CN107727483A - A kind of injection shear and method for being used for ground in-situ test based on fiber grating - Google Patents

Abstract

The invention relates to a penetrating shearing device and method for foundation in-situ testing based on optical fiber gratings. Including multi-function probe, rotary drilling device, fiber grating wireless demodulator, chassis shell and base. The multifunctional probe includes a Y-shaped plate head and a cone-point probe, and the cone-point probe is installed at the bottom of the Y-shaped plate head; the rotary drilling device includes a probe rod, a chuck, a stepping motor, Press into the host, installation platform and fixture; the probe rod runs through the entire rotary drilling device from bottom to top, passing through the chuck, stepping motor, installation platform and press into the host in turn, and the bottom is connected with the multi-function probe The steps of the in-situ test method are: clearing the field, putting in place; penetrating; shearing; pressing the multi-function probe into soil layers of different depths in sequence, repeating the above steps; pulling out the multi-function probe to end the test. The invention has the advantages of high precision, good stability, good water resistance, strong anti-electromagnetic interference ability, multi-parameter monitoring, automatic real-time monitoring and the like.

Description

A Penetration Shearing Device and Method Based on Fiber Bragg Grating for Ground In-Situ Testing

Technology Neighborhood:

The invention relates to the field of optical fiber sensing and foundation in-situ testing, in particular to a penetration shearing device and method for foundation in-situ testing based on an optical fiber grating.

technical background:

As a naturally occurring three-phase medium, soil generally has the characteristics of high moisture content, large void ratio, high compressibility, and low shear strength. It is very harmful in engineering construction, often causing foundation damage and slope loss. Stability and other issues. Therefore, it is an important subject in geotechnical engineering to quickly and effectively measure the physical and mechanical properties of foundation soil. At present, the commonly used foundation in-situ testing methods include plate load test, cross plate shear test and static penetration test.

Generally speaking, the plate load test is the most direct and relatively accurate in-situ test method to determine the bearing capacity of the foundation, but this method is expensive, time-consuming and laborious, which limits its application in engineering. The cross-plate shear test is mostly manual operation, and the manual error is large. The electric cross-plate shear test and static penetration test that have appeared in recent years are relatively perfect in theory, and have the advantages of being fast, economical, and manpower-saving. However, these two methods can only measure a single physical quantity, and the strain gauge The measurement accuracy is limited, and it may be subject to electromagnetic interference during the field test. The strain gauge is prone to short circuit in a humid environment, so it is not suitable for the test of water-rich formation soil.

Optical fiber sensors have developed rapidly in recent years because of their advantages such as high sensitivity, good stability, corrosion resistance, anti-electromagnetic interference, and quasi-distribution. Among them, fiber Bragg grating (fiber Bragg grating, referred to as fiber grating) is currently a relatively mature optical fiber sensing technology, which has been widely used in many fields such as geological engineering, geotechnical engineering, and hydraulic engineering, and is an innovation of in-situ testing methods for foundations. provides a powerful tool. The sensing principle of fiber grating is that when the broadband incident light enters the fiber, the fiber grating will reflect light of a specific wavelength, and the central wavelength λ _B of the reflected light satisfies the following relationship with the strain Δε and temperature ΔT:

In the formula: K _ε is the strain sensing sensitivity coefficient, K _T is the temperature sensing sensitivity coefficient, and Δλ _B is the variation of the central wavelength. For general fiber grating sensors, K _ε ≈0.78×10 ^-6 με ^-1 , K _T ≈6.67×10 ^-6 ℃ ^-1 . The central wavelength of the fiber grating is extremely sensitive to temperature and strain, so the fiber grating strain sensor and temperature sensor have high precision. At the same time, fiber gratings with different central wavelengths can be used in series to form a quasi-distributed sensing sequence to realize automatic collection of strain or temperature data along the optical fiber.

Contents of the invention

Aiming at the deficiencies of the existing foundation in-situ testing technology, the object of the present invention is to provide a penetration shearing device and method for foundation in-situ testing based on fiber gratings. Compared with the traditional method, the present invention has the advantages of high precision, good stability, good water resistance, strong anti-electromagnetic interference ability, multi-parameter monitoring, automatic real-time monitoring, etc., and can simultaneously obtain cone tip resistance, soil shear strength and Probe temperature, and through the fiber grating wireless demodulator to realize the automatic collection of monitoring data, remote transmission and other functions.

The present invention adopts the following technical scheme: a penetrating and shearing device for ground in-situ testing based on fiber gratings, including a multi-functional probe, a rotary drilling device, a fiber grating wireless demodulator, a chassis shell and a base, and more The functional probe penetrates the foundation soil through the base, and the other end is connected to the rotary drilling device, and then connected to the fiber grating wireless demodulator through the signal transmission optical fiber. The rotary drilling device is equipped with a chassis shell, and the chassis shell is connected to the base; The multifunctional probe includes a Y-shaped plate head and a cone-point probe, and the cone-point probe is installed at the bottom of the Y-shaped plate head; the rotary drilling device includes a probe rod, a chuck, a stepping motor, Install the platform, press into the host and the fixing device. The probe rod runs through the entire rotary drilling device from bottom to top, and passes through the chuck, stepping motor, installation platform and press into the host in turn. The bottom of the probe and the multi-functional The probe is connected; the rotary drilling device is installed on the inner wall of the chassis shell through the fixing device; the lower part of the base is provided with rollers and supports.

The Y-shaped plate head is composed of three triangular metal side plates with an angle of 120° to each other. Each metal side plate is equipped with side plate fiber Bragg grating strain sensors, and the side plate fiber Bragg grating strain sensors are connected in series through signal transmission fibers.

A thin groove is engraved on the side plate of the Y-shaped head, and the fiber grating strain sensor on the side plate is tightly pasted in the middle of the thin groove, and the surface is covered with a layer of epoxy resin.

The tapered measuring head is provided with a tapered point, a force transmission column, an elastic metal diaphragm, a tapered fiber grating strain sensor and a fiber grating temperature sensor from bottom to top; the tapered fiber grating strain sensor is closely attached to the elastic On the metal diaphragm, the signal transmission fiber is connected in series with the fiber grating temperature sensor.

The elastic metal diaphragm is a circular thin plate of equal thickness fixed around.

The probe rods are single or multiple in series, and there are slits on the sides of the probe rods, which just allow the signal transmission optical fiber to pass through the slits and be placed in the hollow part of the probe rods.

Using the described method of penetrating a shearing device based on a fiber grating for foundation in-situ testing includes the following steps:

1) Clean up the site and put it in place: clean up and level the site to be tested, fix the base of the device above the foundation to be tested, and connect the signal transmission fiber to the fiber grating wireless demodulator;

2) Penetration: Press into the host to provide thrust, vertically penetrate the multi-function probe to the depth of the foundation to be tested, and measure the cone tip resistance and temperature change of the multi-function probe;

3) Shearing: Clamp the probe rod with a chuck and let it stand for a few minutes. Under the action of the stepping motor, the multi-function probe rotates slowly in the soil layer at a preset shear rate until the surrounding soil is completely Shearing, measuring the shear strength of foundation soil;

4) Re-penetration: After completing a test, let it stand for a few minutes, press down the multi-function probe to each depth to be tested, and repeat steps 2 and 3;

5) Take out: After the test is completed, pull out the probe rod slowly from the soil, clean the multi-function probe, and use the fiber grating wireless demodulator to collect all the data in real time during the test, save the records locally and/or upload them to the cloud sensor for testing obtained and used as temperature compensation for fiber grating strain sensors.

The cone tip resistance of the multifunctional probe described in step (2) is deduced through theoretical formula: In the formula, p _s is the resistance of the cone tip; ε is the tangential strain of the elastic metal diaphragm, which is measured by the fiber grating strain sensor attached to the cone tip; E, h, v are the elastic modulus of the elastic metal diaphragm , thickness and Poisson's ratio.

The foundation soil shear strength described in step (3) is deduced through theoretical formula: In the formula: τ _f is the shear strength of the foundation soil, E is the elastic modulus of the side plate of the Y-shaped plate head; α is the ratio of the axial strain to the radial strain of the side plate during shearing, which is determined by the calibration test; ε _{1 . _}

Beneficial effect

1. Compared with the traditional electric measuring cross-plate shearing instrument and static penetrating probe, the present invention has high precision, good stability, good water resistance, and strong anti-electromagnetic interference ability, and will not be damaged due to aging of the instrument or poor sealing. Short circuit occurs due to damp and other reasons, so it is suitable for in-situ testing of soil in water-rich formations.

2. Multiple physical quantities can be obtained simultaneously by adopting the present invention, including cone tip resistance, shear strength and probe temperature, and the three groups of monitoring data can be compared and verified with each other, which is helpful for correctly evaluating the physical and mechanical properties of the soil and the engineering geological conditions of the site Significance.

3. The present invention adopts a Y-shaped plate head, which is easier to penetrate into the soil than the traditional cross-plate shearer, and reduces the disturbance to the in-situ soil during the test.

4. Through the fiber grating wireless demodulator, the automatic acquisition, remote transmission and real-time display of the readings of the fiber grating sensor are realized.

Description of drawings

FIG. 1 is a schematic diagram of a fiber grating-based penetrating shearing device for foundation in-situ testing according to a preferred embodiment of the present invention.

Among them: 1. Including multi-function probe, 2. Rotary drilling device, 3. Fiber Bragg grating wireless demodulator, 4. Chassis shell, 5. Base, 6. Y-shaped plate head, 7. Conical tip probe, 8. .Probe rod, 9. Chuck, 10. Stepping motor, 11. Installation platform, 12. Press into the host, 13. Fixing device, 14. Roller, 15. Support, 16. Side plate, 17. Fiber grating strain Sensor, 18. Optical fiber for signal transmission.

Fig. 2 is a schematic diagram of a multifunctional probe according to a preferred embodiment of the present invention, including a Y-shaped plate head and a cone-point measuring head.

Among them: 6. Y-shaped plate head, 7. Tapered tip probe, 16. Side plate, 17-1 is the side plate fiber grating strain sensor, 17-2 is the cone tip fiber grating strain sensor, 18. Signal transmission fiber, 19. Tapered tip, 20. Force transmission column, 21. Elastic metal diaphragm, 22. Fiber Bragg grating temperature sensor.

Fig. 3 is a schematic diagram of the stress situation when the Y-shaped plate head side plate of the present invention is sheared. Where τ _f is the shear strength of the foundation soil, F is the earth pressure on the side plate, and 2θ is the apex angle of the conical shear surface.

Fig. 4 is a curve drawn according to the test results of a preferred embodiment of the present invention, including tip resistance-depth, shear strength-depth, temperature-depth curves.

detailed description

The technical solutions of the present invention will be described in more detail below in conjunction with the accompanying drawings and preferred embodiments.

A penetrating shearing device based on fiber gratings for foundation in-situ testing, including a multifunctional probe, a rotary drilling device, a fiber grating wireless demodulator, a case shell and a base. The multifunctional probe includes a Y-shaped plate head and a cone-point probe, and the cone-point probe is installed at the bottom of the Y-shaped plate head; the rotary drilling device includes a probe rod, a chuck, a stepping motor, Install the platform, press into the host and the fixing device; the probe rod runs through the entire rotary drilling device from bottom to top, passes through the chuck, stepping motor, installation platform and press into the host in turn, and connects with the multi-function probe at the bottom The rotary drilling device is installed on the inner wall of the chassis shell through the fixing device; the chassis shell is placed on the upper part of the base, the roller and the support are installed on the lower part, and the multifunctional probe passes through the middle of the base and penetrates into the foundation soil.

As a preference, the Y-shaped plate head is composed of three triangular metal side plates with an included angle of 120° to each other, and a fiber grating strain sensor is installed on each metal side plate, and the three fiber grating strain sensors transmit signals through the optical fiber in series with each other.

As a preference, thin grooves are engraved on the side plate of the Y-shaped head, the fiber grating strain sensor is tightly pasted in the middle of the thin grooves, and the surface is covered with a layer of epoxy resin.

As preferably, the tapered probe includes a tapered point, a force transmission column, an elastic metal diaphragm, an optical fiber grating strain sensor and an optical fiber grating temperature sensor; the optical fiber grating strain sensor is closely attached to the elastic metal diaphragm, and The temperature sensors are connected in series.

As a preference, the elastic metal diaphragm is a circular thin plate of equal thickness fixed around it, which is connected to the cone tip through a force transmission column; when the cone tip is subjected to resistance, the elastic metal diaphragm bends and deforms, driving the fiber grating The strain sensor generates strain.

As a preference, the top of the probe rod can be threaded to connect more probe rods to increase the penetration depth, and each probe rod has a slit on the side, which just allows the signal transmission optical fiber to pass through the slit and be placed on the probe rod hollow part.

Preferably, one end of the signal transmission optical fiber connects all the fiber grating strain sensors and temperature sensors in series, and one end passes through the probe rod, extends out of the casing, and connects with the fiber grating wireless demodulator.

Further, the above-mentioned method of using a fiber grating-based penetrating shear device for foundation in-situ testing includes the following steps:

Step 1 is to clear the site and put it in place: clean and level the site to be tested, fix the base of the device above the foundation to be tested, and connect the signal transmission fiber to the fiber grating wireless demodulator.

Step 2 is penetration: press into the host to provide thrust, vertically penetrate the multi-function probe to the depth of the foundation to be tested, and measure the cone resistance and temperature change of the multi-function probe.

Step 3 is shearing: clamp the probe rod with a chuck and let it stand for a few minutes. Under the action of the stepping motor, the multi-functional probe rotates slowly in the soil layer at a preset shear rate until the surrounding soil Complete shearing, measure the shear strength of foundation soil.

Step 4 is re-penetration: After completing a test, let it stand for a few minutes, press down the multi-function probe to each depth to be tested, and repeat steps 2 and 3.

Step 5 is taking out: After the test is completed, slowly pull out the probe rod from the soil, and clean the multi-function probe.

Preferably, the temperature of the multifunctional probe described in step 2 is measured by the fiber Bragg grating temperature sensor in the tapered probe, and used as temperature compensation for the fiber Bragg grating strain sensor.

As a preference, the cone tip resistance of the multifunctional probe described in step 2 is derived through a theoretical formula: In the formula, p _s is the resistance of the cone tip; ε is the tangential strain of the elastic metal diaphragm, which is measured by the fiber grating strain sensor attached to it; E, h, v are the elastic modulus, thickness and poise of the elastic metal diaphragm, respectively Songby.

As a preference, the shear strength of foundation soil described in step 3 is derived through a theoretical formula: In the formula: τ _f is the shear strength of the foundation soil; E is the elastic modulus of the side plate of the Y-shaped plate head; α is the ratio of the axial strain to the radial strain of the side plate during shearing, which is determined by the calibration test; ε _{1 . _}

Preferably, the temperature and strain data described in steps 2, 3 and 4 are collected in real time with a fiber grating wireless demodulator, recorded and saved locally and/or uploaded to the cloud.

Example

As shown in accompanying drawings 1 and 2, a penetration shearing device based on fiber gratings for foundation in-situ testing includes a multifunctional probe 1, a rotary drilling device 2, a fiber grating wireless demodulator 3, Chassis shell 4 and base 5. The multifunctional probe 1 includes a Y-shaped plate head 6 and a cone-point probe 7, and the cone-point probe 7 is installed at the bottom of the Y-shaped plate head 6; the rotary drilling device 2 includes a probe rod 8, Chuck 9, stepper motor 10, installation platform 11, press-in host machine 12, and fixing device 13; the probe rod 8 runs through the entire rotary drilling device 2 from bottom to top, and passes through the chuck 9, step The motor 10, the installation platform 11 and the press-in host 12 are connected to the bottom of the multi-function probe 1; the rotary drilling device 2 is installed on the inner wall of the chassis shell 4 through the fixing device 13; the chassis shell 4 is placed on the upper part of the base 5, Rollers 14 and bearings 15 are installed in the lower part, and the multifunctional probe 1 passes through the middle of the base 5 and penetrates into the foundation soil.

In this embodiment, the Y-shaped plate head 6 is composed of three triangular metal side plates 16 with an included angle of 120° to each other. The material of the side plates 16 is stainless steel with a linear elastic stress-strain relationship, and the size is thickness d×height H×radius R=0.1cm×10cm×5cm, each metal side plate 16 is engraved with a thin groove, and a side plate fiber grating strain sensor 17-1 is tightly pasted in the middle of the thin groove, and the surface of the sensor is covered with a layer of epoxy resin, The three side plate fiber grating strain sensors 17 - 1 are connected in series with each other through the signal transmission optical fiber 18 .

In this embodiment, the tapered probe 7 includes a tapered head 19 , a force transmission column 20 , an elastic metal diaphragm 21 , a tapered fiber grating strain sensor 17 - 2 and a fiber grating temperature sensor 22 . The tapered fiber grating strain sensor 17 - 2 is closely attached to the elastic metal diaphragm 21 and connected in series with the fiber grating temperature sensor 22 . The elastic metal diaphragm 21 is a circular thin plate with equal cross-section fixed around it, and is connected with the cone point 19 through the force transmission column 20. When the cone point 19 is subjected to resistance, the elastic metal diaphragm 21 bends and deforms, thereby driving The fiber grating strain sensor 17-2 attached above produces strain.

In this embodiment, the probe rods 8 are single or multiple probe rods 8 connected in series through threads or other fasteners to increase the penetration depth. The transmission optical fiber 18 passes through the slit and is placed in the hollow part of the probe rod 8 . The signal transmission optical fiber 18 adopts a single-mode single-core tight-packed optical fiber with a diameter of 0.9mm, and one end connects all the fiber grating strain sensors 17 and the signal transmission optical fiber 18 in series, and one end passes through the hollow part of the probe rod 8 and extends to The outside of the chassis shell 4 is connected with the fiber grating wireless demodulator 3 .

The method for using the above-mentioned fiber grating-based ground in-situ testing device provided in this embodiment includes the following steps:

1) Clear the field and put it in place: clean and level the field to be tested, fix the device base 5 above the foundation to be tested, adjust the level of the base 5, connect the signal transmission fiber 18 to the fiber grating wireless demodulator 3, and debug the fiber signal to ensure that all The sensor is working fine.

2) Penetration: Press into the host machine 12 to provide thrust, and vertically penetrate the multi-function probe 1 to the depth of the foundation to be tested at a speed of about 20mm/s. When penetrating, the cone-point probe 7 measures the cone-point resistance and temperature change of the probe.

3) Shearing: clamp the probe rod 8 with the chuck 9, and let it stand for 2 to 5 minutes. Rotate slowly until the Y-shaped plate head 6 completely cuts the surrounding soil. The fiber grating strain sensor 17-1 on the side plate 16 of the Y-shaped plate head 6 can measure the radial strain of the side plate 16 during the shearing process.

4) Re-penetration: After completing a test, let it stand for a few minutes, press down the multi-function probe 1 to each depth to be tested, and repeat steps 2 and 3. The temperature and strain data are collected, recorded and uploaded to the cloud in real time with demodulation equipment and computers, and quickly transmitted to mobile phones, computers and other clients.

5) Take out: After the test is completed, slowly pull out the probe rod 8 from the soil, and clean the multi-function probe 1 for continued use in the next test.

In the present embodiment, the temperature change of the multifunctional probe 1 is measured by the fiber grating temperature sensor 22 in the tapered probe 7. During the penetrating process of the probe, the temperature of the probe will increase due to friction. In order to eliminate the influence of temperature on the Influenced by the results of the fiber Bragg grating strain sensor 17, a fiber Bragg grating temperature sensor 22 is installed in the tapered probe 7 at the tip of the probe for temperature compensation, and the resistance during penetration can be calculated according to the temperature change of the probe.

In this embodiment, there is the following relationship between the cone resistance of the multifunctional probe 1 and the tangential strain at the center of the elastic metal diaphragm: In the formula, p _s is the resistance of the cone tip; ε is the tangential strain at the center of the elastic metal diaphragm 21, which is measured by the fiber grating strain sensor 17-2 attached to it; E, h, v are the elastic metal diaphragm 21 respectively Elastic modulus, thickness and Poisson's ratio.

In this embodiment, the radial strain of the side plate 16 of the Y-shaped plate head 6 is deduced through a theoretical formula to obtain the value of the shear strength of the foundation soil. Its principle is that according to the bending moment M on the side plate 16 of the Y-shaped plate head 6, the _plate should be equal to the resistance moment M of the shear force on the conical side to the axis center and the resistance moment M of the shear force on the _side and the upper end surface to the axis center _end sum to find the shear strength of foundation soil (accompanying drawing 3), that is: M _plate =M _side +M _end , wherein the resistance moment of the tapered side is The resistive moment of the end face is Y-shaped plate head 6 side plate 16 consists of three parts, the bending moments of which are M ₁ , M ₂ , M ₃ respectively, where M ₂ , M ₃ and so on, the total bending moment Therefore, the shear strength of the foundation soil is In the formula: τ _f is the shear strength of the foundation soil, E is the elastic modulus of the side plate 16 of the Y-shaped plate head 6; α is the ratio of the axial strain to the radial strain of the side plate 16 during shearing, which is determined by the calibration test ; ε ₁ , ε ₂ , ε ₃ are the radial strain on each side plate 16 of the Y-shaped plate head 6 respectively; R, H are the radius and height of the Y-shaped plate head 6 respectively.

It should be noted that, in addition to the above-mentioned embodiments, the patent of the present invention may also have other implementation modes. All technical solutions formed by equivalent replacement, equivalent transformation and modification fall within the protection scope of the patent requirements of the present invention.

Claims (10)

1. A penetrating shearing device based on fiber gratings for foundation in-situ testing, characterized in that it includes a multifunctional probe, a rotary drilling device, a fiber grating wireless demodulator, a chassis shell and a base, and a multifunctional probe Penetrate through the base into the foundation soil, the other end is connected to the rotary drilling device and then connected to the fiber grating wireless demodulator via the signal transmission fiber, the rotary drilling device is equipped with a chassis shell, and the chassis shell is connected to the base; The multifunctional probe includes a Y-shaped plate head and a cone-point measuring head, and the cone-point measuring head is installed at the bottom of the Y-shaped plate head; the rotary drilling device includes a probe rod, a chuck, a stepping motor, and a mounting platform , press into the host and the fixing device, the probe rod runs through the entire rotary drilling device from bottom to top, passes through the chuck, stepping motor, installation platform and presses into the host in turn, and the bottom of the probe rod is connected with the multi-function probe ; The rotary drilling device is installed on the inner wall of the case shell through a fixing device; the lower part of the base is provided with rollers and supports. 2. A penetration shearing device based on fiber gratings for in-situ testing of foundations according to claim 1, wherein the Y-shaped plate head is composed of three triangular metal pieces with an angle of 120° to each other The metal side plates are composed of side plate fiber grating strain sensors, and the side plate fiber grating strain sensors are connected in series through signal transmission fibers. 3. A penetrating shearing device for foundation in-situ testing based on fiber gratings according to claim 1, characterized in that, the side plate of the Y-shaped plate head is engraved with thin grooves, and the side plate optical fiber The grating strain sensor is tightly stuck in the middle of the slot, and the surface is covered with a layer of epoxy resin. 4. A fiber grating-based penetrating shearing device for foundation in-situ testing according to claim 1, characterized in that, the cone-point measuring head is sequentially provided with cone-point, force-transmitting A column, an elastic metal diaphragm, an optical fiber grating strain sensor with a conical tip and an optical fiber grating temperature sensor; the optical fiber grating strain sensor with a conical tip is closely attached to the elastic metal diaphragm, and is connected in series with the optical fiber grating temperature sensor through a signal transmission optical fiber. 5 . The penetration shearing device for foundation in-situ testing based on fiber gratings according to claim 4 , wherein the elastic metal diaphragm is a circular thin plate of equal thickness fixed around. 6 . 6. A fiber grating-based penetrating shearing device for foundation in-situ testing according to claim 1, characterized in that, the probe rods are single or multiple in series, and the side of the probe rod is provided with a thin The slit just allows the signal transmission fiber to pass through the slit and place it in the hollow part of the probe rod. 7. The method of using the fiber grating-based penetration shearing device for foundation in-situ testing according to any one of claims 1 to 6, characterized in that it comprises the following steps: 1) Clean up the site and put it in place: clean up and level the site to be tested, fix the base of the device above the foundation to be tested, and connect the signal transmission fiber to the fiber grating wireless demodulator; 2) Penetration: Press into the host to provide thrust, vertically penetrate the multi-function probe to the depth of the foundation to be tested, and measure the cone tip resistance and temperature change of the multi-function probe; 3) Shearing: Clamp the probe rod with a chuck and let it stand for a few minutes. Under the action of the stepping motor, the multi-function probe rotates slowly in the soil layer at a preset shear rate until the surrounding soil is completely Shearing, measuring the shear strength of foundation soil; 4) Re-penetration: After completing a test, let it stand for a few minutes, press down the multi-function probe to each depth to be tested, and repeat steps 2 and 3; 5) Take out: After the test is completed, slowly pull out the probe rod from the soil, and clean the multi-function probe. All data during the test are collected in real time with a fiber grating wireless demodulator, and the records are saved locally and/or uploaded to the cloud. 8. use according to claim 7 is used for the method for the penetrating shear device of foundation in-situ test based on fiber grating, it is characterized in that, the multifunctional probe temperature described in step (2) is determined by the The FBG temperature sensor is measured and used as temperature compensation for the FBG strain sensor. 9. The method of using a fiber grating-based in-situ testing penetrating shearing device according to claim 7, characterized in that the cone tip resistance of the multifunctional probe described in step (2) is deduced through a theoretical formula inferred: In the formula, p _s is the resistance of the cone tip; ε is the tangential strain of the elastic metal diaphragm, which is measured by the fiber grating strain sensor attached to the cone tip; E, h, v are the elastic modulus of the elastic metal diaphragm , thickness and Poisson's ratio. 10. The method of using a fiber grating-based penetration shearing device for foundation in-situ testing according to claim 7, wherein the foundation soil shear strength described in step (3) is derived through theoretical formulas : In the formula: τ _f is the shear strength of the foundation soil, E is the elastic modulus of the side plate of the Y-shaped plate head; α is the ratio of the axial strain to the radial strain of the side plate during shearing, which is determined by the calibration test; ε _{1 . _}