Method and device for reducing the dilatancy effect of compacted fine-grained soil

Abstract

The present application belongs to the technical field of dredging engineering, and discloses a method and device for reducing the shear dilation effect of dense fine-grained soil, which comprises the following steps: determining the shear dilation zone on the tooth surface of the rake tooth when cutting the soil, and determining the position of the negative pressure center zone and the position of the shear dilation significant zone on the shear dilation zone on the tooth surface of the rake tooth; arranging the soil-breaking structure along the negative pressure center zone on the tooth surface of the rake tooth, and arranging the high-pressure water flushing structure in the shear dilation significant zone on the tooth surface of the rake tooth; assembling the rake tooth with the soil-breaking structure and the high-pressure water flushing structure to the rake head of the rake suction dredger, and cutting the soil to be cut by the rake tooth, so that the soil-breaking structure on the rake tooth cuts the soil to be cut, and the high-pressure water output by the high-pressure water flushing structure can enter the interior of the soil to be cut along the soil-breaking structure. The present application can realize the cooperative operation of mechanical breaking and hydraulic shear dilation effect reduction, and is beneficial to greatly reducing the cutting resistance of the rake tooth.

Description

Technical Field

[0001] This invention relates to the field of dredging engineering technology, and in particular to a method and apparatus for reducing the shear dilatation effect of dense, fine-particle soil. Background Technology

[0002] Trailing suction hopper dredgers are core vessels widely used in dredging engineering, undertaking numerous dredging tasks such as waterway improvement and harbor basin excavation. During dredging operations, trailing suction hopper dredgers frequently encounter dense, compacted silt and dense fine sand, characterized by high density, low compressibility, high strength, and high bearing capacity. They typically have a high standard penetration test blow count, generally exceeding 30N, making them as hard as iron plates; hence, this type of soil is often referred to in the industry as "iron plate sand."

[0003] Because this type of dense, fine-grained soil has significant shear dilatation characteristics, when the rake teeth cut into the dense, fine-grained soil, a certain range of shear dilatation zone will be formed on the surface of the rake teeth. The pore water pressure in the shear dilatation zone is negative. According to the principle of effective stress, the presence of negative pore water pressure will cause the effective stress of the soil to increase, which will significantly increase the cutting resistance of the rake teeth, thereby greatly increasing the difficulty of dredging operations of the trailing suction dredger.

[0004] However, existing dredging operations rely solely on the rake teeth to directly cut the soil, which fails to effectively reduce the dilatation effect in the dilatation zone. This results in difficulties in breaking up the soil, low dredging efficiency, and high energy consumption.

[0005] Therefore, there is an urgent need to propose a method and device to reduce the shear dilatation effect of dense, fine-grained soil in order to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for reducing the dilatation effect of dense fine-grained soil. This method and apparatus can achieve the synergistic effect of mechanical crushing and hydraulic reduction of dilatation effect, which is beneficial to significantly reduce the cutting resistance of the rake teeth. It effectively solves the problems of difficult crushing of dense fine-grained soil, low construction efficiency and high energy consumption, and significantly improves dredging output and operational stability under the condition of dense fine-grained soil.

[0007] Based on the above concept, the technical solution adopted by this invention is as follows: In a first aspect, the present invention provides a method for reducing the shear dilatation effect of dense, fine-grained soil, comprising the following steps: S1. Determine the shear dilatation zone on the tooth surface of the rake teeth when cutting the soil, and determine the position of the negative pressure center zone and the position of the significant shear dilatation zone within the shear dilatation zone on the tooth surface of the rake teeth; S2. A soil-breaking structure is set along the negative pressure center zone on the tooth surface of the rake teeth, and a high-pressure water flushing structure is set in the significant shear dilatation zone on the tooth surface of the rake teeth. S3. The rake teeth with the soil breaking structure and the high-pressure water flushing structure are assembled to the rake head of the dredging vessel. The rake teeth cut the soil to be cut, so that the soil breaking structure on the rake teeth cuts the soil to be cut, and the high-pressure water output by the high-pressure water flushing structure can enter the soil to be cut along the soil breaking structure.

[0008] In some embodiments, determining the shear dilatation zone on the tooth surface of the rake teeth during soil cutting in step S1 includes: S11. Prepare test soil with properties and indicators consistent with the soil to be cut, and test cutting teeth corresponding to the rake teeth; S12. Multiple pore water pressure sensors are arranged in rows and columns on the tooth surface of the test cutter teeth, and the test soil is cut by the test cutter teeth; S13. During the cutting process, the pore water pressure value at the corresponding point on the tooth surface of the test cutter tooth is obtained by multiple pore water pressure sensors. S14. Determine the boundary of the dilatation zone on the tooth surface of the test blade according to the sign of the pore water pressure value at each point, determine the area with a negative pore water pressure value as the dilatation zone, determine the area with a positive pore water pressure value as the non-dilatation zone, and determine the line connecting the positions with a zero pore water pressure value as the boundary line between the dilatation zone and the non-dilatation zone. S15. Based on the shear dilatation zone on the tooth surface of the test cutter, determine the corresponding shear dilatation zone on the tooth surface of the rake tooth.

[0009] In some embodiments, determining the position of the negative pressure center zone and the position of the significant shear dilation zone within the shear dilation zone on the tooth surface of the rake teeth in step S1 includes: S16. Determine the location of the maximum negative pressure of multiple pore water pressure values ​​in each row along the direction from the tip to the root of the test cutter teeth, and determine the line connecting the locations of each maximum negative pressure value as the negative pressure center zone on the tooth surface of the test cutter teeth; and determine the negative pressure concentration area as the significant shear dilation area on the tooth surface of the test cutter teeth. S17. The positions of the negative pressure center zone and the significant shear dilation zone within the shear dilation zone on the tooth surface of the rake teeth are determined accordingly.

[0010] In some embodiments, after step S3, a comparative experiment is further included; the comparative experiment includes: Prepare a first test soil and a second test soil with properties and indices consistent with the soil to be cut; The first test soil was cut using conventional test rake teeth, and the second test soil was cut using test rake teeth including a soil breaking structure and a high-pressure water flushing structure. The cutting resistance value and the suction mud concentration value were collected and compared in real time during the two cutting tests.

[0011] In some embodiments, the flushing water pressure of the high-pressure flushing structure is set to not less than 10 bar.

[0012] In a second aspect, the present invention provides an apparatus for reducing the dilatation effect of dense fine-grained soil, which is applied to the method for reducing the dilatation effect of dense fine-grained soil as described in the first aspect. The device for reducing the shear dilatation effect of dense, fine-grained soil includes a rake head with multiple rake teeth. A soil-breaking structure is provided at the negative pressure center zone on the tooth surface of each rake tooth, and a high-pressure water-flushing structure is provided within the significant shear dilatation zone on the tooth surface of each rake tooth. A water-transporting channel communicating with the high-pressure water-flushing structure is provided inside the rake tooth. The soil-breaking structure is configured to cut the soil to be cut, and the high-pressure water output by the high-pressure water-flushing structure is configured to enter the interior of the soil to be cut along the soil-breaking structure.

[0013] In some embodiments, on the tooth surface of each of the rake teeth, two high-pressure water jet structures are symmetrically arranged in the significant shear dilatation zone on both sides of the soil breaking structure, and the high-pressure water output by the two high-pressure water jet structures can enter the interior of the soil to be cut along the soil breaking structure.

[0014] In some embodiments, the soil-breaking structure is configured as a soil-breaking blade, the width of the blade tail is 0.1 to 0.2 times the width of the tooth tip of the rake tooth surface, and the width of the blade tip is 1 / 3 to 1 / 2 of the width of the blade tail.

[0015] In some embodiments, the protrusion height of the soil-breaking blade relative to the tooth surface of the rake tooth decreases linearly along the direction from the tip of the rake tooth to the root of the rake tooth.

[0016] In some embodiments, the high-pressure flushing structure is configured as a high-pressure flushing hole, the central axis of the high-pressure flushing hole is inclined toward the tooth tip of the rake tooth surface and the included angle between the high-pressure flushing hole and the rake tooth surface is set to 15°~30°, and the included angle between the central axis of the high-pressure flushing hole and the central axis of the soil breaking blade is set to 30°~45°.

[0017] The beneficial effects of this invention are: The method for reducing the dilatation effect of dense, fine-grained soil provided by this invention achieves targeted adaptation and synergistic effect by precisely locating the negative pressure center zone and the significant dilatation zone within the dilatation area on the rake tooth surface, and strategically deploying soil-breaking structures and high-pressure water-flushing structures. Specifically, the soil-breaking structure deployed in the negative pressure center zone prioritizes mechanical breaking of the soil in the core stress concentration area, effectively disturbing the soil structure. Simultaneously, the high-pressure water-flushing structure deployed in the significant dilatation zone precisely targets water injection, directly injecting high-pressure water into the most significant dilatation area of ​​the soil, rapidly converting the negative pore water pressure into positive pore water pressure, significantly reducing the effective stress of the soil and weakening the dilatation effect. Compared to traditional soil-cutting methods, this method achieves synergistic coordination between mechanical breaking and hydraulic dilatation, significantly reducing the cutting resistance of the rake teeth, effectively solving the problems of difficult breaking of dense, fine-grained soil, low construction efficiency, and high energy consumption, and significantly improving dredging output and operational stability under dense, fine-grained soil conditions.

[0018] The device for reducing the dilatation effect of dense, fine-grained soil provided by this invention is based on the aforementioned method and precisely arranges the structure, with the soil breaking structure and the high-pressure water flushing structure respectively positioned in the negative pressure center zone of the rake teeth and the significant dilatation zone. The device also ensures stable delivery of high-pressure water through a built-in water conveyance channel. This enables the coordinated operation of centralized mechanical soil breaking and fixed-point hydraulic dilatation relief, effectively eliminating the negative pore water pressure generated by the cutting of dense, fine-grained soil, weakening the soil dilatation effect, and significantly reducing the cutting resistance of the rake teeth. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of the testing system provided in the embodiment of the present invention; Figure 2 This is a schematic diagram of the soil preparation subsystem provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the cutting subsystem provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the pore water pressure measurement subsystem provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the control subsystem provided in an embodiment of the present invention; Figure 6This is a schematic diagram of the shear dilatation zone range on the toothed surface during a fine sand sample test provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the negative pressure center zone and significant shear dilatation zone on the tooth surface during the fine sand sample test provided in this embodiment of the invention; Figure 8 This is a schematic diagram of the structure of the fine sand sample test provided in this embodiment of the invention, which features a soil-breaking blade and a high-pressure water jet on the toothed surface. Figure 9 This is a schematic diagram of the structure of the apparatus for conducting comparative experiments provided in an embodiment of the present invention; Figure 10 This is a comparison diagram of the cutting resistance of the rake teeth during the fine sand soil sample test provided in the embodiments of the present invention; Figure 11 This is a comparison chart of mud volume concentration during the fine sand soil sample test provided in the embodiments of the present invention; Figure 12 This is a schematic diagram of the shear dilatation zone range on the tooth surface during a silt sample test provided in an embodiment of the present invention; Figure 13 This is a schematic diagram of the negative pressure center zone and significant shear dilatation zone on the tooth surface during the silt sample test provided in this embodiment of the invention; Figure 14 This is a schematic diagram of the structure provided in the embodiment of the present invention, which shows the soil-breaking blade and high-pressure water flushing hole set on the tooth surface during the silt soil sample test. Figure 15 This is a comparison diagram of the cutting resistance of the rake teeth during the silt soil sample test provided in the embodiments of the present invention; Figure 16 This is a comparison chart of mud volume concentration during the silt soil sample test provided in the embodiment of the present invention.

[0021] Figure 1 middle: 51. Soil preparation subsystem; 52. Cutting subsystem; 53. Pore water pressure measurement subsystem; 54. Control subsystem; Figure 2 middle: 11. Suction device; 12. Gas-water separation device; 13. Soil preparation tank; 14. Soil; 15. Water supply device; 16. Vibration compaction device; 17. Leveling device; Figure 3 middle: 21. Test cutter teeth; 22. Tooth holder; 23. Force sensor; 24. Cutting connection device; 25. Angle adjustment hydraulic cylinder; 26. Height adjustment hydraulic cylinder; 27. Trolley; 28. Track; 29. ​​Traction system; Figure 4 middle: 31. Permeable stone; 32. Water body; 33. Pore water pressure sensor; 34. Silica gel; 35. Communication cable; Figure 5 middle: 41. Data acquisition instrument; 42. Data cable; 43. Control device; Figure 6 middle: 61. Pore water pressure sensor; 62. Tooth surface; 63. Shear dilatation zone; Figure 7 middle: 71. Negative pressure center zone; 72. Significant shear dilatation zone; Figure 8 middle: 81. Soil-breaking blade; 82. High-pressure water jet; Figure 9 middle: 91. Rake teeth; 92. Force sensor; 93. Movable cover; 94. High-pressure flushing main pipe; 95. High-pressure flushing branch pipe; 96. Rake suction pipe; 97. Concentration meter; Figure 12 middle: 121. Pore water pressure sensor; 122. Tooth surface; 123. Shear dilatation zone; Figure 13 middle: 131. Negative pressure center zone; 132. Significant shear dilatation zone; Figure 14 middle: 141. Soil-breaking blade; 142. High-pressure water jet hole. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0025] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0029] Example 1 This embodiment provides a method for reducing the shear dilatation effect of dense, fine-grained soil, including the following steps: S1. Determine the shear dilatation zone on the tooth surface of the rake teeth when cutting the soil, and determine the location of the negative pressure center zone and the location of the significant shear dilatation zone within the shear dilatation zone on the tooth surface of the rake teeth; S2. Set up a soil-breaking structure along the negative pressure center zone on the tooth surface of the rake teeth, and set up a high-pressure water flushing structure in the significant shear dilatation zone on the tooth surface of the rake teeth. S3. The rake teeth with soil breaking structure and high-pressure water flushing structure are assembled to the rake head of the dredger. The rake teeth cut the soil to be cut, so that the soil breaking structure on the rake teeth cuts the soil to be cut, and the high-pressure water output by the high-pressure water flushing structure can enter the soil to be cut along the soil breaking structure.

[0030] That is, firstly, the dilatation zone on the tooth surface of the rake is determined, and then the location of the negative pressure center zone and the significant dilatation zone are further determined within the dilatation zone; then, the rake is modified by assembling a soil-breaking structure along the negative pressure center zone on the tooth surface and setting a high-pressure water jet structure within the significant dilatation zone; finally, the modified rake is used to cut the soil to be cut. The soil to be cut is dense, compacted silt, dense fine silt, or other dense, fine-grained soil bodies underwater, and no specific limitation is made here.

[0031] The method for reducing the dilatation effect of dense, fine-grained soil provided in this embodiment achieves targeted adaptation and synergistic effect by precisely locating the negative pressure center zone and the significant dilatation zone within the dilatation area on the rake tooth surface, and strategically deploying soil-breaking and high-pressure water-flushing structures. Specifically, the soil-breaking structure deployed in the negative pressure center zone prioritizes mechanical breaking of the soil in the core stress concentration area, effectively disturbing the soil structure. Simultaneously, the high-pressure water-flushing structure deployed in the significant dilatation zone precisely targets water injection, directly injecting high-pressure water into the most significant dilatation area of ​​the soil, rapidly converting the negative pore water pressure into positive pore water pressure, significantly reducing the effective stress of the soil and weakening the dilatation effect. Compared to traditional soil-cutting methods, this method achieves synergistic coordination between mechanical breaking and hydraulic dilatation, significantly reducing the cutting resistance of the rake teeth, effectively solving the problems of difficult breaking of dense, fine-grained soil, low construction efficiency, and high energy consumption, and significantly improving dredging output and operational stability under dense, fine-grained soil conditions.

[0032] Optionally, the flushing water pressure of the high-pressure flushing structure is set to not less than 10 bar. This setting ensures sufficient water flow impact force and penetration capacity, guaranteeing that the high-pressure water can effectively penetrate the significant shear dilatation zone in dense, fine-grained soil conditions.

[0033] In some embodiments, determining the shear dilatation zone on the tooth surface of the rake teeth during soil cutting in step S1 includes: S11. Prepare test soil with properties and indicators consistent with the soil to be cut, and test cutting teeth corresponding to the rake teeth; S12. Multiple pore water pressure sensors are arranged in rows and columns on the tooth surface of the test cutter teeth, and the test soil is cut by the test cutter teeth; S13. During the cutting process, the pore water pressure values ​​at corresponding points on the tooth surface of the test cutter are obtained through multiple pore water pressure sensors. S14. Determine the boundary of the dilatation zone on the tooth surface of the test cutter according to the sign of the pore water pressure value at each point. Determine the area with a negative pore water pressure value as the dilatation zone, the area with a positive pore water pressure value as the non-dilatation zone, and the line connecting the positions with a zero pore water pressure value as the boundary line between the dilatation zone and the non-dilatation zone. S15. Based on the shear dilatation zone on the tooth surface of the test cutter, determine the corresponding shear dilatation zone on the tooth surface of the rake.

[0034] Specifically, in step S14, the positions where the measured pore water pressure is positive are marked with "+" and the positions where it is negative are marked with "-". For the regions where the positive and negative values ​​are adjacent, the difference is processed to obtain the position where the pore water pressure is zero. The points where the pore water pressure is zero are connected to form a line, which is the boundary line between the dilatation zone and the non-dilatation zone.

[0035] This setup, through experimental calibration, allows for the precise delineation of the boundaries between the dilatation zone and the non-dilatation zone based on the difference in positive and negative pore water pressure values. It enables the objective and accurate location of the dilatation zone, effectively compensating for the subjective errors inherent in traditional experience-based judgments.

[0036] In some embodiments, determining the location of the negative pressure center zone and the location of the significant shear dilation zone within the shear dilation zone on the tooth surface of the rake teeth in step S1 includes: S16. Determine the location of the maximum negative pressure of multiple pore water pressure values ​​in each row along the direction from the tip to the root of the test cutter teeth, and determine the line connecting the locations of each maximum negative pressure value as the negative pressure center zone on the tooth surface of the test cutter teeth; and determine the negative pressure concentration area as the significant shear dilation area on the tooth surface of the test cutter teeth. S17. Determine the position of the negative pressure center zone and the position of the significant shear dilation zone within the shear dilation zone on the tooth surface of the rake teeth.

[0037] This setup allows for precise determination of the core area of ​​shear dilatation based on experimental data, providing accurate information for the subsequent layout of the excavation structure and high-pressure water jetting structure.

[0038] Optionally, such as Figure 1 As shown, the test system for performing steps S11 to S13 includes a soil preparation subsystem 51, a cutting subsystem 52, a pore water pressure measurement subsystem 53, and a control subsystem 54.

[0039] like Figure 2As shown, the soil preparation subsystem 51 mainly consists of a suction device 11, an air-water separation device 12, a soil preparation pool 13, a water supply device 15, a vibration compaction device 16, and a leveling device 17. In step S11, when preparing test soil with properties and indicators consistent with the soil to be cut, impurities (such as stones, garbage, branches, etc.) are removed from the soil 14 excavated from the construction site to ensure the uniformity of the soil 14. The soil 14 with impurities removed is placed in the soil preparation pool 13. The air in the soil 14 is drawn into the air-water separation device 12 by the suction device 11. The moisture in the air collects at the bottom of the air-water separation device 12 and accumulates into water. The air with separated moisture is discharged from the suction device 11 through the suction pipe. Airless water is introduced into the soil 14 through the water supply device 15. Under the continuous action of the suction device 11, the soil 14 is fully saturated and becomes more compacted. After the soil 14 reaches a certain degree of compaction, the soil 14 is vibrated by the vibration compaction device 16 to make it more compacted. After the soil 14 is further vibrated and compacted, the surface of the soil 14 is leveled by the leveling device 17.

[0040] like Figure 3 As shown, the cutting subsystem 52 mainly consists of test cutter teeth 21, tooth holders 22, force sensors 23, cutting connection devices 24, angle adjustment hydraulic cylinders 25, height adjustment hydraulic cylinders 26, trolleys 27, tracks 28, and traction systems 29. Figure 4 As shown, the pore water pressure measurement subsystem 53 mainly consists of permeable stone 31, water body 32, pore water pressure sensor 33, silicone 34, communication cable 35, etc. The pore water pressure sensor 33 is a miniature pressure sensor with a diameter not exceeding 5mm and a thickness not exceeding 1mm. Figure 5 As shown, the control subsystem 54 mainly consists of a data acquisition instrument 41, a data cable 42, and a control device 43.

[0041] In maintenance mode, the control device 43 performs zero-position calibration on the wire ropes of both the trolley 27 and the traction system 29. The control device 43 sets the cutting speed of the test cutter teeth 21, the acquisition frequency of the force sensor 23, and the acquisition frequency of the pore water pressure sensor 33 via the parameter setting module. The cutting control module of the control device 43 adjusts the cutting angle of the test cutter teeth 21 by extending and retracting the piston rod of the angle-adjusting hydraulic cylinder 25 to rotate the cutting connection device 24. It also adjusts the height of the test cutter teeth 21 by extending and retracting the piston rod of the height-adjusting hydraulic cylinder 26 to move the test cutter teeth 21 up and down, thereby adjusting the thickness of the soil 14 cut by the test cutter teeth 21. Under the traction of the traction system 29, the trolley 27 moves along the track 28, causing the test cutter teeth 21 to linearly cut the soil 14 at the set cutting speed.

[0042] When the test cutter tooth 21 cuts the soil 14, the moving speed is no more than 3 m / s and the fluctuation range of the moving speed is no more than 5%. During cutting, the first 5 m is the acceleration section where the speed increases from zero to the moving speed, and the last 5 m is the deceleration section where the speed decreases from the moving speed to zero. The section between the acceleration section and the deceleration section is the stable cutting section, and the length of the stable cutting section is no less than 30 m.

[0043] When the test cutter tooth 21 cuts the soil 14, the pore water pressure sensor 33 measures the pore water pressure at various points on the interface between the test cutter tooth 21 and the soil 14 in real time at a set acquisition frequency. The acquisition control module of the control device 43 receives and stores the pore water pressure value measured by the pore water pressure sensor 33 through the data acquisition instrument 41 at a frequency of once every 1 mm of movement of the test cutter tooth 21.

[0044] In one embodiment, the test soil is fine sand from the Yangtze River waterway. The basic physical properties and strength indicators of the fine sand sample prepared by the soil preparation subsystem 51 are shown in Table 1.

[0045] Table 1. Basic physical properties and strength index values ​​of the prepared fine sand samples Table 2. Hole pressure values ​​of the knife-tooth pattern in fine sand samples. For the fine sand sample in Table 1, under the conditions of cutting angle α=45°, cutting speed v=2m / s, and cutting thickness h=0.1m, the soil 14 was cut using the test cutter tooth 21. The pore pressure values ​​collected on the surface of the test cutter tooth 21 are shown in Table 2. The range of the preliminarily determined shear dilatation zone 63 is as follows. Figure 6 As shown, the negative value region is the dilatation region 63. This is determined by the values ​​listed in Table 2 and... Figure 6 The preliminary determination of the shear dilatation zone 63 revealed that the pore water pressure values ​​measured by pore water pressure sensors 61 (01-08) were all negative. The remaining negative pressure points were generally symmetrically distributed along the line connecting points 01-08. Therefore, the location of the maximum negative pressure value among the multiple pore water pressure values ​​in each row along the tooth tip to tooth root direction of the tooth surface 62 was determined, and a line was drawn connecting these points to determine the location of the negative pressure center zone 71. Figure 7 As shown. Furthermore, by analyzing the values ​​listed in Table 2 and... Figure 6 Analysis shows that the negative pore water pressure gradually decreases with increasing distance from the tooth tip, indicating that shear dilatation is more significant closer to the tooth tip, and it is mainly distributed in... Figure 7 The area is located in the significant dilatation zone 72. Outside this zone, the pore water pressure values ​​are mostly positive, and even if they are negative, they are relatively small, indicating that the dilatation effect is not obvious.

[0046] like Figure 8As shown, in this embodiment, the soil-breaking structure is set as a soil-breaking blade 81, and the high-pressure water flushing structure is set as a high-pressure water flushing hole 82. Based on the determination of the negative pressure center zone 71 and the significant shear dilatation zone 72, the soil-breaking blade 81 is set along the negative pressure center zone 71, and the high-pressure water flushing hole 82 is set in the significant shear dilatation zone 72, so that high-pressure water can enter the soil along the surface of the soil-breaking blade 81. Furthermore, there are two high-pressure water flushing holes 82, which are symmetrically arranged in the significant shear dilatation zone 72 on both sides of the soil-breaking blade 81. The corresponding rake tooth seat is provided with a main high-pressure water flushing channel and a branch high-pressure water flushing channel. The branch high-pressure water flushing channel is divided into two paths, each corresponding to one of the two high-pressure water flushing holes 82.

[0047] To verify the effectiveness of the method, in some embodiments, a comparative experiment is included after step S3. The comparative experiment includes: Prepare a first test soil and a second test soil with properties and indices consistent with the soil to be cut; The first test soil was cut using conventional test rake teeth, and the second test soil was cut using test rake teeth including soil breaking structure and high-pressure water flushing structure. The cutting resistance value and the suction mud concentration value were collected and compared in real time during the two cutting tests.

[0048] Specifically, adopt Figure 9 The apparatus shown was used for comparative testing. First, dense fine sand samples meeting all the indicators in Table 1 were prepared again. Then, a trolley 27 was used to tow the samples at a speed of 2.0 m / s. Figure 9 The apparatus shown was used to conduct soil cutting tests. Two types of rake teeth were used in the comparative test: one was a conventional test rake tooth without the soil-breaking and high-pressure water-flushing structures, and the other was a test rake tooth with the aforementioned soil-breaking and high-pressure water-flushing structures. In the test, three or four rake teeth 91 were placed inside the movable cover 93, the cutting thickness was set to 0.1 m, and the high-pressure water pressure was set to 10 bar. The water entered the rake teeth 91 through the high-pressure water main pipe 94 and high-pressure water branch pipe 95, and was ejected through the high-pressure water-flushing holes 82. The mud formed by the mixture of cut soil and water was sucked away through the rake suction pipe 96. During the soil cutting process, the cutting resistance of the rake teeth 91 was measured in real time using a force sensor 92, the mud concentration was measured in real time using a concentration meter 97, and the data was stored in real time using a control device 43.

[0049] Figure 10 This is a comparison chart of cutting resistance in two cutting tests. Figure 10It can be seen that the average cutting resistance of the rake teeth 91 under the conditions of setting the soil breaking structure and high-pressure water flushing structure is about 3000N, while the average cutting resistance of the rake teeth 91 under the conditions of no soil breaking structure and high-pressure water flushing structure is about 6000N. The cutting resistance is reduced by nearly 50%. Furthermore, the cutting resistance fluctuates greatly under the conditions of setting the soil breaking structure and high-pressure water flushing structure, indicating that the method proposed in this embodiment can accurately and effectively reduce the shear dilatation zone, thereby significantly reducing the effective stress of the soil and thus significantly reducing the cutting resistance of the rake teeth.

[0050] Figure 11 This is a comparison chart of mud concentration from two cutting tests. Figure 11 It can be observed that the average mud concentration under the conditions of setting the soil breaking structure and high-pressure water flushing structure is about 20%, while the average mud concentration under the conditions of not setting the soil breaking structure and high-pressure water flushing structure is about 10%, which is nearly double the concentration. Furthermore, the concentration fluctuates greatly under the conditions of setting the soil breaking structure and high-pressure water flushing structure. This indicates that the method proposed in this embodiment significantly reduces the cutting resistance of the rake teeth while greatly increasing the mud concentration and improving the dredging output.

[0051] In another possible embodiment, the test soil is silt from Huanghua Port. The basic physical properties and strength indices of the silt soil sample prepared by the soil preparation subsystem 51 are shown in Table 3.

[0052] Table 3. Basic physical properties and strength index values ​​of the prepared silty soil samples The silt sample was cut in the same manner as the aforementioned fine sand sample, and the pore pressure values ​​collected on the surface of the test blade teeth 21 are shown in Table 4. The preliminary determined range of the shear dilatation zone 123 is as follows. Figure 12 As shown, the negative value region is the dilatation zone 123. Compared with fine sand samples, silt samples generate greater negative pressure values ​​during cutting, and the distribution range is wider.

[0053] The location of the negative pressure center zone 131 and the significant shear dilatation zone 132 were determined using the same methods and procedures as for the fine sand samples, based on the values ​​listed in Table 4. Figure 12 It was found that the pore water pressure values ​​measured by pore water pressure sensors 121 (01-09) were all negative. The remaining negative pressure points were basically symmetrically distributed along the line connecting points 01-09. Therefore, the location of the maximum negative pressure value among the multiple pore water pressure values ​​in each row along the tooth tip to tooth root direction of tooth surface 122 was determined, and a line was drawn connecting these points to determine the location of the negative pressure center zone 131. Figure 13 As shown. By Figure 13It can be seen that the position and shape of the negative pressure center zone 131 and the significant shear dilatation zone 132 are basically the same as those of the fine sand sample, but the negative pressure center zone 131 extends towards the tooth root, while the position of the significant shear dilatation zone 132 is not much different from that of the fine sand sample.

[0054] Based on the established negative pressure center zone 131 and significant shear dilatation zone 132, a soil-breaking blade 141 is installed along the negative pressure center zone 131, and a high-pressure water jet 142 is installed in the significant shear dilatation zone 132, allowing high-pressure water to enter the soil along the surface of the soil-breaking blade 141. The specific setup is the same as for the fine sand sample, and the arrangement of the soil-breaking blade 141 and high-pressure water jet 142 is as follows: Figure 14 As shown.

[0055] To verify the effectiveness of the method, we also used... Figure 9 A comparative test was conducted using the apparatus shown. First, a silty soil sample meeting all the indicators in Table 3 was prepared again. A soil cutting test was conducted using the same method and procedures as the fine sand sample. During the soil cutting process, the cutting resistance of the rake teeth 91 was measured in real time using a force sensor 92, the mud concentration was measured in real time using a concentration meter 97, and the data was stored in real time using a control device 43.

[0056] Figure 15 This is a comparison chart of cutting resistance in two cutting tests. Figure 15 It can be seen that under the conditions of soil breaking and high-pressure water flushing, the average cutting resistance of the rake teeth 91 is approximately 4000 N, while under the conditions of no soil breaking and high-pressure water flushing, the average cutting resistance of the rake teeth 91 is approximately 7000 N. The cutting resistance is reduced by about 43%, which is slightly lower than the 50% reduction in the fine sand sample cutting test. This is mainly due to the denser silt sample, resulting in a more significant shear dilatation effect. The cutting resistance data from the fine sand and silt sample cutting tests together demonstrate that the method proposed in this embodiment can accurately and effectively reduce the shear dilatation zone, thereby significantly reducing the effective stress of the soil and thus significantly reducing the cutting resistance of the rake teeth.

[0057] Figure 16 This is a comparison chart of mud concentration from two cutting tests. Figure 16 It can be observed that the average mud concentration under the conditions of soil breaking and high-pressure water flushing is approximately 15%, while the average mud concentration under the conditions of no soil breaking and high-pressure water flushing is approximately 8%, representing an increase of nearly 100%. This result is essentially consistent with the results of the fine sand cutting test. The mud concentration data from the fine sand and silt cutting tests also demonstrate that the method proposed in this embodiment significantly reduces the cutting resistance of the rake teeth while substantially increasing the mud concentration, thereby improving dredging output.

[0058] Table 4. Hole pressure values ​​of the knife-tooth pattern in silty soil samples Example 2 This embodiment provides a device for reducing the dilatation effect of dense, fine-grained soil, which is applied to the method for reducing the dilatation effect of dense, fine-grained soil in Embodiment 1.

[0059] The device for reducing the shear dilatation effect of dense, fine-grained soil includes a rake head with multiple rake teeth. A soil-breaking structure is installed at the negative pressure center zone on the tooth surface of each rake tooth, and a high-pressure water-flushing structure is installed within the significant shear dilatation zone on the tooth surface of each rake tooth. A water delivery channel connecting the high-pressure water-flushing structure is provided inside the rake teeth. The soil-breaking structure is configured to cut the soil to be cut, and the high-pressure water output from the high-pressure water-flushing structure is configured to enter the interior of the soil to be cut along the soil-breaking structure.

[0060] The device for reducing the dilatation effect of dense, fine-grained soil provided in this embodiment is based on the aforementioned method to precisely arrange the structure. The soil breaking structure and the high-pressure water flushing structure are respectively arranged in the negative pressure center zone of the rake teeth and the significant dilatation zone. The built-in water conveyance channel ensures stable delivery of high-pressure water. It can realize the coordinated work of centralized mechanical soil breaking and fixed-point hydraulic dilatation relief, which can effectively eliminate the negative pore water pressure generated by cutting dense, fine-grained soil, weaken the soil dilatation effect, and significantly reduce the cutting resistance of the rake teeth.

[0061] In some embodiments, two high-pressure water jetting structures are symmetrically arranged on the tooth surface of each rake tooth within the significant shear dilatation zone on both sides of the soil breaking structure, and the high-pressure water output by the two high-pressure water jetting structures can enter the soil to be cut along the soil breaking structure.

[0062] With this setup, the two high-pressure water jet structures can create a bidirectional, uniform water jet pressure relief effect on both sides of the excavation structure, expanding the high-pressure water seepage range and facilitating the rapid and comprehensive elimination of soil shear dilatation effects.

[0063] In some embodiments, the soil-breaking structure is configured as a soil-breaking blade. The width of the blade tip is 0.1 to 0.2 times the width of the rake tooth tip, and the width of the blade tip is 1 / 3 to 1 / 2 of the width of the blade tip. This size-ratio soil-breaking blade structure is reasonable. The blade tip can concentrate stress to efficiently pierce and break the soil, and the blade tip adapts to the rake tooth surface structure to ensure overall strength. It can accurately disturb the core soil in the negative pressure center zone and reduce the resistance of the soil-breaking structure itself. Combined with the seepage path of high-pressure water flushing, it can ensure the coordinated operation of soil breaking and expansion relief.

[0064] Alternatively, the protrusion height of the breaking blade relative to the tooth surface of the rake tooth decreases linearly from the tip to the root of the rake tooth. The linear decrease in the protrusion height of the breaking blade from the tip to the root of the tooth allows for gradual breaking of the soil, smoothing the flow of soil and water, and reducing the resistance of the rake tooth.

[0065] In some embodiments, the high-pressure flushing structure is configured as a high-pressure flushing hole, the central axis of which is inclined toward the tip of the rake tooth surface and the angle between the central axis and the rake tooth surface is set to 15°~30°, and the angle between the central axis of the high-pressure flushing hole and the central axis of the soil-breaking blade is set to 30°~45°. Exemplarily, the angle between the central axis of the high-pressure flushing hole and the rake tooth surface can be set to 15°, 20°, 25°, or 30°; the angle between the central axis of the high-pressure flushing hole and the central axis of the soil-breaking blade can be set to 30°, 35°, 40°, or 45°.

[0066] With this configuration, the high-pressure water jet is tilted at a reasonable angle, allowing the water to be sprayed towards the cutting edge and injected into the soil close to the cutting edge. This increases the depth of water penetration, thereby quickly dissipating the negative pore water pressure and effectively weakening the shear dilatation effect.

[0067] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for reducing the shear dilatation effect of dense, fine-grained soil, characterized in that, Includes the following steps: S1. Determine the shear dilatation zone on the tooth surface of the rake teeth when cutting the soil, and determine the position of the negative pressure center zone and the position of the significant shear dilatation zone within the shear dilatation zone on the tooth surface of the rake teeth; S2. A soil-breaking structure is set along the negative pressure center zone on the tooth surface of the rake teeth, and a high-pressure water flushing structure is set in the significant shear dilatation zone on the tooth surface of the rake teeth. S3. The rake teeth with the soil breaking structure and the high-pressure water flushing structure are assembled to the rake head of the dredging vessel. The rake teeth cut the soil to be cut, so that the soil breaking structure on the rake teeth cuts the soil to be cut, and the high-pressure water output by the high-pressure water flushing structure can enter the soil to be cut along the soil breaking structure.

2. The method for reducing the shear dilatation effect of dense, fine-grained soil according to claim 1, characterized in that, The determination of the shear dilatation zone on the tooth surface of the rake teeth during soil cutting in step S1 includes: S11. Prepare test soil with properties and indicators consistent with the soil to be cut, and test cutting teeth corresponding to the rake teeth; S12. Multiple pore water pressure sensors are arranged in rows and columns on the tooth surface of the test cutter teeth, and the test soil is cut by the test cutter teeth; S13. During the cutting process, the pore water pressure value at the corresponding point on the tooth surface of the test cutter tooth is obtained by multiple pore water pressure sensors. S14. Determine the boundary of the dilatation zone on the tooth surface of the test blade according to the sign of the pore water pressure value at each point, determine the area with a negative pore water pressure value as the dilatation zone, determine the area with a positive pore water pressure value as the non-dilatation zone, and determine the line connecting the positions with a zero pore water pressure value as the boundary line between the dilatation zone and the non-dilatation zone. S15. Based on the shear dilatation zone on the tooth surface of the test cutter, determine the corresponding shear dilatation zone on the tooth surface of the rake tooth.

3. The method for reducing the shear dilatation effect of dense, fine-grained soil according to claim 2, characterized in that, Determining the position of the negative pressure center zone and the position of the significant shear dilation zone within the shear dilation zone on the tooth surface of the rake teeth in step S1 includes: S16. Determine the location of the maximum negative pressure of multiple pore water pressure values ​​in each row along the direction from the tip to the root of the test cutter teeth, and determine the line connecting the locations of each maximum negative pressure value as the negative pressure center zone on the tooth surface of the test cutter teeth; and determine the negative pressure concentration area as the significant shear dilation area on the tooth surface of the test cutter teeth. S17. The positions of the negative pressure center zone and the significant shear dilation zone within the shear dilation zone on the tooth surface of the rake teeth are determined accordingly.

4. The method for reducing the shear dilatation effect of dense, fine-grained soil according to claim 1, characterized in that, Following step S3, a comparative experiment is also included; the comparative experiment includes: Prepare a first test soil and a second test soil with properties and indices consistent with the soil to be cut; The first test soil was cut using conventional test rake teeth, and the second test soil was cut using test rake teeth including a soil breaking structure and a high-pressure water flushing structure. The cutting resistance value and the suction mud concentration value were collected and compared in real time during the two cutting tests.

5. The method for reducing the shear dilatation effect of dense, fine-grained soil according to claim 1, characterized in that, The flushing water pressure of the high-pressure flushing structure is set to be no less than 10 bar.

6. A device for reducing the shear dilatation effect of dense, fine-grained soil, characterized in that, The method for reducing the shear dilatation effect of dense, fine-grained soil as described in any one of claims 1 to 5; The device for reducing the shear dilatation effect of dense, fine-grained soil includes a rake head with multiple rake teeth. A soil-breaking structure is provided at the negative pressure center zone on the tooth surface of each rake tooth, and a high-pressure water-flushing structure is provided within the significant shear dilatation zone on the tooth surface of each rake tooth. A water-transporting channel communicating with the high-pressure water-flushing structure is provided inside the rake tooth. The soil-breaking structure is configured to cut the soil to be cut, and the high-pressure water output by the high-pressure water-flushing structure is configured to enter the interior of the soil to be cut along the soil-breaking structure.

7. The device for reducing the shear dilatation effect of dense, fine-grained soil according to claim 6, characterized in that, On the tooth surface of each of the rake teeth, two high-pressure water flushing structures are symmetrically arranged in the significant shear dilatation zone on both sides of the soil breaking structure. The high-pressure water output by the two high-pressure water flushing structures can enter the soil to be cut along the soil breaking structure.

8. The device for reducing the shear dilatation effect of dense, fine-grained soil according to claim 7, characterized in that, The soil-breaking structure is configured as a soil-breaking blade, the width of the blade tail is 0.1 to 0.2 times the width of the tooth tip of the rake tooth surface, and the width of the blade tip is 1 / 3 to 1 / 2 of the width of the blade tail.

9. The device for reducing the shear dilatation effect of dense, fine-grained soil according to claim 8, characterized in that, Along the direction from the tip of the rake tooth to the root of the rake tooth, the protrusion height of the soil-breaking blade relative to the tooth surface of the rake tooth shows a linear decreasing trend.

10. The device for reducing the shear dilatation effect of dense, fine-grained soil according to claim 8, characterized in that, The high-pressure flushing structure is configured as a high-pressure flushing hole, the central axis of the high-pressure flushing hole is inclined toward the tip of the rake tooth surface and the included angle between the high-pressure flushing hole and the rake tooth surface is set to 15°~30°, and the included angle between the central axis of the high-pressure flushing hole and the central axis of the soil breaking blade is set to 30°~45°.

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