A temperature shear test device and a test method thereof

Abstract

The invention discloses a temperature shear test device and a test method thereof. The device comprises a soil tube, a cover plate, a porous cover plate, a permeable stone, a heating plate, a test soil, a shear force meter and the like. The invention can carry out determination of the variation law of the shear strength of soil at different times with the distance from the heating surface under local heating conditions. The invention can be used to simulate the situation in which a metal cutter disc forms mud cakes during the tunneling process of a shield machine and generates high temperature due to frictional heat, thereby affecting the properties of the soil on the excavation surface and thus accelerating the formation of mud cakes. A test means is provided for understanding the influence law of the high temperature surface of shield excavation on the shear strength of the soil on the excavation surface under mud cake conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering model tests, and in particular relates to a temperature shear test device and a test method thereof. Background Art

[0002] When the shield cutterhead passes through the clay layer, the clay debris cut off will adhere to the surface of the cutterhead, and form solid or semi-solid blocks through the extrusion of the cutterhead, which will adhere to and block the cutterhead, resulting in reduced penetration of the cutter when cutting the stratum, and reduced shield excavation efficiency. The existence of mud cake will not only increase the torque of the shield cutterhead, but also block the slurry suction port of the slurry discharge pipe, which will seriously affect the shield construction technology and construction safety. The handling and repair of a series of construction problems such as slag improvement, mud cake removal, shield system transformation, shutdown and cabin opening operations, and risk prevention have greatly increased the construction cost.

[0003] Under normal working conditions, the temperature of the shield cutter head is generally 40-50°C. However, during the shield tunneling process, especially under the conditions of composite formations, as the mud cake forms and increases, the cutter head torque and total thrust increase significantly, and the propulsion speed slows down, causing the cutter head temperature to reach 400-500°C, or even higher.

[0004] Studies have shown that the moisture content and temperature of soil have a great influence on the mechanical properties of soil. Therefore, in order to obtain the formation mechanism and development law of shield mud cake and solve the common engineering problem of cutterhead mud cake, it is necessary to understand the properties of the excavation surface soil affected by the high temperature of the cutterhead. Therefore, it is necessary to study the change law of shear strength of soil under heating state. The present invention can provide a temperature shear test device and a test method thereof, which provides a test means for understanding the influence of temperature on the shear strength of soil. Summary of the invention

[0005] In order to study the variation law of the shear strength of soil at different times with the distance from the heating surface under the condition of local heating of soil, the present invention provides a temperature shear testing device and a testing method thereof, which can test the shear strength performance of local heated soil at different times and at different distances from the heating surface, and analyze the influence of local heating time and distance of soil on the shear strength performance of soil.

[0006] The technical solution adopted by the present invention is:

[0007] A temperature shear test device, characterized in that: the device consists of a soil tube, a porous cover plate, a cover plate, a permeable stone, a heating plate, a test soil, a shear force meter, screws, an orifice, a screw plug, and a rubber ring. The left end of the soil tube is fixed to the porous bottom plate with screws, the right side of the bottom plate is close to the permeable stone, and the right end is fixed to the cover plate with screws. The soil tube is filled with test soil, the right end of the test soil is close to the heating plate, and the shear force meter is inserted into the test soil through the orifice to measure the shear force.

[0008] A temperature shear test device according to claim 1, characterized in that: the soil tube is a rectangular tube, the left and right ends of which extend outward in a circle and are provided with screw holes, and a plurality of openings are provided at the upper end of the soil tube, through which the shear force meter can be inserted into the test soil, and the openings are equipped with screw plugs for sealing the openings.

[0009] According to the mud film forming test device described in claim 1, it is characterized in that: the surface of the porous cover plate is provided with a plurality of small holes, and when the soil is heated, the water vapor in the soil can be discharged through the porous cover plate, and a rubber ring is provided around the contact surface between the porous cover plate and the soil tube.

[0010] A mud film forming test device according to claim 1 is characterized in that: a heating plate is provided on the inner side of the cover plate, the cover plate is fixed to the soil tube during the test, the heating plate is in close contact with the test soil, and a rubber ring is provided around the contact surface between the cover plate and the soil tube.

[0011] A temperature shear test method, characterized in that the test is performed using a slurry film forming test device according to any one of claims 1 to 4, comprising the following steps:

[0012] (1) Install a porous cover plate on the left side of the soil tube and fix it with screws. Tighten the screw plug at the hole. Place the soil tube with the left cover plate installed vertically and place a permeable stone in it. Cut a piece of filter paper with the same cross-sectional size as the permeable stone and place it in the soil tube to fit the permeable stone.

[0013] (2) Prepare the test soil according to the test requirements, fill the prepared test soil into the soil cylinder in layers and tamp it to the top of the soil cylinder;

[0014] (3) Smooth the test soil surface at the soil cylinder mouth, cover the cover so that the heating plate is close to the test soil, fix the cover and the soil cylinder with screws, and place the assembled device horizontally;

[0015] (4) Turn on the power of the heating plate, set the heating temperature of the heating plate, and start the test;

[0016] (5) At the moment t1 of soil heating, turn off the power of the heating plate, open the screw plugs of holes 1 to 6 in sequence, insert the shear force meter to the middle of the test soil, and test the shear strength of the soil at different distances from the heating plate at the moment t1. After the test, pull out the shear force meter, plug in the screw plug, turn on the power of the heating plate, and continue to heat the soil;

[0017] (6) When the soil is heated at time t2, the screw plugs of holes A to F are opened in sequence, and the shear force meter is inserted into the middle of the test soil to test the shear strength of the soil at different distances from the heating plate at time t2;

[0018] (7) Compare and analyze the shear strength of the soil at different distances from the heating plate at times t1 and t2 and its changing pattern.

[0019] Beneficial Effects

[0020] The present invention can carry out test determination of the shear strength performance of soil under different temperature conditions, and can be used to simulate the situation in which the metal cutter head forms mud cake during the tunneling process of the shield machine, and the friction heat generates high temperature, which affects the properties of the excavation surface soil and accelerates the formation of mud cake. This provides a testing means to solve the common engineering problem of cutter head mud cake and obtain the formation mechanism and development law of shield mud cake. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a structural diagram of a temperature shear test device provided by the present invention;

[0022] Figure 2 It is a top view of a temperature shear test device provided by the present invention;

[0023] Figure 3 yes Figure 2 Middle hole number;

[0024] Figure 4 yes Figure 1 Medium porous cover plate;

[0025] Figure 5 yes Figure 1 Middle cover;

[0026] In the attached Figure 1-5 middle

[0027] Soil cylinder 1, porous cover plate 2, cover plate 3, permeable stone 4, heating plate 5, test soil 6, shear force meter 7, screw 8, orifice 9, screw plug 10, rubber ring 11. DETAILED DESCRIPTION

[0028] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0029] like Figure 1-5 As shown, a temperature shear test device is characterized in that: the device consists of a soil tube 1, a porous cover plate 2, a cover plate 3, a permeable stone 4, a heating plate 5, a test soil 6, a shear force meter 7, a screw 8, a hole 9, a screw plug 10, and a rubber ring 11. The porous bottom plate is fixed to the left end of the soil tube 1 with a screw 8, the right side of the bottom plate is close to the permeable stone 4, and the cover plate 3 is fixed to the right end with a screw 8. The soil tube 1 is filled with test soil 6, the right end of the test soil 6 is close to the heating plate 5, and the shear force meter 7 is inserted into the test soil 6 through the hole 9 to measure the shear force.

[0030] The soil tube 1 is a rectangular metal tube or organic glass tube, with the left and right ends extending outward in a circle and having screw 8 holes. The upper end of the soil tube 1 is provided with a plurality of holes 9, the size of the holes 9 is slightly larger than the cross-sectional size of the shear plate of the shear force meter 7, and the shear force meter 7 can be inserted into the test soil 6 through the holes 9. When the soil is heated, the hole 9 is blocked with a screw plug 10 adapted to the hole 9, and the screw plug 10 is opened when the soil shear force is measured.

[0031] The porous cover plate 2 has a plurality of small holes on its surface, and when the soil is heated, water vapor in the soil can be discharged through the porous cover plate 2. A rubber ring 11 is arranged around the contact surface between the porous cover plate 2 and the soil tube 1, and water vapor can only be discharged through the small holes on the cover plate 3.

[0032] A heating plate 5 is provided inside the cover plate 3. During the test, the cover plate 3 is fixed to the soil tube 1, and the heating plate 5 is in close contact with the test soil 6. A rubber ring 11 is provided around the contact surface between the cover plate 3 and the soil tube 1 to ensure that water vapor will not be discharged from the contact surface between the cover plate 3 and the soil tube 1.

Claims

1. A temperature shear test device, characterized in that: The device comprises a soil tube (1), a porous cover plate (2), a cover plate (3), a permeable stone (4), a heating plate (5), a test soil (6), a shear force instrument (7), a screw (8), an orifice (9), a screw plug (10), and a rubber ring (11); the porous cover plate (2) is fixed to the left end of the soil tube (1) by a screw (8); the right side of the porous cover plate (2) is in close contact with the permeable stone (4); the cover plate (3) is fixed to the right end by a screw (8); the soil tube (1) is filled with the test soil (6); the right end of the test soil (6) is in close contact with the heating plate (5); and the shear force instrument (7) is inserted into the test soil (6) through the orifice (9) to measure the shear force; The soil tube (1) is a rectangular parallelepiped tube, with the left and right ends extending outwards and provided with screw (8) holes, and a plurality of holes (9) being provided at the upper end of the soil tube (1), through which the shear force instrument (7) can be inserted into the test soil (6), and the holes (9) are provided with screw plugs (10) for sealing the holes (9); The porous cover plate (2) has a plurality of small holes on its surface, and a rubber ring (11) is provided around the contact surface between the porous cover plate (2) and the soil cylinder (1); A heating plate (5) is provided inside the cover plate (3). During the test, the cover plate (3) is fixed to the soil tube (1), the heating plate (5) is in close contact with the test soil (6), and a rubber ring (11) is provided around the contact surface between the cover plate (3) and the soil tube (1).

2. A temperature shear test method, characterized in that: The test is performed using the temperature shear test device described in claim 1, comprising the following steps: Step 1: Install a porous cover plate (2) on the left side of the soil cylinder (1) and fix it with screws (8), plug the hole (9) with a screw plug (10), vertically place the soil cylinder (1) with the porous cover plate (2) on the left side, place a permeable stone (4), cut a piece of filter paper with the same cross-sectional size as the permeable stone (4), and place it in the soil cylinder (1) to fit the permeable stone (4); Step 2: Prepare test soil (6) according to test requirements, fill the prepared test soil (6) into the soil tube (1) in layers and tamp it to the mouth of the soil tube (1); Step 3: Smooth the surface of the test soil (6) at the mouth of the soil tube (1), cover the cover plate (3) so that the heating plate (5) is in close contact with the test soil (6), fix the cover plate (3) and the soil tube (1) with screws (8), and place the assembled device horizontally; Step 4: Turn on the power of the heating plate (5), set the heating temperature of the heating plate (5), and start the test; Step 5: When the soil is heated at time t1, the power supply of the heating plate (5) is turned off, the screw plugs (10) of the orifices (9) 1 to 6 are opened in sequence, and the shear force meter (7) is inserted into the middle of the test soil (6) to test the shear strength of the soil at different distances from the heating plate (5) at time t1. After the test, the shear force meter (7) is pulled out, the screw plug (10) is plugged in, and the power supply of the heating plate (5) is turned on to continue heating the soil; Step 6: When the soil is heated at time t2, the screw plugs (10) of the orifices (9) A to F are opened in sequence, and the shear force meter (7) is inserted into the middle of the test soil (6), and the shear strength of the soil at different distances from the heating plate (5) at time t2 is tested; Step 7: Compare and analyze the shear strength of the soil at different distances from the heating plate (5) at time t1 and time t2 and its variation pattern.

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