Roadbed pavement deflection detection device and use method

Abstract

The invention relates to the technical field of roadbeds and pavements, and discloses a roadbed and pavement deflection detection device and a use method, the roadbed and pavement deflection detection device comprises a bearing plate, a guide rod, a main hammer, an auxiliary hammer and a control assembly; the bottom ends of the guide rods are fixedly connected with the top surface of the bearing plate, and the top ends are detachably connected with the control assembly; the main hammer and the auxiliary hammer are both slidably connected to the guide rod between the control assembly and the bearing plate, and the auxiliary hammer is located below the main hammer. The main hammer is detachably connected with the control assembly, the main hammer is connected with the auxiliary hammer through a pre-pressing elastic element, the distance between the control assembly and the main hammer is adjusted, the corresponding hammer falling height is set, the bearing plate is placed at a point to be detected and leveled, the main hammer is lifted until the main hammer is locked by the control assembly, triggering and releasing are conducted, and deflection detection is conducted. Compared with a traditional deflection measuring device, the roadbed pavement deflection detecting device and the using method have the advantages of being small in size, light in weight, portable, capable of moving rapidly and the like.

Description

Technical Field

[0001] This invention relates to the field of roadbed and pavement technology, and in particular to a roadbed and pavement deflection detection device and its usage method. Background Technology

[0002] Deflection is a key indicator for evaluating the overall structural strength and load-bearing capacity of roadbeds and pavements. Specifically, it refers to the total vertical deformation or vertical rebound deformation that occurs at the wheel gap location under a specified standard axle load, measured in millimeters (0.01 mm). In simpler terms, it reflects the extent to which the pavement is "pressed down" under load. A smaller deflection value indicates greater pavement stiffness and stronger load-bearing capacity; conversely, a larger deflection value may indicate structural weakness or potential damage risk.

[0003] Commonly used deflection testing equipment includes the Benkelman beam, the falling weight deflectometer, and the laser-based automatic deflectometer. The falling weight deflectometer uses a hydraulic system to lift a weight of specified mass to a predetermined height and then release it, impacting a bearing plate to apply a transient pulse load to the road surface, simulating the action of a vehicle wheel. Sensors, such as speedometers or accelerometers, arranged around the bearing plate can accurately measure the deflection basin generated by the road surface.

[0004] Traditional falling weight deflectometers are bulky and typically integrated into trailers, requiring the vehicle to be parked and the road closed during testing. Although portable falling weight deflectometers have been developed, the impact pulses they generate are short, and their force-time curves differ from the waveforms of real vehicle loads, leading to discrepancies between the calculated modulus and other parameters and the actual conditions. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a roadbed and pavement deflection detection device and its usage method. Under the premise of providing the same large load impulse and the same detection accuracy, it features small size, light weight, portability, and rapid mobility, and can be used for deflection measurement of asphalt concrete and cement concrete pavements and roadbeds.

[0006] This invention provides a roadbed and pavement deflection detection device, comprising: a bearing plate, a guide rod, a main hammer, an auxiliary hammer, and a control assembly; The bottom end of the guide rod is fixedly connected to the top surface of the bearing plate, and the top end is detachably connected to the control component. Both the main hammer and the auxiliary hammer are provided with through holes that match the guide rod. The two are sequentially fitted onto the guide rod and can slide freely in the vertical direction on the guide rod section between the control component and the bearing plate. The auxiliary hammer is located below the main hammer. The main hammer and the control component are detachably connected. The control component controls the connection of the main hammer. The main hammer and the auxiliary hammer are connected by a pre-compression elastic element. The pre-compression elastic element is in a compressed state under natural conditions.

[0007] Optionally, the main hammer is a hollow cavity with a counterweight groove inside. The counterweight groove is two semi-circular sections that are symmetrically arranged, and multiple counterweight blocks can be detachably connected inside the counterweight groove.

[0008] Optionally, the preload elastic element includes: multiple preload springs, one end of which is fixedly connected to the lower end face of the main hammer, and the other end of which is fixedly connected to the upper end face of the auxiliary hammer.

[0009] Optionally, the control components include: an electromagnetic chuck and multiple release rods, the electromagnetic chuck being fixed to the upper end of the guide rod, the upper ends of the multiple release rods being magnetically connected to the lower end of the electromagnetic chuck, and the lower ends of the release rods being fixedly connected to the main hammer. Optionally, the length of the release rod is adjustable, and the release rod consists of two rod sections connected by threads.

[0010] Optionally, a height gauge is provided on the guide rod.

[0011] Optionally, the support plate also includes a bubble level, a load sensor, and a displacement sensor; the bubble level is embedded in the upper surface of the support plate, the load sensor is embedded inside the support plate, and the displacement sensor is embedded in the upper surface of the support plate.

[0012] Optionally, the bottom surface of the support plate is provided with anti-slip texture.

[0013] A method for using a roadbed and pavement deflection testing device includes the following steps: Determine the required impact energy based on the design load level or testing requirements of the road surface to be tested; Based on the determined impact energy, the corresponding hammer drop height is set by adjusting the distance between the control components and the main hammer; Place the support plate at the point to be measured and level it; Raise the main hammer until it is locked by the control components; Trigger release, and the auxiliary hammer applies a load to the bearing plate under the combined action of gravitational potential energy and projectile potential energy; Displacement sensors inside the bearing plate record changes in ground displacement in real time, completing deflection detection.

[0014] Optionally, the peak value and duration of the impact pulse can be customized by adjusting one or more parameters of the pre-compression of the pre-compression elastic element, the mass of the main hammer, and the height of the main hammer.

[0015] The technical solution provided by this invention has the following advantages compared with the prior art: The device is placed on the road surface to be tested. The main hammer and auxiliary hammer are raised together to the set drop height by the control component. At this time, the pre-compressed elastic element maintains its pre-compressed state. The control component is operated, the main hammer disengages from the control component, and begins to fall freely under the action of gravity. After the main hammer falls a very short distance, its potential energy is transferred to the auxiliary hammer below. Since the auxiliary hammer is connected to the main hammer through the pre-compressed elastic element, this impact is not a rigid hard-on-hard collision, but a soft contact transmitted through the pre-compressed elastic element. In fact, part of the kinetic energy of the main hammer is converted into the elastic potential energy of the pre-compressed elastic element. The pre-compressed elastic element is further compressed, storing more energy. The compressed pre-compressed elastic element rebounds rapidly, releasing its stored elastic potential energy, like a catapult, giving the auxiliary hammer an additional downward acceleration force. Finally, the auxiliary hammer combines the impact force of the main hammer and the catapult force of the pre-compressed elastic element, acting together on the bearing plate, thereby generating an impact energy greater than that generated by the simple free fall of the main hammer. After the load-bearing plate is subjected to the impact potential energy from above, it applies the load evenly to the ground surface and measures the instantaneous deflection value of the road surface.

[0016] Through the two-stage impact and the buffering effect of the elastic element, the generated load pulse pattern more closely resembles actual traffic loads, especially better reflecting the deformation characteristics of materials under long-cycle loads. This allows the deflection test results to more realistically reflect the road's performance in actual use. The pre-impact of the auxiliary hammer effectively eliminates system gaps and stabilizes the initial state, making the interpretation of the starting point of the deflection curve generated by the main impact clearer. At the same time, this process suppresses the violent high-frequency oscillations that may be caused by a single hammer impact, significantly improving the signal-to-noise ratio of the data and providing higher quality and more reliable raw data for subsequent deflection basin calculations and inversion analysis. Attached Figure Description

[0017] Figure 1 A three-dimensional schematic diagram of a roadbed and pavement deflection detection device provided in an embodiment of the present invention; Figure 2 This is a front view of a roadbed and pavement deflection detection device provided in an embodiment of the present invention; Figure 3 A top view of a roadbed and pavement deflection detection device provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the main hammer provided in an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures: 1. Bearing plate; 2. Guide rod; 3. Main hammer; 4. Auxiliary hammer; 5. Control assembly; 6. Preload elastic element; 31. Counterweight groove; 311. Counterweight block; 61. Spring; 51. Electromagnetic chuck; 52. Release rod; 11. Scale; 8. Bubble level; 9. Load sensor; 10. Displacement sensor. Detailed Implementation

[0019] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this 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. Therefore, they should not be construed as limitations on this invention.

[0021] The present invention will be described below through several specific embodiments. To keep the following description of the embodiments clear and concise, detailed descriptions of known functions and components may be omitted. When any component of an embodiment of the present invention appears in more than one drawing, the component may be represented by the same reference numerals in each drawing.

[0022] Figure 1 This is a three-dimensional schematic diagram of a roadbed and pavement deflection detection device provided in an embodiment of the present invention. Figure 2 This is a front view of a roadbed and pavement deflection detection device provided in an embodiment of the present invention. Figure 3 This is a top view of a roadbed and pavement deflection detection device provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the main hammer provided in an embodiment of the present invention.

[0023] like Figure 1 and Figure 2As shown, this embodiment of the invention provides a roadbed and pavement deflection detection device, including: a bearing plate 1, a guide rod 2, a main hammer 3, an auxiliary hammer 4, and a control component 5; the bottom end of the guide rod 2 is fixedly connected to the top surface of the bearing plate 1, and the top end is detachably connected to the control component 5; both the main hammer 3 and the auxiliary hammer 4 are provided with through holes that match the guide rod 2, and the two are sequentially sleeved on the guide rod 2, and can slide freely in the vertical direction on the section of the guide rod 2 between the control component 5 and the bearing plate 1, and the auxiliary hammer 4 is located below the main hammer 3; the main hammer 3 is detachably connected to the control component 5, and the control component 5 controls the connection of the main hammer 3; the main hammer 3 and the auxiliary hammer 4 are connected by a pre-compression elastic element 6, which is in a compressed state in its natural state.

[0024] Specifically, multiple displacement sensors are fixedly connected to the bearing plate 1. These displacement sensors accurately measure the instantaneous deflection value of the road surface after impact. Specifically, the bearing plate 1 is a thick, round or square steel plate with a flat bottom. It evenly transmits the impact force generated by the hammering to the roadbed or pavement to be tested. As the base of the entire device, the guide rod 2 is fixed to it. The bottom end of the guide rod 2 is securely connected to the center of the bearing plate 1 via a high-strength thread. The bearing plate 1 is equipped with a handle or lifting ring for easy transport.

[0025] Specifically, the guide rod 2 is a single, smooth, cylindrical metal rod that stands vertically on the support plate 1. It provides precise vertical guidance for the lifting and lowering of the main hammer 3 and auxiliary hammer 4, ensuring that the hammers do not sway during descent and that the impact force is directed vertically downwards, thus guaranteeing the accuracy of the detection data. It connects the support plate 1 and the control assembly 5, forming the main frame of the device.

[0026] Furthermore, the upper end of the guide rod 2 is detachably connected to the control assembly 5. This is achieved via threads, pins, or quick-release pins, to facilitate the transportation, assembly, and commissioning of the equipment.

[0027] Furthermore, the main hammer 3 is cylindrical with a precisely machined guide hole at its center, which fits with the guide rod 2 with a clearance to ensure free sliding. During the lifting phase, the control component 5 grips the main hammer 3; when testing is required, the control component 5 releases, and the main hammer 3 falls freely.

[0028] Specifically, the auxiliary hammer 4 is located below the main hammer 3 and has a smaller mass. It is also cylindrical with guide holes. Its function is not direct impact, but rather to serve as a support platform for the preloaded elastic element 6, forming a "collision-spring 61" system together with the main hammer 3. It is connected via the preloaded elastic element 6. It is not directly connected to the control assembly 5.

[0029] Furthermore, the pre-compressed elastic element 6 is pre-compressed and installed between the main hammer 3 and the auxiliary hammer 4. In a static state, the spring 61 has already stored elastic potential energy. The two ends of the spring 61 abut against the lower surface of the main hammer 3 and the upper surface of the auxiliary hammer 4, respectively. Spring 61 seats (recesses or protrusions) are designed on the main hammer 3 and the auxiliary hammer 4 to prevent the spring 61 from slipping. The pre-compression is adjustable. The amount of pre-compression of the spring 61 can be changed by altering the initial distance between the main hammer 3 and the auxiliary hammer 4.

[0030] The device is placed on the road surface to be tested. The main hammer 3 and auxiliary hammer 4 are raised together to the set drop height via control component 5. At this time, the pre-compressed elastic element 6 remains in its pre-compressed state. Control component 5 is operated, and the main hammer 3 detaches from it, beginning its free fall under gravity. After falling a very short distance, the potential energy of the main hammer 3 is transferred to the auxiliary hammer 4 below. Since the auxiliary hammer 4 is connected to the main hammer 3 via a pre-compressed spring 61, this impact is not a rigid, hard collision, but a soft contact transmitted through the spring 61. In effect, the kinetic energy of the main hammer 3 is partially converted into the elastic potential energy of the spring 61. The spring 61 is further compressed, storing more energy. The compressed spring 61 quickly rebounds, releasing its stored elastic potential energy, acting like a catapult, giving the auxiliary hammer 4 an additional downward acceleration force. Finally, the auxiliary hammer 4 combines the impact force of the main hammer 3 and the ejection force of the spring 61, acting together on the bearing plate 1, thus generating an impact energy greater than that generated by the simple free fall of the main hammer 3. After the load-bearing plate is subjected to the impact potential energy from above, it applies the load evenly to the ground surface. The displacement sensor on the load-bearing plate records the deformation of the ground surface in real time, thereby measuring the instantaneous deflection value of the road surface.

[0031] By employing a two-stage impact and the buffering effect of elastic elements, laboratory-level "impact simulation" has been successfully advanced towards "traffic load simulation." The generated load pulse pattern more closely resembles actual traffic loads, especially better reflecting the deformation characteristics of materials under long-cycle loads, allowing deflection test results to more realistically reflect the road's performance in actual use. The pre-impact of auxiliary hammer 4 effectively eliminates system gaps and stabilizes the initial state, making the interpretation of the starting point of the deflection curve generated by the main impact clearer. Simultaneously, this process suppresses the severe high-frequency oscillations that might be caused by a single hammer impact, significantly improving the signal-to-noise ratio of the data and providing higher-quality, more reliable raw data for subsequent deflection basin calculations and inversion analysis.

[0032] Optional, see reference Figure 4 The main hammer 3 is a hollow cavity, and a counterweight groove 31 is provided inside the main hammer 3. The counterweight groove 31 is two semi-circular shapes and is symmetrically arranged. Multiple counterweight blocks 311 can be detachably connected inside the counterweight groove 31.

[0033] Specifically, the main hammer 3 is a large cylindrical or near-cylindrical metal component. Its interior is not solid, but rather a hollow cavity. This significantly reduces the base weight of the main hammer 3 without sacrificing structural strength, facilitating manual handling and the lifting operation of the control component 5; it also provides space for the internal counterweight adjustment system.

[0034] Two semi-circular channels are symmetrically formed within the hollow cavity of the main hammer 3. These channels extend along the central axis of the main hammer 3, and their curvature perfectly matches the inner wall of the cavity. The semi-circular shape makes good use of the internal space of the cylindrical cavity, and its curved structure helps to disperse stress, avoiding stress concentration at the sharp corners of the channels, thus improving the structural strength and fatigue life of the main hammer 3. The two symmetrical semi-circular channels essentially serve as the mounting tracks and storage compartments for the counterweight 311.

[0035] Furthermore, the counterweight 311 is designed as a semi-cylindrical (or fan-shaped) metal block that perfectly matches the shape of the counterweight groove 31. A single counterweight 311 can be precisely embedded into a counterweight groove 31. The counterweight 311 is modular and can be manufactured in various standard weights. Different numbers and combinations of counterweights 311 can be selected for installation as needed. The counterweight 311 is directly embedded into the semi-circular groove. Removable end caps are designed at the top and bottom of the main hammer 3 cavity. By tightening the bolts on the end caps, an axial pressure is generated on all the counterweights 311 in the cavity, pressing them together and fixing them in place. All locking bolts can be equipped with spring washers 61 or thread-locking adhesive to withstand impact vibration.

[0036] In practical applications, it is necessary to test high-load-bearing cement concrete pavements and soft soil subgrades. The required impact energy differs greatly. By adding or removing counterweights 311, a large-scale "step-like" adjustment of the impact energy can be achieved over a wide range. Operators can first quickly adjust the total impact energy to the target range by installing or removing counterweights 311, and then perform final calibration and pulse optimization by finely adjusting the pre-compression of the pre-compression elastic element 6. This combination of "coarse adjustment + fine adjustment" makes the equipment's energy adjustment range extremely wide, with higher accuracy and strong adaptability.

[0037] The equipment needs to be moved frequently between different testing points or transported manually to areas inaccessible by vehicles. During transport, all counterweights 311 can be removed from the main hammer 3 and stored separately. This minimizes the weight of the main hammer 3, lowers the center of gravity of the entire device, and makes the structure more compact, facilitating loading and transportation. Upon arrival at the site, the required counterweights 311 can be quickly installed according to the testing plan. This avoids the cumbersome and dangerous process of traditionally carrying multiple complete heavy hammers. The lightweight main hammer 3 makes it possible for a single person to assemble the equipment and lift the hammer, reducing manpower requirements and improving operational efficiency.

[0038] Under high-energy impact, any imbalance in the hammer body can exacerbate wear on the guide rod 2, and even lead to jamming or off-center impact, affecting data accuracy. The symmetrically arranged semi-circular counterweight groove 31 design ensures that regardless of the number of counterweight blocks 311 installed, its mass distribution remains symmetrical about the central axis of the main hammer 3. This fundamentally guarantees that the center of mass of the main hammer 3 is located at its geometric center, preventing the generation of additional eccentric torque during descent and impact, thereby reducing lateral wear on the guide rod 2, ensuring the impact force is vertically downward, reliable data, smoother equipment operation, and a longer service life.

[0039] Optional, see reference Figure 2 The preload elastic element 6 includes: multiple preload springs 61, the first end of which is fixedly connected to the lower end face of the main hammer 3, and the second end of which is fixedly connected to the upper end face of the auxiliary hammer 4.

[0040] Specifically, the preload elastic element 6 consists of multiple high-strength helical compression springs 61. These preload springs 61 are arranged uniformly around the central axis between the main hammer 3 and the auxiliary hammer 4. The symmetrical and evenly distributed design of multiple springs 61 ensures that the elastic force acts absolutely uniformly on the contact surface of the main hammer 3 and the auxiliary hammer 4. This avoids the torque that might be caused by a single spring 61 or an asymmetrical arrangement, ensuring that the impact force is strictly vertically downward. It suppresses the swing and rotation of the hammer body during movement, protects the guide rod 2, and improves the lifespan of the entire device and the reliability of the measurement data.

[0041] The perfect integration of "coarse adjustment" and "fine adjustment" allows the modular counterweight system to perform a radical, step-like adjustment of the impact energy, while the multi-spring 61 preload system provides smooth, continuous, and linear fine-tuning capabilities. By rotating the adjustment mechanism, the operator can precisely control the preload potential energy of the spring 61, much like adjusting the volume of a radio, thereby achieving precise control over the final impact energy.

[0042] In long-term, high-intensity field operations, the unexpected failure of a single component can disrupt the entire inspection mission. The scheme employing multiple springs 61 connected in parallel is essentially a redundancy design. Even if one spring 61 fails due to extreme conditions, the remaining springs 61 can still maintain the basic function of the system, continuing to transmit impact force (although energy and balance will be affected), allowing inspection personnel to complete the current task before performing maintenance. This significantly improves the reliability and uptime of the equipment in critical missions.

[0043] Optional, see reference Figure 2The control component 5 includes an electromagnetic chuck 51 and multiple release rods 52. The electromagnetic chuck 51 is fixed to the upper end of the guide rod 2, the upper ends of the multiple release rods 52 are magnetically connected to the lower end of the electromagnetic chuck 51, and the lower ends of the release rods 52 are fixedly connected to the main hammer 3.

[0044] Specifically, the electromagnetic chuck 51 is the core power and control unit of the control component 5. It consists of a housing, an internal coil winding, and magnetic pole shoes (such as electrical pure iron) located at the bottom. When the coil is energized, it generates a strong magnetic field, creating an attractive force. When the power is off, the magnetic field disappears instantly, and the attractive force is released. Its core function is to provide a remotely controllable and reliable connection and release mechanism. The center of the electromagnetic chuck 51 is fixed to the top or upper end of the guide rod 2 via a flange connection through a mounting bracket. It is connected to the control box of the device via a cable. The control box contains a capacitor bank that can provide a large instantaneous current to generate a strong attractive force and can receive commands to instantly cut off the power.

[0045] The release rod 52 is a force-transmitting component connecting the electromagnetic chuck 51 and the main hammer 3. Made of high-strength alloy steel, it possesses excellent tensile strength. One end is attracted by the electromagnetic chuck 51, and the other end is connected to the main hammer 3, converting the magnetic force of the electromagnetic chuck 51 into a lifting force on the main hammer 3. The symmetrically distributed design of the multiple rods ensures the uniform transmission of the lifting force.

[0046] Furthermore, the top of the release rod 52 is machined into a smooth plane, or inlaid with a material with high magnetic permeability (such as low carbon steel) to ensure maximum contact area and optimal magnetic circuit with the surface of the electromagnetic chuck 51 pole shoe. When the electromagnet is energized, the release rod 52 is firmly attracted; when the power is off, the connection is immediately released. The lower end of the release rod 52 is fixedly connected to the main hammer 3. The lower end of the release rod 52 is machined with external threads, which are directly screwed into the corresponding threaded hole on the upper end face of the main hammer 3 and locked with a lock nut. To compensate for possible minor installation misalignment, a ball bearing connection can be used, allowing for slight oscillation of the release rod 52, ensuring that the tops of all release rods 52 can make flat contact with the surface of the electromagnetic chuck 51, and avoiding release failure due to uneven force.

[0047] Synchronous and instantaneous release is achieved through electro-controlled magnetic force, laying a solid foundation for obtaining high-quality deflection data; its rapid automatic reset capability and easy integration control characteristics greatly improve on-site testing efficiency; its inherent safety design and multi-rod redundancy ensure the safety of equipment and personnel.

[0048] Optional, see reference Figure 1 The length of the release rod 52 is adjustable, and the release rod 52 consists of two rod sections connected by threads.

[0049] Specifically, the release rod 52 is composed of an upper section and a lower section connected by threads. The upper section is machined into a smooth surface or inlaid with a magnetic plate for good magnetic connection with the electromagnetic chuck 51. The lower end is machined with internal threads to form a connecting sleeve. The lower section has internal threads that match those of the upper section. The lower end is fixedly connected to the main hammer 3. The operator can adjust the overall length of the release rod 52 by rotating the lower section to change the length of the meshing threads between the upper and lower sections. The lower section is machined with knurling and a wrench notch.

[0050] By changing the lifting height of the main hammer 3, the total impact energy can be flexibly adjusted without replacing the main physical components. This allows the same device to generate a series of impact energy levels from low to high, easily meeting the testing needs of structural layers of different depths and stiffnesses, from shallow road base layers to deep subgrades, achieving "one machine for multiple uses" and greatly enhancing the applicability and economy of the equipment.

[0051] Optional, see reference Figure 2 A height scale 11 is installed on the guide rod 2.

[0052] Specifically, the height scale 11 uses laser etching to directly mark the scale lines and numbers on the surface of the guide rod 2. The etched grooves can even be filled with wear-resistant colored paint to improve visibility. The operator can directly observe the position of the pointer on the height scale 11 and precisely align the reference point of the main hammer 3 with the target scale line.

[0053] Optional, see reference Figure 3 It also includes a level bubble 8, a load sensor 9, and a displacement sensor 10. The level bubble 8 is embedded in the upper surface of the bearing plate 1 to adjust the horizontal state of the device; the load sensor 9 is embedded in the inside of the bearing plate 1 to determine the magnitude of the impact load; and the displacement sensor 10 is embedded in the lower surface of the bearing plate 1 to record the deflection value of the roadbed and pavement under the impact load.

[0054] At the start of the test, the operator can quickly and accurately adjust the horizontal state of the bearing plate 1 by observing the position of the bubbles in the level bubble 8. This ensures that the guide rod 2 remains perpendicular to the road surface, thereby guaranteeing that the frictional force experienced by the main hammer 3 and auxiliary hammer 4 during their descent is uniform, and their gravitational potential energy can be completely converted into vertical impact kinetic energy on the road surface. This avoids uneven impact load, energy loss, and distortion of deflection data caused by the tilt of the bearing plate 1, fundamentally ensuring the accuracy and repeatability of the test results.

[0055] Optionally, the bottom surface of the support plate 1 is provided with anti-slip texture.

[0056] The anti-slip texture on the bottom significantly increases the static friction between the bearing plate 1 and the road surface test point. At the moment of impact, the enormous impact force can easily cause the device with a smooth bottom plate to slip, which not only endangers operational safety but also prevents the impact energy from being fully transferred to the test point, resulting in a significant deviation of the deflection measurement value from the true value. This anti-slip texture effectively "grips" the road surface, preventing the device from shifting under impact, ensuring the effective transfer of impact load and the reliability of data, while also improving the safety of the entire testing process. The anti-slip texture embeds itself into the microscopic unevenness of the road surface through its raised ridges, generating enormous mechanical engagement force and friction, firmly "locking" the bearing plate 1. This ensures that the impact energy is entirely used to induce vertical downward deflection deformation in the road surface, rather than being wasted by ineffective bottom plate slippage. This is the physical basis for obtaining true and accurate deflection values. Even a tiny slippage is enough to distort the deflection curve, leading to test failure. This invention provides a method for using a roadbed and pavement deflection detection device, comprising the following steps: determining the required impact energy based on the design load level or detection requirements of the pavement to be tested; setting the corresponding drop height by adjusting the distance between the control component 5 and the main hammer 3 according to the determined impact energy; placing the bearing plate 1 at the test point and leveling it; raising the main hammer 3 until it is locked by the control component 5; triggering the release of the auxiliary hammer 4 to apply a load to the bearing plate 1 under the combined action of gravitational potential energy and projectile potential energy; and having the displacement sensor 10 inside the bearing plate 1 record the changes in ground surface displacement in real time to complete the deflection detection.

[0057] Optionally, the peak value and duration of the impact pulse can be customized by adjusting one or more parameters of the pre-compression amount of the pre-compression elastic element 6, the mass of the main hammer 3, and the height of the main hammer 3.

[0058] First, a reliability check is performed on each component of the device to ensure that the guide rod 2 is clean, the control component 5 operates normally, and the preload elastic element 6 and the locking mechanism of the release rod 52 are not loose. Then, the required impact energy range is determined according to the design load level of the road surface to be tested or the specific testing requirements, and the coarse and fine adjustment targets of the impact energy are set accordingly. The coarse energy adjustment is achieved by adding or removing modular counterweights 311 in the symmetrical counterweight groove 31 of the main hammer 3 to adjust the total mass of the main hammer 3 to the target range. The fine energy adjustment target is to determine the nominal value of the drop hammer height and the preload of the spring 61 corresponding to this test. These parameters can be pre-formulated into a table through tests or procedures for on-site reference. Next, the on-site setup and leveling stage begins. The center of the support plate 1 of the device is aligned with the point to be measured. By observing the horizontal bubble 8 embedded in the upper surface of the support plate 1 and gently tapping the edge of the support plate 1 or inserting a thin sheet, the bubble is made to be in the center circle, ensuring that the support plate 1 is in an absolutely horizontal state. This step is the fundamental prerequisite for ensuring that the impact force is vertically downward and the data is accurate and reliable. At the same time, according to the determined target drop height, the indicator vernier is pre-set near the corresponding scale position by using the height scale 11 on the guide rod 2. Then, the hammer body is lifted and the energy is precisely set. The lifting mechanism is started to smoothly lift the main hammer 3 and the auxiliary hammer 4 connected to it by the preload spring 61. When the pointer on the main hammer 3 approaches the preset vernier, the lifting speed is slowly adjusted. Finally, the hammer is precisely aligned with the target height scale line to set the drop height. This height determines the main part of the impact gravitational potential energy. Next, the preload of the spring 61 is set. With the main hammer 3 locked in the control component 5, the main hammer 3 is rotated. Using the thread between the main hammer 3 and the guide rod 2, the height scale 11 is observed to adjust the offset of the pointer on the main hammer 3 from the initial "zero position", that is, the preload of the spring 61, to the target value. This operation precisely sets the preload elastic potential energy. After completion, the release rod 52 and the electromagnetic chuck 51 are checked and confirmed to be in good contact and all parameters are set correctly. Then, the detection and data acquisition are triggered. The operator issues a command to cut off the power to the electromagnetic chuck 51 from the control box, realizing the synchronous and instantaneous release of multiple release rods 52. This causes the main hammer 3 and auxiliary hammer 4 to fall along the guide rod 2 under the action of gravity. The system then undergoes a two-stage composite impact: the auxiliary hammer 4 first contacts the bearing plate 1 to generate a pre-impact to stabilize the system and define the timing start point. Immediately afterwards, the main hammer 3 transfers kinetic energy and elastic potential energy to the auxiliary hammer 4 through the pre-compression spring 61, generating an optimized main impact that is closer to the pulse shape of the actual traffic load. At the same time, the displacement sensor integrated on the bearing plate 1 is triggered synchronously to collect and record the dynamic deflection time history curve of the road surface under the optimized load. Finally, the reset and subsequent operations are performed. The lifting mechanism is triggered to raise the main hammer 3. The top of the release rod 52 is designed to be a smooth plane. Once it contacts the energized electromagnetic chuck 51, it will be automatically attracted and locked, thus realizing a rapid reset for the next detection. After saving the deflection data of the current measuring point, the device is moved to the next measuring point and the above process is repeated until all detection tasks are completed.

[0059] This method, through a control mode combining coarse adjustment of counterweight 311 with fine adjustment of drop height and preload, fully leverages the modular and adjustable design advantages of the device, achieving stepless adjustment of impact energy over a wide range and with high precision, meeting the multi-scenario testing needs from shallow pavement to deep subgrade. Simultaneously, through the synergistic effect of horizontal leveling, anti-slip texture, synchronous electromagnetic release, symmetrical structure, and the double-hammer-spring 61 system, it fundamentally ensures vertical application of impact force, slip-free stability, load pulse optimization, and high signal-to-noise ratio and accuracy of data acquisition. Furthermore, the height scale 11 and adjustable release rod 52 enable rapid and accurate parameter setting, while electromagnetic release and automatic reset significantly shorten the testing cycle. The integrated design reduces the use of auxiliary tools, and the overall process quantifies and standardizes key parameters, significantly reducing reliance on operator experience and ensuring the efficiency, comparability, and reliability of the testing process.

[0060] The above inventions are merely a few specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A roadbed and pavement deflection detection device, characterized in that, include: Bearing plate, guide rod, main hammer, auxiliary hammer and control components; The bottom end of the guide rod is fixedly connected to the top surface of the bearing plate, and the top end is detachably connected to the control component. The main hammer and the auxiliary hammer are both provided with through holes that match the guide rod. The two are sequentially sleeved on the guide rod and can slide freely in the vertical direction on the guide rod section between the control component and the bearing plate. The auxiliary hammer is located below the main hammer. The main hammer is detachably connected to the control component, which controls the connection of the main hammer. The main hammer and the auxiliary hammer are connected by a pre-compression elastic element, which is in a compressed state under natural conditions.

2. The roadbed and pavement deflection detection device as described in claim 1, characterized in that, The main hammer is a hollow cavity, and a counterweight groove is provided inside the main hammer. The counterweight groove is two semi-circular shapes and is symmetrically arranged. Multiple counterweight blocks can be detachably connected inside the counterweight groove.

3. The roadbed and pavement deflection detection device as described in claim 1, characterized in that, The preload elastic element includes: multiple preload springs, one end of each preload spring being fixedly connected to the lower end face of the main hammer, and the other end being fixedly connected to the upper end face of the auxiliary hammer.

4. The roadbed and pavement deflection detection device as described in claim 1, characterized in that, The control component includes an electromagnetic chuck and multiple release rods. The electromagnetic chuck is fixed to the upper section of the guide rod, and the upper ends of the multiple release rods are magnetically connected to the lower end of the electromagnetic chuck. The lower ends of the release rods are fixedly connected to the main hammer.

5. The roadbed and pavement deflection detection device as described in claim 4, characterized in that, The length of the release rod is adjustable, and the release rod consists of two rod sections connected by threads.

6. The roadbed and pavement deflection detection device as described in claim 5, characterized in that, A height scale is installed on the guide rod.

7. The roadbed and pavement deflection detection device as described in claim 1, characterized in that, It also includes a level bubble, a load sensor, and a displacement sensor. The level bubble is embedded in the upper surface of the bearing plate to adjust the horizontal state of the bearing plate. The load sensor is embedded inside the bearing plate to determine the magnitude of the impact load. The displacement sensor is embedded in the lower surface of the bearing plate to record the deflection value of the roadbed and pavement under impact load.

8. The roadbed and pavement deflection detection device as described in claim 1, characterized in that, The bottom surface of the support plate is provided with anti-slip texture.

9. The method of using the roadbed and pavement deflection testing device as described in claim 6, characterized in that, Includes the following steps: Determine the required impact energy based on the design load level or testing requirements of the road surface to be tested; Based on the determined impact energy, the corresponding hammer drop height is set by adjusting the distance between the control components and the main hammer; Place the support plate at the point to be measured and level it; Raise the main hammer until it is locked by the control components; Trigger release, and the auxiliary hammer applies a load to the bearing plate under the combined action of gravitational potential energy and projectile potential energy; Displacement sensors inside the bearing plate record changes in ground displacement in real time, completing deflection detection.

10. The method of use as described in claim 9, characterized in that, The peak value and duration of the impact pulse are customized by adjusting one or more parameters among the pre-compression amount of the pre-compression elastic element, the mass of the main hammer, and the height of the main hammer.

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