Dynamic penetration testing device and method based on effective penetration energy

Abstract

The invention provides a dynamic penetration testing device and method based on effective penetration energy, and relates to geotechnical engineering reconnaissance, the device comprises a support, a displacement sensor, a guide rod, a center penetrating hammer, a hammer seat, a probe rod, a pipe wrench, a cable, a processor, an energy collection connector and the like, and a strain and acceleration sensor is arranged in the energy collection connector; the strain and acceleration sensor is used for collecting the strain and acceleration fed back by the penetration of the sounding probe into the soil body, and calculating the effective penetration energy of the sounding probe in the hammering process based on the data. The method has the beneficial effects that the effective penetration energy in the successive hammering process is accurately obtained, and fine division of a stratum structure is facilitated; absorption and dissipation of hammering energy by hole depth, side friction resistance and drill rod vibration are eliminated in measurement data, and the measurement data are not limited by the penetration depth in the industry specification any more; proper hammer weight and drop distance can be flexibly selected according to the actual test depth; the automation degree is high, automatic data acquisition and processing can be achieved, and manual errors are effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering exploration equipment technology, and in particular to a dynamic penetration test device and method based on effective penetration energy. Background Technology

[0002] As one of the commonly used in-situ testing methods in geotechnical engineering investigation, the traditional dynamic penetration test uses a hammer of a certain mass (e.g., 63.5 kg) to fall freely from a certain height (e.g., 76 cm) to drive a probe of a certain shape and size into the soil. The number of hammer blows required to penetrate to a certain depth (e.g., 30 cm) is recorded, and the changes in the strata are judged based on the number of hammer blows. The physical and mechanical properties and parameters of the soil are estimated based on empirical relationships.

[0003] The dynamic hammer penetration test is an empirical test method. Currently, the maximum test depth that can be referenced in the standard is limited by the empirical correction coefficient of the rod length, which is generally no more than 20m. For more complex soil and rock masses (such as sand and gravel), there are still many problems, which are mainly manifested in the following aspects: (1) The energy of the dynamic penetration test is mainly determined by the hammer weight, drop distance and number of hammer blows. However, as the test depth increases, the energy dissipation generated in the transmission of the connecting rod, the energy dissipation generated by the friction of the connecting rod sidewall and the energy dissipation generated by the pore water pressure all have a significant impact on the accuracy of the test results. When a certain depth is reached, the existing standard's correction method for the effective energy transfer coefficient can no longer meet the test requirements; (2) In sand and gravel strata, there are sometimes large-sized particles. In this case, it is necessary to crush the large particles during the test. However, the energy consumed in the crushing process cannot truly reflect the soil condition, which can easily cause a large deviation in the test results; (3) The degree of automation is low, and automatic feedback and real-time recording cannot be realized, resulting in certain measurement errors. Summary of the Invention

[0004] In view of this, in order to solve the above-mentioned problems existing in current dynamic penetration tests, embodiments of the present invention provide a dynamic penetration test device and method based on effective penetration energy.

[0005] Embodiments of the present invention provide a dynamic penetration testing device based on effective penetration energy, comprising: The support frame can be erected on the soil. A guide rod, which is vertically movable and suspended on the bracket, is fitted with a hammer seat, and the bracket is equipped with a displacement sensor for collecting the displacement of the guide rod; A through-hole hammer, which is slidably sleeved on the guide rod and located above the hammer seat; The probe rod has its upper end detachably connected to the lower end of the guide rod, and the hammer seat abuts against the upper end of the probe rod; The device includes an energy harvesting connector, the upper end of which is connected to the lower end of the probe rod, and the lower end is connected to the probe head. The energy harvesting connector is equipped with a strain sensor and an acceleration sensor. The strain sensor and the acceleration sensor are used to collect the strain and acceleration feedback during the penetration of the probe into the soil, so as to calculate the effective penetration energy of each hammering process.

[0006] Furthermore, the energy harvesting connector includes a housing with an inner cavity, and the strain sensor and the acceleration sensor are disposed within the inner cavity, with the strain sensor arranged along the axial direction of the probe rod.

[0007] Furthermore, the upper and lower ends of the outer casing are respectively connected to the probe rod and the probe probe by threads.

[0008] Furthermore, the displacement sensor is a wire-type displacement gauge, which is suspended on the bracket. The wire-type displacement gauge is equipped with a displacement steel wire and a pull ring. The displacement steel wire is connected to the pull ring, and the pull ring is connected to the upper end of the guide rod.

[0009] Furthermore, it also includes a pipe wrench, which has a jaw for lowering the probe and the energy harvesting connector.

[0010] Furthermore, it also includes a processor, which is connected to the strain sensor and the acceleration sensor via a first cable and to the displacement sensor via a second cable.

[0011] Furthermore, the surface of the first cable is provided with length markings.

[0012] Furthermore, embodiments of the present invention also provide a dynamic penetration test method based on effective penetration energy, using the aforementioned dynamic penetration test apparatus based on effective penetration energy, and including the following steps: S1. Drill into the soil to the predetermined test location using a drilling rig, and set up the support at the predetermined test location; S2. Lower the probe rod and the energy harvesting connector so that the probe is a predetermined distance above the test position; S3. The guide rod is arranged above the probe rod, the upper end of the probe rod is connected to the lower end of the guide rod, the hammer seat abuts against the upper end of the probe rod, and a displacement sensor for collecting the displacement of the guide rod is arranged on the bracket. S4. After the core hammer is raised to a predetermined height along the guide rod, it is released freely. The core hammer strikes the hammer seat and drives the probe, the energy harvesting connector and the probe rod to penetrate the soil downwards. S5. Repeat step S4 multiple times, first inserting the probe downwards to the predetermined distance, and then inserting it to the required distance. S6. Obtain the strain collected by the strain sensor and the acceleration collected by the acceleration sensor during each hammer blow. Calculate the effective penetration energy of the probe into the soil during each hammer blow based on the integral of the strain and acceleration. ; in, F = kε , ε In response, k proportionality coefficient ，a For acceleration, t For time.

[0013] Furthermore, in step S4, the hammer is lifted and released using an automatic unhooking method.

[0014] The beneficial effects of the technical solutions provided by the embodiments of the present invention are as follows: 1. The present invention provides a dynamic penetration test device and method based on effective penetration energy. The device collects the strain and acceleration feedback of the penetration probe during each hammer blow by the probe through an energy acquisition connector and using strain and acceleration sensors installed inside the energy acquisition connector. Based on this strain and acceleration, the penetration energy of the probe during each hammer blow is accurately calculated, which helps to finely divide the stratigraphic structure and capture poor geological layers with relatively thin local thickness.

[0015] 2. The present invention provides a dynamic penetration test device and method based on effective penetration energy. Its measurement data objectively eliminates the absorption and dissipation of hammer energy by hole depth, side friction, and drill pipe vibration. The test results are not subject to human experience correction and are therefore no longer limited by the penetration depth in industry standards.

[0016] 3. The present invention provides a dynamic penetration test device and method based on effective penetration energy, which can flexibly select appropriate hammer weight and drop distance according to soil conditions and test requirements, without being limited to existing fixed hammer weight and drop distance, and meet the test requirements of complex and deep soil layers such as gravel and soil layers with large thickness.

[0017] 4. The present invention provides a dynamic penetration test device and method based on effective penetration energy, which has a high degree of automation and can automatically collect and process strain, acceleration and displacement data during the test process, effectively avoiding human error and ensuring accurate measurement of data during each hammering process. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a dynamic penetration test device based on effective penetration energy according to the present invention; Figure 2 This is a schematic diagram of the energy harvesting connector; Figure 3This is a cross-sectional view of the energy harvesting connector; Figure 4 This is a schematic diagram of the movable cover plate; Figure 5 This is a schematic diagram of a displacement sensor; Figure 6 It is a calibration curve diagram of the force-strain relationship; Figure 7 It is a curve showing the change of strain signal over time; Figure 8 It is a graph showing the change of acceleration signal over time.

[0019] In the diagram: 1. Soil; 2. Penetration probe; 3. Energy harvesting connector; 301. Housing; 302. Strain sensor; 303. Accelerometer; 304. Threaded connector; 306. Movable cover plate; 305 / 307. Threaded hole; 4. Probe rod; 5. Pipe wrench; 6. First cable; 7. Hammer base; 8. Guide rod; 9. Through hammer; 10. Displacement sensor; 1001. Displacement wire; 1002. Pull ring; 11. Second cable; 12. Support; 13. Processor. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the accompanying drawings. The following description presents a preferred embodiment of the various possible embodiments of the present invention, intended to provide a basic understanding of the invention, but not intended to identify key or decisive elements of the invention or to limit the scope of protection sought.

[0021] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0022] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures. Also, it should be understood that, for ease of description, the dimensions of the various parts shown in the figures are not drawn to actual scale.

[0024] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" 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 this invention based on the specific circumstances.

[0025] Please refer to Figure 1 The present invention provides a dynamic penetration test device based on effective penetration energy, including a support 12, a guide rod 8, a hammer 9, a probe 4, an energy harvesting connector 3, and a displacement sensor 10.

[0026] The support 12 can be erected on the soil 1. The support 12 is generally erected above the test position on the soil 1.

[0027] The guide rod 8 is vertically and movably suspended on the bracket 12. A hammer seat 7 is fitted onto the guide rod 8, and the hammer seat 7 is fixedly connected to the guide rod 8. The bracket 12 is equipped with a displacement sensor 10 for collecting the displacement of the guide rod 8. Specifically, the hammer seat 7 is fixedly connected to the guide rod 8, and movement of the hammer seat 7 will cause the guide rod 8 to move synchronously. Figure 5 As shown, the displacement sensor 10 is a wire-type displacement gauge, which is suspended on the bracket 12. The wire-type displacement gauge has a displacement steel wire 1001 and a pull ring 1002. The displacement steel wire 1001 is connected to the pull ring 1002, and the pull ring 1002 is connected to the upper end of the guide rod 8. The wire-type displacement gauge has a built-in return spring. The contraction force of the return spring keeps the displacement steel wire 1001 taut, ensuring accurate measurement of the displacement of the guide rod 8, that is, accurate measurement of the penetration amount.

[0028] The hammer 9 is slidably sleeved on the guide rod 8 and located above the hammer base 7. The hammer 9 is coaxially arranged with the guide rod 8 and can slide vertically along the guide rod 8, impacting the hammer base 7 when it slides to it.

[0029] The lower end of the guide rod 8 is detachably connected to the upper end of the probe rod 4, such as by a threaded connection, and the hammer seat 7 abuts against the upper end of the probe rod 4. The probe rod 4 is positioned along the downward extension of the guide rod 8. The lower end of the hammer seat 7 abuts against the upper end of the probe rod 4, so that when the hammer seat 7 is impacted, it can drive the probe rod 4 to move downward.

[0030] The upper end of the energy harvesting connector 3 is connected to the lower end of the probe rod 4, and the lower end is connected to the probe probe 2. The energy harvesting connector 3 is internally equipped with a strain sensor 302 and an acceleration sensor 303. The strain sensor 302 and the acceleration sensor 303 are used to collect the strain and acceleration of the probe probe 2 to calculate the effective penetration energy for each hammering process. Specifically, as shown... Figure 2 , 3 As shown in Figure 4, the energy harvesting connector 3 includes a housing 301 with an inner cavity. The strain sensor 302 and the acceleration sensor 303 are disposed within the inner cavity, with the strain sensor 302 arranged axially along the probe 4. The strain sensor 302 is a welded strain sensor 302, rigidly connected to the inner cavity by spot welding. The inner cavity has a groove, and the acceleration sensor 303 is embedded in the groove. The acceleration sensor 303 is bonded and fixed to the energy harvesting connector 3 with epoxy resin. At the same time, the cavity is filled with epoxy resin to seal the strain sensor 302 and the acceleration sensor 303, effectively isolating them from moisture. The outer casing 301 is also provided with a movable cover plate 306. The movable cover plate 306 and the outer casing 301 are respectively provided with threaded holes 307 and 305. The threaded holes on the movable cover plate 306 and the outer casing 301 are aligned and connected by bolts, so that the movable cover plate 306 covers the inner cavity and encloses the strain sensor 302 and the acceleration sensor 303 inside the inner cavity.

[0031] In some embodiments, both the upper and lower ends of the energy harvesting connector 3 are detachable, and the upper and lower ends of the housing 301 are respectively threaded to the probe rod 4 and the probe 2. Both the upper and lower ends of the housing 301 are provided with threaded connectors 304, which are respectively connected to the probe rod 4 and the probe 2.

[0032] To facilitate the accurate lowering of the probe rod 4 and the energy harvesting connector 3, the dynamic penetrating test device based on effective penetration energy of the present invention further includes a pipe wrench 5. The pipe wrench 5 is provided with a bayonet, through which the penetrating probe 2, the energy harvesting connector 3 and the probe rod 4 can be lowered sequentially.

[0033] Furthermore, to achieve automatic acquisition and processing of data such as displacement, strain, and acceleration, the dynamic penetrating test device based on effective penetration energy of the present invention further includes a processor 13. The processor 13 is connected to the strain sensor 302 and the acceleration sensor 303 via a first cable 6, and to the displacement sensor 10 via a second cable 11. The surface of the first cable 6 is provided with length scale markings. For example, the processor 13 is selected as a computer. The computer can automatically acquire the strain data collected by the strain sensor 302, the acceleration data collected by the acceleration sensor 303, and the displacement data collected by the displacement sensor 10. It can calculate the effective penetration energy of each hammering process based on strain and acceleration, and determine the penetration distance based on displacement, thereby realizing automatic data acquisition and processing throughout the entire test process and ensuring accurate measurement of data during each hammering process.

[0034] Furthermore, embodiments of the present invention also provide a dynamic penetration test method based on effective penetration energy, using the aforementioned dynamic penetration test apparatus based on effective penetration energy, and including the following steps: S1. Drill into the soil 1 to the predetermined test position using a drilling rig, and set up the support 12 at the predetermined test position.

[0035] S2. Lower the probe rod 4 and the energy harvesting connector 3 so that the probe probe 2 is a predetermined distance above the test position. Here, the energy harvesting connector 3, the probe rod 4, and the probe probe 2 are pre-connected, and then the probe rod 4 is lowered step by step through the clamp of the pipe clamp 5 so that the probe probe 2 is a predetermined distance above the test position. The predetermined distance can be set according to the test requirements; in this exemplary embodiment, it is set to 15cm.

[0036] S3. The guide rod 8 is arranged above the probe rod 4. The upper end of the probe rod 4 is threadedly connected to the lower end of the guide rod 8. The hammer seat 7 abuts against the upper end of the probe rod 4. A displacement sensor 10 for collecting the displacement of the guide rod 8 is arranged on the bracket 12.

[0037] S4. After lifting the mandrel 9 to a predetermined height along the guide rod 8, it is released freely. The mandrel 9 strikes the hammer seat 7 and drives the probe 2, the energy harvesting connector 3, and the probe rod 4 downward into the soil 1. Here, the mandrel 9 can be lifted and released using an automatic release mechanism. The predetermined height can be set according to the experimental needs; in this exemplary embodiment, it is set to 0.76m.

[0038] S5. Repeat step S4 multiple times, first inserting the probe 2 downwards a predetermined distance, then inserting it to the required distance. The predetermined distance is the distance reserved during the lowering in step 2, which is 15cm in this case. The required distance can be set according to the experimental needs; in this exemplary embodiment, the required distance is set to 30cm. Terminate the experiment after inserting the probe to the required distance.

[0039] S6. Acquire the strain detected by the strain sensor 302 and the acceleration detected by the acceleration sensor 303 each time the hammer 9 strikes the core. The collected strain data is as follows: Figure 7 As shown, the acceleration data is as follows Figure 8 As shown, the effective penetration energy for each hammering process is calculated based on strain and acceleration. ; in, F = kε , ε In response, k For example, the proportionality coefficient. Figure 6 As shown, the scaling factor k It can be determined through a pre-defined force-strain correspondence. a For acceleration, t For time.

[0040] In this document, the directional terms such as front, back, top, and bottom are defined based on the position of the components in the accompanying drawings and their relative positions to each other, solely for the purpose of clarity and convenience in expressing the technical solution. It should be understood that these are relative concepts and can vary depending on different methods of use and placement; the use of these directional terms should not limit the scope of protection claimed in this application.

[0041] Where there is no conflict, the embodiments and features described above can be combined with each other. The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or 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 dynamic penetration testing device based on effective penetration energy, characterized in that, include: The support frame can be erected on the soil. A guide rod, which is vertically movable and suspended on the bracket, is fitted with a hammer seat, and the bracket is equipped with a displacement sensor for collecting the displacement of the guide rod; A through-hole hammer, which is slidably sleeved on the guide rod and located above the hammer seat; The probe rod has its upper end detachably connected to the lower end of the guide rod, and the hammer seat abuts against the upper end of the probe rod; The device includes an energy harvesting connector, the upper end of which is connected to the lower end of the probe rod, and the lower end is connected to the probe head. The energy harvesting connector is equipped with a strain sensor and an acceleration sensor. The strain sensor and the acceleration sensor are used to collect the strain and acceleration feedback during the penetration of the probe into the soil, so as to calculate the effective penetration energy of each hammering process.

2. The dynamic penetration test device based on effective penetration energy as described in claim 1, characterized in that: The energy harvesting connector includes a housing with an inner cavity, and the strain sensor and the acceleration sensor are disposed within the inner cavity, with the strain sensor arranged along the axial direction of the probe rod.

3. The dynamic penetration test device based on effective penetration energy as described in claim 2, characterized in that: The upper and lower ends of the outer casing are respectively connected to the probe rod and the probe probe by threads.

4. The dynamic penetration test device based on effective penetration energy as described in claim 1, characterized in that: The displacement sensor is a wire-type displacement meter, which is suspended on the bracket. The wire-type displacement meter is equipped with a displacement steel wire and a pull ring. The displacement steel wire is connected to the pull ring, and the pull ring is connected to the upper end of the guide rod.

5. The dynamic penetration test device based on effective penetration energy as described in claim 1, characterized in that: It also includes a pipe wrench, which has a jaw for lowering the probe and the energy harvesting connector.

6. The dynamic penetration test device based on effective penetration energy as described in claim 1, characterized in that: It also includes a processor, which is connected to the strain sensor and the acceleration sensor via a first cable and to the displacement sensor via a second cable.

7. The dynamic penetration test device based on effective penetration energy as described in claim 6, characterized in that: The first cable has length markings on its surface.

8. A dynamic penetration test method based on effective penetration energy, characterized in that: Using a dynamic penetration test apparatus based on effective penetration energy as described in any one of claims 1-7, and comprising the following steps: S1. Drill into the soil to the predetermined test location using a drilling rig, and set up the support at the predetermined test location; S2. Lower the probe rod and the energy harvesting connector so that the probe is a predetermined distance above the test position; S3. The guide rod is arranged above the probe rod, the upper end of the probe rod is detachably connected to the lower end of the guide rod, the hammer seat abuts against the upper end of the probe rod, and a displacement sensor for collecting the displacement of the guide rod is arranged on the bracket. S4. After the core hammer is raised to a predetermined height along the guide rod, it is released freely. The core hammer strikes the hammer seat and drives the probe, the energy harvesting connector and the probe rod to penetrate the soil downwards. S5. Repeat step S4 multiple times, first inserting the probe downwards to the predetermined distance, and then inserting it to the required distance. S6. Obtain the strain collected by the strain sensor and the acceleration collected by the acceleration sensor during each hammer blow. Integrate the strain and acceleration data to obtain the effective penetration energy of the probe into the soil during each hammer blow. ； in, F=kε , ε In response, k This is the proportionality coefficient. a For acceleration, t For time.

9. The dynamic penetration test method based on effective penetration energy as described in claim 8, characterized in that: In step S4, the hammer is lifted and released using an automatic unhooking method.

Images