Model test system for simulating influence of pile shoe penetration on adjacent large-diameter single pile

Abstract

The utility model discloses a model test system for simulating the influence of pile shoe penetration on an adjacent large-diameter single pile, which relates to the technical field of geotechnical engineering tests and comprises a model test box, a pile shoe foundation model, a pile foundation model, a loading device and a data acquisition system. According to the device, the model test box is creatively integrated to reproduce the layered structure of the ocean soil layer, the pile shoe loading device is adopted to simulate the pile shoe penetration process, and the horizontal loading device is used for applying lateral load to simulate the loading state of an adjacent pile. A soil body displacement measuring device is embedded in the device, modular design is adopted for a pile foundation model, and working conditions with different length-diameter ratios are simulated through extensible sections and an expanding adapter. The test device not only considers the soil squeezing effect during penetration of the pile shoe, but also performs parametric design for the length-diameter ratio characteristic of the large-diameter single pile, and provides an effective simulation and monitoring means for exploring the mechanical response of the penetration of the pile shoe to the adjacent large-diameter single pile.

Description

Technical Field

[0001] This utility model relates to the field of geotechnical engineering testing technology, and in particular to a model test system for simulating the impact of pile shoe penetration on adjacent large-diameter single piles, with an innovative design specifically for parameterized control of the length-to-diameter ratio of large-diameter single piles. Background Technology

[0002] In offshore oil development and offshore wind power engineering, drilling vessels, as core operational equipment, often use large-diameter pile shoes to temporarily anchor the seabed. During the penetration process, the pile shoes exert significant soil disturbance effects on adjacent existing pile foundations, mainly manifested as the transfer of soil displacement pressure, reconstruction of the soil displacement field, and accumulation of additional bending moments in the pile body. Therefore, quantitatively assessing the impact mechanism of pile shoe penetration on adjacent large-diameter monopiles has become a critical issue that urgently needs to be addressed in the field of marine geotechnical engineering.

[0003] Current research on pile-adjacent pile interactions largely focuses on pile group effects or small-diameter pile foundations, while targeted research on large-diameter single piles is significantly insufficient. Due to their larger length-to-diameter ratio (L / D), large-diameter single piles exhibit load transfer mechanisms and soil response characteristics that differ significantly from traditional small-diameter piles. Specifically, this manifests as a reduced end resistance ratio, a more complex distribution of side friction, and increased sensitivity to pile body flexural deformation.

[0004] To address the aforementioned issues, developing a model test system capable of simulating the length-diameter ratio characteristics of large-diameter single piles is of significant engineering importance. Utility Model Content

[0005] This invention aims to provide a model test system for simulating the impact of pile shoe penetration on adjacent large-diameter monopiles, addressing the challenge of assessing the mechanical response of pile shoe penetration disturbance to adjacent large-diameter monopiles (D > 2m) in marine engineering. Through modular design of the pile foundation model, this system can quantitatively analyze the influence of pile shoe penetration on soil disturbance, additional bending moment of the pile, soil displacement, and the length-to-diameter ratio (L / D) effect, providing experimental basis for engineering safety spacing design and disaster prevention.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A model test system for simulating the impact of pile shoe penetration on adjacent large-diameter single piles includes a model test box, a pile shoe foundation model, a pile foundation model, a loading device, and a data acquisition system.

[0008] The model test chamber consists of, from top to bottom, a foundation, a model soil layer, geotextile and a gravel filter layer;

[0009] The loading device includes a pile shoe loading device and a horizontal loading device. The pile shoe loading device consists of a servo motor, an electric cylinder, a reaction frame, a force sensor, and a displacement sensor. The electric cylinder is vertically mounted on the test soil box through the reaction frame. The electric cylinder rod is vertically downward and connected to the force sensor and the displacement sensor. The other end of the force sensor is connected to the pile shoe through a connecting rod. The horizontal loading device consists of a pulley and a load.

[0010] The data acquisition system includes strain gauges, a soil displacement measuring device, an electromechanical dial gauge, and a computer. The strain gauges are arranged along the center lines on both sides of the pile, with the bottom of the pile foundation model as the reference. The soil displacement measuring device is placed on the other side of the pile shoe, symmetrical to the position of the pile foundation model with the pile shoe as the center. The electromechanical dial gauge is located at a distance above the soil surface. The information collected by the strain gauges, the soil displacement measuring device, and the electromechanical dial gauge is transmitted to the computer system for analysis.

[0011] Furthermore, the model test box is made of circular steel material, and the minimum distance between the wall of the model test box and the model pile is greater than 3 times the pile diameter.

[0012] Furthermore, the pile foundation model has a circular aluminum alloy tube cross-section, consisting of foundation pile segments and expandable segments. Each segment of the expandable segment is connected by a high-precision threaded interface, and an expansion adapter is installed at the pile end.

[0013] Furthermore, the top of the pile foundation model and the bottom of the pile cap are rigidly connected (such as by welding or bolting) to ensure that the horizontal load can be effectively transferred to the pile body, and the pile cap is connected to the reaction frame by a steel sleeve to ensure the stability of the pile cap.

[0014] Furthermore, the strain gauges in the data acquisition system are waterproofed and sealed with waterproof adhesive.

[0015] Furthermore, the soil displacement measuring device in the data acquisition system consists of several measuring units. Each unit consists of a stainless steel shell and an inclination sensor. The top is connected to an aviation connector to lead out the sensor wiring, and the bottom is designed in a wedge shape for easy insertion and fixation. The entire device is encapsulated with a butyl rubber sleeve.

[0016] The principle and beneficial effects of this technical solution:

[0017] This invention provides a model test system for simulating the impact of pile shoe penetration on adjacent large-diameter single piles. Based on similarity theory, the test model is geometrically similar to the prototype. Different length-to-diameter ratio conditions are simulated by adjusting the pile segment combination and the pile end diameter expansion adapter. Axial-lateral coupled loads are applied to simulate the soil squeezing effect and the loading state of adjacent piles during pile shoe penetration.

[0018] This system overcomes the limitations of traditional model tests in simulating large-diameter single piles through parametric design of aspect ratio, providing a reliable test platform for the safety assessment of marine engineering pile foundations and possessing certain engineering application value. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of a model test system that simulates the impact of pile shoe penetration on adjacent large-diameter single piles.

[0020] Figure 2 This is a pile shoe model diagram in a model test system that simulates the impact of pile shoe penetration on adjacent large-diameter single piles;

[0021] Figure 3 This is a diagram of a soil displacement measurement device for a model test system that simulates the impact of pile shoe penetration on adjacent large-diameter single piles.

[0022] The reference numerals in the accompanying drawings of the instruction manual include: 1. Foundation; 2. Model soil layer; 3. Geotextile; 4. Crushed stone filter layer; 5. Servo motor; 6. Electric cylinder; 7. Reaction frame; 8. Force sensor; 9. Displacement sensor; 10. Lead-line pulley; 11. Load; 12. Strain gauge; 13. Soil displacement measuring device; 14. Electromechanical dial indicator; 15. Pile shoe foundation model; 16. Pile foundation model. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0024] like Figure 1 As shown, a model test system for simulating the impact of pile shoe penetration on adjacent large-diameter single piles includes a model test box, a pile shoe foundation model, a pile foundation model, a loading device, and a data acquisition system.

[0025] Model box and soil preparation: Taking saturated fine sand as an example, firstly, a gravel filter layer is laid at the bottom of the model test box, and then a layer of geotextile is laid on top of it; secondly, the air-dried fine sand is evenly laid in the box, and the soil layer is compacted according to the controlled thickness of each layer; finally, after all the soil layers are laid, the water head saturation method is used to saturate the soil layer at the bottom.

[0026] Installation of pile shoe and large-diameter monopile model: The pile shoe is made of aluminum alloy and is placed flush with the mud surface (sand layer surface); the large-diameter monopile model is made according to the designed length-to-diameter ratio and installed in the model box without fixing the pile head.

[0027] Loading device installation: The electric cylinder is vertically mounted on the test soil box via a reaction support. The cylinder's extension rod points vertically downwards and is connected to the force sensor and displacement sensor via connectors. The other end of the force sensor is connected to the pile shoe via a connecting rod. In displacement control mode, the pile shoe penetrates the soil downwards from the position where the maximum diameter surface of the bottom is flush with the mud surface, thus applying an axial load. A pulley is installed on the reaction frame, and the load is transferred to the pile head platform through the pulley, thereby applying a horizontal load to the model pile. The pulley ensures accurate load application direction and uniform load distribution. Simultaneously, the pulley reduces friction between the pulley and the reaction frame, improving the accuracy of the test.

[0028] Installation of the monitoring system: The servo system is activated to control the pile shoe penetration, simultaneously recording penetration resistance, pile bending moment, and displacement changes. Before the test, a soil displacement measuring device is vertically installed, with its bottom measuring unit connected to a wedge-shaped end. This serves two purposes: firstly, it works in conjunction with a stainless steel pressure rod to press the device into the soil, and secondly, it acts as a fixation point. During the test, the pile shoe compresses the soil, causing displacement. The measuring unit moves with the soil, changing its spatial position. Based on the change in the angle between the measuring unit and the direction of gravity, the relative horizontal displacement between the two hinged positions of each measuring unit is calculated. The horizontal displacement of each measuring node is accumulated starting from the bottom. Strain gauges are installed on the pile body, arranged along the center lines on both sides of the pile body, and equidistantly spaced from top to bottom. The measurement position is below the mud surface, used to measure the pile bending moment. A dial gauge is installed on the pile head platform to measure the horizontal displacement of the pile head. The specific location should be close to the load application point to ensure data accuracy.

[0029] Test procedure: The servo control system was activated to allow the pile shoe to penetrate the soil at a constant rate. A horizontal load was applied using a pulley, and strain gauges and a soil horizontal displacement measuring device were used to monitor various data, such as the pile shoe penetration resistance, pile shoe position, and changes in pile bending moment during the pile shoe penetration process.

[0030] Data Acquisition and Analysis: Collect and analyze data in real time to study the influence of length-to-diameter ratio on pile shoe insertion and extraction.

[0031] The above descriptions are merely embodiments of this utility model. Commonly known technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of this utility model. These modifications and improvements should also be considered within the scope of protection of this utility model, and will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A model test system for simulating the effect of pile shoe penetration on a large diameter single pile, characterized by, Includes a model test chamber, a pile shoe foundation model, a pile foundation model, a loading device, and a data acquisition system; The model test chamber consists of a foundation (1), a model soil layer (2), a geotextile (3), and a gravel filter layer (4) from top to bottom. The loading device includes a pile shoe loading device and a horizontal loading device. The pile shoe loading device consists of a servo motor (5), an electric cylinder (6), a reaction frame (7), a force sensor (8), and a displacement sensor (9). The electric cylinder is vertically installed on the test soil box through the reaction frame. The electric cylinder rod is vertically downward and connected to the force sensor and the displacement sensor. The other end of the force sensor is connected to the pile shoe through a connecting rod. The horizontal loading device consists of a lead pulley (10) and a load (11). The data acquisition system includes strain gauges (12), soil displacement measuring devices (13), electromechanical dial gauges (14), and a computer. The strain gauges are arranged along the center lines on both sides of the pile with the bottom of the pile foundation model as the reference. The soil displacement measuring devices are placed on the other side of the pile shoe, symmetrical to the position of the pile foundation model with the pile shoe as the center. The electromechanical dial gauges are located above the soil surface. The information collected by the strain gauges, soil displacement measuring devices, and electromechanical dial gauges is transmitted to the computer system for analysis.

2. The model test system for simulating the influence of pile shoe penetration on adjacent large-diameter single piles according to claim 1, characterized in that, The minimum distance between the wall of the model test chamber and the model pile is greater than 3 times the pile diameter.

3. The model test system for simulating the influence of pile shoe penetration on adjacent large-diameter single piles according to claim 1, characterized in that, The cross-section of the pile foundation model is circular, consisting of foundation pile segments and expandable segments. Each segment of the expandable segment is connected by a high-precision threaded interface, and an expansion adapter is installed at the pile end.

4. The model test system for simulating the influence of pile shoe penetration on adjacent large-diameter single piles according to claim 1, characterized in that, The top of the pile foundation model is rigidly connected to the bottom of the pile cap.

5. The model test system for simulating the influence of pile shoe penetration on adjacent large-diameter single piles according to claim 1, characterized in that, The strain gauges in the data acquisition system are waterproofed and sealed with waterproof adhesive.

6. The model test system for simulating the influence of pile shoe penetration on adjacent large-diameter single piles according to claim 1, characterized in that, The soil displacement measuring device in the data acquisition system consists of a measuring unit, which is composed of a stainless steel shell and an inclination sensor. The sensor wiring is led out from the top by an aviation connector, and the bottom is wedge-shaped. The entire device is encapsulated with a butyl rubber sleeve.

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