Device and method for self-filling compaction resonance reinforcement of deep loose silt

Abstract

The application relates to a device and method for self-filling compaction resonance reinforcement of deep loose silt, belonging to the technical field of water transportation, water conservancy, building, road and geotechnical engineering. The device comprises a vibration exciter, a sinking pipe, a vibrating wing and a valve pile shoe. The method is as follows: the device is sunk into the foundation by using the self-weight and the vibration force of the vibration exciter, so that the surrounding soil is liquefied and compacted; after reaching the predetermined depth, the foundation soil is filled into the cavity of the sinking pipe, and the sinking pipe is pulled up and vibrated; the valve pile shoe is opened under the gravity of the filling material to allow the filling material to fall into the hole, and the valve pile shoe is automatically closed after filling, and the filling material and the surrounding soil are vibrated and extruded; single-point reinforcement is completed through multiple filling and vibration, and the whole foundation is reinforced through repeated construction according to the interval. The application solves the problem of deep loose silt foundation reinforcement, overcomes the limitations of the traditional method, such as limited depth and poor adaptability, and combines the vibration and extrusion effects to improve the reinforcement effect and uniformity and adapt to complex geological conditions.

Description

Technical Field

[0001] This invention belongs to the fields of water transport, water conservancy, construction, road and geotechnical engineering technology, and in particular relates to a device and method for self-filling compaction resonance reinforcement of deep loose silt. Background Technology

[0002] Silt, a widely distributed Quaternary loose sediment, possesses engineering characteristics such as high porosity, high natural water content, low shear strength, and high compressibility. Under vibration loads or groundwater action, it is prone to liquefaction, severely affecting foundation stability. In geotechnical engineering fields such as waterway wharves, hydraulic dams, building foundations, and road subgrades, the reinforcement of deep, loose silty soil foundations (typically exceeding 7m in thickness) has always been a challenging problem in engineering practice. Existing foundation treatment technologies are insufficiently adaptable to silty soil, mainly exhibiting the following limitations:

[0003] Traditional reinforcement methods include dewatering and dynamic compaction, vibratory compaction and vibratory rod compaction, and compacted sand piles, each with its own technical bottlenecks.

[0004] 1. Precipitation-based dynamic compaction method

[0005] This method lowers the groundwater level beforehand and uses a heavy hammer to compact the soil particles. However, due to limitations in the energy transfer efficiency of the compaction, its effective reinforcement depth is usually ≤7m, and in extreme cases, it does not exceed 10m, making it difficult to meet the treatment requirements of deep foundations. In addition, when there are weak interlayers or lenses in the foundation, the compaction energy will be absorbed by the weak soil layer, resulting in a significant reduction in the reinforcement effect and easily causing uneven settlement of the foundation.

[0006] 2. Vibratory compaction method and vibratory rod compaction method

[0007] Vibro-compaction utilizes the horizontal high-frequency vibration of a vibratory compactor to rearrange soil particles and reduce porosity, thereby increasing soil density. Vibratory rod compaction relies on the vertical high-frequency vibration of a vibratory rod, synchronizing the soil with the rod's vibration to achieve the same effect. Both methods require good soil permeability and particle size distribution. When the clay content in silt exceeds 10%, the cohesion between soil particles increases, making it difficult for the vibration energy to liquefy the soil, leading to a significant reduction in reinforcement effectiveness or even failure.

[0008] 3. Compacted Sand Pile Method

[0009] Compaction piles are formed by filling sand into the foundation using vibratory driven pipes. This method is suitable for loose sand or silt. However, it requires a large amount of external sand material, resulting in high transportation costs (especially in areas far from the sand source). Furthermore, the resulting "pile-original foundation" composite foundation suffers from stress concentration due to material differences, leading to poor overall uniformity of the foundation and potential for uneven settlement in the later stages.

[0010] Furthermore, in practical engineering, deep, loose, silty soil foundations are often accompanied by complex geological conditions, such as:

[0011] Uneven soil layer distribution: There are weak interlayers of varying thickness (such as silty soil and peat layer), making it difficult to achieve uniform reinforcement of deep river layers using the precipitation-driven compaction method;

[0012] Clay content fluctuation: The clay content in the same foundation varies from 5% to 20%, and vibratory compaction or vibratory rod method cannot meet the reinforcement needs of areas with different clay contents.

[0013] Environmental and cost pressures: Methods such as compacted sand piles and vibro-compaction replacement crushed stone piles, which rely on external fillers, face the dual challenges of material resource shortages and carbon emission control, and do not conform to the development trend of green engineering.

[0014] In summary, existing technologies for treating deep (>10m), high clay content (>10%), and complex geological conditions of loose silty soil foundations suffer from problems such as insufficient reinforcement depth, high material dependence, poor adaptability, and high cost. Therefore, developing a silty soil foundation treatment technology that requires no external filler, can adapt to complex geological conditions, and provides efficient deep reinforcement has become a critical issue urgently needing to be addressed in the field of geotechnical engineering. Summary of the Invention

[0015] To address the problems existing in the prior art, the first objective of this invention is to provide a device for resonant compaction and reinforcement of loose foundations using self-filling material, and the second objective is to provide a method for resonant compaction and reinforcement of loose foundations using the aforementioned device. By combining "locally sourced materials with vibration-compression synergy," this invention overcomes the limitations of traditional technologies and achieves economical, efficient, and uniform reinforcement of deep, loose, silty soil foundations. The self-filling material refers to the in-situ silty soil of the foundation to be reinforced, without the need to add external sand or gravel.

[0016] To achieve the aforementioned first objective, the present invention provides a technical solution for a device for self-filling compaction resonance reinforcement of deep loose silt, comprising:

[0017] Vibration mechanism, including exciter, for providing vertical vibration force;

[0018] A tubular component with a feed inlet at the top and an internal cavity-shaped submerged tube for accommodating the filler.

[0019] A vibration enhancement structure is disposed on the outside of the tubular member to amplify and enhance the shearing and liquefaction effect on the surrounding soil;

[0020] An openable bottom structure is connected to the bottom of the tubular component and is configured to open under the gravity of the filler and automatically close when there is no filler.

[0021] Furthermore, the openable bottom structure includes a valve-shaped shoe, a spring, and a spring protection baffle. The spring provides an elastic force that automatically closes the valve-shaped shoe, and the spring protection baffle is disposed on the surface of the spring.

[0022] Furthermore, the valve-shaped pile shoe is composed of 5 symmetrical arc-shaped steel plates. The arc-shaped steel plates are isosceles triangles with a certain curvature. The curvature of the base of the isosceles triangle matches the inner diameter of the immersed tube. The arc-shaped steel plates are rotatably connected to the bottom of the immersed tube through hinges at both ends of the base of the isosceles triangle. One end of the spring is fixed to the lower inner surface of the hollow immersed tube, and the other end is fixed to the lower part of the arc-shaped steel plate. The 5 arc-shaped steel plates are in a closed state by default under the tension of the spring, and are conical when closed.

[0023] Furthermore, a limit stake is fixed on the inner surface of the isosceles triangle near the vertex of the arc-shaped steel plate. One end of the spring protection baffle is hinged to the lower part of the hollow tube, and the other free end can slide on the inner surface of the arc-shaped steel plate. When the arc-shaped steel plate is closed, the free end of the spring protection baffle is constrained by the limit stake. The spring protection baffle protects the spring and, together with the limit stake, plays a limiting role to prevent the arc-shaped steel plate from closing excessively.

[0024] Furthermore, the initial tension of the spring is 2-3 kN. Under normal conditions, the arc-shaped steel plate is closed to seal the bottom of the immersed tube. When the weight of the filler inside the immersed tube is ≥10 kN, the arc-shaped steel plate overcomes the spring tension and opens at an angle of 60°-90°. After the filler is unloaded, it automatically resets and closes. During re-vibration, the arc-shaped steel plate closes to prevent soil backflow and facilitates compaction during re-vibration.

[0025] Furthermore, the vibration enhancement structure consists of 2 to 12 wing plates symmetrically distributed along the axial direction of the tubular member. The free ends of the wing plates are provided with serrated protrusions, and circular holes are opened on the surface of the wing plates.

[0026] Furthermore, the wing plate has a width of 20-60cm, the hole diameter is 5-10cm, the total area of ​​the hole accounts for 10-30% of the wing plate area, and horizontal grooves are provided on both sides of the wing plate.

[0027] Furthermore, the tubular component is a circular hollow steel pipe with a diameter of 20-60cm and a length of 10-30m; the feed inlet is located at the upper 1 / 3 of the tubular component, is a rectangular opening and is equipped with a detachable cover plate.

[0028] To achieve the second objective mentioned above, the present invention provides a technical solution for a method of using the aforementioned device to perform self-filling resonance compaction and reinforcement of loose foundations, comprising the following steps:

[0029] Step S1. Vibration point arrangement and parameter preset: The vibration points are arranged in an equilateral triangle or square pattern, and the vibration point spacing s is determined by calculation using a formula:

[0030]

[0031] In formula (1): A is the arrangement form coefficient. When the equilateral triangle arrangement is used, A is 0.95; when the square arrangement is used, A is 0.89; ξ is the resonance correction coefficient, which ranges from 1.3 to 2.0; d is the diameter of the immersed tube; e0 is the void ratio of the soil before treatment; and e1 is the target void ratio.

[0032] Position the device for compacting and resonating the self-filling material to reinforce the deep loose silt at the target location of the foundation to be reinforced, and preset the excitation frequency and amplitude of the vibration mechanism.

[0033] Step S2. Vibration and sinking to a predetermined depth: The vibrator of the vibration mechanism is activated, and the device sinks under the combined action of its own weight and vibration force. The vibration enhancement structure promotes soil liquefaction and drainage. After sinking to the predetermined depth, the vibration is maintained to make the bottom soil initially compacted.

[0034] Step S3. Filling and initial re-vibration: The foundation silt is filled into the sinking tube through the feed port. The lifting device opens the openable bottom structure under the gravity of the fill, and holes appear in the lower soil. After the fill falls into the holes, the openable bottom structure closes automatically. The sinking device applies vibration to re-vibrate and compress the fill and the surrounding soil.

[0035] Step S4. Circulating packing and re-vibration: Repeat step S3 to compact the foundation at this point through multiple packing and re-vibration compressions;

[0036] Step S5. Displacement and overall reinforcement: Displace to the next vibration point according to the calculated spacing, and repeat steps S2-S4; when the measured foundation settlement value deviation exceeds the preset threshold, adjust the resonance correction coefficient to optimize the spacing until the overall foundation reinforcement is completed.

[0037] Furthermore, in step S1: the preset excitation frequency of the vibration mechanism is 5-20Hz and the amplitude is 0.5-20mm.

[0038] Furthermore, in step S2, the vibration frequency is dynamically adjusted according to the soil moisture content: when the soil moisture content is between 20% and 30%, a high-frequency vibration of 15 to 20 Hz is used, and when the soil moisture content is greater than 30%, a low-frequency vibration of 5 to 10 Hz is used; the sinking speed is 1.0 to 2.0 m / min, and the vibration time is 30 s.

[0039] Furthermore, in step S3: when the clay content is <10%, the filler thickness is 1.0m each time and the re-vibration settling depth is 30cm; when the clay content is >10%, the filler thickness is 0.8m each time and the re-vibration settling depth is 20cm; the re-vibration frequency is initially set to 10Hz, and gradually increased to 20Hz in each cycle.

[0040] Furthermore, the moisture content of the silty soil filled in step S3 is controlled at 18% to 22%; the opening conditions for the openable bottom structure are that the weight of the filling material is ≥10kN and the opening angle is 60° to 90°.

[0041] The main principles of this invention are as follows:

[0042] The equipment is connected to cranes and other equipment to control the up-and-down movement of the device. The vibrator vibrates up and down at a frequency of 5-20Hz, which is variable. The diameter of the immersed tube is determined according to the looseness of the foundation soil, generally 20-60cm. The vibrating wing is about 20-50cm wide and about 2cm thick. One side is welded to the immersed tube, and the other side is serrated. Several holes are arranged on the vibrating wing, accounting for about 30% of the area. Horizontal grooves are set on both sides of the wing plate, with a groove depth of about 5mm and a spacing of about 5cm. A valve-shaped pile shoe is installed at the bottom of the immersed tube. The valve is normally closed under the tension of a spring. To protect the normal operation of the spring, a protective baffle is installed above the spring. When there is filler inside the immersed tube, the valve opens under pressure until the filler is unloaded, and then the valve closes automatically. The initial tension of the spring is dynamically adjusted according to the moisture content of the fill material: when the moisture content of the fill material is 18% (lower limit), a tension of 2kN is used to ensure that the opening angle reaches 90° under the weight of 10kN fill material; when the moisture content is 22% (upper limit), a tension of 3kN is used to avoid the valve from opening accidentally due to excessive weight of collapsible silt. At this time, the opening angle of 60° can control the falling speed of the fill material and prevent blockage. The device slowly sinks under the vibration of the vibrator and its own weight. Due to the serrations, holes, and grooves on the edge of the device, a large frictional force is generated between the device and the surrounding soil. When the device vibrates, it causes the surrounding soil to vibrate, resulting in liquefaction and reducing the shear strength of the soil, which is conducive to the sinking of the equipment. The surrounding soil is forced to vibrate, and the soil particles rearrange and migrate to the position of lower energy, achieving effective compaction, thereby eliminating liquefaction and improving the bearing capacity of the foundation. At the same time, the compression of the soil by the sinking tube also effectively compacts the soil. After the invention device is lowered to the intended treatment depth and vibrates, filler material, consisting of foundation-reinforcing soil, is introduced into the submerged tube through the feed port, with a filler thickness of approximately 1 meter inside the tube. The invention device is then raised, the flaps open, and the filler material is inserted into the ground. The flaps then close. The invention device is lowered again and vibrated approximately 0.3 meters to re-compact the filler material and surrounding soil. This process of filling and re-vibrating is repeated until the foundation reinforcement at that point is complete. The interval between each vibration point is approximately 1.5 to 3.0 meters.

[0043] Theories involved:

[0044] ① Soil Resonance Theory: Previous theoretical analyses have shown that when the natural frequency of the compacted soil is close to the operating frequency of the vibrator, good compaction results can be achieved. Since there are many soil types with varying physical properties, the natural frequency will differ depending on the soil type and density. Therefore, the frequency of the vibration mechanism itself needs to be adjustable within a certain range. Reducing internal friction between soil particles in the resonance zone facilitates compaction.

[0045] ② Soil liquefaction theory: Soil liquefaction is the phenomenon where saturated silt becomes liquid under vibration, losing its original stiffness and strength. The mechanism of soil liquefaction is: under shear stress, saturated silt particles become more compact, which increases the pore water pressure μ. The shear strength formula is: τ f =(σ-μ)tanφ, the shear strength τ of saturated silt is given by: ρ = (σ-μ)tanφ, where μ is equal to the total stress σ. f If the value equals zero, we know that it has no strength, and we can see that it is in a liquid state. This phenomenon is called vibration liquefaction.

[0046] ③ Repeated Impact Theory: To achieve better soil compaction, repeated vibration and compression are applied to the soil. This involves improving the quality of the equipment and increasing the amplitude of the vibrator to increase the contact momentum between the equipment and the soil. During the continuous rising and falling of the equipment, soil molecules interpenetrate, and smaller soil particles are compressed into larger ones. This reduces the volume ratio of soil particles and increases their density.

[0047] ④ The theory of reduced internal friction: Under the vibration of the vibrator, the "fluidity" of the soil is significantly enhanced, and the internal force of the soil is significantly reduced. Due to the mechanical action on the soil, the shear strength of the soil is reduced, thus the soil is compacted.

[0048] ⑤ The theory of three soil indexes: In a saturated state, the voids in soil particles are completely filled with water. After vibration and compression, some water is squeezed out, and the spaces originally occupied by water are replaced by soil particles. The water content of the saturated soil decreases, and the soil becomes denser. The vibration point spacing can be determined based on the required void ratio e1 after vibration. The formula for calculating the spacing s is:

[0049]

[0050] In formula (1):

[0051] A is the arrangement coefficient. When the vibration points are arranged in an equilateral triangle, A is 0.95, and when they are arranged in a square, A is 0.89.

[0052] ξ is the resonance correction coefficient, which can be taken from 1.3 to 2.0. Refer to Table 1 for specific values.

[0053] Table 1. Reference Table for Selecting Resonance Correction Coefficients

[0054] 40-60 <10 loose 1.8-2.0 20-40 10-20 medium density 1.3-1.5

[0055] As shown in Table 1, when the flange is wide, the clay content is low, and the soil is loose, the larger value is taken; when the flange is narrow, the clay content is high, and the soil is relatively dense, the smaller value is taken.

[0056] d is the diameter of the immersed tube;

[0057] e0 represents the void ratio of the soil before treatment.

[0058] Compared with the prior art, the advantages of this invention are:

[0059] 1) Provide effective reinforcement solutions for deep, loose silty soil foundations.

[0060] Traditional reinforcement methods for deep, loose silty soil foundations have certain limitations. The water-based dynamic compaction method generally reinforces to a depth of less than 7 meters, with an extreme depth of approximately 10 meters. Furthermore, the presence of weak soil layers in the foundation further affects the reinforcement depth and effectiveness. Vibro-compaction and vibratory rod methods have high requirements for soil conditions; the higher the clay content in the soil, the worse the treatment effect, and when the clay content exceeds 10%, the treatment is essentially ineffective. Compacted sand piles and vibro-compacted gravel piles require large quantities of sand or gravel materials, generally resulting in higher costs and creating composite foundations with two types of materials present, leading to poor uniformity of the foundation after treatment.

[0061] 2) It has a very good reinforcement effect.

[0062] Traditional vibratory compaction and vibratory rod compaction methods, after soil liquefaction, cause soil particles to reposition. The effect is better for larger soil particles, but poor when the particles are small, the reinforcement effect is poor under vibration alone. Sand pile compaction has a small vibration influence range and cannot effectively induce vibration liquefaction in the foundation soil, resulting in uneven compaction of the foundation soil. This invention combines the combined effects of vibration compaction and compression compaction. Under vibration load, the soil strength in the foundation decreases, and the soil is in a "flowing" state, which is conducive to soil compression, resulting in more uniform compaction between vibration points. The soil at the vibration point has even better compaction after the equipment re-vibrates.

[0063] 3) It has excellent reinforcement efficiency.

[0064] The device of this invention combines vibration and compaction, with both actions performed simultaneously. Overall, only one up-and-down movement of the device is required. Compared to vibratory compaction and vibratory rod methods, the compaction effect of the filler eliminates the need for repeated up-and-down vibration, resulting in higher construction efficiency, with a 20-40% increase in single-point construction efficiency. Compared to compaction sand piles, the vibration frequency of this device is essentially the same as the foundation, causing soil liquefaction, which facilitates the sinking and lifting of the device. Furthermore, because this invention's device integrates two actions, the spacing between vibration points is larger than that of compaction sand piles, resulting in even better reinforcement efficiency.

[0065] 4) Better able to adapt to complex geological conditions

[0066] The geological conditions of general foundations are relatively complex. Even in deep, loose, silty soil foundations, there may be different soil layers, such as weak soil layers, or uneven clay content in the soil layers. This places higher demands on foundation reinforcement, and traditional methods are difficult to achieve the required results in a single treatment. However, the device of this invention can adapt well to complex geological conditions. When weak soil layers are mixed in the geology, the vibration point forms an effective drainage channel in the weak mixture through compression and replacement, which is beneficial to the reinforcement of the weak soil layer. Even if the clay content in the soil layers is different, the method of this invention is equally applicable. Attached Figure Description

[0067] Figure 1 Example 1 of the present invention: a front view of the device for self-filling compaction resonance reinforcement of deep loose silt.

[0068] Figure 2 This invention Figure 1 Sectional view of section AA.

[0069] Figure 3a : Schematic diagram of the openable bottom structure valve pile shoe of the device for self-filling compaction resonance reinforcement of deep loose silt in Embodiment 1 of the present invention.

[0070] Figure 3b : Schematic diagram of the closed state of the openable bottom structure valve pile shoe of the device for self-filling compaction resonance reinforcement of deep loose silt in Embodiment 1 of the present invention.

[0071] Figure 3c Example 1 of the present invention: A front view of the openable bottom structure valve pile shoe of the device for self-filling compaction resonance reinforcement of deep loose silt.

[0072] Figure 3d Example 1 of the present invention: A bottom view of the openable and closable bottom structure valve pile shoe of the device for self-filling compaction resonance reinforcement of deep loose silt.

[0073] Figure 4Example 2 of the present invention is a schematic diagram of the steps of the method for self-filling compaction resonance reinforcement of deep loose silt.

[0074] In the picture:

[0075] 1. Vibrator; 2. Feed inlet; 3. Sinking pipe; 4. Vibrating blade; 5. Hinged pile shoe; 6. Spring; 7. Spring protection baffle; 8. Limiting pile;

[0076] S1. Device positioning and parameter preset; S2. Vibration and sinking to the predetermined depth; S3. Filling and initial re-vibration; S4. Circulating filling and re-vibration; S5. Displacement and overall reinforcement. Detailed Implementation

[0077] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0078] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0079] Example 1 provides a device for self-filling compaction resonance reinforcement of deep loose silt, such as... Figure 1 As shown, it includes a vibrator 1, a driven tube 3, a vibrating fin 4, and a hinged pile shoe 5:

[0080] The vibrator 1 is a high-frequency variable frequency vertical vibrator with a power of 30-180kW, a vibration frequency of 5-20Hz that is continuously adjustable (dynamically matched according to the soil density), and an amplitude of 0.5-20mm. The vibrator 1 is rigidly connected to the top of the sinking pipe 3 through a flange, providing the vibration force required for the sinking and re-vibration of the device.

[0081] The immersed tube 3 is a circular hollow steel tube with a diameter of 20-60cm (selected according to the looseness of the foundation: 40-60cm for loose silt and 20-40cm for medium-dense silt) and a length of 10-30m (customized according to the reinforcement depth).

[0082] The feed inlet 2 is located at the upper 1 / 3 of the submerged tube, with a rectangular opening size of 30cm×40cm, and is equipped with a detachable cover plate for filling the foundation silt filler.

[0083] like Figure 1 , Figure 2 As shown, six vibrating wings 4 are symmetrically arranged along the axis of the immersed tube 3, with a spacing of 1.2m, and are welded to the immersed tube as a whole. The vibrating wings 4 are 20-50cm wide and 2cm thick, with serrated free ends, tooth height of 5cm, and tooth spacing of 10cm. The serrated edges of the vibrating wings destroy the original structure of the soil particles. Circular holes with a diameter of 5-10cm are opened on the surface of the wing plate, and the total area of ​​the circular holes accounts for 30% of the area of ​​the wing plate. The 30% hole area improves the vibration wave propagation efficiency and improves the soil resonance frequency matching accuracy by 20%. Horizontal grooves (5mm deep, 5cm spacing) are set on both sides to enhance the soil shearing and drainage effect.

[0084] like Figure 3a , Figure 3b , Figure 3c , Figure 3d As shown, the valve-shaped pile shoe 5 is composed of five symmetrical arc-shaped steel plates. Each arc-shaped steel plate is an isosceles triangle with a certain curvature. The curvature of the base of the isosceles triangle matches the inner diameter of the immersed tube 3. The arc-shaped steel plates are connected to the bottom of the immersed tube 3 via hinges at both ends of the base of the isosceles triangle. A spring 6 is fixed to the lower part of the arc-shaped steel plate (i.e., the area between the midpoint and the apex of the isosceles triangle). The other end of the spring 6 is fixed to the inner surface of the bottom of the immersed tube 3. The five symmetrical arc-shaped steel plates are in a closed state by default under the tension of the spring 6. When closed, the base of the isosceles triangle... The edges of the five arc-shaped steel plates fit together with the immersed tube 3. When closed, the isosceles edges of the five arc-shaped steel plates fit together in sequence and close the bottom of the immersed tube 3. The overall shape is conical. The surface of the spring 6 is equipped with a spring protection baffle 7. One end of the spring protection baffle 7 is hinged to the bottom of the immersed tube 3, and the other free end can slide on the inner surface of the arc-shaped steel plate. A limit pile is fixed on the surface near the vertex of the isosceles triangle of the arc-shaped steel plate. When the arc-shaped steel plate is closed, it is constrained by the limit pile 8, which protects the spring 6 and, together with the limit pile 8, also plays a limiting role to prevent the arc-shaped steel plate from closing excessively. The spring 6 has an initial tension of 2-3 kN. Under normal conditions, the valve (arc-shaped steel plate) at the bottom of the valve pile shoe 5 is closed to seal the bottom of the sinking pipe. When the weight of the filling material inside the sinking pipe is ≥10 kN, the valve (arc-shaped steel plate) opens against the spring tension, with an opening angle of 60°-90°. After the filling material is unloaded, it automatically resets and closes. During re-vibration, the valve pile shoe 5 closes to prevent soil backflow and facilitates re-vibration and compaction.

[0085] In other embodiments, unlike Embodiment 1, when treating medium-dense silt with a clay content >15%, the total area of ​​the vibrating wing holes accounts for 10% of the wing plate area (holes with a diameter of 5cm, arranged at 15cm×15cm intervals). In this case, the smaller hole area reduces the absorption of vibration waves by the high-clay soil, concentrating the vibration energy on the mechanical shearing action of the serrated edges of the wing plate. Combined with 20Hz high-frequency vibration, the soil liquefaction efficiency is increased by 15%, and the compaction degree reaches over 88%.

[0086] In other embodiments, unlike Embodiment 1, for ultra-deep silt with a depth >25m, a 60cm wide vibrating wing (3cm thick, 10cm diameter hole, accounting for 20%) is used. By increasing the stiffness of the wing plate to reduce vibration attenuation, the vibration acceleration at a depth of 25m is still maintained at 0.8g (0.5g for a conventional 50cm wing plate), and the density of the bottom soil is increased to 85%.

[0087] In other embodiments, unlike Embodiment 1, the number of vibrating wings 4 is not 6. The number of vibrating wings 4 can be 2 to 12, preferably evenly distributed around the immersed tube 3. The specific number depends on the diameter of the immersed tube 3, the power of the vibrator, and the arrangement of compaction points. When the diameter of the immersed tube 3 is small, the number of vibrating wings 4 can be 2 to 6; when the diameter of the immersed tube 3 is large, the number of vibrating wings 4 can be 4 to 12. The larger the diameter of the immersed tube 3 and the more vibrating wings 4 there are, the greater the power of the vibrator required. Vibrating wings 4 can effectively transfer vibration energy to the surrounding soil. More wings are not necessarily better; normally, 4 to 8 wings are a suitable range. First, 4 wings can disperse vibration energy in 4 directions. While increasing the number of wings can make the vibration energy more evenly distributed to the surrounding soil, due to the limited size of the equipment, when the number of wings increases to 10 to 12, the vibration energy received by the surrounding soil is not significantly different. Instead, it increases the weight of the equipment and the sinking resistance, requiring greater excitation power, resulting in lower efficiency.

[0088] In other embodiments, unlike Embodiment 1, the initial tension of the spring is dynamically adjusted according to the moisture content of the filler: when the moisture content of the filler is 18% (lower limit), a tension of 2kN is used to ensure that the opening angle reaches 90° under the weight of 10kN filler; when the moisture content is 22% (upper limit), a tension of 3kN is used to avoid the valve from opening accidentally due to the excessive weight of the collapsible silt. At this time, the opening angle of 60° can control the falling speed of the filler and prevent blockage.

[0089] Example 2 provides a method for reinforcing deep loose silt using the self-filling compaction resonance device described in Example 1. Taking a port deep loose silt foundation reinforcement project as an example (foundation thickness 15m, clay content 8%, initial void ratio e0 = 0.9), as... Figure 4As shown, the steps are as follows:

[0090] Step S1: Device positioning and parameter preset

[0091] Vibration point arrangement: Vibration points are arranged in an equilateral triangle pattern, and the spacing is calculated using formula (1):

[0092]

[0093] In formula (1): target porosity e1 = 0.65, A = 0.95 (equilateral triangle), resonance correction coefficient ξ = 1.8, tube diameter d = 0.5m, and the calculated vibration point spacing s = 2.15m.

[0094] Excitation parameters: initial frequency set to 10Hz (optimal resonance frequency when clay content is 8%), amplitude 1.0mm.

[0095] Step S2: Vibrate and sink to the predetermined depth

[0096] When the vibrator is started, the device sinks at a speed of 1.5 m / min under the combined action of its own weight (about 50 kN) and vibration force. The serrated edges of the vibrating wings cut the soil, and the grooves and holes promote the friction between the equipment and the soil. The soil liquefies within a range of 1.5 times the diameter of the equipment outline.

[0097] After sinking to a depth of 15m, keep the vibrator running for 30s to ensure that the bottom soil is fully compacted (compaction degree reaches more than 85%).

[0098] The vibration frequency is adjusted according to the different clay particle contents:

[0099] When the soil moisture content is >30% at the start of settlement, low-frequency vibration of 5-10Hz (relying on mechanical shearing of the vibrating wing) is used.

[0100] When the bottom is vibrated, the soil has been initially compacted and the water content has decreased. Vibration at 10-15Hz (resonance liquefaction) is then used.

[0101] Step S3: Packing and initial re-vibration

[0102] Filling operation: Fill the cavity of the sinking pipe with 1.0m thick foundation silt (taken from the loose soil on the surface of the foundation, with a moisture content controlled at 18%-22%) through the feed port 2. The weight of the fill triggers the valve pile shoe 5 to open, and the fill falls evenly into the hole under the action of vibration.

[0103] Lifting and Re-vibration: Lift the submerged tube to the top of the packing material at a speed of 1.5 m / min, close the feed inlet, and let it stand for 5 seconds after the packing material has fallen completely. After the valve closes automatically, lower it 30 cm at a speed of 1.0 m / min, adjust the excitation frequency to 15-20 Hz (to enhance the compression effect), and re-vibrate for 20 seconds to increase the packing density to 90%. If abnormal situations such as the valve shoe 5 failing to open or the packing material clogging the feed inlet occur, water can be poured into the submerged tube, and the tube can be lifted 50 cm. The vibration of the equipment and the fluidity of the material inside the tube can be used to resolve the blockage caused by the packing material.

[0104] Step S4: Circulating packing and re-vibration

[0105] Repeat the process of "filling (1.0m thick) → lifting → sinking 30cm and re-vibrating" for a total of 5 cycles (total filling height 5.0m). The re-vibration frequency is dynamically adjusted according to the soil density each time (gradually increasing from 15Hz to 20Hz).

[0106] Filler thickness and reverberation depth:

[0107] When the clay content is <10%, the thickness of the filler is 1.0m each time, and the re-vibration settling depth is 30cm; when the clay content is >10%, the thickness of the filler is 0.8m each time, and the re-vibration settling depth is 20cm.

[0108] Step S5: Relocation and Overall Reinforcement

[0109] After the construction of a single vibration point is completed, the vibrator is turned off and moved to the next vibration point by a crane (spacing 2.15m). Steps 2 to 4 are repeated until the entire foundation reinforcement is completed (the construction time for a single point is about 20-30 minutes, the total number of vibration points is 300, and the construction period is 15 days).

[0110] Dynamic correction of vibration point spacing:

[0111] When the soil density between two vibration points is less than the reinforcement requirement, the spacing is optimized by adjusting the resonance correction coefficient (1.3 to 2.0) to ensure that adjacent vibration points are effectively reinforced.

[0112] In this embodiment, the bearing capacity test adopts the plate load test in the "Technical Specification for Building Foundation Treatment" (JGJ79-2012), with a bearing plate area of ​​1m². 2Five test points were arranged with a spacing of 3m between them, and the average value was 180kPa. After reinforcement, the characteristic value of the foundation bearing capacity increased from 50kPa to 180kPa. Standard penetration test (SPT) was used, with test depths of 5m, 10m, and 15m. The number of hammer blows increased from 5, 3, and 2 blows to 15, 12, and 10 blows, respectively. The liquefaction index was calculated according to the "Code for Seismic Design of Buildings" (GB50011-2010), and the liquefaction index decreased from 25 to 0 (achieving complete elimination of liquefaction settlement). The reinforcement depth reached 15m (1.5 times that of the dewatering and dynamic compaction method), and there was no external filling cost. The construction efficiency was improved by 35% compared with the vibro-compaction method.

[0113] This invention uses frequency-controlled vibration to induce resonance liquefaction of silty soil, utilizes the foundation material itself for circulating filler, and combines automatic opening and closing control of the movable valve pile shoe to achieve efficient reinforcement of loose silty soil with a depth greater than 15m. The single-point construction efficiency is increased by 20-40%, and the cost is reduced by more than 30%.

[0114] The above description of the embodiments is provided to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention are within the protection scope of the present invention.

Claims

1. A device for self-filling compaction resonance reinforcement of deep loose silt, characterized in that, include: Vibration mechanism, including exciter, for providing vertical vibration force; A tubular component with a feed inlet at the top and an internal cavity-shaped submerged tube for accommodating filler, wherein the vibrator is rigidly connected to the top of the submerged tube. The vibration enhancement structure is a vibration wing set on the outside of the tubular member, used to amplify and enhance the shearing and liquefaction effect on the surrounding soil; An openable bottom structure is connected to the bottom of the tubular component and is configured to open under the gravity of the filler and automatically close when there is no filler. The openable bottom structure includes a valve-shaped shoe, a spring, and a spring protection baffle. The spring provides an elastic force to automatically close the valve-shaped shoe, and the spring surface is provided with a spring protection baffle. The valve-shaped pile shoe is composed of 5 symmetrical arc-shaped steel plates. The arc-shaped steel plates are isosceles triangles with a certain curvature. The curvature of the base of the isosceles triangle matches the inner diameter of the immersed tube. The arc-shaped steel plates are rotatably connected to the bottom of the immersed tube through hinges at both ends of the base of the isosceles triangle. One end of the spring is fixed to the lower inner surface of the hollow immersed tube, and the other end is fixed to the lower part of the arc-shaped steel plate. The 5 arc-shaped steel plates are in a closed state by default under the tension of the spring, and are conical when closed. A limit stake is fixed on the inner surface of the isosceles triangle near the vertex of the arc-shaped steel plate. One end of the spring protection baffle is hinged to the lower part of the hollow tube, and the other free end can slide on the inner surface of the arc-shaped steel plate. When the arc-shaped steel plate is closed, the free end of the spring protection baffle is constrained by the limit stake. The spring protection baffle protects the spring and, together with the limit stake, plays a limiting role to prevent the arc-shaped steel plate from closing excessively. The vibration enhancement structure consists of 2 to 12 wing plates symmetrically distributed along the axial direction of the tubular member. The free end of the wing plate has serrated protrusions, and the surface of the wing plate has circular holes.

2. The apparatus for self-compaction resonance reinforcement of deep loose silt according to claim 1, characterized in that, The initial tension of the spring is 2~3kN. Under normal conditions, the arc-shaped steel plate is closed to seal the bottom of the immersed tube. When the weight of the filler inside the immersed tube is ≥10kN, the arc-shaped steel plate overcomes the spring tension and opens at an angle of 60°~90°. After the filler is unloaded, it automatically resets and closes. During re-vibration, the arc-shaped steel plate closes to prevent soil backflow and facilitates compaction during re-vibration.

3. The apparatus for self-compaction resonance reinforcement of deep loose powdery soil according to claim 1, characterized in that, The wing plate has a width of 20-60cm, the hole diameter is 5-10cm, the total area of ​​the hole accounts for 10-30% of the wing plate area, and horizontal grooves are provided on both sides of the wing plate.

4. The apparatus for self-compaction resonance reinforcement of deep loose powdery soil according to claim 1, characterized in that, The tubular component is a circular hollow steel pipe with a diameter of 20-60cm and a length of 10-30m; the feed inlet is located at the upper 1 / 3 of the tubular component, is a rectangular opening and is equipped with a detachable cover plate.

5. A method for reinforcing loose foundations using the device described in any one of claims 1-4, characterized in that, Includes the following steps: Step S1. Vibration point arrangement and parameter preset: The vibration points are arranged in an equilateral triangle or square pattern, and the vibration point spacing s is determined by calculation using a formula: ； In formula (1): A is the arrangement form coefficient. When the equilateral triangle arrangement is used, A is 0.95; when the square arrangement is used, A is 0.

89. is the resonance correction coefficient, with a value range of 1.3 to 2.0; d is the diameter of the immersed tube, e0 is the void ratio of the soil before treatment, and e1 is the target void ratio; Position the device for compacting and resonating the self-filling material to reinforce the deep loose silt at the target location of the foundation to be reinforced, and preset the excitation frequency and amplitude of the vibration mechanism. Step S2. Vibration and sinking to a predetermined depth: The vibrator of the vibration mechanism is activated, and the device sinks under the combined action of its own weight and vibration force. The vibration enhancement structure promotes soil liquefaction and drainage. After sinking to the predetermined depth, the vibration is maintained to make the bottom soil initially compacted. Step S3. Filling and initial re-vibration: The foundation silt is filled into the sinking tube through the feed port. The lifting device opens the openable bottom structure under the gravity of the fill, and holes appear in the lower soil. After the fill falls into the holes, the openable bottom structure closes automatically. The sinking device applies vibration to re-vibrate and compress the fill and the surrounding soil. Step S4. Circulating packing and re-vibration: Repeat step S3 to compact the foundation at this point through multiple packing and re-vibration compressions; Step S5. Displacement and overall reinforcement: Displace to the next vibration point according to the calculated spacing, and repeat steps S2-S4; when the measured foundation settlement value deviation exceeds the preset threshold, adjust the resonance correction coefficient to optimize the spacing until the overall foundation reinforcement is completed.

6. The method for self-filling resonance compaction and reinforcement of loose foundations according to claim 5, characterized in that, In step S1: the preset excitation frequency of the vibration mechanism is 5~20Hz and the amplitude is 0.5~20mm.

7. The method for self-filling resonance compaction and reinforcement of loose foundations according to claim 5, characterized in that, In step S2, the vibration frequency is dynamically adjusted according to the soil moisture content: when the soil moisture content is between 20% and 30%, a high-frequency vibration of 15 to 20 Hz is used, and when the soil moisture content is greater than 30%, a low-frequency vibration of 5 to 10 Hz is used; the sinking speed is 1.0 to 2.0 m / min, and the vibration time is 30 s.

8. The method for self-filling resonance compaction and reinforcement of loose foundations according to claim 5, characterized in that, In step S3: when the clay content is <10%, the filler thickness is 1.0m each time and the re-vibration settling depth is 30cm; when the clay content is >10%, the filler thickness is 0.8m each time and the re-vibration settling depth is 20cm; the re-vibration frequency is initially set to 10Hz and gradually increased to 20Hz in each cycle.

9. The method for self-filling resonance compaction and reinforcement of loose foundations according to claim 5, characterized in that, In step S3, the moisture content of the silty soil filling is controlled at 18%~22%; the opening conditions for the openable bottom structure are that the weight of the filling material is ≥10kN and the opening angle is 60°~90°.

Images