Hydrodynamic displacement observation equipment and observation method for static load test

Abstract

The invention discloses a hydraulic displacement observation device and method for a static load test, and the device comprises a base point container, at least two measuring point containers which are disposed on a test pile at the same elevation, and laser displacement sensors which are disposed on the measuring point containers, and the base point container is communicated with the measuring point containers through a pipeline. The laser displacement sensor is used for measuring the displacement of a liquid level line in the measuring point container; according to the invention, a reference beam required by a static load test is canceled, the reference beam is replaced by the relative elevation of the initial liquid level line, the laser displacement sensor is used, and the laser displacement sensor uses the measurement principle of triangulation to amplify the rising displacement of the liquid level line, so that the measurement precision is greatly improved; and the problem of interference on test data due to limited datum beam length and unstable datum pile is thoroughly solved.

Description

Technical Field

[0001] The invention relates to the technical field of settlement observation of a pile foundation or a foundation static load test, and in particular to a hydraulic displacement observation device and an observation method for a static load test. Background Art

[0002] Pile foundation static load test refers to the test method of applying axial pressure, axial upward pull force or horizontal force at the same elevation of the bottom surface of the pile foundation pedestal according to the use function of the pile, observing the settlement, upward pull displacement or horizontal displacement of the corresponding detection point of the pile over time, and determining the corresponding single pile vertical compressive bearing capacity, single pile vertical pull bearing capacity or single pile horizontal bearing capacity according to the relationship between load and displacement. The single pile vertical static load test is the most important method to determine the ultimate bearing capacity and settlement characteristics of a single pile. The reaction force methods for single pile static load test can generally be divided into anchor pile method and pile loading method. As the pile diameter used continues to increase, at present, the single pile vertical static load test of these two reaction force methods has encountered the problem of difficulty in installing the reference beam to varying degrees.

[0003] At present, there are some pile foundation static load tests that do not use a reference beam. According to the fluidity characteristics of the liquid, when two or more containers are connected, the liquid in the container will automatically balance the liquid level. The static load test hydraulic displacement test method makes full use of this feature, also known as the static load test method without a reference beam. The publication number is (CN00131198.0), which states that the patented technology cannot be applied in engineering inspections in the device for remote measurement of vertical settlement without a reference beam. The accuracy of the collected pile settlement displacement test data is difficult to meet the static load test settlement displacement observation accuracy specification requirement of 0.01mm.

[0004] The patented (CN00131198.0) technology displacement sensor consists of a float, a rod-shaped iron core, a primary coil, a secondary coil, etc. The deadweight of the rod-shaped iron core and the magnetic field resistance of the iron core passing through the coil require a certain buoyancy float to move the rod-shaped iron core. The buoyancy of the pile sinking 0.1mm and the liquid level rising 0.05mm makes it difficult for the rod-shaped iron core to move and cut the magnetic lines to generate current.

[0005] This type of mechanical electromagnetic induction displacement sensor is difficult to calibrate, and instruments and equipment that have not been calibrated cannot be used for engineering quality inspection.

[0006] In order to solve the above problems, the present invention provides a hydraulic displacement observation device and an observation method for static load testing. Summary of the invention

[0007] The purpose of the present invention is to provide a hydraulic displacement observation device and observation method for static load test, which solves the problem that the conventional pile foundation static load test process is complicated and the measurement accuracy is not high.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] A hydraulic displacement observation device for static load test comprises a base point container, at least two measuring point containers arranged at the same elevation on a test pile, and a laser displacement sensor arranged on the measuring point containers. The base point container is connected to the measuring point container through a pipeline, and the laser displacement sensor is used to measure the displacement of the liquid level line in the measuring point container.

[0010] Preferably, a laser reflective sheet is provided in the measuring point container. The laser reflective sheet is made of foam wood material and processed into a circle with a thickness of less than 3 mm. The circle size can be put into the measuring point container in a standard manner.

[0011] Preferably, the test accuracy of the laser displacement sensor is selected as 0.02mm to 0.05mm, the effective measurement range is 10mm to 65mm, the working voltage is 2V to 24V, the working environment temperature is minus 30 to 55 degrees, and the protection level is IP66.

[0012] Preferably, a bracket is provided on the side wall of the test pile, the measuring point container is provided on the bracket, the placement point of the base point container is set at a range at least 2 meters away from the test pile, and the elevation of the security point is the same as the elevation of the top surface of the test pile.

[0013] Preferably, the pipeline is a hose, the inner diameter of the hose shall not be less than 9 mm, the length shall not be less than 2 meters, and the outside of the hose is provided with a heat-insulating material.

[0014] Preferably, the measuring point container is a circular measuring cup made of transparent acrylic material, the inner diameter of the circular measuring cup is within 60 mm, the wall thickness is more than 1 mm, the upper part of the circular measuring cup is provided with a cover for fixing the laser sensor, and the bottom is provided with a base.

[0015] Preferably, a joint pipe is provided at the bottom of the measuring point container, and the joint pipe is used to be connected to the hose. The inner diameter of the hose is greater than 5 mm, and the wall thickness is greater than 1 mm.

[0016] A method for observing hydraulic displacement in a static load test comprises the following steps:

[0017] The test pile is loaded, the test pile sinks, and the measuring point container set on the test pile sinks synchronously with the test pile;

[0018] The liquid in the base point container flows into the measuring point container and eventually keeps the liquid level consistent;

[0019] The laser displacement sensor observes the rise of the liquid level line at the measuring point, and obtains the displacement x of the liquid level line at the measuring point, which satisfies the following relationship with the displacement y of the test pile:

[0020] y=kx

[0021]

[0022] b=na

[0023] Setting: a = 1 (kg / cm 3 )

[0024] Where: y is the displacement of the test pile (mm);

[0025] x displacement of the liquid level line (mm);

[0026] k Conversion factor from liquid level line displacement to pile displacement;

[0027] b The volume of the base container (kg / cm 3 );

[0028] a Volume of the measuring point container (kg / cm 3 );

[0029] n natural number n = 1, 2, 3... n;

[0030] Finally, the displacement of the test pile is obtained.

[0031] Compared with the prior art, the present invention has achieved the following technical effects:

[0032] The present invention connects the measuring point container on the test pile with the base point container 2 to 20 meters away from the test pile through a hose, and the initial liquid level line in the container remains stable relative to the ground elevation. When the test pile sinks under load, the liquid level line of the measuring point container rises, and the change in the amount of liquid level rise directly reflects the change in the amount of sinking of the test pile. The traditional static load test installation displacement meter mode is completely simulated, and the digital displacement dial meter is replaced by a laser displacement sensor. 2 to 4 groups of pile settlement displacement test data are observed at the same time to improve the test effect and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a structural schematic diagram of the present invention;

[0035] Figure 2 It is a structural schematic diagram of the measuring point container of the present invention;

[0036] Figure 3It is a structural schematic diagram of the base point container of the present invention;

[0037] Among them, 1. Laser displacement sensor; 2. Laser reflector; 3. Measuring point container; 4. Base point container; 5. Rubber hose; 6. Test pile. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The purpose of the present invention is to provide a hydraulic displacement observation device and observation method for static load test, which solves the problem that the conventional pile foundation static load test process is complicated and the measurement accuracy is not high.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] refer to Figure 1 , a hydraulic displacement observation device for static load test, including a base point container, at least two measuring point containers set at the same elevation on the test pile, and a laser displacement sensor set on the measuring point container, the base point container is connected to the measuring point container through a pipeline, and the laser displacement sensor is used to measure the displacement of the liquid level line in the measuring point container; the present invention connects the measuring point container on the test pile with the base point container hose 3 to 20 meters away from the test pile, and the initial liquid level line in the container is stable relative to the ground elevation. When the test pile sinks under load, the liquid level line of the measuring point container rises, and the change in the liquid level line rise directly reflects the change in the sinking amount of the test pile. The traditional static load test installation displacement meter mode is completely simulated, and the digital displacement percentage meter is replaced by a laser displacement sensor. 2 to 4 groups of pile settlement displacement test data are observed at the same time to improve the test effect and accuracy

[0042] Furthermore, a laser reflective sheet is arranged in the measuring point container. The laser reflective sheet is made of foam wood material and processed into a circle with a thickness of about 1 mm. The circle size is the standard for being placed in the measuring point container.

[0043] Furthermore, the parameters of the laser displacement sensor are as follows: test accuracy within 0.1mm, effective measurement range within 135mm, working voltage 12~24V, working environment temperature -25~55 degrees, protection level IP66; using the principle of triangulation measurement, the liquid level line displacement is amplified. When the liquid level line is displaced, the light incident position on the CMOS will move. By detecting the light incident position, the liquid level line displacement is measured, and the maximum test accuracy is 0.01mm. The existing equipment is simple to operate and easy to install. There is a data output connection line, which can be connected to the static load test equipment for measurement calibration.

[0044] refer to Figure 1 A bracket is provided on the side wall of the test pile, and the measuring point container is provided on the bracket. The placement point of the base point container is set at a distance of at least 3 meters from the test pile and is not affected by the settlement of the test load support plate. The elevation of the base point container placement point is the same as the elevation of the top surface of the test pile.

[0045] Furthermore, the measuring point container may also be placed on the test pile head pad.

[0046] Furthermore, the pipeline is a rubber sleeve tube with an outer diameter of about 20 mm, an inner diameter of about 15 mm, a length greater than 2.0 meters, and an outer jacket of a heat-insulating cotton material tube. In addition, the base point container is placed in an insulation box to prevent the sun's exposure from affecting the test results.

[0047] Furthermore, the liquid uses antifreeze, and the hoses connecting the containers and the base point containers use thermal insulation. The characteristics are to reduce the interference of temperature changes and adapt to the climate in the south and north.

[0048] refer to Figure 2 The measuring point container is a circular measuring cup made of transparent acrylic material, the inner diameter of the circular measuring cup is 60 mm, the outer diameter is 70 mm, the upper part of the circular measuring cup is provided with a cover for fixing the laser sensor, and the bottom is provided with a base.

[0049] refer to Figure 2 A joint pipe is provided at the bottom of the measuring point container, and the joint pipe is used to connect with the rubber sleeve. The inner diameter of the rubber sleeve is more than 5 mm and the wall thickness is more than 1 mm.

[0050] A method for observing hydraulic displacement in a static load test comprises the following steps:

[0051] The test pile is loaded, the test pile sinks, and the measuring point container set on the test pile sinks synchronously with the test pile;

[0052] The liquid in the base point container flows into the measuring point container and eventually keeps the liquid level consistent;

[0053] The laser displacement sensor observes the rise of the liquid level line at the measuring point, and obtains the displacement x of the liquid level line at the measuring point, which satisfies the following relationship with the displacement y of the test pile:

[0054] y=kx

[0055]

[0056] b=na

[0057] Setting: a = 1 (kg / cm 3 )

[0058] Where: y is the displacement of the test pile (mm);

[0059] x displacement of the liquid level line (mm);

[0060] k Conversion factor from liquid level line displacement to pile displacement;

[0061] b: Volume of base point container (kg / cm3);

[0062] a: Volume of the measuring point container (kg / cm3);

[0063] n natural number n = 1, 2, 3... n;

[0064] Finally, the displacement of the test pile is obtained.

[0065] When k = 1, the volume of the base point container is equal to the volume of the measuring point container:

[0066] That is, y = 2x

[0067] When the volume ratio of the measuring point container to the base point container is different, the conversion coefficient (k) of the liquid level line rise displacement value (x) to the pile settlement displacement value (y) is different.

[0068] When the ratio is 1, y=2x, that is, there is 1 container at the measuring point and 1 container at the base point.

[0069] When the ratio is 2, y=3x, that is, there are 2 containers at the measuring point and 1 container at the base point.

[0070] When the ratio is 0.5, y=1.5x, that is, there is 1 container at the measuring point and 2 containers at the base point.

[0071] Furthermore, before the static load test begins, a liquid level line (called the initial liquid level line) is marked on the measuring point container. When the settlement displacement of the test pile exceeds the range of the laser position sensor, the centimeter scale on the measuring point container is observed and the total settlement displacement value of the test pile is recorded.

[0072] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A hydraulic displacement observation device for static load test, characterized in that: It includes a base point container, at least two measuring point containers arranged at the same elevation on the test pile, and a laser displacement sensor arranged on the measuring point containers. The base point container is connected with the measuring point container through a pipeline, and the laser displacement sensor is used to measure the displacement of the liquid level line in the measuring point container.

2. The hydraulic displacement observation device for static load test according to claim 1 is characterized in that: A laser reflective sheet is arranged in the measuring point container. The laser reflective sheet is made of foam wood material and is processed into a circle with a thickness of less than 3 mm. The circle size can be put into the measuring point container in a standard manner.

3. The hydraulic displacement observation device for static load test according to claim 1 is characterized in that: The laser displacement sensor has a test accuracy of 0.02mm to 0.05mm, an effective measurement range of 10mm to 65mm, an operating voltage of 2V to 24V, an operating environment temperature of minus 30 to 55 degrees, and a protection level of IP66.

4. The hydraulic displacement observation device for static load test according to claim 1 is characterized in that: A bracket is arranged on the side wall of the test pile, the measuring point container is arranged on the bracket, the placement point of the base point container is arranged at a range at least 2 meters away from the test pile, and the elevation of the security point is the same as the elevation of the top surface of the test pile.

5. The hydraulic displacement observation device for static load test according to claim 1 is characterized in that: The pipeline is a hose, the inner diameter of which shall not be less than 9 mm, the length of which shall not be less than 2 meters, and the outside of the hose shall be provided with heat-insulating materials.

6. The hydraulic displacement observation device for static load test according to claim 5 is characterized in that: The measuring point container is a circular measuring cup made of transparent acrylic material, the inner diameter of the circular measuring cup is within 60 mm, the wall thickness is more than 1 mm, the upper part of the circular measuring cup is provided with a cover for fixing the laser sensor, and the bottom is provided with a base.

7. The hydraulic displacement observation device for static load test according to claim 6 is characterized in that: A joint pipe is provided at the bottom of the measuring point container, and the joint pipe is used to be connected to the hose. The inner diameter of the hose is greater than 5 mm, and the wall thickness is greater than 1 mm.

8. A method for observing hydraulic displacement in a static load test, characterized in that: The application of the hydraulic displacement observation device for static load test according to any one of claims 1 to 7 comprises the following steps: The test pile is loaded, the test pile sinks, and the measuring point container set on the test pile sinks synchronously with the test pile; The liquid in the base point container flows into the measuring point container and eventually keeps the liquid level consistent; The laser displacement sensor observes the rise of the liquid level line at the measuring point, and obtains the displacement x of the liquid level line at the measuring point, which satisfies the following relationship with the displacement y of the test pile: y=kx b=na Setting: a = 1 (kg / cm 3 ) Where: y is the displacement of the test pile (mm); x displacement of the liquid level line (mm); k Conversion factor from liquid level line displacement to pile displacement; b The volume of the base container (kg / cm 3 ); a Volume of the measuring point container (kg / cm 3 ); n natural number n = 1, 2, 3... n; Finally, the displacement of the test pile is obtained.

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