Device for eliminating the influence of dowel bar weight on the accuracy of spiral plate load test

Abstract

The present invention is a device for eliminating the influence of the weight of the force transfer rod on the accuracy of the spiral plate load test. The present invention balances the friction force with the gravity generated by the weight of the hollow force transfer rod and the hollow force transfer shaft through the adjustable friction force of the friction tube, hinders the downward movement of the hollow force transfer rod and the hollow force transfer shaft, eliminates the load on the spiral pressure plate generated by the weight of the hollow force transfer rod connection combination and the hollow force transfer shaft, and thus significantly improves the accuracy of the spiral plate load test.

Description

Technical Field

[0001] The invention belongs to a spiral plate load test device, in particular to a device for eliminating the influence of the weight of a force transmission rod on the accuracy of the spiral plate load test. Background Art

[0002] Patent No. CN201610061487.3 "Method for eliminating the influence of force transfer rod bending on the accuracy of spiral plate load test and its displacement detector" discloses a spiral plate load test method, which discloses the following structure, including a reaction frame, a hydraulic jack, a hollow force transfer rod connection combination, a sleeve connection combination, a load pressure detector and a linear capacitive grating displacement sensor, the capacitive grating displacement sensor housing composed of a sleeve joint, a transmission joint and a head threaded connection, a hollow force transfer shaft splined with the transmission joint and a compression spring for absorbing vibration and impact energy, a load pressure detector and a spiral pressure plate connected to the hollow force transfer shaft in sequence, a reference beam at the test hole opening, a sleeve chuck fixed to the reference beam, a load pressure detector and a linear capacitive grating displacement sensor signal cable led out from the hollow force transfer rod, and a measurement data recorder connected to the signal cable.

[0003] The above method sets the linear capacitive grid displacement detector for detecting the sinking displacement of the spiral pressure plate underground, i.e. at the bottom of the hollow force transfer rod connection combination, thereby completely eliminating the problem that the bending of the force transfer rod affects the accuracy of the spiral plate load test.

[0004] Before using the aforementioned spiral plate load test equipment, the load pressure displayed on the measurement data recorder is first "cleared to zero". It is generally believed that the load pressure displayed at this time is the pressure value generated by the rotation and penetration of the spiral pressure plate. Research has found that the weight of the hollow force transfer rod connection combination and the hollow force transfer shaft has a certain load on the spiral pressure plate. According to this load, the pressure applied to the spiral pressure plate can be converted. This pressure will inevitably cause the foundation soil to sink. Therefore, the load pressure displayed on the measurement data recorder is "cleared to zero" before the operation, ignoring the load component of the weight of the hollow force transfer rod connection combination and the hollow force transfer shaft, which will inevitably affect the accuracy of the spiral plate load test. Summary of the invention

[0005] The invention discloses a device for eliminating the influence of the weight of a force transmission rod on the accuracy of a spiral plate load test in order to improve the accuracy of the spiral plate load test.

[0006] The present invention adopts the following technical scheme to achieve the above-mentioned purpose: a device to eliminate the influence of the weight of the force transmission rod on the accuracy of the spiral plate load test, comprising a reaction frame, a hydraulic jack, a hollow force transmission rod connection assembly, a sleeve connection assembly, a load pressure detector and a linear capacitive grid displacement sensor, a sleeve joint, a transmission joint and a head threaded connection to form the linear capacitive grid displacement sensor housing, a hollow force transmission shaft spline-connected to the transmission joint and a compression spring for absorbing vibration and impact energy, a load pressure detector and a spiral pressure plate connected to the hollow force transmission shaft in sequence, a reference beam of the test hole position orifice, and a sleeve chuck fixed to the reference beam. The signal cable of the load pressure detector and the signal cable of the linear capacitive displacement sensor led out from the hollow force transfer rod, and the measurement data recorder connected to the signal cables are characterized in that the sleeve fastened to the sleeve chuck has two half-tiles with convex edges and butted together in its port, the convex edges of the two half-tiles are supported on the end edges of the sleeve, and the butted half-tiles support a friction tube whose inner wall is engaged with the hollow force transfer rod, the friction tube is provided with an axial through groove that can make it elastically deformable, and the friction tube is provided with a clamp for adjusting the friction force between it and the hollow force transfer rod, and the friction force is balanced with the gravity generated by the weight of the hollow force transfer rod and the hollow force transfer shaft.

[0007] The present invention can also adopt the following technical measures: the friction tube is a friction tube made of nylon.

[0008] The beneficial effects and advantages of the present invention are as follows: the present invention balances the friction force with the gravity generated by the weight of the hollow force transfer rod and the hollow force transfer shaft through the adjustable friction force of the friction tube, hinders the downward movement of the hollow force transfer rod and the hollow force transfer shaft, eliminates the load on the spiral pressure plate caused by the weight of the hollow force transfer rod connection combination and the hollow force transfer shaft, thereby significantly improving the accuracy of the spiral plate load test. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Attached Figure 1 It is a schematic diagram of the structure of an embodiment of the device.

[0010] Attached Figure 2 yes Figure 1 AA section enlarged view.

[0011] Attached Figure 3 yes Figure 1 A magnified schematic diagram of the cross-section of the relationship between the middle casing and the half-tile structure.

[0012] Attached Figure 4 yes Figure 1 Schematic diagram of the enlarged cross-section of the hollow force transmission shaft and related components.

[0013] Markings in the figure: 1 reaction frame, 2 hydraulic jack, 3 hollow force transfer rod connection combination, 4 friction tube, 4-1: axial through groove, 5 clamp, 6 half tile, 6-1 convex edge, 7 casing chuck, 8 reference beam, 9 casing connection combination, 10 casing joint, 11 transmission joint, 12 head, 13 hollow force transfer shaft, 14 load pressure detector, 15 spiral pressure plate, 16 signal cable, 17 wire flange, 18 linear capacitive displacement sensor, 19 compression spring. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with the embodiments and the accompanying drawings.

[0015] like Figure 1 , 4 As shown, the present invention is an improvement on the structure of "Method for eliminating the influence of force transfer rod bending on the accuracy of spiral plate load test and displacement detector thereof" of patent number CN201610061487.3, and the disclosed structure includes a reaction frame 1, a hydraulic jack 2, a hollow force transfer rod connection assembly 3, a sleeve connection assembly 9, a load pressure detector 14 and a linear capacitive grating displacement sensor 18, a sleeve joint 10, a transmission joint 11 and a head 12 threadedly connected to form the linear capacitive grating displacement sensor housing, a hollow force transfer shaft 13 spline-connected to the transmission joint 11 and a compression spring 19 acting on the hollow force transfer shaft for absorbing vibration and impact energy, and a load pressure detector 14 and a spiral pressure plate 15 connected to the hollow force transfer shaft 13 in sequence.

[0016] It also includes a reference beam 8 at the test hole opening, a sleeve chuck 7 fixed to the reference beam, a load pressure detector and a signal cable 16 of a linear capacitive displacement sensor led out from a through-line flange 17 at the upper end of a hollow force transmission rod, and connected to a ground measurement data recorder (not shown).

[0017] Figure 1 In the figure, the rotating pressurizing device for the casing connection assembly 9 is a drilling rig, and the loading device for the hollow dowel rod connection assembly 3 is a hydraulic jack 2.

[0018] like Figure 1 , 2 As shown in 3, the sleeve fastened to the sleeve chuck 7 has two half-tiles 6 with convex edges 6-1 and butted against each other at its end. The convex edges of the two half-tiles are supported on the end edges of the sleeve, and the butted half-tiles support a friction tube 4 whose inner wall is engaged with the hollow force transfer rod. The friction tube is provided with an axial through groove 4-1 that can make it elastically deformable, and the friction tube 4 is provided with a clamp 5 for adjusting the friction force between it and the hollow force transfer rod. The friction force is adjusted to balance the gravity generated by the hollow force transfer rod and the weight of the hollow force transfer shaft.

[0019] The friction tube 4 of the embodiment is a friction tube made of nylon.

[0020] The following combination Figure 1 , 4 The operation and adjustment steps of the present invention are described:

[0021] 1. Drill holes at the set hole position using a drilling rig and stop drilling at a depth of 1 meter from the test hole;

[0022] 2. The lower end of the hollow force transmission shaft 13 is connected to the load pressure detector 14 and the spiral pressure plate 15 in sequence, the hollow force transmission rod is connected to the upper end of the hollow force transmission shaft 13, and the signal cable 16 is led out from the wire flange 17 at the upper end of the hollow force transmission rod;

[0023] 3. A casing is set on the outside of the hollow force transmission rod, the casing is connected to the casing joint 10, and the upper end of the casing is connected to the drilling rig;

[0024] 4. Start the drilling rig and rotate the casing into the test hole. The amount of casing penetration per rotation is equal to the pitch of the spiral pressure plate 15. Then, add hollow dowel rods and casings section by section to form a hollow dowel rod connection assembly 3 and a casing connection assembly 9, respectively, and lead the signal cable 16 out from each added hollow dowel rod;

[0025] 5. When the spiral pressure plate 15 reaches the set depth, the drilling is stopped, the drilling rig is removed, a reference beam 8 with a casing chuck 7 supported on the ground and fixed by a ground anchor is set, the casing chuck 7 fastens the second section of the casing, the first section of the casing is removed, and a reaction frame 1 corresponding to the hollow force transmission rod connection combination is set;

[0026] 6. Place two half-shells 6 at the upper end of the second casing, butt the two half-shells together and make their convex edges supported on the end edge of the casing, and set a friction tube 4 and a clamp 5 whose inner wall is engaged with the hollow dowel rod on the butt-jointed two half-shells, and tighten the clamp to prevent the hollow dowel rod from falling;

[0027] 7.: Connect the signal cable 16 to the measurement data recorder, install the probe rod puller, loosen the clamp, and while observing the pressure reading, lift the hollow dowel rod through the probe rod puller to make the pressure reading of the measurement data recorder 'zero', adjust the clamp in the tightening direction to increase the friction force of the friction tube 4, and keep the pressure reading at 'zero'. At this time, the friction force of the friction tube 4 is balanced with the gravity generated by the weight of the hollow dowel rod and the hollow dowel shaft, and the lifting distance of the hollow dowel rod is very small. The compression spring 19 mounted on the hollow dowel shaft 13 facilitates the adjustment of the pressure reading to 'zero';

[0028] 8. Through the hydraulic jack 2 between the reaction frame 1 and the hollow dowel rod connection assembly 3, the hollow dowel rod is loaded in stages according to the specifications of the relative stability of settlement method or the equal settlement rate method until the test is completed.

[0029] The following examples illustrate the application effects of the present invention:

[0030] In the 10m and 12m deep spiral plate load test of a subway project in Tianjin, the following verification tests were carried out:

[0031] 1. 10-meter depth test without friction tube: Before the test, connect the signal line of the probe assembly to the data recorder on the ground and reset the load reading of the data recorder to zero. When the spiral pressure plate reaches a depth of 10 meters, fix the casing with the casing chuck and connect the signal cable to the data recorder. At this time, the recorded reading is 84.7kPa.

[0032] 12m depth test without friction tube: Before the test, connect the signal line of the probe assembly to the data recorder on the ground and reset the load reading of the data recorder to zero. When the spiral pressure plate reaches a depth of 12m, fix the casing with the casing chuck and connect the signal cable to the data recorder. The recorded reading is 99.6kPa.

[0033] Analysis: The readings recorded during the test are 84.7kPa and 99.6kPa, which are the deadweights of the hollow dowel rods and hollow dowel shafts at 10m and 12m depths, respectively. The readings increase with the depth of the test, indicating that the increase in the number of hollow dowel rods increases the readings. It also indicates that the deadweight of the hollow dowel rods and hollow dowel shafts has exerted pressure on the test soil, causing the soil to be compressed to a certain extent before the test began. The soil is in a non-in-situ stress state, and the test results cannot reflect the actual situation of the in-situ soil.

[0034] 2. 10-meter-deep test using friction tube: When the spiral pressure plate reaches a depth of 10 meters, fix the casing with a casing chuck, install the two half tiles, install the friction tube and clamp close to the upper part of the two half tiles, connect the signal cable to the measurement data recorder, install the probe puller, loosen the clamp, and while observing the pressure reading, lift the hollow force rod through the probe puller to make the pressure reading of the measurement data recorder zero, adjust the clamp in the tightening direction to increase the friction of the friction tube, and after the recorder reading is kept at 0kPa, the spiral plate load test can be carried out.

[0035] Analysis: After using the friction tube, the friction force between the friction tube and the hollow dowel rod is adjusted before the test starts so that the friction force offsets the deadweight of the hollow dowel rod and the hollow dowel shaft. When the test depth is reached, the deadweight of the hollow dowel rod will not produce pressure on the soil, so that the soil is in an in-situ stress state, ensuring the accuracy of the spiral plate load test results.

Claims

1. A device for eliminating the influence of the weight of the force transmission rod on the accuracy of the spiral plate load test, comprising a reaction frame, a hydraulic jack, a hollow force transmission rod connection assembly, a sleeve connection assembly, a load pressure detector and a linear capacitive grating displacement sensor, a housing of the linear capacitive grating displacement sensor formed by a sleeve joint, a transmission joint and a head threaded connection, a hollow force transmission shaft spline-connected to the transmission joint and a compression spring for absorbing vibration and impact energy, a load pressure detector and a spiral pressure plate connected to the hollow force transmission shaft in sequence, a reference beam of the test hole position orifice, a sleeve chuck fixed to the reference beam, a signal cable of the load pressure detector and a signal cable of the linear capacitive grating displacement sensor led out from the hollow force transmission rod, and a measurement data recorder connected to the signal cable, characterized in that: The sleeve fastened to the sleeve chuck has two half-shells with convex edges and butted against each other in its port, the convex edges of the two half-shells are supported on the end edges of the sleeve, the butted half-shells support a friction tube whose inner wall is engaged with a hollow force transfer rod, the friction tube is provided with an axial through groove that allows it to be elastically deformed, the friction tube is provided with a clamp for adjusting the friction force between it and the hollow force transfer rod, and the friction force is balanced with the gravity generated by the weight of the hollow force transfer rod and the hollow force transfer shaft.

2. The device for eliminating the influence of the weight of the dowel rod on the accuracy of the spiral plate load test according to claim 1 is characterized in that: The friction tube is made of nylon.

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