Device and method for testing horizontal load of ultra-long diameter pile foundation

Abstract

The present invention relates to a horizontal load testing device and method for an extra-long diameter pile foundation, comprising the following steps: driving a fixed column and an inclined bottom-expanded reaction pile on opposite sides of an extra-long diameter pile body to be tested; installing a steel bearing and a pulley on the top of the fixed column; installing a winch on the top of the inclined bottom-expanded reaction pile; installing a jack foundation, a hydraulic jack, a pad, and a pressure sensor; passing a steel cable around the pulley and fixing it to a steel fixed port; starting the hydraulic jack and the winch, and drawing a single pile horizontal static load test curve based on horizontal force and pile top displacement data. The beneficial effects of the present invention are: the horizontal load bearing limit of the inclined bottom-expanded reaction pile is increased through the dual effects of pile body bottom expansion and tilting, which helps to provide a higher horizontal reaction force for supporting the hydraulic jack; the winch is arranged above the top of the inclined bottom-expanded reaction pile, and is superimposed in the same direction as the thrust generated by the hydraulic jack, thereby increasing the applied strength limit of the horizontal load and the test accuracy.

Description

Technical Field

[0001] The invention belongs to the field of pile foundation horizontal bearing capacity measurement, and in particular relates to a device and method for testing the horizontal load of an ultra-long-diameter pile foundation. Background Art

[0002] As my country's civil engineering industry continues to develop, cast-in-place piles, the most common foundation type for structures like super-high-rise buildings and long-span bridges, are becoming increasingly larger in diameter, length, and bearing capacity. The horizontal bearing capacity of a pile is its ability and characteristics to resist horizontal loads. Horizontal loads on piles come in many forms: wind loads, earthquake loads, wave loads, crane braking forces, and the impact of floating ice and ships. The stress response of a pile foundation under horizontal loads is essentially a complex interaction between the pile and the soil. The ultimate horizontal load of a pile foundation is closely related to the type of pile, its geometry, the constraints on the pile top, the strength of the pile shaft material, and the type of soil. In engineering projects such as ports, bridges, and marine projects, pile foundations are subject to horizontal loads generated by factors such as lateral soil pressure, waves, and earthquakes. The horizontal load behavior of the pile body is a significant factor affecting foundation stability, and therefore, the horizontal load borne by the foundation has become a primary consideration in pile foundation design.

[0003] However, the existing methods for measuring the horizontal bearing capacity of pile foundations often use a single reaction pile measurement method, that is, a reaction pile is set on one side of the pile foundation to be measured and a horizontal load is applied in a single direction. The reaction piles required for measuring high-strength, ultra-long diameter pile foundations require high strength and cost, and the damage to the pile foundation itself is also great. Therefore, there is an urgent need for a horizontal load testing device and method for ultra-long diameter pile foundations. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a device and method for testing the horizontal load of an ultra-long diameter pile foundation.

[0005] The device for testing horizontal loads on ultra-long diameter pile foundations includes a steel bearing, a pulley, a fixing column, a steel fixing port, a steel protective shell, a ball joint, an ultra-long diameter pile body to be tested, a reaction pile protective shell, an inclined expanded bottom reaction pile, a tension sensor, a winch, a jack foundation, and a displacement sensor.

[0006] The steel bearing is anchored at the top of the fixed column, and the pulley sleeve is on the outside of the steel bearing; the steel protective shell is arranged at the top of the super-long large diameter pile to be tested, and the steel fixing port and the ball joint are respectively welded on both sides of the steel protective shell; a concrete reaction pile cap is cast on the top of the inclined expanded bottom reaction pile, and the reaction pile protective shell covers the reaction pile cap. The upper end of the reaction pile protective shell is fixed to the winch with a fixing bolt, and the winch and the steel fixing port are connected by a steel cable through a pulley. The tension sensor is arranged at one end of the steel cable near the steel fixing port, and a pressure sensor, a pad and a hydraulic jack are sequentially arranged between the reaction pile protective shell and the ball joint; the displacement sensor is connected to the jack foundation through a support plate.

[0007] Preferably, a fixed column expanded bottom foundation is provided at the bottom of the fixed column, and the fixed column is located on the side of the extra-long large diameter pile body to be tested with a steel fixing mouth; the inclined expanded bottom reaction pile is located on the side of the extra-long large diameter pile body to be tested with a ball joint, and the inclination angle of the inclined expanded bottom reaction pile along the vertical direction is between 30° and 45°; the fixed column, the extra-long large diameter pile body to be tested and the inclined expanded bottom reaction pile are located on the same horizontal central axis.

[0008] Preferably, the tension sensor, steel fixing port, ball joint, hydraulic jack, pad and pressure sensor are located on the same axis, and the axis passes through the center of the extra-long diameter pile to be measured, and the hydraulic jack is connected to an oil pressure gauge.

[0009] Preferably, the steel protective shell is composed of two symmetrical semicircular steel protective shells, which are fixedly connected as a whole by high-strength bolts and nuts; a steel top protective plate is provided at the upper end of the steel protective shell.

[0010] The testing method of the ultra-long diameter pile foundation horizontal load testing device comprises the following steps:

[0011] Step 1: Drive the fixed column and the inclined expanded bottom reaction pile on opposite sides of the oversized long diameter pile to be tested; install the steel bearing and pulley on the top of the fixed column;

[0012] Step 2: Cast the reaction pile cap on the top of the inclined expanded bottom reaction pile and install the winch; install the steel protective shell on the top of the super-long diameter pile to be tested;

[0013] Step 3: Install the jack foundation, hydraulic jack, pads, and pressure sensor; install a displacement sensor between the jack foundation and the extra-long diameter pile to be tested; install a tension sensor near the end of the winch's steel cable, pass the steel cable over the pulley, and securely connect it to the steel fixing port;

[0014] Step 4: Synchronously start the hydraulic jack and winch, and apply horizontal loads in stages to the pile head of the super-long diameter pile to be tested. After the constant load at each stage stabilizes, record the readings of the pressure sensor, tension sensor, and displacement sensor.

[0015] Step 5: Draw the single pile horizontal static load test curve based on the horizontal force and pile top displacement data to determine the single pile horizontal critical load and ultimate load of the super-long and long diameter pile foundation.

[0016] Preferably, in step two, a reaction pile protective shell is installed on the top of the reaction pile cap, and then the winch is anchored to the reaction pile protective shell by fixing bolts; a steel protective shell is installed on the top of the super-long diameter pile body to be tested, and the steel protective shell is connected and fixed with high-strength bolts and nuts, and then a steel top protective plate is welded on the top of the steel protective shell.

[0017] Preferably, in step three, a jack foundation, a hydraulic jack, a pad and a pressure sensor are installed in sequence between the extra-long diameter pile to be tested and the inclined bottom-expanded reaction pile; two support plates are anchored on the jack foundation, and the displacement sensors are arranged in two parallel positions along the upper and lower ends of the pile head of the extra-long diameter pile to be tested; the piston head of the hydraulic jack is in contact with the ball joint.

[0018] Preferably, in step 4, before starting the hydraulic jack and the winch, the initial readings of the pressure sensor, the tension sensor, and the displacement sensor are recorded respectively; a multi-cycle loading and unloading method is used to apply the horizontal load in stages, and the staged application of the horizontal load includes the thrust generated by the hydraulic jack and the tension generated by the winch pulling and tightening the steel cable.

[0019] The beneficial effects of the present invention are:

[0020] 1) The present invention adopts the inclined expanded bottom reaction pile support technology, which improves the horizontal load bearing limit of the inclined expanded bottom reaction pile through the dual effects of pile bottom expansion and tilting, helps the inclined expanded bottom reaction pile provide a higher horizontal reaction force for supporting the hydraulic jack, and at the same time reduces the strength requirement of the inclined expanded bottom reaction pile.

[0021] 2) The present invention adopts the winch pulley same-direction pulling technology. By cleverly setting the winch above the top of the inclined expanded bottom reaction pile and utilizing the principle of pulley conversion of force direction, the horizontal pulling force is applied to the other side of the extra-long diameter pile to be tested, and superimposed in the same direction with the thrust generated by the hydraulic jack, further improving the applied strength limit of the horizontal load and the test accuracy.

[0022] 3) The present invention adopts a steel protective shell and a steel top protective plate, which can effectively protect the pile body to be tested during the pile foundation bearing capacity test, preventing the applied load from directly contacting the concrete surface of the pile body and causing structural damage; the reaction pile cap and reaction pile protective shell are arranged on the top of the inclined expanded bottom reaction pile, which also has a certain protective effect on the inclined expanded bottom reaction pile structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a transverse elevation view of a device and method for testing horizontal loads on ultra-long diameter pile foundations;

[0024] Figure 2 It is a horizontal top view of a device and method for testing horizontal loads on ultra-long diameter pile foundations;

[0025] Figure 3 It is a horizontal elevation view of the steel protective housing;

[0026] Figure 4 It is a horizontal top view of the steel protective shell.

[0027] Explanation of the accompanying reference numerals: 1-steel bearing, 2-pulley, 3-fixed column, 4-fixed column expanded bottom foundation, 5-steel fixing port, 6-steel protective shell, 7-steel top protection plate, 8-bolt, 9-nut, 10-ball joint, 11-extra-long diameter pile to be tested, 12-oil pressure gauge, 13-pad, 14-oil hydraulic jack, 15-reaction pile protective shell, 16-inclined expanded bottom reaction pile, 17-reaction pile cap, 18-pressure sensor, 19-fixing bolt, 20-tension sensor, 21-steel cable, 22-winch, 23-jack foundation, 24-displacement sensor, 25-support plate. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the following examples. The following examples are provided only to facilitate understanding of the present invention. It should be noted that, without departing from the principles of the present invention, it is possible for a person skilled in the art to make various modifications to the present invention, and such improvements and modifications fall within the scope of the claims of the present invention.

[0029] Example 1

[0030] As an example, Figures 1 to 4As shown, a horizontal load test device for an extra-long diameter pile foundation includes a steel bearing 1, a pulley 2, a fixed column 3, a fixed column expanded bottom foundation 4, a steel fixing port 5, a steel protective shell 6, a steel top protective plate 7, a high-strength bolt 8, a nut 9, a ball joint 10, an extra-long diameter pile body to be tested 11, an oil pressure gauge 12, a pad 13, an oil pressure jack 14, a reaction pile protective shell 15, an inclined expanded bottom reaction pile 16, a reaction pile cap 17, a pressure sensor 18, a fixing bolt 19, a tension sensor 20, a steel cable 21, a winch 22, a jack base 23, a displacement sensor 24, and a support plate 25.

[0031] like Figure 1 As shown, the steel bearing 1 is anchored at the top of the fixed column 3, and the pulley 2 is hooped on the outside of the steel bearing 1; the steel protective shell 6 is arranged on the top of the super-long diameter pile body 11 to be tested, the steel top protection plate 7 is located at the upper end of the steel protective shell 6, and the steel fixing port 5 and the ball joint 10 are respectively welded on both sides of the steel protective shell 6; the top of the inclined expanded bottom reaction pile 16 is cast with a concrete reaction pile cap 17, the reaction pile protective shell 15 covers the reaction pile cap 17, and the reaction pile protection The winch 22 is fixed to the upper end of the shell 15 by a fixing bolt 19, and the winch 22 and the steel fixing port 5 are connected by a steel cable 21 through a pulley 2. The tension sensor 20 is arranged at one end of the steel cable 21 near the steel fixing port 5. A pressure sensor 18, a pad 13, and a hydraulic jack 14 are arranged in sequence between the reaction pile protection shell 15 and the ball joint 10. The hydraulic jack 14 is connected to the oil pressure gauge 12; the displacement sensor 24 is fixed to the jack base 23 through a support plate 25.

[0032] A fixed column expanded bottom foundation 4 is provided at the bottom of the fixed column 3, which is located on the side of the extra-long diameter pile body 11 to be tested with a steel fixing mouth 5; the inclined expanded bottom reaction pile 16 is located on the side of the extra-long diameter pile body 11 to be tested with a ball joint 10, and the inclination angle of the pile body along the vertical direction is between 30° and 45°; the fixed column 3, the extra-long diameter pile body 11 to be tested, and the inclined expanded bottom reaction pile 16 are located on the same horizontal central axis.

[0033] like Figure 2 As shown, the tension sensor 20, the steel fixing port 5, the ball joint 10, the hydraulic jack 14, the pad 13, and the pressure sensor 18 are located on the same axis passing through the center of the extra-long diameter pile 11 to be measured.

[0034] like Figure 3 and Figure 4 As shown, the steel protective shell 6 is composed of two symmetrical semicircular steel protective shells, which are fixedly connected as a whole by high-strength bolts 8 and nuts 9.

[0035] Example 2

[0036] As another embodiment, the testing method of the ultra-long long diameter pile foundation horizontal load testing device described in the first embodiment includes the following steps:

[0037] Step 1: Through the processes of drilling and bottom expansion, hoisting the steel cage, pouring concrete, and curing, the fixed column 3 and the inclined bottom expansion reaction pile 16 are respectively driven on the opposite sides of the oversized long diameter pile body 11 to be tested;

[0038] Clean and polish the top of the fixed column 3, and install the steel bearing 1 and pulley 2;

[0039] Step 2: Pour concrete on the top of the inclined expanded bottom reaction pile 16 to form the reaction pile cap 17, cover the top of the reaction pile cap 17 with the reaction pile protective shell 15, and then anchor the winch 22 to the reaction pile protective shell 15 with the fixing bolts 19;

[0040] Install a steel protective shell 6 on top of the super-long diameter pile 11 to be tested, and use high-strength bolts 8 and nuts 9 to connect and fix it, and then weld a steel top protective plate 7 on the top of the steel protective shell 6;

[0041] Step 3: Install the jack foundation 23, the hydraulic jack 14, the pad 13 and the pressure sensor 18 in sequence between the extra-long diameter pile body 11 to be tested and the inclined bottom-expanded reaction pile 16; anchor two support plates 25 between the jack foundation 23 and the extra-long diameter pile body 11 to be tested, and install and debug the fixed displacement sensor 24 on them; adjust the test hydraulic jack 14 so that its piston head is exactly in contact with the ball joint 10; the displacement sensors 24 are arranged in two parallel positions along the pile head of the extra-long diameter pile body 11 to be tested.

[0042] Install a tension sensor 20 near the end of the steel cable 21 of the hoist 22, pass the steel cable 21 around the pulley 2 and fix it to the steel fixing port 5, and adjust the hoist 22 to pull the steel cable 21 to make it horizontal and tightened;

[0043] Step 4: After the equipment is debugged and qualified, the initial readings of the pressure sensor 18, the tension sensor 20, and the displacement sensor 24 are recorded respectively. The hydraulic jack 14 and the winch 22 are started simultaneously. A multi-cycle loading and unloading method is used to apply a staged horizontal load to the pile head of the super-long-diameter pile 11 to be tested. After the constant load of each stage is stabilized, the readings of the pressure sensor 18, the tension sensor 20, and the displacement sensor 24 are recorded. The staged horizontal load application includes the thrust generated by the hydraulic jack 14 and the tension generated by the winch 22 pulling and tightening the steel cable 21.

[0044] Step 5: After the loading termination condition is reached, the hydraulic jack 14 and the winch 22 are turned off, and a single pile horizontal static load test curve is drawn based on the horizontal force and the displacement data of the pile top of the super-long large diameter pile body 11 to be tested, so as to determine the single pile horizontal critical load and ultimate load of the super-long large diameter pile foundation.

Claims

1. A horizontal load testing device for an ultra-long diameter pile foundation, characterized by: It includes a steel bearing (1), a pulley (2), a fixing column (3), a steel fixing port (5), a steel protective shell (6), a ball joint (10), an extra-long diameter pile body to be tested (11), a reaction pile protective shell (15), an inclined bottom-expanded reaction pile (16), a tension sensor (20), a winch (22), a jack base (23) and a displacement sensor (24); The steel bearing (1) is anchored at the top of the fixed column (3), and the pulley (2) is sleeved on the outside of the steel bearing (1); the steel protective shell (6) is arranged on the top of the super-long diameter pile body (11) to be tested, and the steel fixing port (5) and the ball joint (10) are respectively welded on both sides of the steel protective shell (6); a concrete reaction pile cap (17) is cast on the top of the inclined expanded bottom reaction pile (16), and the reaction pile protective shell (15) covers the reaction pile cap (17). The upper end of the reaction pile protective shell (15) is fixed with a winch (22) by a fixing bolt (19), and the winch (22) is connected to the steel fixing port (5). The steel cable (21) is connected through the pulley (2), the tension sensor (20) is arranged at one end of the steel cable (21) near the steel fixing port (5), and a pressure sensor (18), a pad (13) and a hydraulic jack (14) are arranged in sequence between the reaction pile protection shell (15) and the ball joint (10); the displacement sensor (24) is connected to the jack base (23) through the support plate (25); the fixed column (3) is located on the side of the super-long diameter pile body (11) to be tested with the steel fixing port (5); the inclined bottom-expanded reaction pile (16) is located on the side of the super-long diameter pile body (11) to be tested with the ball joint (10).

2. The horizontal load testing device for super-long-diameter pile foundation according to claim 1, characterized in that: A fixed column expanded bottom foundation (4) is provided at the bottom of the fixed column (3); the inclined expanded bottom reaction pile (16) has an inclination angle in the vertical direction of 30° to 45°; the fixed column (3), the super-long diameter pile body (11) to be tested, and the inclined expanded bottom reaction pile (16) are located on the same horizontal central axis.

3. The ultra-long diameter pile foundation horizontal load testing device according to claim 1, characterized in that: The tension sensor (20), the steel fixing port (5), the ball joint (10), the hydraulic jack (14), the pad (13) and the pressure sensor (18) are located on the same axis, and the axis passes through the center of the super-long diameter pile body (11) to be measured, and the hydraulic jack (14) is connected to the oil pressure gauge (12).

4. The ultra-long diameter pile foundation horizontal load testing device according to claim 1, characterized in that: The steel protective shell (6) is composed of two symmetrical semicircular steel protective shells, which are fixedly connected as a whole by high-strength bolts (8) and nuts (9); a steel top protective plate (7) is provided at the upper end of the steel protective shell (6).

5. The testing method for the horizontal load testing device for super-long long diameter pile foundation according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: Step 1: respectively driving a fixed column (3) and an inclined bottom-expanded reaction pile (16) on opposite sides of the oversized long-diameter pile body (11) to be tested; installing a steel bearing (1) and a pulley (2) on the top of the fixed column (3); Step 2: Cast the reaction pile cap (17) on the top of the inclined expanded bottom reaction pile (16) and install the winch (22); install the steel protective shell (6) on the top of the super-long diameter pile body (11) to be tested; Step 3: Install the jack base (23), the hydraulic jack (14), the pad (13) and the pressure sensor (18); install the displacement sensor (24) between the jack base (23) and the super-long diameter pile body (11) to be measured; install the tension sensor (20) near the end of the steel cable (21) of the winch (22), and pass the steel cable (21) around the pulley (2) and fix it to the steel fixing port (5); Step 4: Synchronously start the hydraulic jack (14) and the winch (22), apply a horizontal load in stages to the pile head of the super-long diameter pile (11) to be tested, and record the readings of the pressure sensor (18), the tension sensor (20) and the displacement sensor (24) after the constant load of each stage is stable; Step 5: Draw the single pile horizontal static load test curve based on the horizontal force and pile top displacement data to determine the single pile horizontal critical load and ultimate load of the super-long and long diameter pile foundation.

6. The testing method of the ultra-long-diameter pile foundation horizontal load testing device according to claim 5, characterized in that: In step 2, a reaction pile protective shell (15) is installed on the top of the reaction pile cap (17), and then the winch (22) is anchored to the reaction pile protective shell (15) by fixing bolts (19); a steel protective shell (6) is installed on the top of the super-long diameter pile body (11) to be tested, and the steel protective shell (6) is connected and fixed by high-strength bolts (8) and nuts (9), and then a steel top protective plate (7) is welded on the top of the steel protective shell (6).

7. The testing method of the ultra-long-diameter pile foundation horizontal load testing device according to claim 5, characterized in that: In step three, a jack foundation (23), a hydraulic jack (14), a pad (13) and a pressure sensor (18) are sequentially installed between the super-long diameter pile body (11) to be tested and the inclined bottom-expanded reaction pile (16); two support plates (25) are anchored on the jack foundation (23); the displacement sensor (24) is arranged at two locations parallel to the pile head of the super-long diameter pile body (11) to be tested; and the piston head of the hydraulic jack (14) is in contact with the ball joint (10).

8. The testing method of the ultra-long-diameter pile foundation horizontal load testing device according to claim 5, characterized in that: In step 4, before starting the hydraulic jack (14) and the winch (22), the initial readings of the pressure sensor (18), the tension sensor (20), and the displacement sensor (24) are recorded respectively; a multi-cycle loading and unloading method is used to apply a horizontal load in stages, wherein the staged horizontal load includes the thrust generated by the hydraulic jack (14) and the tension generated by the winch (22) pulling and tightening the steel cable (21).

Images