A soft soil penetration test platform with switchable loading mode

Abstract

This utility model discloses a soft soil penetration test platform with switchable loading modes, comprising: a model box for holding soft soil samples; an annular slide rail guide mechanism fixedly installed on the top of the model box, the annular slide rail guide mechanism having multiple lower positioning holes evenly distributed circumferentially; and a loading device including a projectile loading device and a static loading device, the projectile loading device and the static loading device being selectively installed on the annular slide rail guide mechanism; the bottom of the projectile loading device and the static loading device are respectively provided with upper positioning holes corresponding to the lower positioning holes. By inserting positioning elements into the corresponding upper and lower positioning holes, the projectile loading device and the static loading device can be detachably fixed to a predetermined circumferential position of the annular slide rail guide mechanism, providing a technical basis for accurately studying the strain rate effect of soft soil.

Description

Technical Field

[0001] This utility model relates to the technical field of geotechnical engineering test devices, and in particular to an indoor penetration test platform for studying the strain rate effect of soft soil, especially a soft soil penetration test platform with multi-mode loading capability, adjustable loading speed, and rapid structural switching. Background Technology

[0002] Cone penetration test (CPTU) with pore-water pressure measurement (PFRP) and free-fall penetrometer (FFP) are important in-situ testing techniques for assessing the mechanical properties of seabed soils. CPTU uses quasi-static penetration, and the penetration resistance obtained reflects the quasi-static strength of the soil. FFP, on the other hand, is a dynamic penetration test, and its penetration resistance exhibits a significant strain rate effect. The shear strength of marine sediments is closely related to the strain rate. If the dynamic resistance of FFP is used directly to assess soil strength without proper strain rate correction, it can easily lead to overestimation of the results and pose potential engineering safety hazards.

[0003] Currently, empirical formulas are commonly used to correct the rate of dynamic resistance in FFP (Fluorescent Phosphate Particle) tests. However, the strain rate sensitivity varies significantly among different types of sediments, and field tests are costly and environmentally complex, making it difficult to obtain sufficient data to establish accurate and universally applicable correction models. Existing indoor penetration testing devices are typically single-function, capable only of static or projectile penetration, and cannot perform wide-range, multi-mode penetration tests from quasi-static to dynamic on the same platform and the same soil sample. This prevents the systematic study of the strain rate effect of soft soil while eliminating the interference of spatial variability in soil samples, thus hindering the precise engineering application of FFP technology.

[0004] Therefore, there is an urgent need in this field for an integrated testing platform that can quickly switch between different loading modes and test the same soil sample over a wide range of penetration rates, thereby providing reliable experimental data for studying strain rate effects and establishing accurate inversion models. Utility Model Content

[0005] The technical problem to be solved by this utility model is: how to improve the experimental accuracy and efficiency of soft soil strain rate effect research, and to provide a modular test platform with fast-switching loading modes, so as to accurately study the strain rate effect of soft soil from quasi-static to high-speed penetration under the condition of eliminating the interference of spatial variability of soil samples.

[0006] The technical problem of this utility model is solved by the following technical solution:

[0007] A soft soil penetration test platform with switchable loading modes includes:

[0008] The model box is used to hold soft soil samples;

[0009] A ring slide rail guide mechanism is fixedly installed on the top of the model box, and the ring slide rail guide mechanism is provided with multiple lower positioning holes evenly distributed along the circumference;

[0010] The loading device includes a catapult loading device and a static loading device, wherein the catapult loading device and the static loading device can be selectively mounted on the annular slide rail guide mechanism;

[0011] The bottom of the ejector loading device and the static loading device are respectively provided with upper positioning holes corresponding to the lower positioning hole. By inserting positioning members into the corresponding upper and lower positioning holes, the ejector loading device and the static loading device can be detachably fixed to the predetermined circumferential position of the annular slide rail guide mechanism.

[0012] In some embodiments, the following technical features are also included:

[0013] The ejection loading device includes:

[0014] Supporting framework;

[0015] A spring energy storage device includes a spring and a compression spring member for compressing the spring, the spring being housed within a spring outer sleeve;

[0016] An electric actuator is mounted on the support frame;

[0017] A detachable connecting mechanism is connected to the compression spring component;

[0018] A mechanical release mechanism, connected to the spring, is used to release the spring after it has been compressed;

[0019] The first penetration probe is connected to the end of the spring.

[0020] In some embodiments, the detachable connection mechanism includes a force-transmitting ring disposed on the first penetration probe, and the mechanical release mechanism includes a height-adjustable triggering member, a triggered member for gripping the force-transmitting ring, a vertically arranged adjusting rod, and an adjusting nut for locking the height of the triggering member; the triggering member is sleeved on the adjusting rod.

[0021] In some embodiments, the static loading device includes:

[0022] Gear motor;

[0023] A friction wheel assembly consisting of a driving friction wheel and a driven friction wheel, wherein the reduction motor is connected to the driving friction wheel in a driving transmission.

[0024] The probe rod has a second penetration probe connected to its lower part and is positioned between the active friction wheel and the driven friction wheel at its upper part.

[0025] A friction wheel cylinder, the output end of which is connected to the driven friction wheel, is used to drive the driven friction wheel to press or release the probe rod.

[0026] In some embodiments, the contact surfaces between the active friction wheel and the driven friction wheel and the probe rod are arc-shaped, and the contact surfaces are provided with toothed structures.

[0027] In some embodiments, an encoder for monitoring the rotational speed of the friction wheel assembly is also included.

[0028] In some embodiments, the first penetration probe and the second penetration probe integrate a sensor group; the sensor group includes a strain sensor for measuring penetration resistance, a pore pressure sensor for measuring pore water pressure, an acceleration sensor, and a gyroscope for tilt correction.

[0029] In some embodiments, the second penetration probe is connected to a data line for real-time data transmission; the first penetration probe is a self-contained probe that integrates a data storage chip and a data interface.

[0030] In some embodiments, the annular slide rail guide mechanism is further provided with rollers for guiding the movement of the ejector loading device and the static loading device; the bottom of the ejector loading device and the static loading device is provided with grooves or guide rails that cooperate with the rollers.

[0031] In some embodiments, the model box is composed of multiple segmented tanks vertically spliced ​​together, and the side walls are provided with observation windows.

[0032] The beneficial effects of this utility model compared with the prior art include:

[0033] This invention provides a switchable loading mode soft soil penetration test platform. Through a unique annular sliding rail guiding mechanism and modular loading device design, it achieves rapid switching and precise positioning between static loading and ejection loading modes on the same platform. This design ensures that the two loading modes have completely consistent centering accuracy and load transmission path, thereby making the static and dynamic test data obtained on the same soil sample highly comparable, providing a technical foundation for the accurate study of soft soil strain rate effects.

[0034] Specifically, the design of the ring slide rail guide mechanism and the positioning hole system not only enables rapid positioning and fixing of the loading device, but also ensures the consistency between the penetration path and the soil sample axis each time; the modular design of the loading device allows static loading and ejection loading to share the same model box and testing environment, eliminating the data deviation caused by sample preparation differences in traditional split equipment; the wide speed range coverage (0.01-12m / s) enables a single platform to meet the full spectrum of testing needs from quasi-static to high-speed disturbance.

[0035] The synergistic effect of these technical features ultimately achieves the top-level beneficial effect of improving the accuracy and efficiency of soft soil strain rate effect research. Specifically, this is manifested in the following ways: by ensuring data acquisition from the same soil sample, at the same test location, and under different loading modes, the testing error caused by sample spatial variability is greatly reduced, improving the fitting accuracy of the strain rate correction coefficient by an order of magnitude; through a rapid switching mechanism, the mode switching time is shortened from the traditional several hours to tens of minutes, significantly improving experimental efficiency and reducing costs; and through multi-point penetration capability, valuable soil sample resources are utilized to the maximum extent, supporting more comprehensive statistical analysis. The adoption of a universal ring-shaped guide mechanism and modular design allows for rapid switching between two loading modes on the same baseline, ensuring consistency of penetration path and test conditions, ultimately eliminating interference from soil sample spatial variability and achieving the top-level beneficial effect of improving research accuracy and efficiency.

[0036] In addition, some embodiments also have the following beneficial effects:

[0037] The mechanical release mechanism employed in the ejection loading device provides a reliable high-speed release mechanism, ensuring accurate control and repeatability of the ejection speed.

[0038] The static loading device uses a friction wheel drive system combined with encoder monitoring to achieve precise control and measurement of the penetration speed, ensuring the accuracy of the quasi-static test.

[0039] The integrated sensor array penetration probe design enables real-time measurement of penetration resistance and pore water pressure, providing complete data support for strain rate effect research.

[0040] The roller design of the annular slide rail guide mechanism makes the movement and adjustment of the loading device more convenient and improves operating efficiency.

[0041] The segmented model housing design balances testing requirements with ease of operation, and the observation window facilitates observation during the test process.

[0042] Other beneficial effects of the embodiments of this utility model will be further described below. Attached Figure Description

[0043] Figure 1This is a schematic diagram of the overall structure of the soft soil penetration test platform in this embodiment of the utility model (with the ejector loading device installed).

[0044] Figure 2a This is a front view of the static loading device module in an embodiment of this utility model.

[0045] Figure 2b This is a top view of the static loading device module in an embodiment of this utility model.

[0046] Figure 3 This is a schematic diagram of the structure of the annular slide rail guide mechanism in an embodiment of this utility model.

[0047] Figure 4 This is a schematic diagram of the overall structure of the soft soil penetration test platform in another embodiment of this utility model (static loading device installation state).

[0048] The annotations in the attached figures are explained as follows:

[0049] 1. Ejector loading device; 2. First penetration probe; 3. Circular slide rail guide mechanism; 4. Model box; 5. First upper positioning hole; 6. Lower positioning hole; 7. Static loading device; 71. Probe rod; 72. Driven friction wheel; 73. Friction wheel cylinder; 74. Static loading device base plate; 75. Gear motor; 76. Second penetration probe; 77. Active friction wheel; 78. Second upper positioning hole; 79. Drive shaft. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0051] It should be noted that the directional terms such as left, right, up, down, top, and bottom used in this embodiment are only relative concepts or are based on the normal use of the product, and should not be considered as restrictive.

[0052] This embodiment aims to provide a soft soil penetration test platform with switchable loading modes. Its core is to integrate the static loading module and the ejection loading module onto the same platform frame through a universal annular sliding rail guide mechanism with precise positioning function, so as to realize the rapid and accurate switching and positioning of the two loading modes and ensure that penetration response data with a wide range of strain rates are obtained under the same soil sample reference.

[0053] Example 1

[0054] refer to Figures 1 to 4This embodiment provides a soft soil penetration test platform with switchable loading modes, including a model box 4 for holding soft soil samples; an annular slide rail guide mechanism 3, fixedly installed on the top of the model box 4, the annular slide rail guide mechanism 3 having multiple lower positioning holes 6 evenly distributed circumferentially; and a loading device including a catapult loading device 1 and a static loading device 7, the catapult loading device 1 and the static loading device 7 being selectively installed on the annular slide rail guide mechanism; wherein, the bottom of the catapult loading device 1 and the static loading device 7 are respectively provided with a first upper positioning hole 5 and a second upper positioning hole 78 corresponding to the lower positioning holes 6, and by inserting positioning parts into the corresponding first upper positioning hole, second upper positioning hole and lower positioning hole, the catapult loading device 1 and the static loading device 7 can be detachably fixed to a predetermined circumferential position of the annular slide rail guide mechanism 3. The model housing 4 is preferably a cylindrical container with a total height of 4 meters and a diameter of 1 meter. This container is composed of four segmented circular tanks, each 1 meter high, vertically spliced ​​together by flanges and sealing rings. One or more of the segmented tanks have observation windows on their side walls. These windows are made of high-strength transparent acrylic sheets and are approximately 300mm × 300mm in size, used for optical observation during the experiment. The annular guide rail mechanism is preferably an annular guide rail machined from Q235 steel, with its outer diameter matching the outer diameter of the top of the model housing. It is fixed to the top flange of the housing with bolts. Twelve lower positioning holes are evenly machined along the circumference of this annular guide rail. These holes are open-aperture holes with a diameter of 12mm, and their positional accuracy is ensured by a CNC machine tool. The positioning element is preferably a positioning pin with a diameter of 12mm and a length of 50mm. The positioning element can also be a block, a snap-fit, or an electromagnetic lock, etc. The loading device has an upper positioning hole and a groove at its bottom. Specifically, the bottom of the ejector loading device 1 is provided with a steel base plate, on which a first upper positioning hole 5 is machined, the same size as the lower positioning hole. Two parallel grooves are also machined on the bottom of the base plate. The bottom of the static loading device is provided with a steel static loading device base plate 74, on which a second upper positioning hole 78 is machined, the same size as the lower positioning hole. Two parallel grooves are machined on the bottom of the static loading device base plate. The annular slide rail guide mechanism 3 is also provided with rollers, preferably multiple deep groove ball bearings, which are mounted on the upper surface of the annular guide rail by brackets. Their arrangement cooperates with the grooves at the bottom of the loading device to form a sliding pair for guiding the movement of the loading device.

[0055] This embodiment solves the problem of traditional test platforms having limited functionality and being unable to quickly conduct multi-mode comparative tests on the same soil sample. The core of the platform consists of a model box, a universal guide rail, and two sets of interchangeable loading devices. The model box is located at the bottom of the entire platform. The annular slide rail guide mechanism is fixedly installed at the top center of the model box by bolts. The ejector loading device and the static loading device sit on the rollers of the annular slide rail guide mechanism through grooves at their bottoms and can slide circumferentially along the rollers. By aligning the upper positioning hole of the loading device's base plate with a lower positioning hole on the annular slide rail guide mechanism and inserting a positioning pin, the loading device can be fixed in that circumferential position. At this time, the penetration path of the loading device coincides with the central axis of the model box. Its working principle is: through the sliding and positioning mechanism, the two loading devices can be quickly replaced and accurately positioned on the same reference platform, ensuring the consistency of the penetration path. The specific dimensions are as follows: the model box is 4m high and 1m in diameter; the outer diameter of the circular slide rail guide mechanism is 1m; the lower positioning hole has a diameter of 12mm and a total of 12 holes; the positioning pin has a diameter of 12mm and a length of 50mm; and the outer diameter of the roller (bearing) is 20mm.

[0056] The specific implementation steps of this embodiment are as follows:

[0057] Step 1. Prepare soil samples: Assemble the four segmented tanks into a model box, lay a 20-30cm thick layer of medium-coarse sand at the bottom, and then fill it with the prepared soft clay sample.

[0058] Step 2. Install the device: Select either a catapult loading device or a static loading device according to the test requirements. Align the groove at the bottom of the device with the roller on the annular slide rail guide mechanism, and gently push the loading device to make it slide.

[0059] Step 3. Positioning and locking: Slide the loading device to the target circumferential position, adjust the position so that the upper positioning hole on the loading device base plate is aligned with one of the lower positioning holes on the annular slide rail guide mechanism 3, insert the positioning pin, and complete the installation and centering.

[0060] Step 4. Conduct the test: Run the installed loading device to conduct a penetration test.

[0061] Step 5. Switching Modes: After the test is complete, pull out the positioning pin and slide the current loading device off the guide rail. Then take another loading device and repeat steps 2-4 to switch to another loading mode for the test.

[0062] Example 2

[0063] This embodiment is a further optimization of Embodiment 1. The ejector loading device 1 of this embodiment includes a support frame; a spring energy storage device, including a spring and a compression spring member (i.e., a compression spring sheet) for compressing the spring; the spring is housed in a spring outer sleeve; an electric push rod, mounted on the support frame; a first penetration probe 2, which is a free-fall type, with a recovery hole at its top for connecting and recovering the steel cable; a detachable connection mechanism, including a force transmission ring disposed on the first penetration probe 2; and a mechanical release mechanism, including a height-adjustable triggering member (i.e., a disc triggering mechanism) and a triggered member (i.e., a spring hook) linked to the detachable connection mechanism. The spring hook is hinged to the output end of the electric push rod and is configured with an elastic element that gives it a normally closed tendency; the disc triggering mechanism has a guide ramp; and the mechanical release mechanism further includes a vertically arranged adjusting rod and an adjusting nut for locking the height of the disc triggering mechanism. The disc trigger mechanism is sleeved on the adjusting rod, and its fixed height on the adjusting rod can be precisely changed by turning the adjusting nut. A sleeve structure is provided, with a sleeve sleeved outside the first penetration probe 2, its lower end fixedly connected to the compression spring, and its upper end limiting the force transmission ring. The spring is sleeved outside the sleeve. The base includes a guide rail for fixing the entire mechanism to the test platform and a sliding component (i.e., a roller) cooperating with the guide rail. The first penetration probe 2 integrates a sensor group, including a strain sensor for measuring penetration resistance, a piezoelectric air pressure sensor for measuring pore water pressure, an acceleration sensor, and a gyroscope for tilt correction. The first penetration probe 2 is a "self-contained probe," and it also integrates a data storage chip (such as a Micro SD card) and a charging data interface (such as a USB-C interface). The probe has a built-in rechargeable lithium battery to power the entire measurement system. The spring is preferably a large, high-strength compression helical spring with a stiffness coefficient preferably of 10.3 kN / m.

[0064] The difference between this embodiment and Embodiment 1 is that it defines in detail the specific structure of the ejection loading device, the release mechanism, and the measurement and data storage methods of the probe.

[0065] The specific implementation steps of this embodiment are refined based on step 4 of embodiment 1: Step 4. Perform a catapult loading test: a. Energy storage stage: The electric push rod extends downward, driving the spring hook at its end to move downward to grab the force transmission ring on the first penetration probe 2; subsequently, the electric push rod retracts and moves upward, pulling the first penetration probe 2 and the sleeve and compression spring fixed thereto upward through the spring hook and force transmission ring, thereby compressing the spring to store energy. b. Locked and ready-to-trigger state: When the spring hook rises with the electric push rod to the preset height (close to the height position of the disc trigger mechanism set by the adjusting nut), its exterior has not yet contacted the guide slope of the disc trigger mechanism, the spring hook remains closed, firmly gripping the force transmission ring, and the system is in the energy storage ready-to-excite state. c. Trigger release: When the spring hook continues to rise with the electric push rod to the height position of the disc trigger mechanism, the upper end of the spring hook is constrained by the guide slope of the disc trigger mechanism, and the spring hook opens under the action of its own hinge point and elastic element, instantly releasing the force transmission ring and the first penetration probe 2. The compressed spring rapidly releases its energy, which is then transferred to the force transmission ring via the compression spring plate and sleeve, ultimately driving the first penetration probe 2 to eject at high speed. d. The spring hook instantly disengages, and the compressed spring rapidly releases its elastic potential energy, propelling the first penetration probe into the soil sample at high speed. e. The sensor inside the probe synchronously collects data during penetration and stores it in the built-in storage chip. f. After the test, a retrieval device (such as a winch and wire rope) is used to pull the probe out of the soil. g. The test data stored inside the probe is read through the data interface.

[0066] Example 3

[0067] This embodiment is a further optimization of Embodiment 1. The static loading device 7 in this embodiment includes a geared motor; a friction wheel assembly consisting of an active friction wheel 77 and a driven friction wheel 72, wherein the geared motor 75 is connected to the active friction wheel 77 via a transmission shaft 79; a probe 71, the lower part of which is connected to a second penetration probe 76, and the upper part is positioned between the active friction wheel 77 and the driven friction wheel 72; and a friction wheel cylinder 73, the output end of which is connected to the driven friction wheel 72, for driving the driven friction wheel 72 to press or release the probe 71. The contact surfaces between the active and driven friction wheels and the probe 71 are arc-shaped, and the contact surfaces are provided with toothed structures. Preferably, both friction wheels are made of 42CrMo alloy steel and surface-hardened to HRC50-55. The included angle of their V-grooves is 90°, matching the diameter of the cylindrical probe 71. The V-groove surface is machined with a fine tooth structure, 0.5mm deep, to enhance clamping force and prevent slippage. It also includes an encoder for monitoring the rotational speed of the friction wheel assembly, preferably an incremental rotary encoder, directly mounted on the output shaft of the reduction motor 75 or the shaft of the active friction wheel 77, for real-time monitoring of the actual rotational speed of the friction wheels. The second penetration probe 76 integrates a sensor group, including a strain gauge force sensor for measuring penetration resistance, a piezoelectric pore pressure sensor for measuring pore water pressure, and a gyroscope for tilt correction. The second penetration probe 76 is connected to a shielded data cable for real-time data transmission, arranged along the inner side of the probe rod and connected to a data acquisition device at the top of the platform. The friction wheel cylinder is preferably a double-acting hydraulic cylinder, powered by a hydraulic station. The system can provide approximately 1 ton of clamping force during clamping.

[0068] The difference between this embodiment and Embodiment 1 is that it defines in detail the specific structure, transmission mechanism, and measurement and data transmission method of the probe of the static loading device.

[0069] The specific implementation steps of this embodiment are refined based on step 4 of embodiment 1: Step 4. Conduct a static loading test: a. Start the friction wheel cylinder to push the driven friction wheel to press the probe rod, and the clamping force is controlled by the hydraulic system. b. Start the reduction motor and set the target speed (corresponding to the target penetration speed) through the controller. c. The motor drives the active friction wheel to rotate, and the friction force drives the probe rod and the second penetration probe to penetrate the soil sample at a constant speed. d. The encoder monitors the friction wheel speed in real time and feeds the signal back to the PLC or single-chip microcomputer control system. The control system uses a PID algorithm to compare the actual speed with the set speed and dynamically adjust the motor output to maintain a stable penetration speed. e. The sensor in the second penetration probe collects data in real time and transmits it to the data acquisition instrument for display and recording via a data cable. f. After penetrating to the predetermined depth, the motor is reversed to lift the probe out of the soil sample at a constant speed.

[0070] The purpose of this utility model embodiment is to overcome the problems of existing penetration test devices, such as single loading mode, limited speed range, insufficient strain rate control capability, and poor structural adaptability. It provides a soft soil penetration test platform with switchable loading modes, which can achieve a wide range of penetration speed coverage from quasi-static (0.01 m / s) to high-speed disturbance (12 m / s) in a controlled indoor environment. This supports the study of the strength response and pore pressure change of soft soil under different strain rate conditions, and improves the accuracy and efficiency of experimental research on the penetration mechanism of soft soil.

[0071] The embodiments of this utility model include the following key contents:

[0072] Rapid switching of loading modes: An adjustable static loading device is designed, and an interface plate structure is provided in the loading area of ​​the original catapult-type experimental platform to support the rapid positioning and fixing of different types of penetration devices. This ensures the centering accuracy and ease of operation during the replacement of static / catapult loading devices, enabling rapid switching between quasi-static penetration tests and high-speed disturbance tests without disassembling the main body of the model box. The annular slide rail guide mechanism is a structural pair consisting of the interface plate and the top of the model box, with the interface plate being part of the guide mechanism; both refer to the circular plate structures on the top of the system where the two test devices are connected and installed.

[0073] Wide penetration speed range: The static loading section uses a combination of a geared motor and a screw propulsion mechanism, and the penetration speed is continuously adjustable, ranging from 0.01 m / s to 0.5 m / s; the ejection loading section achieves high-speed penetration of 6~12 m / s through an adjustable compression spring and a mechanical release structure, covering the typical CPTU and FFP loading rate range, and can realize the construction of continuous strain rate response curves.

[0074] The guide rail sliding platform supports multi-point penetration: A ring-shaped guide rail mechanism is installed at the top of the platform, allowing the loading unit to slide and lock circumferentially, enabling the same sample to be penetrated at multiple locations on the same plane, enhancing soil sample utilization and test comparability. The rail structure is compatible with both static and ejection loading devices, ensuring high accuracy and repeatability of penetration points. Existing research indicates that the influence range of the penetrated soil is generally within three times the diameter of the penetration probe. This platform design fully considers this issue; the interval between each pair of adjacent test locking points is six times the probe diameter, and the test points are symmetrically distributed during actual testing. Two consecutive tests will not use adjacent points, but rather symmetrically alternating test points, ensuring that the results of the subsequent test are not affected by the results of the previous test.

[0075] In some embodiments, the switchable structure of the loading device is designed as follows:

[0076] The platform's loading area features an integrated annular slide rail guide mechanism with universal grooves and limiting holes for rapid installation and stable alignment of different types of loading devices. This annular slide rail guide mechanism is fixedly connected to the platform's top frame, serving as a structural bridge unit between the loading device and the model box. The annular slide rail guide mechanism has mounting and positioning holes, allowing for quick installation and disassembly of both types of loading devices by inserting fastening bolts or positioning pins through these holes. This eliminates the need to replace the model box or slide rail structure, enabling indoor switching between loading modes.

[0077] A penetration speed control system is adopted:

[0078] The ejection loading module uses a vertically arranged compression spring as its power source. A pressure plate (or a compression spring sheet) is connected to the bottom of the spring. An electric push rod pre-compresses the spring by pulling a release mechanism (e.g., a hook or pin) connected to the pressure plate. By precisely controlling the stroke of the electric push rod, the initial compression of the spring can be set, thereby precisely controlling the initial penetration velocity of the probe after release and stabilizing it within the range of 6~12 m / s. The spring release mechanism is a mechanical structure. When the electric push rod pulls the spring hook to the disc trigger position, it triggers the release of the small spring, completing the high-speed release of the probe. After the ejection test, the probe is pulled out and retrieved via a steel cable connected to it. The penetration velocity of this device can be adjusted within the range of 6~12 m / s.

[0079] The static loading module uses a horizontally mounted geared motor to transmit kinetic energy to friction wheels via its output shaft. The friction wheels clamp the probe rod, which acts as a penetration device, using friction to drive the probe rod up and down, achieving downward penetration and upward lifting. The penetration speed can be controlled by adjusting the motor speed, ultimately achieving a probe rod penetration speed range of 0.01 m / s to 0.5 m / s (where m / s represents meters per second), meeting the requirements of soil response testing under quasi-static conditions. The static loading section abandons the traditional hydraulic cylinder or long lead screw design, adopting an active friction wheel drive mode to adapt to the requirements of long-stroke continuous penetration.

[0080] The kinetic energy of the geared motor 75 is directly transmitted to the active friction wheel 77 through the transmission shaft 79. The motor speed is adjusted by the controller, and thus linearly mapped to the penetration speed of the probe (0.01~0.5 m / s).

[0081] The friction wheel cylinder 73 drives the driven friction wheel 72 to move horizontally towards the driving wheel, tightly clamping the inserted probe 71 in the V-shaped or concave groove between the two wheels. The static friction force generated by the high positive pressure overcomes the soil resistance, achieving stable sinking and uniform retrieval of the probe.

[0082] The sliding platform structure enables multi-point penetration:

[0083] The loading area at the top of the platform is equipped with a ring-shaped guide rail mechanism, on which several rollers are arranged and a lower positioning hole is provided. The bottom plate of the loading device has an upper positioning hole and a groove. Placing the loading device in the groove on the rollers achieves horizontal positioning. Adjust the loading device to move circumferentially along the top surface of the model box. When it moves to the designated penetration point, insert the positioning pin into the upper and lower positioning holes and tighten to lock it in place. The centerline of the guide rail coincides with the centerline of the model box to ensure that the penetration path is consistent with the axial direction of the soil sample each time.

[0084] This embodiment provides a soft soil penetration test platform with switchable loading modes, enabling free switching between projectile loading and static loading on the same platform structure, meeting the testing requirements for the mechanical response of soft soil under different penetration speed conditions. The following is combined with... Figures 1-4 The structure shown is explained in detail, along with the platform's configuration and operation process.

[0085] In some embodiments, the overall structure of the test platform and the arrangement of the model housing are as follows:

[0086] like Figure 1 As shown, the entire test platform consists of a model box 4, a catapult loading device 1, a first penetration probe 2 (preferably an FFP probe), and a ring-shaped guide rail mechanism 3. The model box 4 is composed of multiple segmented tanks with a diameter of 1 meter and a height of 1 meter, vertically spliced ​​together. A transparent observation window is provided in the middle of the tank to facilitate synchronous observation by an external high-speed camera during the test.

[0087] The model box 4 has a drainage outlet at the bottom, which can be filled with clean water through top water injection or pumping to simulate the saturated environment of the seabed. A ring-shaped sliding rail guide mechanism 3 is installed on the top surface of the box to support the loading device and adjust its position in the circumferential direction.

[0088] Installation and operation of the catapult loading device:

[0089] like Figure 1 As shown, the catapult loading device 1 is aligned with the lower positioning hole 6 of the annular slide rail guide mechanism by the first upper positioning hole 5 on the base plate of the catapult device, and fixed by inserting a positioning pin, which can be reinforced with bolts. After the device is installed, its initial penetration path is consistent with the central axis of the model box 4. If repeated testing is required, the radial slide rail of the catapult device can be adjusted according to the test position requirements to make the catapult device reach the designated position.

[0090] Before the test begins, the operator uses an electric actuator (which can be a mechanical device that converts the rotary motion of an electric motor into linear reciprocating motion) to pull the spring plate upward, compressing the internal single helical spring, and sets the compression stroke length to control the energy release. Once the set stroke is reached, the spring hook is pushed or pulled to the position of the disc trigger mechanism, activating the small spring mechanism and automatically releasing the spring hook, thus completing the ejection release of the first penetration probe 2. At this point, the probe enters the soil at a speed of 6-12 m / s, simulating the soil response process under high-speed disturbance conditions. After the test, the probe can be pulled back using the top retrieval device or a cable system. The electric actuator moves the spring plate upward, causing the compressed spring to deform. By precisely controlling the extension and retraction stroke of the electric actuator, the elastic potential energy storage of the spring can be quantitatively adjusted, thereby precisely setting the initial penetration velocity of 6-12 m / s. The spring hook cooperates with the disc trigger mechanism; when the electric actuator is pulled to the predetermined limit position, it triggers the small spring to instantly disengage the spring hook. After the probe is unconstrained, it is ejected at high speed by an elastic impact, thus simulating a high-speed disturbance condition.

[0091] Installation and operation of static loading devices:

[0092] like Figure 2a and Figure 2b As shown, the static loading device 7 includes a probe 71, a second penetration probe 76 (preferably a CPTU probe with an international standard 10cm2 specification), a reduction motor 75, a friction wheel assembly (including an active friction wheel 77, a driven friction wheel 72 and a friction wheel cylinder 73), and a drive shaft 79, among other components.

[0093] When a static penetration test is required, first disassemble the ejection loading device 1, and then install the static loading device 7 (see...). Figure 4 Place the static loading device on the same interface plate, align the bottom groove of the static loading device with the annular slide rail guide mechanism 3, and align the second upper positioning hole 78 with the lower positioning hole 6 of the annular slide rail guide mechanism 3. Insert the positioning bolt and tighten it to complete the installation of the static module.

[0094] During operation, the geared motor 75 starts and drives the transmission shaft 79 to rotate, which in turn drives the active friction wheel 77 to rotate. The friction wheel cylinder 73 then causes the driven friction wheel 72 to clamp the probe 71, which is then pushed downwards by friction. The motor speed can be continuously adjusted within the range of 0.01 m / s to 0.5 m / s to meet the requirements for sediment shear strength testing under quasi-static penetration conditions. After the test, the motor reverses to lift and retract the probe. The driven friction wheel 72, along with the transmission shaft 79, is pushed as a whole by the friction wheel cylinder 73, causing the arc-shaped contact surfaces of the two friction wheels to press synchronously onto the probe for clamping, based on conventional hydraulic principles.

[0095] In this embodiment, the contact surface between the friction wheel and the probe rod adopts an arc-shaped design, which fits the outer cylindrical surface of the probe rod. The contact surface is designed with a toothed structure. The friction wheel is made of alloy as a whole, and the contact surface is hardened by quenching. The clamping contact effect is ensured by metal hard contact.

[0096] The clamping force generated in this embodiment is about 1 ton, which can ensure the clamping effect. Since the friction wheel is made of hard alloy, its teeth are embedded in the probe to a certain extent, so there is no possibility of slippage.

[0097] In this embodiment, an encoder is used on the friction wheel to record its rotation, including its rotational speed and stroke. A PID control algorithm is then used to maintain a constant rotational speed. Since there is no slippage, the rotational speed is equivalent to the probe penetration speed.

[0098] Loading point position adjustment and multi-point penetration test:

[0099] When repeated tests are required, the loading device can be adjusted horizontally by pushing the annular slide rail guide mechanism 3 set on the top of the platform. For example... Figure 1 and Figure 4 As shown, the lower part of the base plate of both the catapult loading device 1 and the static loading device 7 is equipped with a roller groove structure, which can slide and adjust the position within a circular track. During adjustment, the operator gently pushes the device to rotate it on the slide rail to the new target point. After confirming alignment, the positioning bolt is inserted into the mating holes to lock the new position. This structure ensures that the penetration axis is perpendicularly aligned with the model box each time, supports multi-point penetration test arrangements, and facilitates comparison of soil response differences at different points.

[0100] This utility model provides an indoor penetration test platform for studying the strain rate effect of soft soil. It has advantages such as switchable loading modes, controllable penetration rate, convenient operation, and strong structural versatility, and has the following significant technical effects and practical application value:

[0101] Rapid switching of loading modes improves test efficiency: Thanks to the integrated ring slide rail guide mechanism and quick positioning hole design, both loading devices can be connected to the platform frame through a universal interface, enabling rapid switching between static and catapult devices without disassembling the model box body, significantly shortening preparation time and ensuring centering accuracy.

[0102] Covering a wide range of penetration velocities, supporting systematic research on strain rate effects: Combining a geared motor helical propulsion mechanism with a catapult-type compression spring drive system, the penetration velocity can be covered from quasi-static (0.01 m / s) to high-speed disturbance (12 m / s), solving the problem of limited loading range of a single device, and providing experimental support for constructing a complete soft soil strain rate response curve.

[0103] The sliding platform structure improves soil sample utilization: By setting a ring-shaped sliding rail guide mechanism and a positioning pin locking structure at the top of the platform, the loading unit can move smoothly in the circumference and lock at multiple points. This makes it possible to conduct multiple comparative tests at different locations on the same sample section, maximizing the utilization of soil sample resources within the large-size model box.

[0104] The device features a compact and versatile structure, suitable for various penetration test requirements: its modular design allows for compatibility with guide rails via grooves in the base plate and roller grooves, enabling one model housing to accommodate multiple penetration mechanisms. This highly versatile structural design reduces the need for repeated construction for different test environments, making it highly valuable for engineering applications and widespread adoption.

[0105] During the ejection penetration test, the FFP probe is self-contained. After the probe is launched, it will automatically collect data and store it in an internal memory card. After the test is completed, the probe can be retrieved and the memory card can be removed to read the data. In addition, the probe is also equipped with a data transmission interface. When the internal battery of the probe is low, it can also be connected to a cable to achieve power supply and data transmission (this mode is generally not used, as the cable will bring resistance and reduce speed).

[0106] The model box is 4m high and is composed of four circular tanks, each 1m high and 1m in diameter. During the test, a 20-30cm layer of sand is usually laid at the bottom, and then the test soil sample is laid on top of it. The bottom sand layer protects the probe, preventing it from directly impacting the bottom of the model box.

[0107] In this embodiment of the invention, only the loading device on the top of the model box needs to be replaced in both modes.

[0108] This invention integrates traditionally independent and single-function static and dynamic penetration devices into a modular test platform covering the entire rate range by developing a universal sliding rail interface system with "precise spatial positioning and rigid load transmission" functions. This system enables rapid switching and precise positioning of the static friction propulsion module and the high-speed catapult drive module under the same reference, ensuring continuous acquisition of penetration response data from quasi-static to high-speed (0.01-12 m / s) on the same soil sample plane within a short period. This design fundamentally solves the interference of spatial and temporal variability in sample preparation on experimental results, providing a unified experimental platform for accurately analyzing the strain rate effect of soft soil.

[0109] In geotechnical engineering experiments, soil sample preparation is time-consuming and labor-intensive (for example, preparing soft clay samples similar to deep-sea sediments can take months). The size design and multi-functional guide rail system of this invention allow for multiple penetrations from a single sample preparation without interference between experimental results, significantly saving sample preparation time and improving experimental efficiency. Furthermore, the rapid positioning and switching system of this invention enables static and dynamic tests to be completed at similar distances on the same soil sample cross-section within tens of minutes. This eliminates the "spatial variability" interference caused by re-sample preparation in traditional experiments, ensuring that differences in penetration resistance are 100% attributed to strain rate effects, thereby improving the fitting accuracy of the strain rate correction coefficient by an order of magnitude.

[0110] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, with identical performance or use, should be considered within the protection scope of the present invention.

Claims

1. A soft soil penetration test platform with switchable loading modes, characterized in that, include: Model box (4) is used to hold soft soil samples; The annular slide rail guide mechanism (3) is fixedly installed on the top of the model box (4), and the annular slide rail guide mechanism (3) is provided with multiple lower positioning holes (6) evenly distributed along the circumference. The loading device includes a catapult loading device (1) and a static loading device (7), wherein the catapult loading device (1) and the static loading device (7) are optionally mounted on the annular slide rail guide mechanism (3); The bottom of the ejector loading device (1) and the static loading device (7) are respectively provided with a first upper positioning hole (5) and a second upper positioning hole (78) corresponding to the lower positioning hole (6). By inserting the positioning member into the corresponding first upper positioning hole (5), second upper positioning hole (78) and lower positioning hole (6), the ejector loading device (1) and the static loading device (7) can be detachably fixed to the predetermined circumferential position of the annular slide rail guide mechanism (3).

2. The soft soil penetration test platform with switchable loading modes according to claim 1, characterized in that, The ejection loading device (1) includes: Supporting framework; A spring energy storage device includes a spring and a compression spring member for compressing the spring, the spring being housed within a spring outer sleeve; An electric actuator is mounted on the support frame; A detachable connecting mechanism is connected to the compression spring component; A mechanical release mechanism, connected to the spring, is used to release the spring after it has been compressed; The first penetration probe (2) is connected to the end of the spring.

3. The soft soil penetration test platform with switchable loading modes according to claim 2, characterized in that, The detachable connection mechanism includes a force transmission ring disposed on the first penetration probe (2), and the mechanical release mechanism includes a height-adjustable triggering component, a triggered component for gripping the force transmission ring, a vertically arranged adjusting rod, and an adjusting nut for locking the height of the triggering component; the triggering component is sleeved on the adjusting rod.

4. The soft soil penetration test platform with switchable loading mode according to claim 3, characterized in that, The static loading device (7) includes: Gear motor (75); A friction wheel assembly consisting of an active friction wheel (77) and a driven friction wheel (72) is provided, wherein the reduction motor (75) is connected to the active friction wheel (77) in a transmission connection. The probe rod (71) is connected to the second penetration probe (76) at its lower part and is positioned between the active friction wheel (77) and the driven friction wheel (72) at its upper part. The friction wheel cylinder (73) has its output end connected to the driven friction wheel (72) and is used to drive the driven friction wheel (72) to press or release the probe (71).

5. The soft soil penetration test platform with switchable loading modes according to claim 4, characterized in that, The contact surfaces of the active friction wheel (77) and the driven friction wheel (72) with the probe (71) are arc-shaped, and the contact surfaces are provided with toothed structures.

6. The soft soil penetration test platform with switchable loading mode according to claim 4 or 5, characterized in that, It also includes an encoder for monitoring the rotational speed of the friction wheel assembly.

7. The soft soil penetration test platform with switchable loading modes according to claim 4, characterized in that, The first penetration probe (2) and the second penetration probe (76) have integrated sensor groups inside; the sensor groups include a strain sensor for measuring penetration resistance, a pore pressure sensor for measuring pore water pressure, an acceleration sensor, and a gyroscope for tilt correction.

8. The soft soil penetration test platform with switchable loading mode according to claim 7, characterized in that, The second penetration probe (76) is connected to a data line for real-time data transmission; the first penetration probe (2) is a self-contained probe with an integrated data storage chip and data interface.

9. The soft soil penetration test platform with switchable loading modes according to claim 1, characterized in that, The annular slide rail guide mechanism (3) is also provided with rollers for guiding the movement of the ejector loading device (1) and the static loading device (7); the bottom of the ejector loading device (1) and the static loading device (7) is provided with grooves or guide rails that cooperate with the rollers.

10. The soft soil penetration test platform with switchable loading mode according to claim 1, characterized in that, The model box (4) is composed of multiple segmented tanks vertically spliced ​​together, and the side wall is provided with an observation window.

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