A three-dimensional vector measurement sphere with a fixed base

Abstract

The present invention belongs to the field of stress testing and relates to a three-dimensional vector measurement sphere with a fixed base, including a spherical base, a plurality of pressure modules arranged on the spherical base, and a multi-core cable; a wire matching the number of the pressure modules is arranged in the multi-core cable, and each pressure module is connected to one wire; a fixing system is further included, and the fixing system includes a positioning rod passing through the spherical base and a base under-reamer arranged at the bottom of the spherical base; an anchor rod for fixing is arranged on one side of the base under-reamer away from the spherical base. The present invention fixes the sensor to the surrounding soil mass, and it is not easy to separate from the surrounding soil mass under the action of explosion shock waves, thereby improving the measurement accuracy. The positioning rod on the upper part of the sensor plays a role in assisting the embedding, and it can extend into the measuring hole or can be held by hand to realize the observation and adjustment of the measuring point direction.

Description

Technical Field

[0001] The present invention belongs to the field of stress testing and relates to a three-dimensional vector measurement sphere with a fixed base. Background Art

[0002] In geotechnical engineering, affected by complex external loads and the actual engineering environment, the stress state of soil is extremely complex. However, as a porous and multiphase medium, the mechanical properties of soil are significantly affected by factors such as stress magnitude, stress direction, stress path, and stress history. In order to characterize the stress state of soil, the stress at a point is usually expressed as a vector. In three-dimensional space, a vector has six degrees of freedom, so six independent variables are required to characterize the stress state at a point. In the principal stress space, these six degrees of freedom are reflected in the three magnitudes of the principal stresses and the three direction vectors of the principal stress coordinate system. Therefore, only by accurately obtaining the stress magnitude and direction at a point in soil simultaneously can the stress state be characterized, and then scientific safety and stability evaluation of geotechnical engineering and construction maintenance analysis can be carried out.

[0003] Compressive stress testing usually uses piezoresistive sensors for measurement. In general civil engineering, long-term static loads, construction loads, traffic loads, and other low-frequency loads are mainly measured. In special engineering, it is mainly for high-frequency loads such as explosion and impact loads and earthquake loads. The latter has high requirements for indicators such as the integrity, stiffness, and natural frequency of the sensor.

[0004] The earth pressure cell needs to be manually buried inside the soil mass. Whether it is the currently widely used one-way earth pressure cell or the existing three-dimensional measurement sphere, they both exist in the form of independent individuals in specific implementations, and usually use the method of "manual hole digging - handheld embedding - backfilling and ramming".

[0005] Since the one-way earth pressure cell or the three-dimensional measurement sphere is directly placed in the measurement hole, the backfilled soil is relatively loose. Due to the relatively large density of the sensor and the relatively small density of the soil, under strong impact such as earthquake or explosion, the sensor is extremely likely to have a large displacement, causing the sensitive surface of the sensor to separate from the soil, and thus resulting in the measured data being much smaller than the actual pressure in the soil. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a three-dimensional vector measurement sphere with a fixed base to solve the problem that the existing sensors may have a large displacement under explosion and impact.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A three-dimensional vector measurement sphere with a fixed base, comprising a spherical base, a plurality of pressure modules arranged on the spherical base, and a multi-core cable; a wire matching the number of the pressure modules is arranged in the multi-core cable, and each pressure module is connected to one wire; a fixing system is further included, and the fixing system includes a positioning rod passing through the spherical base and a base bottom expansion arranged at the bottom of the spherical base; an anchor rod for fixing is arranged on one side of the base bottom expansion away from the spherical base.

[0009] Optionally, the base bottom expansion includes a connecting part and a supporting part, and the anchor rod is arranged on the supporting part; the cross-sectional dimension of the supporting part is larger than that of the connecting part.

[0010] Optionally, the pressure module includes a pressure-sensitive surface and a silicon piezoresistive module which are matched with each other, and the pressure-sensitive surface faces the outside of the spherical base.

[0011] Optionally, a groove for assembling the pressure module is arranged on the spherical base, the pressure module is arranged in the groove, and the number of the grooves is greater than or equal to the number of the pressure modules.

[0012] Optionally, a wire hole for the wire to pass through is arranged in the groove.

[0013] Optionally, the multi-core cable includes a cable shielding layer and a cable insulating layer wrapped outside the cable shielding layer.

[0014] Optionally, the wire includes a core wire, a wire shielding layer wrapped outside the core wire, and a wire insulating layer wrapped outside the wire shielding layer.

[0015] Optionally, there are 8 setting points for the pressure modules, including 2 groups. The first group includes 4 setting points, which are evenly distributed on the symmetry plane of the spherical base, and this symmetry plane is perpendicular to the positioning rod; the axis of the positioning rod is the Z axis, and the X axis and the Y axis are selected on this symmetry plane to form a Cartesian coordinate system; the third group includes the remaining 4 setting points, and the normal positions thereof are the isoclinic lines of the Cartesian coordinate system.

[0016] Optionally, at least 6 pressure modules are provided.

[0017] Optionally, the number of wires in the multi-core cable is at least one more than the number of pressure modules.

[0018] The beneficial effects of the present invention are as follows:

[0019] The sensors in the prior art are not fixed and are prone to separation from the surrounding soil under the action of the explosion shock wave, resulting in a smaller measured soil pressure value. However, the present invention fixes the sensor through a fixing system to ensure that the sensor remains in its original measurement position under the action of the explosion shock wave, thus ensuring the accuracy of the measured soil pressure value.

[0020] The sensors in the prior art are relatively small in size. When the hole depth is large, it is difficult to operate manually when burying them. When burying the sensors, manual holding is relied on for orientation. However, when backfilling the soil, after the hand is released, the sensors will inevitably be disturbed to a certain extent under the compaction effect, and the direction of the measuring point will probably change, resulting in a decrease in the accuracy of the final result. The present invention can directly hold and bury the sensors through the positioning rod, and it is also convenient to measure the verticality of the positioning rod to ensure that the burial orientation and angle of the soil pressure sensor do not shift during the burial process.

[0021] In the prior art, the overall shape of the sensor is spherical. When backfilling after burial, it is extremely easy to have a cavity between the bottom of the spherical sensor and the bottom soil, further reducing the anchoring of the sensor to the surrounding soil and making it easier to move. The present invention strengthens the anchoring of the sensor to the surrounding soil by setting up a fixing system.

[0022] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, they will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0024] Figure 1 is the longitudinal sectional view of the present invention;

[0025] Figure 2 is the longitudinal sectional view of the base;

[0026] Figure 3 is the equatorial sectional view of the sensor;

[0027] Figure 4 is the exploded equatorial sectional view of the sensor;

[0028] Figure 5 is the structure diagram of the pressure module;

[0029] Figure 6 is the exploded view of the pressure module;

[0030] Figure 7Schematic diagram of a multi-core cable structure;

[0031] Figure 8 Longitudinal sectional view of the fixing system;

[0032] Figure 9 Transverse sectional view of the enlarged bottom of the base;

[0033] Figure 10 Schematic diagram after the present invention is buried. Detailed implementation manners

[0034] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0035] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0036] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0037] Please refer to Figures 1-10, the present invention relates to a three-dimensional vector measurement sphere with a fixed base, which includes a spherical base 1, a pressure module 2, and a fixing system 3. The spherical base 1 is provided with a positioning rod hole 11, a base groove 12, a wire hole 13, a base hole 14, and an internal cavity 15. The pressure module 2 is composed of a pressure-sensitive surface 21, a silicon piezoresistive module 22, a wire 23, and a multi-core cable 24. The fixing system 3 is composed of a positioning rod 31, a connecting part 32, a supporting part 33, an anchor rod 34, and an anchoring tip 35.

[0038] The spherical base 1 is integrally a hollow sphere, and 8 base grooves 12 are reserved on its outer surface. A wire hole 13 communicating with the internal cavity 15 of the spherical base 1 is reserved at the bottom of each groove for the routing of the wire 23.

[0039] The positioning rod 31, the connecting part 32, and the supporting part 33 of the fixing system 3 can be integrally manufactured. An anchor rod 34 is arranged below the supporting part 33, and the front section of the anchor rod 34 is made into an anchoring tip 35. The supporting part 33 can effectively increase the torsional resistance of the overall structure. The anchor rod 34 and the anchoring tip 35 are embedded into the soil body to form a bottom support.

[0040] The positioning rod 31 passes through the positioning rod hole 11 of the spherical base 1 and is fixed by cementing; the connecting part 32 passes through the base hole 14 and is fixed by cementing. The length of the positioning rod 31 can be determined according to the actual embedding depth of the sensor.

[0041] The multi-core cable 24 includes an insulating layer 241 and a shielding layer 242, and internally contains at least 7 wires 23. Each wire 23 is a four-core shielded cable, and the wire 23 from the outside to the inside is respectively a wire insulating layer 231, a wire shielding layer 232, and a silver-plated core wire 233.

[0042] There are a total of 8 base grooves 12. Assuming the direction of the positioning rod 31 is the z direction, the x and y directions are selected on the equatorial plane perpendicular to the z direction to jointly form a Cartesian coordinate system. The base grooves 12 can be divided into two groups. The first group has 4 in total, which are evenly distributed along the x-y plane, and the normal direction is parallel to the x-axis or the y-axis; the second group has 4 in total, which are located between the positioning rod 31 and the second group, and its normal is the isoclinic line of the x-y-z coordinate system. As described above, in order to facilitate the determination of the orientation, a coordinate diagram is drawn on the top of the positioning rod 31, and its x and y directions are consistent with the aforementioned x-y-z coordinate system.

[0043] The pressure module 2 is encapsulated on the base groove 12. One end of the wire 23 is connected to the silicon piezoresistive module 22, and one end passes through the wire 241 hole and is connected to the multi-core cable 24. The multi-core cable 24 is inside the positioning rod 31. One end passes through the wire hole 241, and the other end passes through the top of the positioning rod 31 and is connected to an external data acquisition device. The multi-core cable 24 is used to transmit the piezoelectric signal of the pressure module to the acquisition end.

[0044] To minimize the influence of the sensor on the stress distribution, according to the existing technical capabilities, the diameter of the pressure module is about 25 mm, and the depth of the base groove is 3 mm. Accordingly, the diameter of the spherical base 1 is about 60 - 70 mm. The internal cavity 15 inside the spherical base 1 can be filled and sealed with hot melt adhesive or glass glue to fix the internal components.

[0045] To bury the vectorized three-dimensional principal stress measurement sphere at the position where stress needs to be measured, during the implementation process, the soil above the measurement point can be removed by excavation or drilling methods. Then, hold the positioning rod 31 and insert the entire sensor into the measurement hole. Adjust the normal direction of each pressure module 2 by rotating the positioning rod 31 to ensure that the measurement point direction is the designed direction.

[0046] After the orientation is determined, embed the anchoring tip 35 into the soil at the bottom of the measurement hole. To improve the coordination between the measurement device and the soil, try to embed all the anchor rods 34 into the soil. If necessary, use a soft wooden hammer to tap the top of the positioning rod 31. After the bottom is fixed, gradually backfill the soil in the measurement hole and tamp it to complete the burying operation.

[0047] During the measurement operation, it is necessary to collect data from 4 sensors located on the isoclinic line in the x - y - z coordinate system. One data can be collected from each of the 2 sensors located on the x - axis and y - axis respectively according to actual needs, that is, a total of 6 sensors' data can be collected. The specific calculation method after data collection is as follows:

[0048] Mark the 6 sensors as 10, 20, 30, 40, 50, 60 respectively, and the measured stresses are σ 10 、σ 20 、σ 30 、σ 40 、σ 50 、σ 60 , and the normal directions of each pressure module are {α i , β i , γ i}(i = 10, 20, 30, 40, 50, 60). Then the measured three-dimensional stress state at the measurement point is recorded in matrix form in the level - geomagnetic coordinate system as:

[0049] {σ ij} = {σ x σ y σ z σ xy σ yz σ zx}

[0050] = {σ 10 σ 20 σ 30 -σ 40 -σ50 -σ 60} (1)

[0051] Subsequent calculations of stress are basic calculations in this field, and detailed content will not be elaborated.

[0052] In the present invention, the sensor is fixed to the surrounding soil through the anchoring system at the bottom and the positioning rod at the upper part, and is not easily separated from the surrounding soil under the action of the explosion shock wave, thereby improving the measurement accuracy. For deeper measurement points, the length of the positioning rod can be appropriately increased. The positioning rod at the upper part of the sensor plays an auxiliary role in burying, and can extend into the measurement hole or be held by hand to observe and adjust the direction of the measurement point. The whole sensor is spherical, and the bottom is connected to the base as a whole. The places in contact with the soil are all obtuse angles, avoiding the problem that there is extremely likely to be a cavity between the bottom of the spherical sensor and the bottom soil, and improving the bonding force between the sensor and the soil.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A three-dimensional vector measurement sphere with a fixed base, characterized in that, It includes a spherical base, several pressure modules arranged on the spherical base, and a multi-core cable; the spherical base is provided with a positioning rod hole, a base groove, a wire hole, a base hole, and an internal cavity; the multi-core cable is provided with wires matching the number of the pressure modules, and each pressure module is connected to one wire; it further includes a fixing system, the fixing system includes a positioning rod passing through the spherical base and a base under-reaming arranged at the bottom of the spherical base; the positioning rod passes through the positioning rod hole of the spherical base and is fixed by cementing; the connecting part passes through the base hole of the spherical base and is fixed by cementing; an anchor rod for fixing is arranged on one side of the base under-reaming away from the spherical base; there are 8 setting points for the pressure modules, including 2 groups, the first group includes 4 setting points, which are evenly distributed on the symmetry plane of the spherical base, and this symmetry plane is perpendicular to the positioning rod; the axis of the positioning rod is the Z-axis, and the X-axis and the Y-axis are selected on this symmetry plane to form a Cartesian coordinate system; the second group includes the remaining 4 setting points, and their normal positions are the isoclinic lines of the Cartesian coordinate system; the base under-reaming includes a connecting part and a supporting part, and the anchor rod is arranged on the supporting part; the cross-sectional dimension of the supporting part is larger than that of the connecting part; the sensor is spherical as a whole, the bottom of the spherical base is connected to the base under-reaming as a whole, and the places in contact with the soil are all obtuse angles.

2. The three-dimensional vector measurement sphere with a fixed base as described in claim 1, characterized in that, The pressure module includes a pressure-sensitive surface and a silicon piezoresistive module that cooperate with each other, and the pressure-sensitive surface faces the outside of the spherical base.

3. The three-dimensional vector measurement sphere with a fixed base as described in claim 1, characterized in that, The spherical base is provided with grooves for assembling the pressure modules, the pressure modules are arranged in the grooves, and the number of the grooves is greater than or equal to the number of the pressure modules.

4. The three-dimensional vector measurement sphere with a fixed base as described in claim 3, characterized in that, Wire holes for wires to pass through are opened in the grooves.

5. The three-dimensional vector measurement sphere with a fixed base as described in claim 1, characterized in that, The multi-core cable includes a cable shielding layer and a cable insulating layer wrapped outside the cable shielding layer.

6. The three-dimensional vector measurement sphere with a fixed base as described in claim 1, wherein, The wire includes a core wire, a wire shielding layer wrapped outside the core wire, and a wire insulating layer wrapped outside the wire shielding layer.

7. The three-dimensional vector measurement sphere with a fixed base as described in claim 1, wherein There are at least 6 pressure modules.

8. The three-dimensional vector measurement sphere with a fixed base as described in claim 1, characterized in that, The number of wires in the multi-core cable is at least one more than the number of the pressure modules.

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