Foundation pile static load test ballasting platform counterforce device

Abstract

The utility model discloses a counterforce device of a ballasting platform for a foundation pile static load test. The counterforce device solves the problem that an existing counterforce device of the ballasting platform for the foundation pile static load test is poor in comprehensive performance such as construction and safety. The device comprises a control tower assembly body, a weight assembly body, a steel strand, a loading jack and a high-pressure oil pump station, wherein cantilever beams are fixed at the top end of a tower body and are uniformly distributed along the circumferential direction of the tower body; the weight assembly body is an annular body composed of a plurality of standard arc-shaped bodies, the tower body is sleeved with the weight assembly body, and the weight assembly body and the cantilever beam are connected in a suspended mode through a plurality of steel strands; a loading jack is arranged between the tower body and the pile head; the loading jack is in hydraulic control oil way connection with the high-pressure oil pump station; according to the technology, the counter weight applying mode of a counter-force platform is adjusted from direct pressure bearing to shoulder pole type bearing, counter weights at the two ends of a shoulder pole are concentrated at the geometric center position of the counter-force platform through steel strands, and therefore counter force is concentrated at the pile head position.

Description

Technical Field

[0001] This utility model relates to the field of pile foundation loading test technology in civil engineering. Background Technology

[0002] According to relevant civil engineering specifications, the slow-speed sustained load method is generally used to conduct loading tests on foundation piles, and a stacking platform reaction device should be used.

[0003] In existing technologies, the reaction device of the pile static load test platform generally uses precast concrete blocks (strips) as the main components of the load. An ultra-high pressure oil pump drives a jack to vertically load the pile foundation. The load process is measured by a pressure gauge and controlled by a pile static load test and analysis instrument. The settlement of the pile top is transmitted to the pile static load test and analysis system through a displacement sensor.

[0004] With the center point of the pile as the center of the platform, a counterweight platform is erected directly above the pile, such as... Figure 1 As shown, the load transfer path is as follows: the mass load of the counterweight is transferred to the main beam through the secondary beam, and the load is applied to the piles in stages from the main beam by the jacks, thus achieving the test objective.

[0005] The existing precast concrete blocks have the following technical defects in application:

[0006] The main problem with commonly used counterweight platform reaction devices is the limited achievable load capacity; exceeding 36,000 kN becomes extremely difficult. Increasing the platform's load capacity would necessitate a significant increase in the length and stiffness of the main beam, multiplying its weight and making hoisting and transportation extremely challenging. Furthermore, the platform's stability and safety would be difficult to guarantee. For example, a 4m*1m*1m precast concrete block (strip) weighs approximately 10 tons, making hoisting and transportation very difficult.

[0007] Lin Chunwei et al. from the Guangxi Zhuang Autonomous Region Construction Engineering Quality Testing Center published a technical paper entitled "Introduction to the Reaction Device of the Ultra-Large Tonnage Ballast Platform for Static Load Testing of Foundation Piles." This paper presents a loading scheme using a stacked loading method. The reaction device for the ballast platform in this stacked loading method consists of a main tower, stay cables, main beams, secondary beams, anti-slip cross braces, quick connectors, and counterweights. The device symmetrically stacks the ballast platform around the pile center point, with four stacks being optimal for balanced force distribution. The stay cables and main tower connect the stacks into a unified whole. The force transmission path is as follows: the mass load of the counterweights on each symmetrical ballast platform is transferred to the main beam through the secondary beams, then to the main tower through the stay cables. Several parallel jacks apply the load from the main tower to the pile head in stages, achieving the test objective. The anti-slip cross braces mainly balance the horizontal component of the stay cables; the quick connectors quickly connect the stay cables to the main tower and main beam.

[0008] In practical applications, we have found that the weight of each stack, its distance from the main tower, and its height above the ground cannot be precisely controlled, meaning there is a high possibility of instability, thus raising serious concerns about its safety. Utility Model Content

[0009] Based on the technical defects existing in the background technology, this utility model provides a reaction device for a static load test platform for foundation piles, which solves the problems of poor overall performance in terms of construction and safety of existing static load test platform reaction devices for foundation piles.

[0010] The technical solution adopted by this utility model to solve its technical problem is as follows:

[0011] A reaction device for a ballast platform in a static load test of a foundation pile includes a tower assembly, a ballast assembly, steel strands, loading jacks, and a high-pressure oil pump station. The tower assembly is characterized by the following: the tower assembly is a steel frame structure composed of a tower body and cantilever beams, with the cantilever beams fixed to the top of the tower body and evenly distributed along its circumference; the ballast assembly is a ring-shaped structure composed of multiple standard arc-shaped bodies, fitted onto the outside of the tower body, and suspended from the cantilever beams by multiple steel strands; a loading jack is installed between the tower body and the pile head, and this loading jack is connected to the high-pressure oil pump station via a hydraulic control circuit.

[0012] It also includes a fully automatic static load testing instrument, tensile stress strain gauges, a laser displacement and settlement observation instrument, and a biaxial tilt meter; among which,

[0013] The fully automatic static load tester is connected to the high-pressure oil pump station;

[0014] The tensile stress strain gauge is attached to the steel strand;

[0015] The laser displacement settlement monitoring instrument is placed on the reference piles on both sides of the pile head to monitor the settlement of the pile head;

[0016] A dual-axis tilting inclinometer is installed on the tower assembly.

[0017] Furthermore, the tower body refers to a standard segment of a tower crane.

[0018] Furthermore, there are four cantilever beams arranged in a cross shape at the top of the tower.

[0019] Furthermore, the arc-shaped body is a precast reinforced concrete component.

[0020] Furthermore, the mating surface of the arc-shaped body is provided with a concave-convex structure, and two adjacent arc-shaped bodies abut and cooperate through this concave-convex structure.

[0021] Furthermore, the overlapping area of ​​the two arc-shaped bodies is reinforced with steel plates.

[0022] Furthermore, a fixed-length support rod is provided between the counterweight assembly and the tower assembly, with the two ends of the fixed-length support rod connected to the arc-shaped body and the tower body, respectively.

[0023] Furthermore, a pressure sensor is installed at the contact surface between the loading jack and the pile head.

[0024] Furthermore, the counterweight assembly consists of multiple components, which are stacked one on top of the other.

[0025] Furthermore, the steel strand is anchored using a steel strand locking head.

[0026] The beneficial effects of this utility model are:

[0027] This technology changes the way the counterweight is applied to the reaction platform from direct bearing to a spreader-type bearing. The counterweight at both ends of the spreader is concentrated at the geometric center of the reaction platform by steel strands, so that the reaction force is concentrated at the pile head. Due to the balancing force of the steel strands, there is no pressure or very little pressure between the precast concrete counterweight assembly on both sides of the spreader and the foundation, thereby reducing the requirements for the bearing foundation. Basic leveling is sufficient to meet the requirements.

[0028] Secondly, the structure of the counterweight assembly was partially improved, so that a mechanical connection structure is formed between two adjacent precast concrete blocks, and a whole ring is formed to distribute it evenly around the pile foundation. With the help of a vertical constraint mechanism, lateral slippage is prevented and the basic outline of the counterweight remains unchanged.

[0029] Thirdly, the suspension method, combined with the combined action of pressure sensors and hydraulic jacks, maintains a gap between the counterweight assembly and the ground, just lifting it off the ground, effectively improving the safety of the entire system. Furthermore, the pressure sensors control the ground clearance of the counterweight assembly, preventing instability and loss of control, thus enhancing safety during the test and preventing major safety accidents.

[0030] Fourth, by modifying the tower crane body and cantilever, the tower assembly can be quickly assembled while maintaining structural stability and economy, and has the advantage of being reusable. Attached Figure Description

[0031] Figure 1 Elevation layout of the existing stacking platform.

[0032] Figure 2 This is a diagram showing the platform elevation layout of this utility model.

[0033] Figure 3 This is a three-dimensional view of the device.

[0034] Figure 4This is a top view of the device.

[0035] Figure 5 This is a three-dimensional diagram of an arc-shaped object.

[0036] Figure 6 This is a platform elevation layout diagram for Example 2.

[0037] In the picture:

[0038] 100 tower assembly, 110 columns, 120 crossbeams.

[0039] 200 load jacks,

[0040] 300 steel strand, 310 locking head,

[0041] 400 counterweight assembly, 410 curved body, 411 protrusion, 412 recess, 413 steel plate mounting groove, 420 steel plate.

[0042] 00 pile head. Detailed Implementation

[0043] The hardware structure of the device includes: a tower assembly, a counterweight assembly, steel strands and locking heads, loading jacks and a high-pressure oil pump station, and is reasonably equipped with monitoring instruments such as a laser displacement settlement observation instrument, a biaxial tilt meter, strain gauges, and a fully automatic static load test instrument.

[0044] Refer to the instruction manual. Figure 1 To be continued Figure 5 This first embodiment will be described in detail.

[0045] The tower assembly 100 is rapidly formed by mechanical assembly of steel columns 110 and crossbeams 120, and has an overall T-shaped structure. The crossbeams 120 are placed horizontally at the top of the columns, and the two are fastened together by bolts to form a single unit.

[0046] The aforementioned column 110 adopts a standard segment of the tower crane body from existing technology, reducing implementation costs. The crossbeam is made from a scrapped tower crane crossbeam and modified into a cross-shaped structure, with the cross-shaped crossbeam centrally located at the top of the column, and the two are fastened together using high-strength bolts.

[0047] One or more loading jacks 200 are provided at the center of the bottom end of the aforementioned column 110. The loading jacks are integrated into the bottom end of the aforementioned column. During the test, the loading jacks are installed between the pile head to be tested and the bottom of the column for vertical lifting to maintain basic balance.

[0048] The cantilever section of the crossbeam 120 has a structure for anchoring steel strands 300, so that the steel strands are anchored at this point. One steel strand 300 is fixed at each of the four cantilever sections to form a suspension structure.

[0049] The anchoring of the aforementioned steel strand 300 is performed using a special locking head 310.

[0050] Furthermore, the aforementioned beams and columns are obtained by modifying existing components from discarded tower cranes, which helps to reduce costs.

[0051] The counterweight assembly 400, once assembled, forms a circular structure. Taking a diameter of 5 meters as an example, the circular ring of this counterweight assembly is formed by assembling four standard arc-shaped sections 410. These arc-shaped sections combine to form the ring, with each arc-shaped section containing a steel strand 300. The lower end of the steel strand is anchored to the arc-shaped section using a locking head. The counterweight assembly is gradually lifted in height by loading the steel strands. The ring is tightened around its perimeter by four steel strands, forming the aforementioned lifting structure.

[0052] Furthermore, the side mating surface of the aforementioned arc-shaped body 410 is provided with a concave-convex structure, namely, a protrusion 411 and a recess 412. Specifically, at the mating interface of two adjacent arc-shaped bodies, the protrusion can be inserted into the recess to form a lock. On the surface of the arc-shaped body, a steel plate mounting groove 413 is provided at the overlapping position. The two adjacent arc-shaped bodies are quickly locked by installing the steel plate. The locking method is to fasten the steel plate 420 with screws. When the assembly is completed, under the uniform force of the steel strand 300, there is a compressive force between the arc-shaped bodies, thereby ensuring the stability of the system.

[0053] (1) Loading system configuration: The static load test is controlled by a fully automatic static load tester as the central control and processing system. The loading value is controlled in real time by a precision hydraulic sensor. The load output value of four 200-ton separate hydraulic jacks connected in parallel is controlled by a high-pressure oil pump station. The four QF type 200-ton separate hydraulic jacks connected in parallel and the high-pressure oil pump constitute the loading system configuration for loading.

[0054] (2) Data testing system configuration: 1 fully automatic static load tester for automatic control of static load test. The tester can automatically control the pressure of the jack and the displacement data of the height of the jack during the pressurization process.

[0055] Tensile strain gauges were attached to the four steel strands to monitor the stress in the four steel strands and to provide operational guidance on tension.

[0056] During the specific installation process, the slow loading method specified in the standard was used to load the load in stages, and the changes in load, displacement, and axial force at the pile bottom were recorded during the loading process.

[0057] Laser displacement settlement monitoring instruments are placed on the reference piles on both sides of the pile head 00 to monitor the settlement data of the pile head at that location. Auxiliary piles should be driven at the locations of the aforementioned laser displacement settlement monitoring instruments to form reference points.

[0058] When the pile settles, the laser displacement settlement monitoring instrument monitors the settlement data and records the vertical settlement data.

[0059] In addition, to ensure personnel safety during the test, a dual-axis tilt meter is installed on the top section of the tower assembly. This tilt meter is connected to an alarm device to monitor the tilt of the tower body at all times during the test. If the tilt exceeds the standard, the alarm device will issue a warning, and personnel should immediately stop the test and evacuate quickly.

[0060] Tensile stress strain gauges were attached to the aforementioned steel strand 300 to collect tensile stress data on the four steel strands of the platform, ensuring that the data remained consistent.

[0061] The arc-shaped body 410 is a precast reinforced concrete component with standardized dimensions and specifications.

[0062] Furthermore, the aforementioned arc-shaped bodies 410 interlock with each other, making the structure of the counterweight assembly robust. In this structure, the inner and outer arc-shaped bodies are mechanically connected by steel plates and screws.

[0063] Furthermore, a fixed-length support rod is installed between the aforementioned counterweight assembly and the tower assembly. One end of the fixed-length support rod is fixedly connected to the arc-shaped body, and the other end is quickly connected to the tower body. Through this fixed-length support rod, the vertical centers of the counterweight assembly and the tower body assembly overlap. With the adjustment of the eight steel strands, the geometric center of the entire device is kept consistent with the loading center of the four loading jacks.

[0064] The specific experimental procedure is as follows:

[0065] During the assembly of the tower assembly, it should be ensured that the assembly is carried out from bottom to top, and that the geometric center of the tower body is completely consistent with the center of the test pile. Pressure sensors should be installed at the contact surface between the loading jack and the pile head to ensure the positional accuracy of the four pressure sensors and the jack.

[0066] Refer to the instruction manual. Figure 6 Example 2 will be described in detail.

[0067] Based on Example 1, when additional counterweight is required, multiple counterweight assemblies can be formed by stacking, thereby multiplying the counterweight data. The number of counterweight assemblies can be adjusted according to the tonnage requirements of the loading test.

[0068] The embodiments described above are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Without departing from the spirit of the present utility model, all modifications and improvements to the present utility model by those skilled in the art should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A reaction device for a static load test platform for foundation piles, comprising a tower assembly, a counterweight assembly, steel strands, loading jacks, and a high-pressure oil pump station, characterized in that: The tower assembly is a steel frame consisting of a tower body and cantilever beams. The cantilever beams are fixed to the top of the tower body and evenly distributed along the circumference of the tower body. The counterweight assembly is a ring-shaped body composed of multiple standard arc-shaped bodies. The counterweight assembly is fitted onto the outside of the tower body, and the counterweight assembly and the cantilever beams are suspended and connected by multiple steel strands. A loading jack is installed between the tower body and the pile head, and the loading jack is connected to the high-pressure oil pump station through a hydraulic control oil circuit. It also includes a fully automatic static load testing instrument, tensile stress strain gauges, a laser displacement and settlement observation instrument, and a biaxial tilt meter; among which, The fully automatic static load tester is connected to the high-pressure oil pump station; The tensile stress strain gauge is attached to the steel strand; The laser displacement settlement monitoring instrument is placed on the reference piles on both sides of the pile head to monitor the settlement of the pile head; A dual-axis tilting inclinometer is installed on the tower assembly.

2. The reaction device for the static load test platform of the foundation pile according to claim 1, characterized in that, The tower body refers to a standard segment of the tower crane.

3. The reaction device for the static load test platform of the foundation pile according to claim 2, characterized in that, There are four cantilever beams, arranged in a cross shape at the top of the tower.

4. The reaction device of the pile static load test counterweight platform according to claim 1, characterized in that, The arc-shaped body is a precast reinforced concrete component.

5. The reaction device for the static load test platform of the foundation pile according to claim 4, characterized in that, The mating surface of the arc-shaped body is provided with a concave-convex structure, and two adjacent arc-shaped bodies are mated and engaged through this concave-convex structure.

6. The reaction device for the static load test platform of the foundation pile according to claim 5, characterized in that, The overlapping area of ​​the two arc-shaped bodies is reinforced with steel plates.

7. The reaction device for the static load test platform of the foundation pile according to claim 1, characterized in that, A fixed-length support rod is provided between the counterweight assembly and the tower assembly, with the two ends of the fixed-length support rod connected to the arc-shaped body and the tower body, respectively.

8. The reaction device for the static load test platform of the foundation pile according to claim 1, characterized in that, A pressure sensor is installed at the contact surface between the loading jack and the pile head.

9. The reaction device for the static load test platform of the foundation pile according to claim 1, characterized in that, The counterweight assembly consists of multiple components, which are stacked on top of each other.

10. The reaction device for the static load test platform of the foundation pile according to claim 1, characterized in that, The steel strand is anchored using a steel strand locking head.

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