Foundation pile frictional resistance testing device

Abstract

The utility model relates to the field of pile foundations, in particular to a foundation pile frictional resistance testing device. The testing device comprises an upper fixed plate (1) and a lower fixed plate (2), the upper fixed plate (1) and the lower fixed plate (2) pass through a piston rod (6), and a lower movable plate (4) is arranged below a cylinder barrel (5); the middle parts of the upper fixing plate (1) and the lower fixing plate (2) are also connected through a central hole (12), the central hole (12) is cylindrical, and an inner sleeve (7) is arranged on the wall of the central hole (12); the space below the lower movable plate (4) and above the lower fixed plate (2) is a cavity (9); the test pile section is arranged between the upper movable plate (3) and the lower movable plate (4); the lower end of the displacement wire (11) is fixed on the upper movable plate (3) and penetrates through the upper fixed plate (1); and the high-pressure oil pipe (10) leads to the interior of the cylinder barrel (5) and can push the cylinder barrel (5) to move downwards.

Description

Technical Field

[0001] The utility model relates to the field of pile foundations, in particular to a test device and method for the skin friction of foundation piles. Background Art

[0002] As one of the important foundation forms of construction projects, pile foundations are widely used. The characteristic of pile foundations is to provide bearing capacity and transfer the upper structure load box to the foundation.

[0003] The bearing capacity of a single foundation pile is mainly composed of the skin friction along the pile side and the end bearing resistance. The skin friction along the pile side and the end bearing resistance are also related to the formation characteristics. In different sites and different formations, the skin friction along the pile side and the end bearing friction are different. Therefore, in the early stage of construction, through corresponding technical means, the skin friction along the pile side and the end bearing resistance of each formation should be measured, and then the design of the foundation pile should be carried out to determine the bearing capacity of a single pile, and then the piles should be reasonably arranged so that the bearing capacity of the group pile foundation can meet the requirements of the upper load and ensure the safe use of the building.

[0004] The bearing capacity of a single pile can be measured through static load tests. In the early stage, it can also be calculated and determined according to the side resistance and end bearing resistance of each formation, and verified through single-pile bearing capacity tests in the later stage.

[0005] The end bearing resistance can be evaluated through in-situ tests, such as deep plate load tests, dynamic penetration tests, and axial compressive strength of rocks, etc.

[0006] The test of the skin friction along the pile side can be measured through methods such as single-pile static load tests and embedding test elements in the pile body, such as steel bar stress gauges, to obtain the distribution and magnitude of the skin friction of each formation.

[0007] Through various test means, the skin friction and end bearing resistance of each formation are obtained to provide necessary parameters for the design of pile foundations. Content of the Utility Model

[0008] Purpose of the utility model: To provide a test device and method for the skin friction of foundation piles with better effects. The specific purpose can be seen in the multiple substantial technical effects in the specific implementation part.

[0009] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0010] A test device for the skin friction of foundation piles, characterized in that

[0011] The test device includes an upper fixing plate 1 and a lower fixing plate 2. The upper fixing plate 1 and the lower fixing plate 2 are connected by a piston rod 6. The piston rod 6 passes through the inside of a cylinder barrel 5. Above the cylinder barrel 5 is an upper movable plate 3, and below the cylinder barrel 5 is a lower movable plate 4;

[0012] The middle parts of the upper fixing plate 1 and the lower fixing plate 2 are also connected by a central hole 12. The central hole 12 is cylindrical, and its wall is an inner sleeve 7;

[0013] The middle parts of the upper movable plate 3 and the lower movable plate 4 are also connected by an outer sleeve 8;

[0014] The outer sleeve 8 can move up and down along the inner sleeve 7;

[0015] The space below the lower movable plate 4 and above the lower fixing plate 2 is a cavity 9;

[0016] The test pile section is arranged between the upper movable plate 3 and the lower movable plate 4;

[0017] The lower end of the displacement wire 11 is fixed on the upper movable plate 3 and passes through the upper fixing plate 1;

[0018] The high-pressure oil pipe (10) leads to the inside of the cylinder barrel 5 and can push the cylinder barrel 5 to move downward.

[0019] A further technical solution of the present utility model is that the piston rod 6 includes a protrusion, and the protrusion fits the inner wall of the cylinder barrel 5.

[0020] A further technical solution of the present utility model is that the side of the cavity 9 is a flexible isolation body 13.

[0021] A further technical solution of the present utility model is that the base pile skin friction test device is arranged at the bottom of the cast-in-place pile 18.

[0022] A further technical solution of the present utility model is that the base pile skin friction test device includes multiple groups, each corresponding to a formation environment.

[0023] A further technical solution of the present utility model is that there are multiple piston rods 6 and corresponding cylinder barrels 5, which are evenly distributed around the central hole 12.

[0024] A further technical solution of the present utility model is that grouting is arranged in the middle of the central hole 12.

[0025] A method for testing the skin friction of a base pile, characterized in that it uses the base pile skin friction test device described in any one of the above, and includes the following steps. To cause relative displacement between the pile and the soil in a certain test pile section of the cast-in-place pile, a pile side skin friction tester needs to be pre-embedded in the test pile section in advance, and there needs to be a cavity below the test pile section. During the test, using the upper pile above the test pile section as the reaction force, under the action of the thrust of the hydraulic cylinder of the pile side skin friction tester, the test pile section is displaced downward, and at the same time, the applied force value and the displacement that occur are measured to determine the ultimate bearing capacity of a single pile for this test pile section. Since the bottom of the test pile section is a cavity, there is no end resistance for the test pile section, and it is a friction pile. Dividing the ultimate bearing capacity of a single pile by the lateral surface area of this section of the pile can obtain the pile side skin friction value of this formation.

[0026] A further technical solution of the utility model is that the device consists of two upper and lower fixed steel plates, namely an upper fixed plate 1 and a lower fixed plate 2, and two middle movable steel plates, namely an upper movable plate 3 and a lower movable plate 4;

[0027] Central holes are opened in the centers of the four steel plates. The central holes are for the concrete to pass through.

[0028] The upper fixed plate is welded to the steel reinforcement cage of the upper pile section, and the lower fixed plate is welded to the steel reinforcement cage of the lower pile section;

[0029] The upper fixed plate 1 and the lower fixed plate 2 are connected by the piston rod 6 of the hydraulic cylinder, so that the upper fixed plate 1, the lower fixed plate 2 and the piston rod 6 are in a relatively fixed state;

[0030] The upper movable plate 3 and the lower movable plate 4 are connected by the cylinder barrel 5 of the hydraulic cylinder, so that the upper movable plate 3, the lower movable plate 4 and the cylinder barrel 5 are in a relatively fixed state;

[0031] When the cylinder barrel 5 and the piston rod 6 move relative to each other under the action of hydraulic pressure, the upper movable plate 3 and the lower movable plate 4 are driven to move;

[0032] The concrete between the upper movable plate 3 and the lower movable plate 4 will move along with the plates, realizing the relative movement of the pile and soil of the test pile section to be mobilized and achieving the test purpose;

[0033] A displacement wire 11 is connected to the upper movable plate 3, and the displacement amount is measured by a displacement meter;

[0034] The thrust generated by the hydraulic cylinder is measured by an oil pressure gauge connected to the hydraulic pump, and then converted into thrust;

[0035] A flexible isolation body 13 is arranged around the outer periphery of the lower movable plate 4 and the lower fixed plate 2 to block the vertical penetration of the surrounding concrete, completely separating the upper and lower pile sections, and at the same time preventing the concrete from entering the cavity 9;

[0036] Inner sleeves 7 are arranged in the central holes of the upper fixed plate 1 and the lower fixed plate 2, and they are relatively fixed to each other;

[0037] Outer sleeves 8 are arranged in the central holes of the upper movable plate 3 and the lower movable plate 4, and they are relatively fixed to each other;

[0038] The outer sleeve 8 can move along with the cylinder barrel 5 of the hydraulic cylinder; that is, the outer sleeve 8 can move relative to the inner sleeve 7;

[0039] The outer diameters of the upper and lower four plates should be slightly smaller than the diameter of the pile hole to facilitate hoisting into the pile hole;

[0040] The flexible isolation body 13 around the cavity 9 should be closely attached to the hole wall to completely separate the upper and lower concrete sections;

[0041] The flexible isolation body 13 can be longitudinally compressed.

[0042] The utility model adopting the above technical solution has the following beneficial effects compared with the prior art: When the test pile section moves downward under the action of the pile side friction resistance tester, the cavity gradually becomes smaller, and the flexible isolation body is gradually compressed. The test pile section and the hole wall formation have relative movement, so that according to the applied force value, displacement and the diameter of the basic pile, the pile side friction resistance value of this section of the formation can be calculated. The test method is simple, without a ground reaction force system such as a counterweight and an anchor pile, reducing the test cost and potential safety hazards. The test result is intuitive, eliminating the complex calculation of the test components; it has high reliability, and the hydraulic cylinder is stable and reliable compared with the electronic test components; the pile side friction resistance of multiple layers of soil can be tested for the same pile; the test pile section can be made to move upward or downward through the oil circuit control, and the upward or downward friction resistance can be measured respectively; the utility model provides a new method for testing the pile side friction resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to further illustrate the present utility model, the following is further described in conjunction with the drawings:

[0044] Figure 1 It is a corresponding setting schematic diagram of the bottom layer for the multi - layer formation pile side friction resistance test method schematic diagram;

[0045] Figure 2 It is a top view schematic diagram of the utility model;

[0046] Figure 3 For Figure 2 A - A cross - section schematic diagram;

[0047] Figure 4 It is an installation diagram of the pile side friction resistance tester;

[0048] Figure 5 It is a further improvement diagram of the pile side friction resistance tester;

[0049] Figure 6 It is a schematic diagram of the basic pile friction resistance test principle;

[0050] Wherein: 1 - upper fixing plate, 2 - lower fixing plate, 3 - upper movable plate, 4 - lower movable plate, 5 - cylinder barrel, 6 - piston rod, 7 - inner sleeve, 8 - outer sleeve, 9 - cavity, 10 - high - pressure oil pipe, 11 - displacement wire, 12 - central hole, 13 - flexible isolation body; 14. formation one; 15. formation two; 16. formation three; 17. formation four; 18. cast - in - place pile; 19. test pile section. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] The present utility model will be further illustrated in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present utility model and not to limit the scope of the present utility model. In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings. These are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present utility model. In addition, unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0052] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0053] This patent provides multiple parallel solutions. For different expressions, they are improvement solutions or parallel solutions based on the basic solution. Each solution has its own unique features. In addition, the technical features involved in different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other. The fixing method not described in the text can be any one of screw fixing, bolt fixing or glue bonding, etc.

[0054] Embodiment 1: In combination with all the accompanying drawings; a pile shaft friction test device, characterized in that

[0055] The test device includes an upper fixing plate 1 and a lower fixing plate 2. The upper fixing plate 1 and the lower fixing plate 2 are connected by a piston rod 6. The piston rod 6 passes through the cylinder barrel 5 inside. Above the cylinder barrel 5 is an upper movable plate 3, and below the cylinder barrel 5 is a lower movable plate 4;

[0056] The middle parts of the upper fixing plate 1 and the lower fixing plate 2 are also connected by the central hole 12. The central hole 12 is cylindrical, and its wall is the inner sleeve 7;

[0057] The middle parts of the upper movable plate 3 and the lower movable plate 4 are also connected by the outer sleeve 8;

[0058] The outer sleeve 8 can move up and down along the inner sleeve 7;

[0059] The space below the lower movable plate 4 and above the lower fixing plate 2 is the cavity 9;

[0060] The test pile section is arranged between the upper movable plate 3 and the lower movable plate 4;

[0061] The lower end of the displacement wire 11 is fixed on the upper movable plate 3 and passes through the upper fixing plate 1;

[0062] The high-pressure oil pipe (10) leads to the inside of the cylinder barrel 5 and can push the cylinder barrel 5 to move downward. The substantial technical effect and its implementation process, that is, the basic function of the technical solution herein are as follows: For the method of testing the skin friction of a foundation pile, it is characterized in that by using the foundation pile skin friction testing device described in any one of the above, the following steps are included. To cause relative displacement between the pile and the soil in a certain test pile section of a cast-in-place pile, a pile side skin friction tester needs to be pre-embedded in the test pile section in advance, and there needs to be a cavity below the test pile section. During the test, taking the upper pile section above the test pile section as the reaction force, under the action of the thrust of the hydraulic cylinder of the pile side skin friction tester, the test pile section moves downward, and at the same time, the applied force value and the displacement that occur are measured, and the ultimate bearing capacity of a single pile of this test pile section is determined. Since the bottom of the test pile section is a cavity, there is no end resistance for the test pile section, which is a friction pile. Dividing the ultimate bearing capacity of a single pile by the lateral surface area of this section of the pile can obtain the pile side skin friction value of this stratum.

[0063] More specifically: There are central holes in the centers of the four steel plates. The central holes are for the concrete to pass through,

[0064] The upper fixing plate is welded to the upper pile reinforcement cage, and the lower fixing plate is welded to the lower pile reinforcement cage;

[0065] The upper fixing plate 1 and the lower fixing plate 2 are connected by the piston rod 6 of the hydraulic cylinder, so that the upper fixing plate 1 and the lower fixing plate 2 and the piston rod 6 are in a relatively fixed state;

[0066] The upper movable plate 3 and the lower movable plate 4 are connected by the cylinder barrel 5 of the hydraulic cylinder, so that the upper movable plate 3 and the lower movable plate 4 and the cylinder barrel 5 are in a relatively fixed state;

[0067] When the cylinder barrel 5 and the piston rod 6 move relative to each other under the action of hydraulic pressure, they drive the upper movable plate 3 and the lower movable plate 4 to move;

[0068] The concrete between the upper movable plate 3 and the lower movable plate 4 will move along with the plates, realizing the relative movement of the pile and soil of the test pile section and achieving the test purpose;

[0069] The upper movable plate 3 is connected to the displacement wire 11, and the displacement is measured by a displacement gauge;

[0070] The thrust generated by the hydraulic cylinder is measured by an oil pressure gauge connected to the hydraulic pump, and then converted into thrust;

[0071] A flexible isolation body 13 is arranged around the periphery of the lower movable plate 4 and the lower fixed plate 2 to block the vertical penetration of the surrounding concrete, completely separating the upper and lower sections of the pile, and also preventing the concrete from entering the cavity 9;

[0072] Inner sleeves 7 are arranged in the central holes of the upper fixed plate 1 and the lower fixed plate 2, and they are relatively fixed to each other;

[0073] Outer sleeves 8 are arranged in the central holes of the upper movable plate 3 and the lower movable plate 4, and they are relatively fixed to each other;

[0074] The outer sleeve 8 can move along with the cylinder barrel 5 of the hydraulic cylinder; that is, the outer sleeve 8 can move relative to the inner sleeve 7;

[0075] The outer diameters of the upper and lower four plates should be slightly smaller than the diameter of the pile hole to facilitate hoisting into the pile hole;

[0076] The flexible isolation body 13 around the cavity 9 should be closely attached to the hole wall to completely separate the upper and lower sections of the concrete;

[0077] The flexible isolation body 13 can be longitudinally compressed.

[0078] Embodiment 2: As a further improvable solution or a parallel solution or an alternative independent solution, the piston rod 6 includes a protrusion, and the protrusion fits the inner wall of the cylinder barrel 5. The substantial technical effect achieved by the technical solution here and its implementation process, that is, the basic function, are as follows: facilitating the downward movement of the cylinder barrel.

[0079] Embodiment 3: As a further improvable solution or a parallel solution or an alternative independent solution, the side of the cavity 9 is a flexible isolation body 13. The substantial technical effect achieved by the technical solution here and its implementation process, that is, the basic function, are as follows: The present invention is a new method for testing the side friction resistance of piles. By applying forces to piles in various strata, the relative displacement of the pile and soil in various strata is mobilized, and then according to the relationship between the force value and the displacement, the side friction resistance of piles in various strata is accurately measured, providing a necessary design basis for the design of foundation piles. To mobilize the relative displacement of the pile and soil of a section of pile in a certain stratum, a side friction resistance tester for piles is used, which is a special test device developed with a set of hydraulic cylinders as the core components. The flexible isolation body 13 can be used as the part to be extruded.

[0080] Embodiment 4: As a further improvable solution, a parallel solution, or an alternative independent solution, the base pile friction resistance testing device is arranged at the bottom of the cast-in-place pile 18. The substantial technical effects and their implementation processes, i.e., the basic functions, achieved by the technical solution herein are as follows: Therefore, there is no resistance at the pile bottom.

[0081] Embodiment 5: As a further improvable solution, a parallel solution, or an alternative independent solution, the base pile friction resistance testing device includes multiple groups, each corresponding to a formation environment. The substantial technical effects and their implementation processes, i.e., the basic functions, achieved by the technical solution herein are as follows: It can measure the pressures of different formations.

[0082] Embodiment 6: As a further improvable solution, a parallel solution, or an alternative independent solution, the piston rod 6 and the corresponding cylinder barrel 5 are multiple and evenly distributed around the central hole 12. The substantial technical effects and their implementation processes, i.e., the basic functions, achieved by the technical solution herein are as follows: The force is better evenly distributed.

[0083] Embodiment 7: As a further improvable solution, a parallel solution, or an alternative independent solution, grouting is arranged in the middle of the central hole 12.

[0084] Embodiment 8: As a further improvable solution, a parallel solution, or an alternative independent solution, the device consists of two upper and lower fixed steel plates, the upper fixed plate 1 and the lower fixed plate 2, and two middle movable steel plates, the upper movable plate 3 and the lower movable plate 4;

[0085] Innovatively, the above various effects exist independently, and the combination of the above results can also be achieved with a set of structures.

[0086] It should be noted that the multiple solutions provided by this patent include their own basic solutions, which are independent of each other and do not restrict each other. However, they can also be combined with each other without conflict to achieve the co - realization of multiple effects.

[0087] The above shows and describes the basic principles, main features, and advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above - mentioned embodiments. What is described in the above - mentioned embodiments and the specification only illustrates the principle of the present utility model. Without departing from the spirit and scope of the present utility model, the present utility model will have various changes and improvements, and these changes and improvements all fall within the scope of the claimed protection.

Claims

1. The base pile friction resistance testing device is characterized in that the testing device includes an upper fixing plate (1) and a lower fixing plate (2). The upper fixing plate (1) and the lower fixing plate (2) are connected by a piston rod (6). The piston rod (6) passes through the cylinder barrel (5) internally. Above the cylinder barrel (5) is an upper movable plate (3), and below the cylinder barrel (5) is a lower movable plate (4); the middle parts of the upper fixing plate (1) and the lower fixing plate (2) are also connected by a central hole (12). The central hole (12) is cylindrical, and its wall is an inner sleeve (7); the middle parts of the upper movable plate (3) and the lower movable plate (4) are also connected by an outer sleeve (8); the outer sleeve (8) can move up and down along the inner sleeve (7); the space below the lower movable plate (4) and above the lower fixing plate (2) is a cavity (9); the test pile section is arranged between the upper movable plate (3) and the lower movable plate (4); the lower end of the displacement wire (11) is fixed on the upper movable plate (3) and passes through the upper fixing plate (1); the high-pressure oil pipe (10) leads to the inside of the cylinder barrel (5) and can push the cylinder barrel (5) to move downward.

2. The pile shaft friction testing device according to claim 1, wherein, the piston rod (6) has a protrusion, and the protrusion fits the inner wall of the cylinder barrel (5).

3. The pile shaft friction testing device according to claim 1, wherein, the side of the cavity (9) is a flexible isolation body (13).

4. The pile foundation skin friction testing device according to claim 1, wherein, the base pile friction resistance testing device is arranged at the bottom of the cast-in-place pile (18).

5. The pile shaft friction testing device according to claim 1, characterized in that, the base pile friction resistance testing device includes multiple groups, corresponding to a formation environment respectively.

6. The pile shaft friction testing device according to claim 1, wherein, the piston rod (6) and the corresponding cylinder barrel (5) are multiple and evenly distributed around the central hole (12).

7. The pile shaft friction testing device according to claim 1, characterized in that, grouting is arranged in the middle of the central hole (12).

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