Heavy dynamic penetrometer capable of reducing rebound of drop hammer

Abstract

The utility model discloses a heavy dynamic penetrometer capable of reducing rebound of a drop hammer, which comprises the drop hammer, a probe rod, an electromagnetic buffer device and a lifting device, and a plurality of layers of composite buffer gaskets are respectively arranged between a first connector and the drop hammer and between a second connector and the probe rod; a cross-shaped separation structure for separating the rod body into four units is arranged in the probe rod; an electromagnetic buffer device is arranged above an impact point at the top of the probe rod; the electromagnetic buffer device comprises a first electromagnetic coil, a second electromagnetic coil and a connecting rod; magnetic fields in opposite directions are formed by using the Lenz's law to restrain drop hammer rebound; the two sensors are arranged below the electromagnetic coil at the top of the probe rod, electrically connected with the electromagnetic coil and used for controlling the electromagnetic coil to be powered on and off; the lifting device comprises an electric pulley arranged at the top of the instrument and four lifting ropes penetrating through the drop hammer body. According to the utility model, the rebound of the drop hammer is effectively reduced, the measurement of the hammering number and the penetration depth is more accurate, and powerful support is provided for long-term monitoring and quality evaluation of engineering geology.

Description

Technical Field

[0001] This utility model relates to the field of foundation testing technology, specifically a heavy-duty dynamic penetrometer that reduces the rebound of a falling hammer. Background Technology

[0002] Heavy dynamic cone penetrometers (HPPs) are commonly used instruments in in-situ testing of foundation soils, widely applied in cone penetration tests and standard penetration tests. This equipment uses the impact force generated by the free fall of a hammer to penetrate the soil, and assesses the soil properties based on the number of blows required to reach a specified penetration depth. Currently, there are two main types of HPPs on the market: manual and electric. Although electric equipment can reduce the workload of testing personnel, it still has significant shortcomings in dealing with the problem of hammer rebound.

[0003] Drop hammer rebound is a common phenomenon in practical operations, especially in dense soils such as medium-coarse sand and gravelly soils. When the hammer's impact energy acts on the probe, causing it to penetrate the soil, the soil exerts a reaction force on the probe that is equal in magnitude and opposite in direction. This reaction force is transmitted to the drop hammer through the probe. If the reaction force is greater than the remaining kinetic energy of the drop hammer, it will rebound. Furthermore, while the hollow structure of the probe facilitates replacement and maintenance, in heavy and super-heavy dynamic penetration tests, the probe's elastic deformation is significant. During the recovery period, it tends to exert an upward force on the drop hammer, further increasing the probability of rebound.

[0004] Drop hammer bounce not only interferes with the accuracy of test data, causing deviations in hammer count and penetration depth measurements, but also affects the consistency of testing and reduces work efficiency. Prolonged drop hammer bounce can also damage instruments and equipment, increasing maintenance costs and equipment failure rates. Therefore, there is an urgent need for a heavy-duty dynamic penetrometer that can effectively reduce drop hammer bounce to improve the accuracy of test data and the stability of the equipment.

[0005] In summary, while existing heavy-duty dynamic penetrometers have certain advantages in data acquisition and equipment stability, they have significant shortcomings in addressing the problem of hammer bounce. This utility model patent aims to provide a heavy-duty dynamic penetrometer that reduces hammer bounce, thereby solving the aforementioned problem. Utility Model Content

[0006] To address the shortcomings of existing technologies, this utility model discloses a heavy-duty dynamic penetrometer that reduces the rebound of the falling hammer, thereby solving the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model provides the following technical solution: a heavy-duty power penetrometer for reducing hammer rebound, comprising a probe rod, a hammer, an electromagnetic buffer device, and a lifting device. The lower end of the hammer has a first connector, and the upper end of the probe rod has a second connector. Multiple layers of composite buffer pads are respectively provided between the first connector and the hammer, and between the second connector and the probe rod. The probe rod has a cross-shaped partition structure inside that divides the rod body into four units. An electromagnetic buffer device is provided above the impact point at the top of the probe rod.

[0008] The electromagnetic buffer device includes a first electromagnetic coil, a second electromagnetic coil, and a connecting rod. The first electromagnetic coil is installed on the surface of the falling hammer. The second electromagnetic coil is installed on the top of the probe rod, and the second electromagnetic coil is higher than the impact point of the first connector and the second connector. The second electromagnetic coil is supported by connecting rods on both sides of the probe rod. The currents of the two electromagnetic coils are in opposite directions, and Lenz's law is used to form magnetic fields in opposite directions to suppress the rebound of the falling hammer. Two sensors are located below the electromagnetic coil at the top of the probe rod. The sensors are electrically connected to the electromagnetic coil and control its power supply.

[0009] The lifting device includes an electric pulley located at the top of the instrument and four lifting ropes running through the drop hammer body.

[0010] Preferably, the composite buffer pad has a layered composite structure, comprising a high-damping rubber layer and a high-strength fiber layer; wherein the high-damping rubber layer directly contacts the top of the probe, and the high-strength fiber layer covers the outside of the rubber layer.

[0011] Preferably, the cross-shaped partition structure of the probe is a four-cavity structure with uniformly distributed cross-sections.

[0012] Preferably, the installation positions of the first electromagnetic coil and the second electromagnetic coil are such that when the drop hammer is in the starting position of free fall, the two coils are on the same axis.

[0013] Preferably, the second electromagnetic coil is connected to a current controller; the current controller is a programmable logic controller with multi-level current adjustment function.

[0014] Preferably, the connecting rod is an L-shaped metal rod, with its upper end connected to the second electromagnetic coil and its lower end connected to the side of the probe rod via a buckle.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0016] 1. This invention effectively reduces hammer rebound, making the measurement of hammer blow count and penetration depth more accurate. Traditional heavy-duty dynamic penetrometers suffer from hammer rebound, leading to errors in hammer blow count and inaccurate penetration depth measurement due to abnormal hammer movement. The improved equipment ensures stable hammer movement, allowing each hammer blow to accurately reflect soil resistance, improving the accuracy of in-situ detection data, and avoiding engineering design errors caused by inaccurate data.

[0017] 2. The reduced rebound of the falling hammer in this invention makes the testing process smoother. Previously, due to falling hammer rebound, operators had to frequently pause testing to check equipment, adjust parameters, and even retest at different points, severely impacting work efficiency. Now, testing can be conducted continuously, significantly improving work efficiency. Especially in large-scale geotechnical engineering testing projects, it can greatly shorten the testing cycle and accelerate the testing progress.

[0018] 3. This invention enables the dynamic penetrometer to adapt to different types of soil and complex construction environments. Whether it's low-strength soil in soft foundations or high-strength soil in hard rock strata, by adjusting the current intensity, the electromagnetic buffer device can effectively reduce the rebound height of the hammer, and the optimized structure of the probe rod can stably withstand different levels of reaction force, ensuring smooth testing. Not only in common dense sand and clay, but also in complex terrains such as mountainous areas (gravelly soil) and glaciers (tillage), the heavy-duty dynamic penetrometer can still operate reliably, reducing hammer rebound and improving the equipment's versatility.

[0019] 4. This invention can improve the stability and accuracy of dynamic penetration test data. The stable testing process and accurate data make the test data from different test points and at different times more comparable. The data is also more convincing when monitoring changes in foundation soil properties over time or assessing the uniformity of foundations in different areas, providing strong support for long-term monitoring and quality assessment of engineering geology.

[0020] 5. This invention reduces the impact of the falling hammer's rebound on the equipment, lowering the risk of wear and damage to key components of the power penetrometer. The optimized structure of the probe enhances its resistance to deformation; probes that were previously prone to bending and deformation under frequent hammer blows can now have a significantly extended service life. The buffer pad effectively protects the contact area between the falling hammer and the probe, reducing wear and lowering equipment maintenance and replacement costs. Attached Figure Description

[0021] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0022] In the attached diagram:

[0023] Figure 1This is a schematic diagram of the overall structure of the heavy-duty dynamic penetrometer of this utility model;

[0024] Figure 2 This is a schematic diagram of the structure of the drop hammer and probe of this utility model;

[0025] Figure 3 This is an internal cross-sectional view of the probe of this utility model;

[0026] The following are the labels in the diagram: 1. Drop hammer; 101. First connector; 2. Probe rod; 201. Second connector; 301. First electromagnetic coil; 302. Second electromagnetic coil; 303. Connecting rod; 304. Sensor; 305. Current controller; 401. Electric pulley; 402. Lifting rope; 5. Composite buffer pad; 6. Cross-shaped partition structure; 7. Wire. Detailed Implementation

[0027] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0028] Example: Figures 1-3 As shown, a heavy-duty dynamic penetrometer for reducing hammer rebound includes a probe rod 2, a hammer 1, an electromagnetic buffer device, and a lifting device. The lower end of the hammer 1 has a first connector 101, and the upper end of the probe rod 2 has a second connector 201. Multi-layer composite buffer pads 5 are respectively provided between the first connector 101 and the hammer 1, and between the second connector 201 and the probe rod 2. The composite buffer pads 5 have a layered composite structure, comprising a high-damping rubber layer and a high-strength fiber layer. The high-damping rubber layer directly contacts the top of the probe rod 2, and the high-strength fiber layer covers the outside of the rubber layer. The high-damping rubber layer uses high-damping rubber, which possesses unique viscoelasticity, enabling it to convert impact energy into heat energy and dissipate it in a very short time, effectively weakening the impact peak. When subjected to a sudden, powerful impact, the friction between the high-damping rubber molecular chains generates heat, rapidly absorbing energy and significantly reducing the force transmitted to the hammer 1. The outer high-strength fiber layer, such as aramid fiber, has high tensile strength and good toughness, and can withstand long-term impact stress, preventing the gasket from tearing or breaking under repeated impacts, thus ensuring the durability of the cushioning performance.

[0029] A cross-shaped partition structure 6 is located inside the probe rod 2, dividing the rod body into four units. This cross-shaped partition structure 6 is a four-cavity structure with uniformly distributed cross-sections. This structure greatly enhances the bending and torsional resistance of the probe rod 2. From a mechanical perspective, when the probe rod 2 is subjected to lateral bending force, the cross-shaped structure forms a stable support system inside the rod, limiting the deformation of the rod wall and converting the external bending moment into the internal force of the support structure. This improves the rod's bending resistance, avoids local stress concentration, maintains the overall shape stability of the probe rod 2, reduces the torsional deformation of the probe rod 2, and consequently reduces the rebound of the drop hammer 1 caused by the deformation of the probe rod 2.

[0030] An electromagnetic buffer device is provided above the impact point at the top of the probe rod 2; the electromagnetic buffer device includes a first electromagnetic coil 301, a second electromagnetic coil 302, and a connecting rod; the first electromagnetic coil 301 is installed on the surface of the drop hammer 1; the second electromagnetic coil 302 is installed at the top of the probe rod 2, and the second electromagnetic coil 302 is higher than the impact point position of the first connector 101 and the second connector 201, and the second electromagnetic coil 302 is supported by connecting rods 303 provided on both sides of the probe rod 2; the connecting rod 303 is an L-shaped metal rod, the upper end of which is connected to the second electromagnetic coil 302, and the lower end is connected to the side of the probe rod 2 by a buckle; and the first electromagnetic coil 301 and the second electromagnetic coil 302 are connected to the impact point at the top of the probe rod 2, and the second electromagnetic coil 302 is ... The currents on both sides of coil 302 are in opposite directions, forming opposing magnetic fields using Lenz's law to suppress the rebound of the falling hammer 1. The installation positions of the first electromagnetic coil 301 and the second electromagnetic coil 302 ensure that when the falling hammer 1 is at the starting position of free fall, the two coils are on the same axis, and the falling distance of the falling hammer 1 is 76cm. The electromagnetic buffer device utilizes the principle of electromagnetic induction, installing electromagnetic coils at positions slightly above the height of the falling hammer 1 and the top impact point of the probe rod 2, with the currents flowing in opposite directions. Lenz's law is used to form opposing magnetic fields, suppressing the rebound of the falling hammer 1. This is a novel application of physical principles, reducing the rebound of the falling hammer 1 without affecting its free fall impact. Two sensors 304 are installed below the electromagnetic coil at the top of the probe rod 2 to precisely control the energizing timing of the electromagnetic coil. The electromagnetic coil is de-energized when the falling hammer 1 is in free fall to avoid interference with the accumulation of impact potential energy; after the falling hammer 1 passes, the electromagnetic coil is energized to generate a suppressing magnetic field. This precise collaborative working mechanism is a key innovation of the patent, greatly improving the working efficiency and testing accuracy of the heavy-duty dynamic penetrometer. Two sensors 304 are located below the electromagnetic coil at the top of the probe rod 2. The sensors 304 are electrically connected to the electromagnetic coil and control its power supply. The second electromagnetic coil 302 is connected to a current controller 305 via wire 7. The current controller 305 is a programmable logic controller with multi-level current adjustment function. The lifting device includes an electric pulley 401 located at the top of the instrument and four lifting ropes 402 running through the body of the drop hammer 1. The lifting device is connected to the current controller 305 via wire 7.

[0031] During the dynamic penetration test, the drop hammer 1 falls freely from a set height, generating a powerful impact force. When the drop hammer 1 contacts the top of the probe rod 2, the multi-layer composite buffer pad 5 first comes into play. The high-damping rubber quickly absorbs the impact energy and converts it into heat energy, effectively reducing the peak impact force and the reaction force transmitted to the drop hammer 1. At the same time, the outer high-strength fiber material ensures the stability of the pad structure and continues to provide a buffering effect.

[0032] In this test, the internal cross-shaped hollow structure of probe 2 plays a crucial role when subjected to the impact force of the drop hammer 1 and the reaction force of the soil. Regarding bending resistance, when probe 2 is subjected to lateral bending force, the cross-shaped structure evenly distributes the force to each unit, keeping probe 2 stable as a whole and reducing bending deformation. Regarding torsional resistance, each unit works together to resist torque, preventing excessive twisting of probe 2. This structure allows probe 2 to better withstand forces, reducing the additional force transmitted to drop hammer 1 due to its own deformation, thereby effectively reducing the rebound phenomenon of drop hammer 1 and ensuring the stable and accurate conduct of the dynamic penetration test.

[0033] This heavy-duty dynamic penetrometer uses electromagnetic principles to suppress the rebound of the falling hammer 1, based on Lenz's law. The specific working process is as follows:

[0034] Electromagnetic coils are installed at positions slightly above the height of the drop hammer 1 and probe 2, with the first electromagnetic coil 301 of the drop hammer 1 directly attached to it. The second electromagnetic coil 302 of the probe 2 is connected to the probe 2 by a connecting rod 303. The connecting rod 303 does not affect the free fall of the drop hammer 1. When energized, the two electromagnetic coils are set to opposite current directions. According to the principles of electromagnetism, reverse current will generate two magnetic fields in opposite directions. To ensure that the impact potential energy accumulated by the drop hammer 1 during its free fall is not affected, two sensors 304 are installed below the second electromagnetic coil 302 at the top of the probe 2. The sensors 304 start working when the drop hammer 1 falls freely. Before the drop hammer 1 passes through the electromagnetic coils, the electromagnetic coils are de-energized to ensure that the drop hammer 1 is not subject to any electromagnetic interference, allowing it to fall freely and fully accumulate impact potential energy. Once sensor 304 detects that the falling hammer 1 has passed the second electromagnetic coil 302, it immediately sends a signal. At this time, the two electromagnetic coils are energized. Since the currents are in opposite directions, the two opposing magnetic fields begin to function, exerting a suppressive force on the falling hammer 1 as it attempts to rebound after its impact. This effectively controls the rebound of the falling hammer 1, improving the working efficiency and testing accuracy of the heavy-duty dynamic penetrometer. A controller is also added to the second electromagnetic coil 302 at probe 2 to control the current magnitude, allowing for the selection of different suppressive currents for different geological conditions and rebound heights. Finally, since the externally installed electromagnetic coil affects the manual lifting of the falling hammer 1, an electric pulley 401 is added to the top of the instrument, and four lifting ropes 402 are threaded onto the falling hammer 1, with the pulley used for electric control of the lifting.

[0035] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A heavy-duty dynamic penetrometer that reduces hammer bounce, characterized in that: The device includes a drop hammer, a probe rod, an electromagnetic buffer device, and a lifting device. The drop hammer has a first connector at its lower end and a second connector at its upper end. Multi-layer composite buffer pads are provided between the first connector and the drop hammer, and between the second connector and the probe rod. The probe rod has a cross-shaped partition structure inside that divides the rod body into four units. An electromagnetic buffer device is provided above the impact point at the top of the probe rod. The electromagnetic buffer device includes a first electromagnetic coil, a second electromagnetic coil, and connecting rods. The first electromagnetic coil is installed on the surface of the falling hammer. The second electromagnetic coil is installed on the top of the probe rod, and the second electromagnetic coil is higher than the impact point of the first and second connecting heads. The second electromagnetic coil is supported by connecting rods on both sides of the probe rod. The currents flowing through the two electromagnetic coils are in opposite directions, forming magnetic fields in opposite directions using Lenz's law to suppress the rebound of the falling hammer. Two sensors are located below the electromagnetic coil at the top of the probe rod, and the sensors are electrically connected to the electromagnetic coil and control its power supply. The lifting device includes an electric pulley located at the top of the instrument and four lifting ropes running through the drop hammer body.

2. The heavy-duty dynamic penetrometer for reducing hammer bounce according to claim 1, characterized in that: The composite buffer pad has a layered composite structure, comprising a high-damping rubber layer and a high-strength fiber layer; wherein the high-damping rubber layer directly contacts the top of the probe, and the high-strength fiber layer covers the outside of the rubber layer.

3. A heavy-duty dynamic penetrometer for reducing hammer bounce according to claim 1, characterized in that: The probe rod has a cross-shaped partition structure, which is a four-cavity structure with uniform cross-section distribution.

4. A heavy-duty dynamic penetrometer for reducing hammer bounce according to claim 1, characterized in that: The installation positions of the first electromagnetic coil and the second electromagnetic coil are such that when the drop hammer is in the starting position of free fall, the two coils are on the same axis.

5. A heavy-duty dynamic penetrometer for reducing hammer bounce according to claim 1, characterized in that: The second electromagnetic coil is connected to a current controller; the current controller is a programmable logic controller with multi-level current adjustment function.

6. A heavy-duty dynamic penetrometer for reducing hammer bounce according to claim 1, characterized in that: The connecting rod is an L-shaped metal rod, with its upper end connected to the second electromagnetic coil and its lower end connected to the side of the probe rod via a buckle.

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