Stress ring-based interface soil pressure detection apparatus and method

Abstract

The application discloses an interface soil pressure detection equipment and method based on a stress ring, and the pressure gauge comprises an outer protective cover, an upper bearing plate, an upper supporting plate, a fixed plate, an elongated rod, a stress ring, a supporting ring, a lower supporting plate, a lower bearing plate and a one-way hinge, wherein the outer protective cover is a protective cover used when the interface soil pressure detection equipment is used, damage of the pressure gauge is reduced, pressure is borne by the upper bearing plate and the lower bearing plate, measurement is performed through deformation of the stress ring in the middle of the interface soil pressure detection equipment, the one-way hinge is used for converting pressure of the upper bearing plate into a resultant force and uniformly transmitting the resultant force to the stress ring, the soil arching effect caused by the fact that the pressure film is depressed below the pressure gauge shell is avoided by guaranteeing flatness and a large surface area of the upper bearing plate. The application constructs a multi-stage decoupling interface stress transmission and sensing architecture, realizes complete immunity to bending moment and shear interference, and fundamentally solves the technical problem that the traditional pressure gauge fails due to eccentric load and soil effect.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering testing technology, and more specifically, relates to an interface earth pressure testing device and method based on stress rings. Background Technology

[0002] Interface soil pressure testing equipment, as a core device for safety monitoring in geotechnical engineering, is mainly used to measure the compressive stress changes at the interface between structures and soil, playing a crucial role in scenarios such as tunnel support, dam foundations, and slope protection. As global infrastructure construction expands into deeper and more complex environments, the demand for real-time and accurate pressure monitoring has significantly increased. Currently, mainstream interface soil pressure testing equipment is primarily based on vibrating wire and differential resistance technologies. Among these, vibrating wire products hold over 65% of the market share due to their long-term stability advantages. Their core principle is to transmit stress to the vibrating wire through the deformation of a sensing plate, with frequency changes reflecting the pressure value.

[0003] Existing interface soil pressure testing equipment generally adopts a structural design of "sensing membrane + sensing element". Vibrating wire type products receive soil pressure through a circular sensing membrane. After deformation, it drives the steel wire to stretch and change the vibration frequency, thereby completing the conversion of pressure into signal. Differential resistance type uses the displacement of the pressure-bearing panel to push the pressure-transmitting liquid, causing the sensing membrane to deform and causing a change in the resistance ratio of the steel wire. It uses a three-wire measurement to eliminate interference from the lead wire. In recent years, although the application of MEMS technology and graphene materials has improved the accuracy of some products from ±2% to ±0.5%, the core structure has not broken through the traditional framework. Moreover, due to the structural characteristics of the interface type, which is "without pressure transmission tube and the sensing membrane directly contacts the soil", its measurement performance still falls short of the actual engineering needs.

[0004] The existing technical solutions have the following problems: (1) The measurement accuracy is inherently insufficient. The vibrating wire structure needs to transmit stress through multiple nodes such as "pressure → membrane bending → steel wire fixed pile displacement → steel wire tension". The conversion of arc length change to linear strain results in the input-output relationship being only approximately linear. Moreover, the annular steel shaft occupies a large amount of sensing area. Although the differential resistance type optimizes the circuit interference problem, the temperature expansion effect of the pressure-transmitting liquid will still cause a drift error of ±0.02% / ℃. (2) Environmental adaptability is limited. Traditional products have extremely high requirements for load uniformity and can only adapt to ideal uniform pressure scenarios. The accuracy drops significantly under concentrated loads or uneven soil settlement conditions. Furthermore, the sensing membrane is easily affected by groundwater erosion and soil expansion and compression, resulting in long-term monitoring stability decay. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides an interface earth pressure detection device and method based on a stress ring. This invention constructs a multi-level decoupled interface stress transmission and sensing architecture. It employs a large-size rigid load-bearing plate to ensure the fidelity of the soil-structure interface stress field, overcoming measurement inaccuracies caused by the "soil arching effect" at its source. It innovatively couples a spherical adaptive self-aligning structure with a built-in unidirectional hinge, forming a composite force transmission hub. This hub mechanism automatically decouples received complex eccentric loads, extracting only the pure normal pressure component and uniformly transmitting it to the vertically arranged stress ring sensing element. This systematic design, from "stress field fidelity" to "multi-dimensional load decoupling," achieves complete immunity to bending moment and shear interference, fundamentally solving the technical problem of traditional pressure gauge failure due to eccentric loading and soil effects, making high-precision interface normal stress measurement possible.

[0006] To achieve the above objectives, according to a first aspect of the present invention, an interface earth pressure detection device based on a stress ring is provided, comprising:

[0007] The device comprises a disc-shaped upper support plate at the top, an upper support plate located at the bottom of the upper support plate and concentric with the upper support plate, having a concave arc surface on the outer bottom surface, a fixing plate with a convex arc surface at the top closely attached to the concave arc surface at the bottom of the upper support plate, a ring-shaped stress ring located at the bottom of the fixing plate, and a support ring connected to the fixing plate. The stress ring is arranged vertically and perpendicular to the direction of the compressive stress surface force. Another fixing plate is also provided at the bottom of the stress ring. The stress ring is used in conjunction with a vibrating wire strain gauge to measure the pressure accurately. The outer arc surface of the support ring is in close contact with the arc surfaces of the upper and lower support plates.

[0008] The lower support plate, with its top concave arc surface closely attached to the convex arc surface of the fixing plate, and the lower support plate, which is in the shape of a disc, are connected to the bottom of the lower support plate; the lower support plate and the lower support plate must be concentric.

[0009] A cylindrical one-way hinge is located inside the fixed plate. The one-way hinge and the top surface of the stress ring form a one-way hinge structure, which can convert the pressure acting on the upper bearing plate into a resultant force and transmit it evenly to the stress ring. By ensuring the flatness and large surface area of ​​the upper bearing plate, the soil arching effect caused by the pressure membrane sinking under the pressure gauge housing is avoided.

[0010] Furthermore, the top surface of the upper bearing plate has a large and flat area, which is used to eliminate soil particles and avoid the arching effect of the soil.

[0011] Furthermore, the one-way hinge is the same length as the stress ring thickness, and the direction of the one-way hinge is parallel to the axis.

[0012] Furthermore, it also includes an outer protective cover located outside the interface earth pressure testing device, which is used to shield the lateral forces acting on the soil.

[0013] Furthermore, the outer protective cover is made of plastic or metal tubing, and its surface is coated with polyurethane foam material with a thickness of about 10-20mm.

[0014] Furthermore, it also includes an extension rod connected to the bottom of the fixed plate, the extension rod being connected to the fixed plate and the stress ring by welding.

[0015] According to a second aspect of the present invention, a method for measuring interfacial earth pressure based on a stress ring is provided, implemented using an interfacial earth pressure detection device based on a stress ring, comprising:

[0016] S100: Before the project is implemented, based on the structural characteristics, soil properties and stress analysis, interface earth pressure detection equipment should be installed at key locations where the stress is greatest and the soil quality changes significantly at the interface between the structure and the soil.

[0017] S200: In the vertical direction during deployment, the spacing between monitoring points should be 2-5 meters, and the spacing at key stress-bearing parts should be increased to 1-2 meters.

[0018] S300: Ensure that all components of the interface earth pressure testing equipment are inspected in a clean and dry environment. If abnormal elastic deformation of the stress ring is found, the component of the same specification must be replaced and the equipment must not be used.

[0019] S400: Ensure that the lower support plate is in close contact with the rigid support to avoid uneven initial stress on the stress ring due to uneven reference surface, which would affect the linearity of subsequent pressure transmission.

[0020] S500: Ensures that the upper load-bearing plate transmits pressure evenly to the stress ring through a one-way hinge, realizing the core function of "converting surface force into resultant force" and avoiding stress concentration or arching effect due to improper assembly;

[0021] S600: Accurately measure and mark the installation location on the foundation soil surface. Lay a leveling layer of about 20 mm thick with fine sand or fine soil to ensure that the soil surface is uniform and flat. Make the pressure surface of the pressure gauge fit tightly with the fine sand layer. Use a spirit level to check whether the pressure surface is level. In accordance with the principle of "compact first, then bury", compact the pressure gauge first, and then pour the concrete.

[0022] S700: Ensures the instrument operates reliably in long-term monitoring scenarios, avoiding measurement failure due to component aging or damage;

[0023] S800: Safety precautions must be taken during maintenance. Replacement parts must be of the same specifications as the patented design. Arbitrary replacement is prohibited. After maintenance, the initial frequency must be recalibrated to ensure the continuity of measurement values.

[0024] Further, step S500 includes:

[0025] Based on the characteristics of installing a vibrating wire strain gauge at the center of the stress loop, the temperature-frequency drift correction is established as follows:

[0026]

[0027] in: The frequency of the vibrating string after compensation; This is the original frequency of the vibrating string; β T is the temperature drift coefficient of the vibrating wire; T is the real-time monitored temperature. For calibration reference temperature;

[0028] The revised Replace the original frequency of the vibrating wire strain gauge Perform initial stress testing on the stress ring. The calculation yields the conversion results from drift correction to stress correction.

[0029] Further, step S500 includes:

[0030] Based on the properties of GCr15 material, a temperature-stress correction model is established and deformation correction is introduced as follows:

[0031]

[0032] in: This is the actual stress value after temperature compensation; α represents the original stress corresponding to the original measurement value of the vibrating wire strain gauge; α is the temperature coefficient of GCr15; T is the real-time monitoring temperature. For calibrating the reference temperature.

[0033] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0034] 1. This invention constructs a multi-level decoupled interface stress transfer and sensing architecture. It employs a large-size rigid load-bearing plate to ensure the fidelity of the soil-structure interface stress field, overcoming measurement inaccuracies caused by the "soil arching effect" at its source. It innovatively couples a spherical adaptive self-aligning structure with a built-in unidirectional hinge, forming a composite force transmission hub. This hub mechanism can automatically decouple received complex eccentric loads, extracting only the pure normal pressure component and uniformly transmitting it to vertically arranged stress loop sensing elements. This systematic design, from "stress field fidelity" to "multi-dimensional load decoupling," achieves complete immunity to bending moment and shear interference, fundamentally solving the technical problem of traditional pressure gauge failure due to eccentric loading and soil effects, making high-precision interface normal stress measurement possible.

[0035] 2. The interface pressure detection device of the present invention, through the stress ring made of GCr15 material, has the advantages of high precision and high linearity. By combining the stress ring with a vibrating wire strain gauge, it can accurately measure the pressure (surface force). By ensuring the flatness and large surface area of ​​the upper support plate, it avoids the soil arching effect caused by the pressure membrane sinking under the pressure gauge shell. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the interface earth pressure detection device based on a stress ring according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the interface earth pressure detection device and outer protective cover based on the stress ring according to an embodiment of the present invention;

[0038] Figure 3 This is a front view of the interface earth pressure detection device based on a stress ring according to an embodiment of the present invention;

[0039] Figure 4 This is a cross-sectional view at point A of the stress ring-based interface earth pressure detection device according to an embodiment of the present invention;

[0040] Figure 5 This is a side view of the interface earth pressure detection device based on a stress ring according to an embodiment of the present invention;

[0041] Figure 6 This is a cross-sectional view at point B of the interface earth pressure detection device based on a stress ring according to an embodiment of the present invention;

[0042] Figure 7 This is a flowchart illustrating the workflow of the interface earth pressure detection device based on a stress ring, according to an embodiment of the present invention.

[0043] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1-outer protective cover, 2-upper support plate, 3-upper support plate, 4-fixed plate, 5-extension rod, 6-stress ring, 7-support ring, 8-lower support plate, 9-lower support plate, 10-one-way hinge. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0045] In the description of the embodiments of the present invention, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first," "second," and "third" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0046] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0047] In the description of the embodiments of the present invention, "multiple" means at least two.

[0048] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0049] This invention provides an interface earth pressure detection device based on a stress ring, such as... Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6As shown, the device includes an outer protective cover 1, an upper support plate 2, an upper support plate 3, a fixing plate 4, an extension rod 5, a stress ring 6, a support ring 7, a lower support plate 8, a lower support plate 9, and a one-way hinge 10. The outer protective cover 1 is a tubular structure that completely encloses the interface earth pressure testing equipment. It is made of plastic or metal tubing and coated with approximately 10-20mm thick polyurethane foam. The outer protective cover 1 effectively shields the lateral forces of the soil. The upper support plate 2 is located at the top of the interface earth pressure testing equipment, and the upper support plate 3... The upper support plate 2 and the upper support plate 3 are both disc-shaped structures, and during installation, it is necessary to ensure that the upper support plate 2 and the upper support plate 3 are concentric. The outer surface of the bottom of the upper support plate 3 has a concave arc surface. The outer surfaces of the fixing plate 4 and the support ring 7 are in close contact with the concave arc surface of the bottom of the upper support plate 3. The support ring 7 is a tubular structure with a through square hole. The fixing plate 4 is installed on the upper and lower sides of the support ring 7 by bolt connection. The top of the fixing plate 4 has a convex arc surface. The fixing plate 4 is installed after the support ring 7 and is connected by bolts. The fixing plate 4 is installed on the bottom concave surface of the upper support plate 3 from top to bottom, ensuring that the arc surfaces of the upper support plate 3, fixing plate 4, and support ring 7 fit tightly. An installation hole for an extension rod 5 is provided at the bottom of the fixing plate 4. After inserting the extension rod 5 into the bottom of the fixing plate 4, the connection is reinforced by welding. One side of the extension rod 5 is connected to the bottom of the fixing plate 4 by welding, and the other side is connected to the stress ring 6 by welding. The stress ring 6 is vertically arranged and perpendicular to the direction of the compressive stress. A vibrating wire strain gauge is installed at the center of the stress ring 6. The design includes extension rods 5 welded to both the upper and lower sides of the stress ring 6. One side of the extension rod 5 located at the lower part of the stress ring 6 is connected to the fixing plate 4 at the bottom of the interface earth pressure testing device. The lower support plate 9 is located at the bottom of the interface earth pressure testing device, and the lower support plate 8 is installed on top of the lower support plate 9 by bolt connection. Both the lower support plate 8 and the lower support plate 9 are disc structures. During installation, it is necessary to ensure that the lower support plate 8 and the lower support plate 9 are concentric. The top outer surface of the lower support plate 8 has a concave arc surface, and it is necessary to ensure that the fixing plate 4, the support ring 7, and the top arc surface of the lower support plate 8 fit tightly. The interface earth pressure testing device of the present invention uses a tubular outer protective cover to protect the entire interface earth pressure testing device inside, avoiding damage to the pressure gauge by the lateral force of the soil. The support ring is firmly connected to the arc surface of the upper and lower support plates through the top arc surface of the fixing plate, and the stress ring is firmly welded to the interface earth pressure testing device through the upper and lower extension rods. This invention constructs a multi-level decoupled interface stress transfer and sensing architecture. It uses a large-size rigid load-bearing plate to ensure the fidelity of the soil-structure interface stress field, overcoming the measurement inaccuracies caused by the "soil arching effect" from the source; it innovatively couples a spherical adaptive self-aligning structure with a built-in unidirectional hinge to form a composite force transmission hub.This hub mechanism can automatically decouple received complex eccentric loads, extracting only the pure normal pressure component and uniformly transmitting it to vertically arranged stress loop sensing elements. This systematic design, from "stress field fidelity" to "multidimensional load decoupling," achieves complete immunity to bending moment and shear disturbances, fundamentally solving the technical problem of traditional pressure gauges failing due to eccentric loading and soil effects, and making high-precision interface normal stress measurement possible.

[0050] Specifically, such as Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, the interface earth pressure testing equipment is used to measure the pressure exerted by soil on a support structure. The support structure is typically rigid, does not deform, and is therefore suitable for monitoring the magnitude and distribution of pressure applied to the soil under these conditions. In this equipment, a stress ring 6 is used as the sensing element, paired with a high-precision vibrating wire strain gauge to measure the strain of the elastic body. The pressure (surface force) on the bearing plate is then calculated from the monitored strain. The stress ring 6 is made of highly elastic and highly linear GCr15 material. Under the same stress conditions, the deformation of the stress ring 6 is much greater than that of the traditional rod-shaped sensing element. The vertical deformation of the stress ring 6 is always directly proportional to the radially applied external force, thus eliminating nonlinearity issues at small ranges. The natural frequency of the vibrating wire sensor depends only on its structure, the common mass of the steel wire, and the elastic coefficient. The output signal is a frequency, not a voltage. The frequency signal transmission... The vibration wire sensor is largely unaffected by conductor resistance and distributed capacitance, and is minimally affected by temperature fluctuations and changes in insulation resistance. Its passive internal structure provides excellent durability, exhibiting superior long-term stability even in harsh environments. In this interface soil pressure testing device, pressure is transmitted via a one-way hinge 10, a 5-10mm thin round bar. The hinge 10 is the same length as the stress ring 6 and its direction is parallel to the axis. After assembly, the hinge 10, together with the upper support plate 2, forms a one-way hinge structure, converting the pressure (surface force) acting on the upper support plate 2 into a resultant force (linear load) and uniformly transmitting it to the stress ring 6. The upper support plate 2 requires a sufficiently large area to eliminate the influence of soil particles and the flatness of the support plate. Simultaneously, the upper support plate 2 must ensure structural flatness to prevent the pressure membrane from sinking below the pressure gauge housing, thus avoiding the arching effect of the soil and ensuring the accuracy of measurements under field conditions. The interface soil pressure testing device of the present invention uses a stress ring made of GCr15 material, which has the advantages of high precision and high linearity. By combining the stress ring with a vibrating wire strain gauge, it can accurately measure the pressure (surface force). By ensuring the flatness and large surface area of ​​the upper bearing plate, it avoids the soil arching effect caused by the pressure membrane sinking under the pressure gauge shell.

[0051] Specifically, in stress ring 6, the elastic modulus of the stress ring 6 made of GCr15 material has inherent characteristics that change with temperature. In the actual use of this interface earth pressure detection equipment, the ambient temperature is a factor that cannot be ignored. The elastic modulus of GCr15 material is relatively stable in the range of -30℃ to 60℃. Therefore, a PT1000 high-precision temperature sensor is used to measure the ambient temperature of the interface earth pressure detection equipment in real time. Then, a preset temperature-stress correction model is established to automatically calibrate and correct the stress value output by stress ring 6. This improves the measurement accuracy and avoids the instantaneous error caused by sudden temperature changes.

[0052] Based on the characteristics of installing a vibrating wire strain gauge at the center of stress ring 6, a temperature-frequency drift correction formula is established as follows:

[0053]

[0054] in: The frequency of the vibrating string after compensation; This is the original frequency of the vibrating string; β is the temperature drift coefficient of the vibrating wire (calibrated according to the vibrating wire model selected in the patent, usually 0.5Hz / ℃); T is the real-time monitored temperature; The calibration reference temperature is set to 20℃ by default.

[0055] The revised Replace the original frequency of the vibrating wire strain gauge Perform the original stress test on stress ring 6. In the calculation, the conversion result from drift correction to stress correction is obtained.

[0056] Subsequently, based on the properties of GCr15 material, a temperature-stress correction model was established and deformation correction was introduced, as shown in the following formula:

[0057]

[0058] in: This is the actual stress value after temperature compensation; α represents the original stress corresponding to the original measurement value of the vibrating wire strain gauge; α is the temperature coefficient of GCr15; T is the real-time monitoring temperature. The calibration reference temperature is set to 20℃ by default.

[0059] The actual stress value after temperature compensation Substitute the values ​​into the "surface force to resultant force" function to obtain the actual earth pressure (surface force) borne by the upper bearing plate 2, ensuring that the final output value is consistent with the actual force exerted by the soil.

[0060] As a preferred embodiment, in some other embodiments, this interface earth pressure testing device can not only measure earth pressure, but also measure the pressure between the tunnel lining concrete and the rock surface. In the tunnel lining concrete, the lining is a permanent structure of the tunnel, with a smooth surface and no honeycomb pitting, which meets the measurement conditions of this interface earth pressure testing device. The pressure (surface force) provided by the concrete on the upper bearing plate 2 is converted into a resultant force (linear load) by this interface earth pressure testing device. The resultant force is reflected by the elastic deformation of the stress ring 6. Because the deformation of the concrete surface is small, the stress ring 6 made of highly elastic and highly linear GCr15 material has more advantages in measurement. Even small deformations can produce good measurement results. In the rock surface, the deformation of the rock surface is small, and it is exposed to harsh outdoor conditions for a long time. The vibrating wire strain sensor has excellent stability and excellent internal durability, which can adapt to harsh working conditions and ensure the accuracy of the measurement values.

[0061] As a preferred option, in some other embodiments, the one-way hinge 10 can be replaced with a self-lubricating spherical bearing. This not only allows it to operate under high stress concentration for extended periods but also improves wear resistance and uniform force transmission. The one-way hinge 10 is a thin round bar, which is susceptible to soil particle compression, corrosion, or installation eccentricity, potentially leading to uneven force transmission or localized yielding. The self-lubricating spherical bearing contains solid lubricating material that continuously releases lubricant during operation, eliminating the need for external oiling or periodic lubrication. It is suitable for long-term burial, enclosed structures, or harsh environments. Furthermore, the sliding surface is typically made of composite materials, exhibiting excellent wear resistance and a long service life. The self-lubricating spherical bearing can also withstand higher radial loads, axial loads, and combined loads. Replacing the one-way hinge 10 with a self-lubricating spherical bearing significantly improves the stability and load-bearing capacity of the interface soil pressure detection equipment.

[0062] Although the outer protective cover 1 of this disclosure is described as a tubular structure, this disclosure is not limited to this. For example, the outer protective cover 1 can be changed to a rectangular shell structure according to the soil characteristics and construction requirements on site. The main function of the outer protective cover 1 is to shield the lateral forces of the soil. The use of a tubular structure is mainly based on the actual materials on the construction site. There are no special requirements in terms of shape. The shape of the outer protective cover 1 can be changed according to the specific circumstances.

[0063] like Figure 7 As shown, in another embodiment of the present invention, a method for measuring interfacial earth pressure based on a stress ring is provided, comprising the following steps:

[0064] Before the project is implemented, based on the structural characteristics, soil properties and stress analysis, interface earth pressure testing equipment should be installed at key locations where the stress is greatest and the soil quality changes significantly at the interface between the structure and the soil.

[0065] In the vertical direction during deployment, the spacing between monitoring points should be 2-5 meters, and the spacing between key stress-bearing parts (such as structural corners and joints) should be increased to 1-2 meters.

[0066] All components of the interface soil pressure testing equipment must be inspected in a clean and dry environment (temperature 15-25℃, humidity ≤60%). If abnormal elastic deformation of stress ring 6 is found (such as slow rebound after pressing), the component of the same specification must be replaced immediately and the equipment must not be used.

[0067] Ensure that the lower bearing plate 9 is in close contact with the rigid support (such as retaining wall or tunnel lining) to avoid uneven initial stress on the stress ring 6 due to uneven reference surface, which would affect the linearity of subsequent pressure transmission.

[0068] Ensure that the upper load-bearing plate 2 transmits pressure evenly to the stress ring 6 through the one-way hinge 10, realize the core function of "converting surface force into resultant force", and avoid stress concentration or arching effect caused by improper assembly.

[0069] Accurately measure and mark the installation location on the foundation soil surface. Lay a leveling layer of about 20 mm thick with fine sand or fine soil to ensure that the soil surface is uniform and flat. Make sure the pressure surface of the pressure gauge is in close contact with the fine sand layer. Use a spirit level to check whether the pressure surface is level. In accordance with the principle of "compact first, then bury", compact the pressure gauge first, and then pour the concrete.

[0070] Ensure that the instrument operates reliably in long-term monitoring scenarios and avoid measurement failure due to component aging or damage.

[0071] During maintenance, safety precautions must be taken. Replacement parts must be of the same specifications as the patented design. Arbitrary replacement is prohibited. After maintenance, the initial frequency must be recalibrated to ensure the continuity of measurements.

[0072] In summary, this stress ring-based interface earth pressure detection device and method can eliminate nonlinearity at small ranges and eliminate soil arching effect. In addition, it has the advantages of good stability and high resolution. Furthermore, the stress ring, made of GCr15 material, has the advantages of high precision and high linearity. By combining the stress ring with a vibrating wire strain gauge, accurate measurement of pressure (surface force) can be achieved. By ensuring the flatness and large surface area of ​​the upper bearing plate, the soil arching effect caused by the pressure membrane sinking under the pressure gauge shell is avoided.

[0073] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A stress ring based interface soil pressure detection apparatus, characterized by, include: The device includes a disc-shaped upper support plate (2) at the top of the testing equipment, an upper support plate (3) located at the bottom of the upper support plate (2) and concentric with the upper support plate (2) with a concave arc surface on the bottom outer surface, a fixing plate (4) with a convex arc surface on the top closely attached to the concave arc surface at the bottom of the upper support plate (3), a ring-shaped stress ring (6) located at the bottom of the fixing plate (4), and a support ring (7) connected to the fixing plate (4); the stress ring (6) is arranged vertically and perpendicular to the direction of the compressive stress surface force, and another fixing plate (4) is provided at the bottom of the stress ring (6). The stress ring is used in conjunction with a vibrating wire strain gauge to measure the pressure accurately. The outer arc surface of the support ring (7) is in close contact with the arc surfaces of the upper support plate (3) and the lower support plate (8); The lower support plate (8) with its top concave arc surface closely attached to the convex arc surface of the fixing plate (4) is connected to the bottom of the lower support plate (8) in the shape of a disc-shaped lower support plate (9); the lower support plate (8) and the lower support plate (9) must be concentric. A cylindrical one-way hinge (10) is provided inside the fixed plate (4). The one-way hinge (10) and the top surface of the stress ring (6) form a one-way hinge structure, which can convert the pressure acting on the upper bearing plate (2) into a resultant force and transmit it evenly to the stress ring (6). By ensuring the flatness and large surface area of ​​the upper bearing plate (2), the soil arching effect caused by the pressure membrane sinking under the pressure gauge housing is avoided.

2. The interface earth pressure detection device based on a stress ring according to claim 1, characterized in that, The top surface of the upper bearing plate (2) has a large and flat area, which is used to eliminate soil particles and avoid the arching effect of the soil.

3. The stress ring based interface soil pressure detection device according to claim 2, wherein, The one-way hinge (10) has the same thickness as the stress ring (6), and the direction of the one-way hinge (10) is parallel to the axis.

4. A stress ring based interface soil pressure detection device according to any one of claims 1-3, characterized in that, It also includes an outer protective cover (1) located outside the interface earth pressure testing equipment, which is used to shield the lateral forces of the soil.

5. The stress ring based interface soil pressure detection device according to claim 4, wherein, The outer protective cover (1) is made of plastic or metal tubes, and its surface is coated with polyurethane foam material with a thickness of about 10-20mm.

6. A stress ring-based interface earth pressure detection device according to any one of claims 1-3, characterized in that, It also includes an extension rod (5) connected to the bottom of the fixed plate (4), the extension rod (5) being connected to the fixed plate (4) and the stress ring (6) by welding.

7. A method of measuring interface soil pressure based on a stress ring, characterized by, The application of a stress ring-based interface earth pressure detection device as described in any one of claims 1-6 includes: S100: Before the project is implemented, based on the structural characteristics, soil properties and stress analysis, interface earth pressure detection equipment should be installed at key locations where the stress is greatest and the soil quality changes significantly at the interface between the structure and the soil. S200: In the vertical direction during deployment, the spacing between monitoring points should be 2-5 meters, and the spacing at key stress-bearing parts should be increased to 1-2 meters. S300: Ensure that all components of the interface earth pressure testing equipment are inspected in a clean and dry environment. If abnormal elastic deformation of the stress ring (6) is found, the same specification component must be replaced and the equipment must not be used. S400: Ensure that the lower support plate (9) fits tightly with the rigid support to avoid uneven initial stress on the stress ring (6) due to uneven reference surface, which would affect the linearity of subsequent pressure transmission. S500: Ensure that the upper bearing plate (2) transmits the pressure evenly to the stress ring (6) through the one-way hinge (10), realize the core function of "surface force to resultant force", and avoid stress concentration or arching effect due to improper assembly; S600: Accurately measure and mark the installation location on the foundation soil surface. Lay a leveling layer of about 20 mm thick with fine sand or fine soil to ensure that the soil surface is uniform and flat. Make the pressure surface of the pressure gauge fit tightly with the fine sand layer. Use a spirit level to check whether the pressure surface is level. In accordance with the principle of "compact first, then bury", compact the pressure gauge first, and then pour the concrete. S700: Ensures the instrument operates reliably in long-term monitoring scenarios, avoiding measurement failure due to component aging or damage; S800: Safety precautions must be taken during maintenance. Replacement parts must be of the same specifications as the patented design. Arbitrary replacement is prohibited. After maintenance, the initial frequency must be recalibrated to ensure the continuity of measurement values.

8. The method for measuring interfacial earth pressure based on stress rings according to claim 7, characterized in that, Step S500 includes: Based on the characteristics of installing a vibrating wire strain gauge at the center of the stress ring (6), the temperature-frequency drift correction is established as follows: wherein: is the compensated vibrating wire frequency; is the vibrating wire original frequency; β is the vibrating wire temperature drift coefficient; T is the real-time monitoring temperature; is the calibration reference temperature; The modified Substitution of the original frequency of the vibrating wire strain gauge The calculation of the original stress of the stress ring (6) is performed The conversion result of the drift correction to the stress correction is obtained.

9. The method of measuring interface soil pressure based on stress ring according to claim 7, characterized in that, Step S500 includes: Based on the properties of GCr15 material, a temperature-stress correction model is established and deformation correction is introduced as follows: in: This is the actual stress value after temperature compensation; α represents the original stress corresponding to the original measurement value of the vibrating wire strain gauge; α is the temperature coefficient of GCr15; T is the real-time monitoring temperature. For calibrating the reference temperature.

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