Mechanism for reducing frictional resistance of test pile

Abstract

The utility model discloses a mechanism for reducing frictional resistance of a test pile, which relates to the technical field of test of foundation pit test piles and comprises an outer sleeve, an inner sleeve, a plastic sealing ring and an extrusion mechanism, the inner diameter of the outer sleeve is larger than the outer diameter of the inner sleeve, and the outer sleeve is coaxially sleeved outside the inner sleeve. An anti-friction ring groove is formed between the inner wall of the outer sleeve and the outer wall of the inner sleeve, and the bottom end of the outer sleeve is higher than the bottom end of the inner sleeve; the plastic sealing ring is coaxially arranged at the bottom end of the outer sleeve and is in a conical funnel shape, so that the arrangement height of an inner ring of the plastic sealing ring is higher than that of an outer ring of the plastic sealing ring, and the inner diameter of the plastic sealing ring is slightly larger than the outer diameter of the inner sleeve; the extrusion mechanism is detachably arranged in the antifriction ring groove and can press the conical face of the plastic sealing ring downwards so that the inner ring of the plastic sealing ring and the outer wall of the inner sleeve can be tightly pressed in a sealed mode. The problem that sealing between an inner cylinder and an outer cylinder of an existing double-sleeve mechanism is not ideal can be solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a foundation pit test pile testing technical field, concretely relates to a mechanism that reduces test pile friction resistance. BACKGROUND

[0002] The bearing capacity requirement of high-rise building to pile foundation is very high, and how to effectively determine the single pile bearing capacity through test is the key of pile foundation design. For such engineering, the single pile bearing capacity can be determined by carrying out single pile static load test in the proposed site. In the test process, whether the bearing capacity and settlement of pile foundation meet the design requirements are detected by applying or unloading load to the test pile, so as to ensure the construction quality.

[0003] But in order to save time and improve the determination efficiency, the construction of test pile is usually carried out before the building foundation pit is excavated or before the excavation reaches the slot bottom elevation; and in actual engineering, engineering pile is pressed or drilled from the excavated foundation pit bottom, and the top of engineering pile is located at the bottom surface of foundation pit, so that there is a soil layer between the top elevation of test pile and the design top elevation of engineering pile, the soil layer has a great influence on the bearing capacity and settlement of test pile, and then the test data of test pile cannot truly reflect the actual bearing capacity and settlement of engineering pile, thereby affecting the adjustment of engineering pile design parameters.

[0004] In order to ensure that the test data of test pile can truly reflect the actual bearing capacity and settlement of engineering pile, the prior art usually adopts double sleeve static load detection method, and under the condition that the pile cannot be driven after excavation, the test pile is usually constructed on the natural ground. In order to reduce the friction between the ground and the soil layer at the bottom of foundation pit, and improve the accuracy of pile foundation detection, the double sleeve structure is used for the natural ground to the bottom of test pile in design. In the loading test, the outer sleeve remains stationary, the inner sleeve and the upper pile jointly transmit force, and the detection is also carried out on the natural ground.

[0005] In order to reduce the hoisting difficulty, the inner and outer sleeves of the double sleeve mechanism generally adopt the process of hoisting the inner and outer sleeves in sequence, and then the waterproof sealing treatment between the inner and outer sleeves is carried out, but in actual use, due to the large depth, the slurry pressure is large, so that the waterproof sealing effect is generally not ideal, and the slurry is easy to enter the gap between the double sleeves, which affects the test result.

[0006] In view of this, the present application is proposed. UTILITY MODEL CONTENTS

[0007] The utility model aims at providing a mechanism that reduces test pile friction resistance, and solves the problem of unsatisfactory sealing between the inner and outer sleeves of the existing double sleeve mechanism.

[0008] The utility model realizes the following technical scheme:

[0009] The application relates to a mechanism for reducing the friction resistance of a test pile, which comprises an outer sleeve and an inner sleeve, the inner diameter of the outer sleeve is larger than the outer diameter of the inner sleeve, the outer sleeve is coaxially sleeved outside the inner sleeve to form a friction-reducing annular groove between the inner wall of the outer sleeve and the outer wall of the inner sleeve, and the setting height of the bottom end of the outer sleeve is higher than the setting height of the bottom end of the inner sleeve; a plastic sealing ring is coaxially arranged at the bottom end of the outer sleeve, the plastic sealing ring is in the shape of a conical funnel, the setting height of the inner ring of the plastic sealing ring is higher than the setting height of the outer ring, and the inner diameter of the plastic sealing ring is slightly larger than the outer diameter of the inner sleeve; and an extrusion mechanism is detachably arranged in the friction-reducing annular groove, the extrusion mechanism can press the conical surface of the plastic sealing ring downwards so that the inner ring of the plastic sealing ring is tightly pressed against the outer wall of the inner sleeve.

[0010] In another preferred embodiment, the outer ring of the plastic sealing ring extends horizontally outward to form a connecting ring edge, the width of the connecting ring edge matches the width of the bottom end of the outer sleeve, the connecting ring edge is coaxially attached to the bottom end surface of the outer sleeve, and the connecting ring edge is fixedly connected through a plurality of bolts; a rubber ring is arranged on the top surface of the plastic sealing ring, the outer edge of the rubber ring is clamped between the outer sleeve and the plastic sealing ring, and the inner diameter of the rubber ring is smaller than the outer diameter of the inner sleeve.

[0011] In another preferred embodiment, the extrusion mechanism comprises an extrusion ring and a counterweight assembly; the outer diameter of the extrusion ring is slightly smaller than the inner diameter of the outer sleeve, the inner diameter of the extrusion ring is slightly larger than the outer diameter of the inner sleeve, the extrusion ring is coaxially and detachably sleeved in the friction-reducing annular groove, the bottom surface of the extrusion ring is in the shape of a conical surface, and the taper of the conical surface is slightly smaller than the taper of the conical surface of the plastic sealing ring; and the counterweight assembly is detachably arranged in the friction-reducing annular groove, the counterweight assembly is in contact with and extrudes the top of the extrusion ring.

[0012] In another preferred embodiment, the counterweight assembly comprises a plurality of positioning rods, a plurality of buffer cylinders and a plurality of counterweight rings; the positioning rods are vertically arranged, the bottom ends of the positioning rods are fixedly connected with the extrusion ring; the buffer cylinders and the counterweight rings are sleeved on the positioning rods, and each of the counterweight rings is below a buffer cylinder.

[0013] In another preferred embodiment, the outer diameter of the counterweight ring is slightly smaller than the inner diameter of the outer sleeve, the inner diameter of the counterweight ring is slightly larger than the outer diameter of the inner sleeve, a plurality of through holes are formed in the counterweight ring along the thickness direction, and the width of the through holes is slightly larger than the diameter of the positioning rods; the size of the bottom surface of the counterweight ring is smaller than the size of the top surface, so that the side wall of the counterweight ring is in the shape of a smooth transition slope or arc surface.

[0014] In another preferred embodiment, the extrusion mechanism further comprises a plurality of pressing cylinders and a pressing cover; all the positioning rods are arranged in a ring shape and uniformly spaced, and the positioning rods are located at the middle ring line of the antifriction ring groove; the upper part of the positioning rod is provided with external threads, the number of the pressing cylinders is the same as the number of the positioning rods and one-to-one corresponding, the pressing cylinder is coaxially screwed on the upper part of the corresponding positioning rod, so that the setting height of the top end of the pressing cylinder is slightly higher than the setting height of the top end of the outer sleeve, the outer diameter of the pressing cylinder matches the groove width of the antifriction ring groove; the pressing cover is a ring-shaped cover, the pressing cover is coaxially arranged at the top end of the outer sleeve and fixedly connected with the outer sleeve and / or the inner sleeve through a plurality of bolts, so that the bottom surface of the pressing cover contacts and presses the pressing cylinder; the positioning rod penetrates through the pressing cover and is screwed with a fastening nut.

[0015] In another preferred embodiment, the pressing cylinder and the uppermost counterweight ring are clamped with an elastic cylinder, and the elastic cylinder is coaxially sleeved on the positioning rod.

[0016] In another preferred embodiment, the bottom of the pressing cylinder is provided in a circular truncated cone shape; the top end of the pressing cylinder is provided with an external tooth groove and / or an internal tooth groove.

[0017] In another preferred embodiment, the outer ring of the pressing cover extends downward to form a cover cylinder, and the inner diameter of the cover cylinder matches the outer diameter of the outer sleeve.

[0018] In another preferred embodiment, a plurality of fixing plates are pre-embedded in the outer sleeve and / or the inner sleeve, respectively, the fixing plates are provided with a plurality of screw holes, the screw holes are throughly arranged and screwed with bolts; the fixing plates are horizontally arranged or vertically arranged; the pressing cover is provided with a plurality of fixing holes corresponding to the screw holes.

[0019] The utility model discloses the technical scheme, compared with the prior art, has the positive effect:

[0020] The utility model discloses a kind of mechanism for reducing test pile frictional resistance, by setting outer sleeve and inner sleeve, and reserved antifriction ring groove between both, build double-sleeve mechanism to reduce the lateral frictional resistance of test pile;On this basis, by setting plastic sealing ring, set it as gradually increasing conical funnel shape along radial direction inward, and set its inner diameter slightly greater than the outer diameter of inner sleeve, on the one hand, facilitate hoisting into inner sleeve and outer sleeve in succession, second aspect utilizes plastic sealing ring to preliminarily form sealing structure;On this basis, by setting extrusion mechanism, set it can be detached in antifriction ring groove, when inner sleeve and outer sleeve are hoisted into in succession, hoist into extrusion mechanism again, utilize the conical surface of extrusion mechanism to press plastic sealing ring, to force it to occur plastic deformation, so that its inner ring gradually close and extrude the outer wall of inner sleeve, to seal the bottom of antifriction ring groove;When slurry pouring is completed and solidifies, remove extrusion mechanism, and hoist inner sleeve (and test pile) up and down, can be sealed by friction compression plastic sealing ring, so that its inner ring is expanded, to form double-sleeve test mechanism with lateral friction force small enough under the premise that antifriction ring groove is not entered slurry;By the mutual cooperation of above-mentioned each feature, the mechanism for reducing test pile frictional resistance can effectively solve the problem that sealing between inner and outer cylinder of existing double-sleeve mechanism is not ideal. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application. In the drawings:

[0022] Figure 1 It is a side view schematic diagram of the mechanism for reducing test pile frictional resistance provided by the utility model embodiment;

[0023] Figure 2 It is a top view schematic diagram after removing gland of the mechanism for reducing test pile frictional resistance provided by the utility model embodiment;

[0024] Figure 3 It is Figure 1 The local enlarged view of A of the mechanism for reducing test pile frictional resistance provided by the utility model embodiment;

[0025] Figure 4 It is Figure 1 The local enlarged view of B of the mechanism for reducing test pile frictional resistance provided by the utility model embodiment;

[0026] Figure 5 It is a side view schematic diagram after removing extrusion mechanism of the mechanism for reducing test pile frictional resistance provided by the utility model embodiment.

[0027] Mark and corresponding component name in drawing:

[0028] 10 - outer sleeve; 11 - fixing plate; 20 - inner sleeve; 30 - plastic sealing ring; 31 - connecting ring; 32 - rubber ring; 40 - extrusion ring; 41 - positioning rod; 42 - buffer cylinder; 43 - counterweight ring; 44 - pressing cylinder; 45 - gland; 451 - cover cylinder; 46 - elastic cylinder. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0030] In the description of the present application, it should be understood that the orientation or position relationship indicated by the terms "up", "down", "left", "right", "inner", "outer", "front", "back", "horizontal", "vertical" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application, and does not indicate or imply that the device or element referred to must have a particular orientation, therefore it cannot be understood as a limitation on the present application.

[0031] It should be particularly pointed out that "horizontal" and "vertical" in the present application are used to illustrate the approximate position relationship, and not a strict "horizontal plane" or "vertical plane". EMBODIMENT

[0032] Please refer to Figures 1 to 5 It is provided that the present embodiment reduces the friction resistance of the test pile, which comprises an outer sleeve 10 and an inner sleeve 20, the inner diameter of the outer sleeve 10 is greater than the outer diameter of the inner sleeve 20, the outer sleeve 10 is coaxially sleeved on the outer sleeve 20 to form a friction-reducing groove between the inner wall of the outer sleeve 10 and the outer wall of the inner sleeve 20, and the setting height of the bottom end of the outer sleeve 10 is higher than that of the inner sleeve 20; secondly, a plastic sealing ring 30 is provided, which is coaxially arranged at the bottom end of the outer sleeve 10, and the plastic sealing ring 30 is provided in the shape of a conical funnel, so that the setting height of the inner ring of the plastic sealing ring 30 is higher than that of the outer ring, and the inner diameter of the plastic sealing ring 30 is slightly larger than the outer diameter of the inner sleeve 20; thirdly, an extrusion mechanism is provided, which is detachably arranged in the friction-reducing groove, and the extrusion mechanism can press the conical surface of the plastic sealing ring 30, so that the inner ring of the plastic sealing ring 30 is tightly sealed and pressed against the outer wall of the inner sleeve 20.

[0033] The mechanism for reducing the friction resistance of the test pile disclosed in the embodiment is characterized in that: the outer sleeve 10 and the inner sleeve 20 are arranged, and the friction-reducing ring groove is reserved between the outer sleeve 10 and the inner sleeve 20, and the double-sleeve mechanism is built to reduce the lateral friction resistance of the test pile; on this basis, the plastic sealing ring 30 is arranged, which is in the shape of a conical funnel gradually increasing in the radial direction, and the inner diameter of the plastic sealing ring 30 is slightly larger than the outer diameter of the inner sleeve 20, so that the inner sleeve 20 and the outer sleeve 10 can be hoisted into the double-sleeve mechanism in sequence, and the plastic sealing ring 30 is used to preliminarily form a sealing structure; on this basis, the extrusion mechanism is arranged, which is detachably arranged in the friction-reducing ring groove, and after the inner sleeve 20 and the outer sleeve 10 are hoisted into the double-sleeve mechanism in sequence, the extrusion mechanism is hoisted into the double-sleeve mechanism, the conical surface of the plastic sealing ring 30 is pressed by the extrusion mechanism, so that the plastic sealing ring 30 is forced to plastically deform, the inner ring of the plastic sealing ring 30 is gradually close to and extrudes the outer wall of the inner sleeve 20, and the bottom of the friction-reducing ring groove is sealed; after the grout is poured and solidified, the extrusion mechanism is removed, and the inner sleeve 20 (and the test pile) is hoisted up and down, so that the inner ring of the plastic sealing ring 30 is expanded by the friction and extrusion, and the double-sleeve test mechanism with small lateral friction is formed on the premise that the grout does not enter the friction-reducing ring groove; through the cooperation of the above-mentioned features, the mechanism for reducing the friction resistance of the test pile can effectively solve the problem of the unsatisfactory sealing between the inner sleeve and the outer sleeve of the existing double-sleeve mechanism.

[0034] In order to further explain the connection structure of the plastic sealing ring 30 and the outer sleeve 10, the outer ring of the plastic sealing ring 30 extends outwardly and horizontally to form a connecting ring 31, the width of the connecting ring 31 matches the width of the bottom end of the outer sleeve 10, the connecting ring 31 is coaxially attached to the bottom end surface of the outer sleeve 10, and is fixedly connected by a plurality of bolts; the top surface of the plastic sealing ring 30 is paved with a rubber ring 32, the outer edge of the rubber ring 32 is clamped between the outer sleeve 10 and the plastic sealing ring 30, and the inner diameter of the rubber ring 32 is smaller than the outer diameter of the inner sleeve 20.

[0035] By arranging the connecting ring 31, the contact area between the plastic sealing ring 30 and the bottom end surface of the outer sleeve 10 is increased, so that the connection performance between the two is improved; by arranging the rubber ring 32, the sealing performance between the plastic sealing ring 30 and the outer wall of the inner sleeve 20 is further improved.

[0036] In order to further explain the extrusion mechanism, the extrusion mechanism includes an extrusion ring 40 and a counterweight assembly; the outer diameter of the extrusion ring 40 is slightly smaller than the inner diameter of the outer sleeve 10, the inner diameter of the extrusion ring 40 is slightly larger than the outer diameter of the inner sleeve 20, the extrusion ring 40 is coaxially and detachably arranged in the friction-reducing ring groove, the bottom surface of the extrusion ring 40 is arranged in the shape of a conical surface, and the taper of the conical surface is slightly smaller than the taper of the conical surface of the plastic sealing ring 30; the counterweight assembly is detachably arranged in the friction-reducing ring groove, and the counterweight assembly is in contact with and extrudes the top of the extrusion ring 40.

[0037] Through the above setting, the plastic sealing ring 30 is pressed down by the weight of the extrusion ring 40, and the extrusion and plastic deformation are controlled by the difference between the two tapers; by setting the counterweight assembly, the weight of the extrusion ring 40 is further increased, ensuring that the plastic sealing ring 30 has sufficient plastic deformation, thereby ensuring the sealing performance.

[0038] In order to further explain the specific structure of the counterweight assembly, the counterweight assembly includes a plurality of positioning rods 41, a plurality of buffer barrels 42, and a plurality of counterweight rings 43; the positioning rods 41 are vertically arranged, and the bottom ends of the positioning rods 41 are fixedly connected with the extrusion ring 40; the buffer barrels 42 and the counterweight rings 43 are sleeved on the positioning rods 41, and each of the counterweight rings 43 is provided below with a buffer barrel 42.

[0039] By setting a plurality of counterweight rings 43 to provide sufficient weight, and by setting a plurality of buffer barrels 42 and positioning rods 41, the positioning rods 41 are used for positioning, and the buffer barrels 42 are used for buffering the impact during the lowering of the counterweight rings 43.

[0040] In order to further improve the concentricity between the outer sleeve 10 and the inner sleeve 20 before pouring, the outer diameter of the counterweight ring 43 is slightly smaller than the inner diameter of the outer sleeve 10, the inner diameter of the counterweight ring 43 is slightly larger than the outer diameter of the inner sleeve 20, the counterweight ring 43 is provided with a plurality of through holes in the thickness direction, and the width of the through holes is slightly larger than the diameter of the positioning rod 41; the size of the bottom surface of the counterweight ring 43 is smaller than the size of the top surface, so that the side wall of the counterweight ring 43 is a smooth transition slope or arc surface.

[0041] In order to further improve the extrusion performance and concentricity, the extrusion mechanism further includes a plurality of pressing barrels 44 and a pressing cover 45; all the positioning rods 41 are arranged in a ring shape and uniformly spaced, and the positioning rods 41 are located at the middle ring line of the antifriction ring groove; the upper part of the positioning rod 41 is provided with external threads, the number of the pressing barrels 44 is the same as and corresponds to the number of the positioning rods 41, the pressing barrels 44 are coaxially screwed on the upper part of the corresponding positioning rods 41, so that the setting height of the top end of the pressing barrel 44 is slightly higher than the setting height of the top end of the outer sleeve 10, and the outer diameter of the pressing barrel 44 matches the groove width of the antifriction ring groove; the pressing cover 45 is a ring-shaped cover, which is coaxially covered on the top end of the outer sleeve 10 and is fixedly connected with the outer sleeve 10 and / or the inner sleeve 20 through a plurality of bolts, so that the bottom surface of the pressing cover 45 contacts and presses down the pressing barrel 44; the positioning rod 41 penetrates through the pressing cover 45 and is screwed with a fastening nut.

[0042] Through the above setting, the positioning outer sleeve 10 and the inner sleeve 20 are respectively extruded by the pressing cylinder 44, the positioning rod 41 is indirectly pressed down by the way that the pressing cylinder 44 is pressed down by the pressing cap 45, the extrusion ring 40 is indirectly pressed down, and the top end of the antifriction ring groove is closed by the setting of the pressing cap 45, so that the slurry is prevented from penetrating into the antifriction ring groove from the top during the pouring process.

[0043] In order to avoid overpressure of the pressing cylinder 44 on the buffer cylinder 42, the elastic cylinder 46 is arranged between the pressing cylinder 44 and the uppermost counterweight ring 43, and the elastic cylinder 46 is coaxially sleeved on the positioning rod 41.

[0044] In order to facilitate the setting of the pressing cylinder 44, the bottom of the pressing cylinder 44 is provided in a circular truncated cone shape, and the top end of the pressing cylinder 44 is provided with an outer tooth groove and / or an inner tooth groove.

[0045] The bottom end of the pressing cylinder 44 is provided in a circular truncated cone shape, so that it is convenient to extrude into the antifriction ring groove during the screwing process, and the outer tooth groove or the inner tooth groove is provided, so that it is convenient to cooperate with the screwing tool (such as a wrench) and facilitate screwing force.

[0046] In order to further improve the connection performance of the pressing cap 45 and the outer sleeve 10, thereby improving the pressing effect, the outer ring of the pressing cap 45 is extended downward to form a cap cylinder 451, and the inner diameter of the cap cylinder 451 matches the outer diameter of the outer sleeve 10.

[0047] In order to further improve the fixing effect of the bolt when fixing the pressing cap 45, a plurality of fixing plates 11 are respectively embedded in the outer sleeve 10 and / or the inner sleeve 20, the fixing plate 11 is provided with a plurality of screw holes, the screw holes are throughly arranged and are threadedly connected with bolts, the fixing plate 11 is horizontally arranged or vertically arranged, and the pressing cap 45 is provided with a plurality of fixing holes corresponding to the screw holes.

[0048] The above only describes the preferred embodiments of the present application, and does not limit the implementation and protection scope of the present application. For those skilled in the art, it should be realized that any equivalent replacement and obvious changes made according to the content of the present application can be included in the protection scope of the present application.

Claims

1. A mechanism for reducing the frictional resistance of a test pile, characterized by, The application relates to a sealing device for a bearing, which comprises the following parts: an outer sleeve (10) and an inner sleeve (20), the inner diameter of the outer sleeve (10) is larger than the outer diameter of the inner sleeve (20), the outer sleeve (10) is coaxially sleeved on the outer sleeve (20) to form a friction-reducing annular groove between the inner wall of the outer sleeve (10) and the outer wall of the inner sleeve (20), and the setting height of the bottom end of the outer sleeve (10) is higher than the setting height of the bottom end of the inner sleeve (20); a plastic sealing ring (30) which is coaxially arranged at the bottom end of the outer sleeve (10), the plastic sealing ring (30) is arranged in a conical funnel shape, the setting height of the inner ring of the plastic sealing ring (30) is higher than the setting height of the outer ring, and the inner diameter of the plastic sealing ring (30) is slightly larger than the outer diameter of the inner sleeve (20); a pressing mechanism which is detachably arranged in the friction-reducing annular groove, the pressing mechanism can press the conical surface of the plastic sealing ring (30) to tightly seal the inner ring of the plastic sealing ring (30) and the outer wall of the inner sleeve (20).

2. The mechanism for reducing frictional resistance of a test pile according to claim 1, characterized by, The outer ring of the plastic sealing ring (30) extends outwardly and horizontally to form a connecting ring (31), the width of the connecting ring (31) matches the width of the bottom end of the outer sleeve (10), the connecting ring (31) is coaxially arranged on the bottom end surface of the outer sleeve (10) and is fixedly connected through a plurality of bolts; a rubber ring (32) is arranged on the top surface of the plastic sealing ring (30), the outer edge of the rubber ring (32) is clamped between the outer sleeve (10) and the plastic sealing ring (30), and the inner diameter of the rubber ring (32) is smaller than the outer diameter of the inner sleeve (20).

3. The mechanism for reducing frictional resistance of a test pile according to claim 2, characterized by, The pressing mechanism comprises a pressing ring (40) and a counterweight assembly. The outer diameter of the pressing ring (40) is slightly smaller than the inner diameter of the outer sleeve (10), the inner diameter of the pressing ring (40) is slightly larger than the outer diameter of the inner sleeve (20), the pressing ring (40) is coaxially and detachably sleeved in the friction-reducing annular groove, the bottom surface of the pressing ring (40) is arranged in a conical surface, and the taper of the conical surface is slightly smaller than the taper of the conical surface of the plastic sealing ring (30). The counterweight assembly is detachably arranged in the friction-reducing annular groove, the counterweight assembly is in contact with and presses the top of the pressing ring (40).

4. The mechanism for reducing frictional resistance of a test pile according to claim 3, characterized by, The counterweight assembly comprises a plurality of positioning rods (41), a plurality of buffer cylinders (42) and a plurality of counterweight rings (43). The positioning rods (41) are vertically arranged, the bottom ends of the positioning rods (41) are fixedly connected with the pressing ring (40). The buffer cylinders (42) and the counterweight rings (43) are sleeved on the positioning rods (41), and each of the counterweight rings (43) is below a buffer cylinder (42).

5. The mechanism for reducing frictional resistance of a test pile according to claim 4, characterized by, The outer diameter of the counterweight ring (43) is slightly smaller than the inner diameter of the outer sleeve (10), the inner diameter of the counterweight ring (43) is slightly larger than the outer diameter of the inner sleeve (20), a plurality of through holes are formed in the counterweight ring (43) along the thickness direction, and the width of the through holes is slightly larger than the diameter of the positioning rods (41). The bottom surface of the counterweight ring (43) is smaller than the top surface, so that the sidewall of the counterweight ring (43) is a smooth transition slope or arc.

6. The mechanism for reducing frictional resistance of a test pile according to claim 5, wherein The pressing mechanism further comprises a plurality of pressing cylinders (44) and a pressing cover (45); All the positioning rods (41) are arranged in a ring shape and uniformly spaced, and the positioning rods (41) are located at the middle ring line of the antifriction ring groove; The upper part of the positioning rod (41) is externally threaded, the number of the pressing cylinders (44) is the same as the number of the positioning rods (41) and one-to-one corresponding, the pressing cylinder (44) is coaxially screwed on the upper part of the corresponding positioning rod (41), so that the top end of the pressing cylinder (44) is slightly higher than the top end of the outer sleeve (10) in height, and the outer diameter of the pressing cylinder (44) matches the groove width of the antifriction ring groove; The pressing cover (45) is a ring-shaped cover, which is coaxially arranged on the top end of the outer sleeve (10) and fixedly connected with the outer sleeve (10) and / or the inner sleeve (20) through a plurality of bolts, so that the bottom surface of the pressing cover (45) contacts and presses the pressing cylinder (44); The positioning rod (41) penetrates the pressing cover (45) and is screwed with a fastening nut.

7. A mechanism for reducing frictional resistance of a test pile according to claim 6, characterized in that, An elastic cylinder (46) is clamped between the pressing cylinder (44) and the uppermost counterweight ring (43), and the elastic cylinder (46) is coaxially sleeved on the positioning rod (41).

8. A mechanism for reducing frictional resistance of a test pile according to claim 7, characterized by The bottom of the pressing cylinder (44) is provided in a circular truncated cone shape. The top end of the pressing cylinder (44) is provided with an external tooth groove and / or an internal tooth groove.

9. The mechanism for reducing frictional resistance of a test pile according to claim 6, characterized by, The outer ring of the pressing cover (45) extends downward to form a cover cylinder (451), and the inner diameter of the cover cylinder (451) matches the outer diameter of the outer sleeve (10).

10. The mechanism for reducing frictional resistance of a test pile according to claim 9, characterized by, A plurality of fixing plates (11) are pre-embedded in the outer sleeve (10) and / or the inner sleeve (20), respectively, and the fixing plate (11) is provided with a plurality of screw holes which are throughly arranged and screwed with bolts; The fixing plate (11) is horizontally arranged or vertically arranged; The pressing cover (45) is provided with a plurality of fixing holes corresponding to the screw holes.

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