Specifically, the sand pressure and water content above the first piston 3 are relatively large, and the sand and water may penetrate into the gap between the first piston 3 and the upper shell 1 or flow into the first accommodating space or the second accommodating space through the gap.

[0051] If sand enters the gap between the first piston 3 and the upper shell 1, it will hinder the up and down movement of the first piston 3, thereby causing the entire device to fail to work properly, or the infiltration of water will also cause corrosion to the inner wall of the upper shell 1, the structure in the first accommodating space or the structure in the second accommodating space, thereby affecting the normal operation of the device and affecting the service life of the device.

[0052] The patent application adopts a double-section design. The cooperation between the first piston 3 and the upper shell 1, and the cooperation between the second piston 4 and the lower shell 2 always ensure that the test device for simulating formation damage under extreme conditions is always in a closed state when working, preventing sand and water from entering.

[0053] At the same time, since the upper shell 1 and the lower shell 2 are detachably connected, and it can be seen from the abutment between the second piston 4 and the bottom wall of the upper shell 1 that the longitudinal cross-sectional area of ​​the lower shell 2 is larger than the longitudinal cross-sectional area of ​​the upper shell 1, even if water leaks between the upper shell 1 and the first piston 3, the falling water will not fall into the gap between the lower shell 2 and the second piston 4.

[0054] A movable door is formed between the first piston 3, the second piston 4 and the piston connector 5. The upper shell 1 and the lower shell 2 are both made of steel material, surrounding the first piston 3 and the second piston 4 to protect the movable door formed by the first piston 3, the second piston 4 and the piston connector 5 to prevent sand and soil from entering the movable door.

[0055] The upper shell 1 and the lower shell 2 are both subjected to hardening and rust-proofing treatments, such as surface quenching treatment, spraying of hard coatings, hard chrome plating, and the like.

[0056] The upper shell 1 comprises an upper shell body 11 and a first shell connecting member 12. The upper shell body 11 is in the shape of a cube, the first accommodation space is arranged in the upper shell body 11, and the first connecting hole is arranged at the top of the upper shell body 11.

[0057] The first housing connection member 12 is disposed around the outer circumference of the upper housing body 11 , and the first housing connection member 12 is disposed at the outer circumference of the bottom of the upper housing body 11 .

[0058] The lower shell 2 includes a lower shell body 21 and a second shell connector 22. The lower shell body 21 is in the shape of a cube, the second accommodation space is arranged in the lower shell body 21, and the second connection hole is arranged at the bottom of the lower shell body 21.

[0059] The second housing connection piece 22 is disposed around the outer circumference of the lower housing body 21 , and the second housing connection piece 22 is disposed on the outer circumference of the top of the lower housing body 21 .

[0060] The upper shell body 11 and the lower shell body 21 are coaxially arranged, and the area of ​​the radial cross section of the upper shell body 11 is smaller than the area of ​​the radial cross section of the lower shell body 21 .

[0061] The first piston 3 can slide up and down along the axial direction of the upper shell body 11, and the second piston 4 can slide up and down along the axial direction of the lower shell body 21. Since the first piston 3 and the second piston 4 are connected by the piston connector 5, the first piston 3 and the second piston 4 can be driven to slide in the same direction at the same time by the driving of the driving member.

[0062] The first piston 3 and the second piston 4 are both flexible polyurethane pistons. The first piston 3 can fit well with the inner wall of the upper shell body 11, and the second piston 4 can fit well with the inner wall of the lower shell body 21, thereby providing a good sealing effect to prevent sand or water from entering the gap between the upper shell body 11 and the first piston 3 and entering the first accommodating space or the second accommodating space through the gap.

[0063] In order to improve the airtightness between the first piston 3 and the second piston 4 , when the first piston 3 and the top surface of the upper shell body 11 are in the same plane, the second piston 4 abuts against the bottom wall of the upper shell body 11 .

[0064] Furthermore, the axial length of the lower shell body 21 is greater than or equal to the axial length of the upper shell body 11 to ensure that when the first piston 3 moves to the connection between the upper shell body 11 and the lower shell body 21 , the second piston 4 will not extend from the second communicating hole 211 .

[0065] The first shell connector 12 and the second shell connector 22 are respectively annular connecting plates, which are respectively fixedly surrounded by the outer circumference of the upper shell body 11 and the lower shell body 21, and the first shell connector 12 and the second shell connector 22 are both provided with threaded through holes, and the first shell connector 12 and the second shell connector 22 are screwed together to realize a double-section design of splicing the upper shell 1 and the lower shell 2.

[0066] If the upper shell 1 and the lower shell 2 are designed as an integral whole, once water leakage occurs between the upper shell 1 and the first piston 3 or between the lower shell 2 and the second piston 4, causing the upper shell 1 or the lower shell 2 to rust, the upper shell 1 and the lower shell 2 need to be replaced as a whole, increasing the investment cost after the accident occurs.

[0067] The patent application adopts a detachable double-section setting of the upper shell 1 and the lower shell 2, which is more modular as a whole. The upper shell 1 and the lower shell 2 are relatively independent, which can save costs after an accident occurs.

[0068] During operation, the driving member drives the first piston 3 to move up and down, thereby loosening the soil above the first piston 3, so as to detect the deformation and failure pattern of the soil.

[0069] In the present patent application, the upper shell 1 and the lower shell 2 adopt a spliced ​​double-section design. During the downward movement, the first piston 3 and the second piston 4 rub against the upper shell body 11 and the lower shell body 21 respectively, which will increase the friction and make it easier to withstand the high pressure from the soil above.

[0070] Furthermore, since the areas of the axial cross-sections of the upper shell body 11 and the lower shell body 21 are different, the contact position between the lower shell body 21 and the second piston 4 is not directly opposite to the contact position between the upper shell body 11 and the first piston 3. Even if water leakage occurs between the upper shell 1 and the first piston 3, water will not drip into the gap between the lower shell body 21 and the second piston 4, thereby improving the airtightness of the test device for simulating bottom layer damage under extreme conditions.

[0071] The sealing member is a sealing ring, and the sealing member is arranged between the first shell connecting member 12 and the second shell connecting member 22 to maintain good sealing performance and fill the gap after the bolt connection.

[0072] like Figure 1 As shown, a fixing member 113 is provided on the outer surface of the upper shell 1, and the fixing member 113 is used to fix the test device for simulating bottom layer damage under extreme conditions on the operating platform.

[0073] Specifically, the fixing member 113 is an annular steel ring, and the fixing member 113 is arranged on the outer surface of the upper shell body 11. A plurality of screw holes are arranged at intervals on the fixing member 113, and the fixing member 113 is screwed and fixed to the operating platform to be fixedly installed through the screw holes.

[0074] like Figure 3 and Figure 4 As shown, a first sealing ring 31 is provided on the first piston 3 , and a second sealing ring 41 is provided on the second piston 4 .

[0075] Specifically, the first sealing ring 31 is disposed on the outer periphery where the first piston 3 contacts the inner wall of the upper shell body 11 , and the second sealing ring 41 is disposed on the outer periphery where the second piston 4 contacts the inner wall of the lower shell body 21 .

[0076] When the first piston 3 moves up and down along the upper shell body 11 and the second piston 4 moves up and down along the lower shell body 21, the first sealing ring 31 and the second sealing ring 41 can effectively prevent the leakage of sand or water, thereby improving the airtightness of the test device simulating bottom layer damage under extreme conditions.

[0077] like Figure 1 and Figure 2 As shown, an anti-leakage frame 112 is provided on the top of the first piston 3 , and the anti-leakage frame 112 is used to prevent sand and soil from squeezing into the gap between the first piston 3 and the upper shell 1 .

[0078] Specifically, an annular mounting groove connected end to end is provided on the top periphery of the first piston 3 , and the anti-leakage frame 112 is provided on the bottom of the annular mounting groove, and the upper surface of the anti-leakage frame 112 is flush with the top upper surface of the first piston 3 .

[0079] The anti-leakage frame 112 is a metal frame that is not easily deformed, and can effectively prevent the first piston 3 from being squeezed by sand from above, resulting in a large gap between the first piston 3 and the upper shell body 11, causing sand to enter the gap between the upper shell body 11 and the first piston 3.

[0080] To facilitate replacement of the anti-leakage frame 112 , the anti-leakage frame 112 is screwed to the bottom of the annular installation groove.

[0081] like Figure 1 and Figure 2 As shown, the test device for simulating formation damage under extreme conditions includes a middle control unit, and a soil pressure sensor 32 is arranged on the first piston 3. The soil pressure sensor 32 is used to detect the soil pressure information exerted on the first piston 3, and the soil pressure sensor 32 is electrically connected to the middle control unit.

[0082] Specifically, the soil pressure sensor 32 is arranged on the top surface of the first piston 3, and can directly contact the sand above the first piston 3 to obtain the soil pressure information of the sand above the first piston 3 as the first piston 3 moves up and down, and upload the obtained soil pressure information to the central control unit.

[0083] like Figure 1 and Figure 2 As shown, a pore water sensor 34 is provided on the first piston 3. The pore water sensor 34 is used to detect the pore water pressure information in the sand. The pore water sensor 34 is electrically connected to the central control unit.

[0084] Specifically, the pore water sensor 34 is disposed on the top surface of the first piston 3, and can be in direct contact with the sand above the first piston 3 to monitor the pore water pressure information in the soil, and upload the acquired pore water pressure information to the central control unit.

[0085] like Figure 1 and Figure 3 As shown, the test device for simulating formation damage under extreme conditions includes a drainage component, which is arranged on the first piston 3 and is used to absorb water on the first piston 3 and discharge it.

[0086] Specifically, the drainage assembly includes a water seepage member 33, a first drainage pipe 35 and a water tank.

[0087] The water seepage member 33 is a permeable stone, which is a stone material with good water permeability and can provide good seepage conditions. There are multiple water seepage members 33, and in this embodiment, there are three water seepage members 33. Multiple permeable stones are arranged on the first piston 3 at intervals.

[0088] A first drainage pipe 35 is connected to the bottom of each water seepage stone, and the other end of the first drainage pipe 35 is connected to the water tank. Water seeping from the water seepage stone can be collected by the water tank through the first drainage pipe 35.

[0089] like Figure 3 and Figure 4 As shown, a third accommodating space is formed between the first piston 3, the second piston 4 and the piston connector 5, and a third connecting hole 43 is provided on the second piston 4, and the third connecting hole 43 connects the third accommodating space and the second accommodating space respectively; the first drain pipe 35 is located in the third accommodating space; a fourth connecting hole 44 is provided on the second piston 4, and the fourth connecting hole 44 connects the first accommodating space and the second accommodating space respectively; the test device for simulating formation damage under extreme conditions includes a second drain pipe 42, one end of the second drain pipe 42 is provided on the second piston 4 and connected to the second connecting hole 211, and the other end is connected to the water tank.

[0090] Specifically, the piston connector 5 is in a rectangular cylindrical shape, one end of the piston connector 5 is connected to the first piston 3, and the other end is connected to the second piston 4. The first piston 3, the second piston 4 and the piston connector 5 together form a third accommodation space, and the first drain pipe 35 is located in the third accommodation space and extends from the third connecting hole 43 to be connected to the water tank.

[0091] The third accommodation space can provide an accommodation space for the first drain pipe 35 and play a protective role.

[0092] At least two fourth connecting holes 44 are provided, and at least two fourth connecting holes 44 are located outside the third accommodation space, and at least two fourth connecting holes are provided around the central circumference of the second piston 4. Each fourth connecting hole 44 is directly opposite to the gap between the first piston 3 and the upper shell body 11 above.

[0093] If leakage occurs in the gap between the first piston 3 and the upper shell body 11, the leakage may drip into the fourth connecting hole 44 directly below and be collected by the water tank through the second drain pipe 42, thereby preventing water from gathering in the first storage space and also preventing water from entering the second storage space through the gap between the second piston 4 and the lower shell body 21.

[0094] like Figure 1 , Figure 4 and Figure 5 As shown, the test device for simulating formation damage under extreme conditions includes a limit fitting 6 and a limit fitting 7. The limit fitting 6 is arranged on the side of the second piston 4 away from the first piston 3. The limit fitting 6 is provided with a first limit hole 63, and the lower shell 2 is provided with a second limit hole 212. The first limit hole 63 is concentrically arranged with the second limit hole 212, and the limit fitting 7 is screwed with the first limit hole 63 and the second limit hole 212 respectively.

[0095] Specifically, the position-limiting fitting 6 passes through the second communicating hole 211 and extends into the second accommodation space, and is disposed directly below the second piston 4. The position-limiting fitting 6 is threadedly connected to the second piston 4.

[0096] An avoidance space is formed in the limiting fitting 6, and a first avoidance hole 61 is arranged on the top of the limiting fitting 6. The first avoidance hole 61 is connected to the avoidance space, and the first avoidance hole 61 is arranged concentrically with the third connecting hole 43. Multiple first drain pipes 35 can pass through the third connecting hole 43 and the first avoidance hole 61 in sequence to enter the avoidance space.

[0097] The limiting fitting 6 is provided with a plurality of drainage outlet holes 62 , which are connected to the avoidance space. The plurality of first drainage pipes 35 can be led out from the plurality of drainage outlet holes 62 so as to be connected to an external water tank.

[0098] In this embodiment, four drainage outlet holes 62 are provided, and the four drainage outlet holes 62 are respectively provided on the left and right side walls and the front and rear side walls of the position-limiting fitting 6. The four drainage outlet holes 62 are all provided close to the second piston 4.

[0099] The first limiting hole 63 penetrates through the front and rear side walls of the limiting fitting 6, and the second limiting hole 212 is also provided on the front and rear side walls of the lower shell body 21. The two second limiting holes 212 are provided concentrically with the first limiting hole 63.

[0100] The stopper 7 is inserted from the second stopper hole 212 on one side, passes through the first stopper hole 63 and passes out from the second stopper hole 212 on the other side. Thus, the stopper fitting 6 and the lower shell body 21 are fixed together by the stopper 7, so that the movable door (the movable door is composed of the first piston 3, the second piston 4 and the connecting member) can be prevented from moving up and down, so as to prevent the movable door from moving down during the filling process (the filling is to cover the experimental soil for the simulation experiment above the first piston 3).

[0101] The limiting member 7 is also provided with a card-connecting through hole, which is provided at one end of the limiting member 7 passing through the second limiting hole 212 on the other side. A card-connecting through hole can be inserted into the card-connecting through hole to prevent the limiting member 7 from shaking, thereby increasing the overall stability during the filling process.

[0102] The driving member is arranged at one end of the limiting fitting 6 away from the second piston 4. The driving member can be a combined driving member of a servo motor and a ball screw, a cylinder, a hydraulic cylinder, etc. The driving member can push the limiting fitting 6 and then drive the movable door to move up and down.

[0103] like Figure 6 As shown, a method for simulating formation damage under extreme conditions is applied to any of the above-mentioned test devices for simulating formation damage under extreme conditions, comprising the steps of:

[0104] S100, filling sand and soil, and obtaining first soil pressure information and first pore water pressure information in real time.

[0105] Specifically, before filling the sand, the soil pressure sensor 32 and the pore water sensor 34 are reset to zero, and the position of the movable door is reset to zero (i.e., the first piston 3 and the upper surface of the upper shell body 11 are in the same plane, and the second piston 4 is against the lower surface of the upper shell body 11). Then, the soil pressure sensor 32 and the pore water sensor 34 are turned on. Then, the sand is filled above the first piston 3. Since the strata in nature are often layered, different strata have different particle compositions, densities and mechanical properties. In order to approximately simulate this real stratum structure, the layered filling method is adopted for sand filling.

[0106] During the layered filling process, the soil pressure sensor 32 and the pore water sensor 34 obtain the current first soil pressure information and the first pore water pressure information in real time and upload them to the central control unit.

[0107] After the sand is filled, the sand above the movable door is pressurized to simulate the real soil environment. After the water pressure or loading pressure is loaded, and after the indications of the first soil pressure information and the first pore water pressure information uploaded by the soil pressure sensor 32 and the pore water sensor 34 have no obvious changes, the current indications of the first soil pressure information and the first pore water pressure information are recorded.

[0108] S200, starting the driving member to control the first piston 3 to move downward, and obtaining the second soil pressure information and the second pore water pressure information in real time.

[0109] Specifically, before controlling the first piston 3 to move downward (i.e., controlling the movable door to move downward), check whether the driving member is online, then remove the insertion pin 71, take the limiting member 7 out of the first limiting hole 63 and the second limiting hole 212, set the camera and check whether it is connected so that the camera can record in real time later.

[0110] Then, the soil pressure sensor 32 and the pore water sensor 34 start to collect data again, and check whether the limiting member 7 is taken out from the first limiting hole 63 and the second limiting hole 212 .

[0111] Then, the driving member is started, and the driving member drives the movable door to move downward to a predetermined distance at a predetermined speed. During this process, the first piston 3 and the second piston 4 move downward at the same time.

[0112] It should be noted that the number of test devices simulating bottom layer damage under extreme conditions can be multiple, and the installation arrangement of multiple test devices simulating bottom layer damage under extreme conditions can be changed according to different test plans or purposes. The moving distance of the movable door in each test device simulating bottom layer damage under extreme conditions can also be adjusted according to different working conditions.

[0113] As the movable door moves downward, the supporting part of the sand body above the first piston 3 will lose support, causing damage to the soil. During the descent of the movable door, the soil pressure sensor 32 and the pore water sensor 34 collect signals, obtain the second soil pressure information and the second pore water pressure information and upload them to the central control unit until the movable door descends to a predetermined distance, at which time the soil pressure sensor 32 and the pore water sensor 34 stop collecting data.

[0114] Finally, the sand and soil are cleaned up. After the sand and soil are cleaned up, the movable door is controlled to return to zero displacement, the limiter 7 is reinserted, and the drive member is closed.

[0115] Before performing step S100, it is necessary to prepare for the experiment: first, determine the specific plan of the main body test, such as the loading pressure of the upper sand, the amount, distance and speed of the movable door moving downward, etc. Check whether the drive switch, soil pressure sensor 32 and pore water sensor 34 are connected normally, check the insertion of the limiter 7, and check whether the connection between the movable door and the drive is normal.

[0116] In summary, a test device and method for simulating formation damage under extreme conditions includes an upper shell 1, a lower shell 2, a first piston 3, a second piston 4, a piston connector 5 and a driving member. A first accommodating space is formed in the upper shell 1, a first connecting hole 111 is provided at the top of the upper shell 1, and the first connecting hole 111 is connected to the first accommodating space; the top of the lower shell 2 is connected to the bottom of the upper shell 1, a second accommodating space is formed in the lower shell 2, and the second accommodating space is connected to the first accommodating space, a second connecting hole 211 is provided at the bottom of the lower shell 2, and the second connecting hole 211 is connected to the second accommodating space; the first piston 3 is slidably arranged in the first accommodating space; the second piston 4 is slidably arranged in the second accommodating space, and the second piston 4 abuts against the bottom wall of the upper shell 1; one end of the piston connector 5 is connected to the first piston 3, and the other end is connected to the second piston 4; the driving member is arranged on the side of the second piston 4 away from the first piston 3, and the driving member is used to drive the second piston 4 to move.

[0117] The first piston 3 is connected to the second piston 4 via the piston connector 5, so the driving member drives the first piston 3 and the second piston 4 to move simultaneously in the same direction.

[0118] The patent application adopts a double-section design of an upper shell 1 and a lower shell 2, where two pistons rub against their corresponding inner walls of the shell, thereby increasing the overall friction and making it easier to withstand the high pressure from the upper soil under extreme conditions.

[0119] The invention solves the problem of poor bearing capacity of the existing test device for simulating stratum damage.

[0120] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0121] It should be noted that the present invention introduces the specific structure and working principle of the present invention by taking a test device and method for simulating formation damage under extreme conditions as an example, but the application of the present invention is not limited to a test device and method for simulating formation damage under extreme conditions, and can also be applied to the production and use of other similar workpieces.

[0122] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A test device for simulating formation damage under extreme conditions, characterized in that: include: An upper shell, wherein a first accommodation space is formed therein, and a first communication hole is provided at the top of the upper shell, wherein the first communication hole is communicated with the first accommodation space; A lower shell, the top of which is connected to the bottom of the upper shell, a second accommodating space is formed in the lower shell, the second accommodating space is communicated with the first accommodating space, and a second communicating hole is provided at the bottom of the lower shell, the second communicating hole is communicated with the second accommodating space; A first piston is slidably disposed in the first accommodation space; a second piston slidably disposed in the second accommodation space, the second piston abutting against the bottom wall of the upper shell; a piston connector, one end of which is connected to the first piston, and the other end of which is connected to the second piston; A driving member is arranged on a side of the second piston away from the first piston, and is used for driving the second piston to move.

2. The test device for simulating formation damage under extreme conditions according to claim 1 is characterized in that: The upper shell and the lower shell are detachably connected; A sealing member is arranged between the upper shell and the lower shell.

3. The test device for simulating formation damage under extreme conditions according to claim 1, characterized in that: The first piston is provided with a first sealing ring, and the second piston is provided with a second sealing ring.

4. The test device for simulating formation damage under extreme conditions according to claim 1, characterized in that: The test device for simulating formation damage under extreme conditions includes a middle control component, and a soil pressure sensor is arranged on the first piston. The soil pressure sensor is used to detect soil pressure information exerted on the first piston, and the soil pressure sensor is electrically connected to the middle control component.

5. The test device for simulating formation damage under extreme conditions according to claim 4 is characterized in that: A pore water sensor is provided on the first piston, and the pore water sensor is used to detect pore water pressure information in sand. The pore water sensor is electrically connected to the central control unit.

6. The test device for simulating formation damage under extreme conditions according to claim 5, characterized in that: The test device for simulating formation damage under extreme conditions includes a drainage component, which is arranged on the first piston and is used to absorb water on the first piston and discharge it.

7. The test device for simulating formation damage under extreme conditions according to claim 6, characterized in that: The drainage assembly includes a water seepage member, a first drainage pipe and a water tank. The water seepage member is arranged on the first piston. One end of the first drainage pipe is connected to the water seepage member, and the other end is connected to the water tank.

8. The test device for simulating formation damage under extreme conditions according to claim 7 is characterized in that: A third accommodating space is formed between the first piston, the second piston and the piston connector, and a third communicating hole is provided on the second piston, and the third communicating hole is respectively connected with the third accommodating space and the second accommodating space; The first drain pipe is located in the third accommodating space; The second piston is provided with a fourth communicating hole, and the fourth communicating hole is respectively connected with the first accommodating space and the second accommodating space; The test device for simulating formation damage under extreme conditions comprises a second drainage pipe, one end of which is arranged on the second piston and communicated with the second connecting hole, and the other end of which is connected to the water tank.

9. The test device for simulating formation damage under extreme conditions according to claim 8, characterized in that: The test device for simulating formation damage under extreme conditions includes a limit fitting and a limit member. The limit fitting is arranged on the side of the second piston away from the first piston. The limit fitting is provided with a first limit hole, and the lower shell is provided with a second limit hole. The first limit hole and the second limit hole are arranged concentrically, and the limit member is screwed to the first limit hole and the second limit hole respectively.

10. A method for simulating formation damage under extreme conditions, characterized in that: A test device for simulating formation damage under extreme conditions as claimed in any one of claims 1 to 9, the test device for simulating formation damage under extreme conditions comprising a middle control, a soil pressure sensor and a pore water sensor are provided on the first piston, the soil pressure sensor is used to detect soil pressure information on the first piston, the soil pressure sensor is electrically connected to the middle control, the pore water sensor is used to detect pore water pressure information in sand, and the pore water sensor is electrically connected to the middle control; The method comprises: Filling sand and soil, and obtaining first soil pressure information and first pore water pressure information in real time; The driving member is started to control the first piston to move downward, and the second soil pressure information and the second pore water pressure information are obtained in real time.

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