Drilling and underpinning pile cylinder type foundation bearing capacity indoor model experiment device and implementation method

Abstract

The application discloses a drilling bite pile cylinder type foundation bearing capacity indoor model experiment device and an implementation method, and relates to the technical field of foundation engineering. The experiment device comprises a bearing platform foundation; an anchor cage is embedded at the center position of the bearing platform foundation; a tower cylinder is arranged at the center position of the anchor cage; the bottom of the bearing platform foundation is connected with the top of a model pile structure around the periphery; the model pile structure comprises a plurality of model piles; the plurality of model piles comprise a plurality of composite piles and plain piles, the composite piles and the plain piles are alternately distributed and mutually bite; the bottom of the model pile structure is fixedly connected with a fixed plate of a pile bottom circular hoop; the anchor cage comprises an anchor cage main body; a bearing platform top anchor plate is arranged at the top of the anchor cage main body; a plurality of anchors are arranged on the anchor cage main body; the anchor cage main body is connected with the bearing platform top anchor plate and the bearing platform foundation through the anchors. The application changes the roughness (i.e. friction) between the composite piles and the plain piles, and then simulates the connection state between different pile foundations; and the force transmission path of a real cylinder type foundation is checked through the anchors arranged in the middle of the bearing platform foundation.

Description

Technical Field

[0001] This invention relates to the field of onshore wind power technology, and in particular to an indoor model experimental device and implementation method for the bearing capacity of drilled interlocking pile cylindrical foundations. Background Technology

[0002] Onshore wind power foundations come in various structural types, with cylindrical foundations being the main type of foundation in the wind power field in recent years. Among them, the drilled interlocking pile cylindrical foundation is a new type of cylindrical foundation. It has a simple structure, small footprint, high bearing capacity, and strong resistance to overturning, which can meet the requirements of large wind turbines.

[0003] Currently, simplified cylindrical foundation model experimental devices are often used in simple indoor experimental models. However, in actual experiments, it has been found that the multidimensional loads on existing simplified cylindrical foundation model experimental devices differ from the loads on actual engineering devices. After repeated experiments, the following problems were found with existing simplified cylindrical foundation model experimental devices:

[0004] Problem 1: The pile foundation of the simplified cylindrical experimental device differs from that of the actual engineering pile foundation. In the actual engineering device, there are non-negligible cold joints between the pile foundations. Due to the existence of cold joints, the simplified cylindrical foundation model experimental device cannot simulate the requirements of the actual project. The connection method between its cylindrical skirt piles does not match the actual situation, resulting in inaccurate experimental results.

[0005] Question 2: In the simplified cylindrical foundation experimental device, the pile foundation uses materials with the same stiffness, ignoring the stiffness difference between the reinforced piles (hard piles) and plain concrete piles (plain piles) in the skirt of the actual engineering device. This results in the simplified cylindrical foundation model experimental device and the actual engineering device being inconsistent in stiffness, lacking rigor.

[0006] Question 3: In the simplified cylindrical foundation model, the bottom of the loading tower is rigidly connected directly to the top of the foundation, ignoring the presence of the anchor cage in actual engineering. This results in a load transfer path of tower - top of foundation - foundation - bottom of foundation - pile foundation - soil. However, in actual engineering installations, the anchor cage penetrates both the top and bottom of the foundation, and the actual load transfer path is tower - anchor - bottom of foundation - foundation - pile foundation - soil. The difference in load transfer paths between the simplified cylindrical foundation model and the actual engineering installation leads to inaccuracies in the model experiment results.

[0007] Therefore, there is an urgent need to develop a technology that can solve the above-mentioned technical problems. Summary of the Invention

[0008] The purpose of this invention is to address the technical deficiencies of existing technologies by providing an indoor model experimental device and implementation method for the bearing capacity of drilled interlocking pile cylindrical foundations.

[0009] To this end, the present invention provides an indoor model test device and implementation method for the bearing capacity of drilled interlocking pile tube foundation, which includes a pile cap foundation;

[0010] An anchor cage is embedded in the center of the foundation cap;

[0011] At the center of the anchor cage, vertically distributed tower sections are installed protruding upwards;

[0012] The bottom edges of the foundation cap are connected to the top of the surrounding model pile structure;

[0013] The model pile structure includes multiple model piles;

[0014] Multiple model piles, including multiple solid piles and multiple plain piles, with solid and plain piles alternating and interlocking with each other;

[0015] The bottom of the model pile structure is fixedly connected to the circular hoop fixing base plate at the pile bottom.

[0016] Among them, the anchor cage includes the anchor cage body distributed around the perimeter;

[0017] The top of the anchor cage body is provided with a top anchor plate of the support platform;

[0018] On the main body of the anchor cage, there are multiple vertically arranged anchors evenly distributed along the circumference;

[0019] The anchor cage body is connected to the anchor plate on the top of the pier cap and the pier cap foundation by anchor bolts.

[0020] Furthermore, the present invention also provides a method for implementing the indoor model test device for the bearing capacity of drilled interlocking pile cylindrical foundation as described above, comprising the following steps:

[0021] The first step is to vertically place the indoor model test device for bearing capacity of the drilled interlocking pile tube foundation in the soil test box with the top opening, and bury the part of the model pile structure below the bottom surface of the foundation into the soil layer in the soil test box, and then compact the soil layer.

[0022] The second step is to fill the soil test chamber with water. When water seeps out from the top soil layer of the soil test chamber, stop adding water and allow it to cure for 24 hours.

[0023] The third step is to conduct loading tests on vertical and horizontal loads after the curing is completed.

[0024] As can be seen from the technical solutions provided by the present invention above, compared with the prior art, the present invention provides an indoor model experimental device and implementation method for the bearing capacity of bored interlocking pile cylindrical foundations. The design is scientific. The experimental device provided by the present invention can realistically simulate the bonding force and friction force between bored interlocking piles (i.e., solid piles and plain piles), which has significant practical significance.

[0025] Furthermore, this invention can realistically simulate the relative stiffness of solid and unsolid piles in actual engineering projects. By using the principle of model similarity, the overall size of the model is reduced while maintaining approximation of the magnitude and direction of the model load and stiffness. This makes it easy to place indoors and facilitates indoor experiments on drilled interlocking pile tube foundations. It is also beneficial to verify the real force transmission path of the model experiment by loading various loads, which has significant practical significance.

[0026] In addition, this invention simulates the connection state between different pile foundations by changing the roughness (i.e., friction) between the solid and plain piles; at the same time, through the model similarity principle theory, it determines that the relative stiffness between the solid and plain piles is consistent with the stiffness of the pile foundation in actual engineering; furthermore, this invention also verifies the force transmission path of the real cylindrical foundation by setting anchor bolts (i.e., pile cap fixing bolts) in the middle of the pile cap foundation. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view of the indoor model experimental device for bearing capacity of drilled interlocking pile cylindrical foundation provided by the present invention;

[0028] Figure 2 This is a front view of the indoor model experimental device for bearing capacity of drilled interlocking pile cylindrical foundation provided by the present invention;

[0029] Figure 3a This is a bottom side view of the indoor model experimental device for bearing capacity of drilled interlocking pile cylindrical foundation provided by the present invention;

[0030] Figure 3b This is a top side view of the indoor model experimental device for bearing capacity of drilled interlocking pile cylindrical foundation provided by the present invention;

[0031] Figure 4 This is a top view of the indoor model experimental device for bearing capacity of drilled interlocking pile cylindrical foundation provided by the present invention;

[0032] Figure 5 This is a schematic diagram of the stiffness of the solid pile and the plain pile in the indoor model test device for bearing capacity of the drilled interlocking pile tube foundation provided by the present invention.

[0033] Figure 6 This is a schematic diagram of the connection gap between the solid pile and the plain pile in the indoor model test device for bearing capacity of the drilled interlocking pile tube foundation provided by the present invention.

[0034] Figure 7 This is a schematic diagram of the anchor bolt cage of the pile cap foundation in the indoor model experimental device for bearing capacity of drilled interlocking pile tube foundation provided by the present invention.

[0035] Figure 8This is a schematic diagram of the circular hoop fixing plate at the bottom of the pile in the indoor model test device for bearing capacity of drilled interlocking pile cylindrical foundation provided by the present invention.

[0036] In the diagram, 1-tower cylinder; 2-screw hole on the upper part of the foundation; 3-screw hole on the outer edge of the foundation; 4-pile; 5-plain pile;

[0037] 6-Anchor plate at the top of the foundation; 71-First bolt; 72-Second bolt; 73-Third bolt;

[0038] 8-Anchor cage; 80-Anchor cage body; 81-Anchor bolt (i.e., foundation fixing bolt); 82-Fastening nut; 801-Tower insertion hole;

[0039] 9- Circular hoop fixing base plate at the pile bottom; 901- Screw hole for fixing base plate; 10- Screw hole at the top of the model pile;

[0040] 12-Pile cap foundation. Detailed Implementation

[0041] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0045] See Figures 1 to 2 , Figures 3a to 3b , Figures 4 to 8 This invention provides an indoor model experimental device for the bearing capacity of drilled interlocking pile tube foundations, which is a drilled interlocking pile tube foundation device suitable for onshore wind power, involving the experimental field of tensile and compressive strength after being inserted into the soil, and includes: a pile cap foundation 12;

[0046] An anchor cage 8 is embedded in the center of the foundation 12;

[0047] At the center of the anchor cage 8, a vertically distributed tower cylinder 1 is provided protruding upwards;

[0048] The bottom edges of the foundation 12 are connected to the top of the surrounding model pile structure;

[0049] See also Figure 5 , Figure 6 As shown, the model pile structure includes multiple model piles;

[0050] Multiple model piles, including multiple solid piles 4 and multiple plain piles 5, with solid piles 4 and plain piles 5 distributed alternately and interlocking with each other;

[0051] The bottom of the model pile structure is fixedly connected to the pile bottom circular hoop fixing base plate 9;

[0052] It should be noted that "4-pile with reinforcement cage" refers to a concrete pile with a steel cage (i.e., an internal steel reinforcement frame). "5-pile with reinforcement cage" refers to a pure concrete pile without a steel cage.

[0053] See also Figure 7 As shown, the anchor cage 8 includes anchor cage bodies 80 distributed around it;

[0054] The top of the anchor cage body 80 is provided with a top anchor plate 6 of the support platform;

[0055] On the anchor cage body 80, there are multiple vertically arranged anchor bolts 81 evenly distributed along the circumference;

[0056] The anchor cage body 80 is connected to the anchor plate 6 on the top of the foundation and the foundation 12 of the foundation via anchor bolts 81.

[0057] In this invention, the top anchor plate 6 of the pier cap is provided with a top screw hole 2 at a position corresponding to each anchor bolt 81;

[0058] At the lower end of the foundation 12, a foundation through hole is provided at the position corresponding to each anchor bolt 81;

[0059] The upper and lower ends of the anchor bolt 81 are threadedly connected to a fastening nut 82 after passing through the upper screw hole 2 of the bearing platform and the through hole of the bearing platform foundation, respectively.

[0060] In practice, the main body 80 of the anchor cage is formed by concrete pouring.

[0061] It should be noted that, for the present invention, the anchor cage 8 ensures that the experimental device has the correct force transmission path, specifically: tower 1 - anchor 81 - bottom of the foundation (i.e., the bottom of the foundation 12) - foundation (i.e. the entire foundation 12) - pile foundation (i.e., model pile) - soil (i.e. soil layer).

[0062] It should be noted that the anchor cage 8 is connected to the top anchor plate 6 of the foundation through the upper screw hole 2 of the foundation, thereby connecting the tower 1 and the foundation 12.

[0063] In practice, a tower insertion hole 801 is provided at the center of the anchor cage body 80;

[0064] The tower is embedded in hole 801, at the lower end of tower 1.

[0065] In this invention, the foundation 12 is fixedly connected to the top of the model pile by a plurality of first bolts 71.

[0066] In practice, multiple vertical through bolt holes 3 are evenly distributed along the circumference of the foundation 12 on the outer edge of the foundation.

[0067] A model pile is set directly below each of the screw holes 3 on the outer edge of the pile cap;

[0068] Each model pile has a top screw hole 10 at its center.

[0069] The bolt holes 10 on the upper part of the model pile are set to correspond exactly with the bolt holes 3 on the outer edge of the pile cap;

[0070] The first bolt 71 passes through the screw hole 3 on the outer edge of the foundation 12 from top to bottom and is then threadedly fixed to the screw hole 10 on the upper part of the model pile corresponding to the position.

[0071] In this invention, the model pile structure is fixedly connected to the pile bottom circular hoop fixing base plate 9 by multiple second bolts 72;

[0072] In practice, a screw hole is provided at the bottom center of each model pile;

[0073] The circular hoop fixing base plate 9 at the bottom of the pile is provided with a fixing base plate screw hole 901 at the position corresponding to the screw hole at the bottom of each model pile;

[0074] The second bolt 72 passes through the screw hole 901 in the fixing base plate from bottom to top and is then threadedly fixed to the screw hole at the bottom of the model pile corresponding to the position.

[0075] In this invention, for specific implementation, see [link to relevant documentation]. Figure 1 , Figure 2 , Figures 3a to 3b As shown, the model pile structure is fixedly connected to the lower four sides of the foundation 12 by multiple third bolts 73.

[0076] The lower part of the foundation 12 has a downward-opening groove for installing model piles (with a circular cross-section);

[0077] The top of the model pile is located in the model pile installation groove and is set directly corresponding to the screw hole 3 on the outer edge of the foundation 12;

[0078] The foundation 12 has multiple side wall through holes that are connected to the model pile installation groove evenly arranged around the model pile installation groove.

[0079] Each model pile has a third bolt threaded hole at the position corresponding to the through hole in the side wall;

[0080] After the third bolt 73 passes through a side wall through hole on the foundation 12, it is threadedly fixed to the corresponding third bolt threaded hole.

[0081] In this invention, the portion of the model pile structure located below the bottom surface of the foundation 12 is embedded in the soil layer.

[0082] In this invention, specifically, the rotten pile 4 and the plain pile 5 have the same radius of their circular cross-sections;

[0083] Each solid pile 4 has the same height as each solid pile 5, ensuring the stability of the cylindrical foundation.

[0084] In this invention, specifically, the plain pile 5 has a concave groove on the side opposite to each adjacent plain pile 4.

[0085] The shape and size of the groove correspond to and match the shape and size of the cylindrical surface of the pile 4.

[0086] In this invention, specifically, the contact surfaces of the solid pile 4 and the plain pile 5 are bonded together.

[0087] In this invention, specifically, the contact surface between the non-stick pile 4 and the plain pile 5 is a smooth surface.

[0088] It should be noted that due to the specific connection method (i.e., interlocking connection) between the solid and non-solid piles, gaps may appear between adjacent piles.

[0089] For the present invention, the roughness between the rough pile 4 and the plain pile 5 can be changed by the gap in the following ways:

[0090] 1. Sand each pile with sandpaper to make its surface (specifically, the cylindrical surface around the pile) smooth, thereby reducing the friction between the piles;

[0091] 2. Use adhesives with different bonding strengths to reinforce and connect the raw and unreinforced piles;

[0092] 3. Use the circular hoop at the bottom of the pile to fix the base plate 9, and reinforce the bottom of the foundation of the solid pile 4 and the plain pile 5.

[0093] All three methods can reduce the gap between solid and plain piles, thereby simulating the connection state of pile foundations under different conditions.

[0094] It should be noted that the circular hoop fixing plate 9 at the pile bottom includes multiple fixing plate screw holes 901, the radius of which is the same as the number and radius of the screw holes at the bottom of the solid pile and plain pile (i.e., the screw holes at the bottom of the model pile).

[0095] In this invention, specifically, the cross-sectional shape and size of the circular hoop fixing base plate 9 at the pile bottom are the same as the cross-sectional shape and size of the model pile structure.

[0096] It should be noted that the circular hoop fixing plate 9 at the bottom of the pile is consistent with the overall cross section of the arranged model pile structure. The cylindrical foundation is reinforced by the lower screw hole of the model pile structure (i.e., the lower screw hole of the model pile) and the second bolt 72, which ensures that there is no deformation or displacement between the solid pile and the plain pile, thereby further reducing the gap between the pile foundations.

[0097] In this invention, the model piles (pile 4 and plain pile 5) in the experimental device (i.e., experimental model) of this invention can be derived using formulas based on the principle of similarity (geometric similarity, load similarity, and physical similarity), thereby determining the consistency between the load application position and the relative stiffness of the materials of the model piles (pile 4 and plain pile 5) in the experimental device (i.e., experimental model) of this invention and the actual engineering device.

[0098] In specific implementation, the consistency between the size of the model piles (sturdy pile 4 and plain pile 5) in the experimental device (i.e., experimental model) of the present invention and the actual engineering device is determined by using the geometric similarity principle formula.

[0099] The model piles (sturdy pile 4 and plain pile 5) in the experimental apparatus (i.e., experimental model) of the present invention satisfy the geometric similarity principle formula, which is as follows:

[0100]

[0101] In formula (1), l, b, and h are the linear dimensions of the structure in the length, width, and height directions, respectively;

[0102] m and p represent the experimental model (i.e., the experimental device of this invention) and the prototype (i.e., the actual engineering device), respectively;

[0103] l m b m h m These are the linear dimensions of the model piles (stub pile 4 or plain pile 5) in the experimental model (i.e., the experimental device of this invention) in the three directions of length, width, and height. The length is obtained by measuring tape and kept approximately the same as the prototype (i.e. the actual engineering device) to ensure the scientific rigor of the experiment.

[0104] l p b p h p These are the linear dimensions of the raw or plain pile in the prototype (i.e., the actual engineering device) in the three directions of length, width, and height, enlarged according to the same scale model as the experimental model (e.g., 1:40 scale).

[0105] S l It is a geometric similarity constant.

[0106] In specific implementation, the load application positions of the model piles (plain piles 4 and plain piles 5) in the experimental device (i.e., experimental model) of the present invention are determined to be consistent with those of the actual engineering device by using the load similarity principle formula.

[0107] The so-called load application location refers to the location where various loads are applied to the prototype under extreme conditions. In the experiment, since the load is often applied to the upper region of tower 1, the load application location is usually the upper region of tower 1.

[0108] The model piles (plain pile 4 and solid pile 5) in the experimental apparatus (i.e., experimental model) of this invention satisfy the load similarity principle formula, which is as follows:

[0109]

[0110] In formula (2), m and p represent the experimental model (i.e., the experimental device of the present invention) and the prototype (i.e., the actual engineering device), respectively;

[0111] P, A, and σ represent the load, cross-sectional area, and stress, respectively.

[0112] Sσ It is the stress similarity constant. Stress refers to the reaction or deformation of an object after being subjected to force. The stress similarity constant means that the stress at each corresponding point in the prototype and the model is proportional in time. The magnitude of the stress is obtained by installing sensors on the experimental model.

[0113] S l 2 It is the area similarity constant, which is the area of ​​the load being applied. Its size is obtained through measurement. The area similarity constant is the constant that is proportional to the area of ​​the experimental model being applied to the area of ​​the prototype being applied to.

[0114] S P It is the similarity constant for concentrated loads, obtained by the scale ratio between the prototype and the experimental model (specifically, the size ratio), or equal to S. σ and S l 2 The product of S is obtained by finding S. σ and S l 2 The product is obtained;

[0115] It should be noted that, through formula (2), the load direction of the experimental device (i.e., experimental model) of the present invention can be made consistent with that of the prototype (i.e., actual engineering device), and the magnitudes are proportional.

[0116] In specific implementation, the material relative stiffness of the model piles (plain pile 4 and plain pile 5) in the experimental device (i.e., experimental model) of the present invention is determined by the physical similarity principle formula, and the consistency with the actual engineering device is achieved.

[0117] The model piles (sturdy pile 4 and plain pile 5) in the experimental apparatus (i.e., experimental model) of this invention satisfy the physical similarity principle formula, which is as follows:

[0118]

[0119] By using the above formulas (3) to (5), the relative stiffness of the drilled interlocking pile tube foundation (i.e., experimental model) provided by the present invention can be kept consistent with that of the pile foundation of the actual engineering device (i.e., prototype).

[0120] In formulas (3) to (5), S σ S E S ε S τ S G S γ S μThese are the similarity constants for normal stress, elastic modulus, normal strain, shear stress, shear modulus, shear strain, and Poisson's ratio, respectively.

[0121] Among them, the so-called normal stress is the stress component perpendicular to the cross section;

[0122] Elastic modulus is the stress divided by the strain in a uniaxial stress state.

[0123] Normal strain is the ratio of the increase in length of a small line segment due to deformation in a certain direction (positive when elongated) to the original length.

[0124] Shear stress is the shear force per unit area, and the direction of the force is orthogonal to the normal direction of the surface on which the force is applied.

[0125] Shear modulus is a material constant, which is the ratio of shear stress to strain.

[0126] Shear strain is the degree of deformation at various points within an object when it is subjected to force and deforms.

[0127] Poisson's ratio is the ratio of transverse normal strain to axial normal strain of a material under uniaxial tension or compression.

[0128] It should be noted that physical similarity means that the relationship between stress and strain, stiffness and deformation is similar between the experimental device (i.e., experimental model) and the prototype (i.e., actual engineering device).

[0129] Where σ in formula (3) m σ p E m E p ε m ε p These represent model stress, prototype stress, model elastic modulus, prototype elastic modulus, model normal strain, and prototype normal strain, respectively.

[0130] τ in formula (4) m τ p G m G p γ m γ p These represent the model shear stress, prototype shear stress, model shear modulus, prototype shear modulus, model shear strain, and prototype shear strain, respectively.

[0131] μ in formula (5) m μ p These represent the model Poisson's ratio and the prototype Poisson's ratio, respectively.

[0132] All the parameters mentioned above are used in the above formula. Normal stress, normal strain, shear stress, and shear strain are obtained by sensors installed on the experimental model. Elastic modulus, shear modulus, and Poisson's ratio are input according to the corresponding data of the material used in the experiment (these parameters are fixed constants and do not need to be measured).

[0133] In summary, for this invention, by applying the principles of geometric similarity, load similarity, and physical similarity, and referring to the relative stiffness of solid and plain piles in actual engineering, after multiple experiments, aluminum alloy solid piles and acrylic plain piles were determined as the cylindrical foundation materials for the indoor model experiment of bearing capacity. This ensures that the drilled interlocking pile cylindrical foundation (i.e., the experimental device of this invention) and the actual engineering device are consistent in terms of the relative stiffness of the pile foundation.

[0134] To better understand the technical solution of the present invention, the working principle of the present invention is explained below.

[0135] In this invention, by completing the assembly of the drilled interlocking pile tube foundation (i.e., the experimental device of this invention), and then conducting experiments on the drilled interlocking pile tube foundation under different working conditions, by changing the friction between the piles, the state between different pile foundations is simulated, and the problem 1 mentioned in the background section is further solved.

[0136] In addition, based on the actual engineering device, pile foundation materials suitable for indoor experiments were selected through similarity theory, so that the relative stiffness between the solid pile 4 and the plain pile 5 was consistent with the engineering device, further solving problem 2 mentioned in the background technology section;

[0137] In addition, the connection between the tower 1 and the foundation 12 is completed by embedding the anchor cage 8 into the foundation 12 and the anchor plate 6 on the top of the foundation, ensuring the same force transmission path as in the actual project: tower - anchor - foundation bottom - foundation - pile foundation - soil, further solving problem 3 mentioned in the background section.

[0138] The assembly process of the indoor model experimental device for bearing capacity of bored interlocking pile tube foundation provided by the present invention includes the following steps:

[0139] Step S1, as follows Figure 1 , Figure 2 and Figure 7 As shown, the anchor cage 8 is connected to the top anchor plate 6 of the foundation through the upper screw hole 2 and the anchor bolt 81 (i.e., the foundation fixing bolt) to fix the tower 1 and the foundation 12.

[0140] Step S2, as shown in Figure 3. Figure 5 and Figure 6As shown, the rough pile 4 and plain pile 5 are alternately inserted into the screw hole 3 on the outer edge of the foundation. Then, the first bolt 71 is rotated to fix the rough pile 4 and plain pile 5 to the foundation 12, thereby completing the assembly of the indoor model of the bearing capacity of the drilled interlocking pile tube foundation (i.e., the experimental device of the present invention).

[0141] It should be noted that, given that an unavoidable gap is formed between the solid pile 4 and the plain pile 5 in actual engineering, and the existing simplified cylindrical foundation model experimental device does not take this gap problem into account, the present invention solves the gap problem by using a drilled interlocking pile cylindrical foundation indoor experimental device.

[0142] In practice, during the assembly process, the roughness between the piles (i.e., the rough pile 4 and the plain pile 5) is changed by at least one of the following methods, thereby reducing the gap between the rough pile 4 and the plain pile 5:

[0143] Method 1: After completing step S1, sand each of the inner pile 4 and the outer pile 5 with sandpaper to make its surface smooth. Use the sanded inner pile 4 and the outer pile 5 to complete step S2, thereby reducing the internal friction between the inner pile 4 and the outer pile 5, thus narrowing the gap between the pile foundations and strengthening the connection between the inner pile 4 and the outer pile 5.

[0144] Method 2: After completing step S1, perform the following operations:

[0145] Step S11: When inserting the first pile 4 into the foundation 12, apply a layer of hot melt adhesive coating to the left and right sides of the circumferential cylindrical surface (i.e. arc surface) of the first pile 4 using a hot melt gun.

[0146] Step S12: Immediately insert two adjacent plain stakes 5 on both sides of the first solid stake 4;

[0147] Step S13: Apply hot melt adhesive coating to the grooved parts (i.e. the outer side of the recess) on the sides of the two plain stakes 5.

[0148] Step S14: Repeat steps S11 to S13 and alternate the remaining raw piles 4 and plain piles 5 in sequence, and reduce the gap between raw piles 4 and plain piles 5 (i.e. the gap of the drilled interlocking pile tube foundation) by using the adhesive force of hot melt adhesive.

[0149] Therefore, after step S14, once the hot melt adhesive has cooled, the bare pile 4 and the solid pile 5 can be connected to the foundation 12 of the foundation using the first bolt 71, the second bolt 72, and the screw hole 3 on the outer edge of the foundation.

[0150] In this invention, to ensure the scientific nature of the experiment, various hot melt adhesives with different bonding strengths can be used to connect the piles, and indoor tensile and compressive strength tests can be repeatedly conducted, with each working condition recorded.

[0151] Method 3: After steps S1 and S2, the following steps are also included:

[0152] Step S3, according to Figure 3, Figure 8 As shown, the second bolt 72 connects the bottom circular hoop fixing plate 9 to the bolt holes at the bottom of the model piles 4 and 5, thereby achieving a fixed connection and reinforcing the bottom of the experimental device (i.e., the drilled interlocking pile tube foundation) of the present invention, reducing the gap between the pile foundation (specifically, the pile 4 and the pile 5).

[0153] Through the above three working conditions (i.e. three methods), the present invention simulates the adjacent pile connection state of the drilled interlocking pile tube foundation under various conditions. By changing the friction between the solid pile 4 and the plain pile 5, the gap between the piles is reduced, thus solving the problem 1 mentioned in the background section.

[0154] In this invention, specifically, the material of the pile 4 is preferably aluminum alloy;

[0155] The preferred material for the plain pile 5 is acrylic.

[0156] It should be noted that, for this invention, in order to ensure the consistency between indoor experiments and actual engineering, the principles of geometric similarity, load similarity, and physical similarity were used to conduct repeated experiments on pile foundations made of various materials with different stiffnesses, such as aluminum alloy, acrylic, wood, and plastic. After multiple experimental screenings, the experiments finally determined that the aluminum alloy pile 4 and the acrylic pile 5 were the best materials. This ensures that the indoor model experimental device for the bearing capacity of the interlocking pile cylindrical foundation provided by this invention is consistent with the actual engineering device in terms of relative stiffness, thus solving the stiffness problem of the simplified cylindrical experimental device, which solves problem 2 mentioned in the background section.

[0157] After addressing the problems under the background conditions, based on the indoor model test device for the bearing capacity of bored interlocking pile cylindrical foundations provided by the present invention, the present invention also provides an implementation method for the indoor model test device for the bearing capacity of bored interlocking pile cylindrical foundations, which includes the following steps for conducting indoor model tests on bearing capacity:

[0158] The first step is to vertically place the indoor model test device for bearing capacity of the drilled interlocking pile tube foundation in the soil test box with the top opening, and bury the part of the model pile structure below the bottom surface of the foundation 12 into the soil layer in the soil test box, and then compact the soil layer.

[0159] It should be noted that, in this invention, the indoor model test device for bearing capacity of the drilled interlocking pile tube foundation placed in the first step needs to satisfy the above formulas (1) to (5).

[0160] In the first step, specifically, the soil in the soil test chamber is used to simulate the soil structure in a real onshore wind farm. It is the same soil as the soil structure in a real onshore wind farm in terms of mechanical properties and foundation bearing characteristics, so as to better understand the interaction between the soil and the experimental device.

[0161] It should be noted that, for this invention, the soil volume is removed according to the corresponding dimensions of the cylindrical foundation (i.e., the experimental device of this invention), and some soil is added into the cylindrical foundation. Then, a crane is used to place the drilled interlocking pile cylindrical foundation (i.e., the experimental device of this invention) into the soil test box. The inclination of the foundation is manually adjusted, and the angles in the x and y directions of the horizontal coordinate system are controlled within 0.2°. The removed soil is then placed back into the test box and compacted.

[0162] The second step is to fill the soil test chamber with water. When water seeps out from the top soil layer of the soil test chamber, stop adding water and allow it to cure for 24 hours.

[0163] It should be noted that, for this invention, after the first step, a water pipe can be connected to the soil test chamber to release water. When a small amount of water seeps out from the top soil layer of the soil test chamber, the water should be stopped and the chamber should be cured for 24 hours.

[0164] The third step is to conduct loading tests on vertical and horizontal loads after the curing is completed.

[0165] It should be noted that, based on the above Figures 1 to 2 , Figures 3a to 3b as well as Figures 4 to 8 The experimental apparatus of the present invention shown can be used to perform existing and well-known vertical compressive loading experiments (vertical bearing capacity loading experiments, i.e., vertical load loading experiments) and horizontal bearing capacity loading experiments (i.e., horizontal load loading experiments).

[0166] It should be noted that before conducting the vertical compressive loading test, all equipment and instruments must be correctly connected, and the functionality of all sensors and data acquisition instruments must be checked. The load is applied via the hydraulic system, and the earth pressure sensor readings are observed using a data acquisition instrument. Once the earth pressure sensor on the top cover registers a reading, sampling and loading begin, while maintaining the entire structure horizontal. Loading is stopped and real-time data is recorded after the load reaches the ultimate bearing capacity or the maximum bearing capacity of the reaction beam.

[0167] It should be noted that after the vertical bearing capacity loading test is completed, a horizontal bearing capacity loading test is performed. The instrument checks for the vertical loading test are repeated. The horizontal force transmission rod is fixed to the model, and the drilled interlocking pile cylindrical foundation is vertically inserted into the soil. When the reading of the soil pressure sensor on the pile cap changes, preparations for horizontal loading can begin. The soil pressure sensor on the cylinder wall and the horizontal force-applying hydraulic system should be kept in the same direction, with the hydraulic cylinder pressing against the pressure sensor. During loading, both should be kept in place to prevent misalignment. The changes in soil pressure on the pile cap are observed. Once the pile cap and soil contact stabilize, horizontal loading begins, and sampling is performed simultaneously. When the displacement of the model cylinder changes rapidly (tilt angle around 6°), loading and sampling are stopped.

[0168] The equipment and methods used in the above-mentioned vertical compressive loading test (vertical bearing capacity loading test) and horizontal bearing capacity loading test are all existing, mature, and well-known technologies, and will not be elaborated further here.

[0169] In practice, to ensure the scientific rigor of the experiment, multiple sets of experiments must be completed. By changing the forces of the vertical and horizontal loads and the height of the loading point, the active and passive earth pressure patterns on the inner and outer sides of the cylinder wall are measured, thus realizing foundation loading experiments under different load combinations.

[0170] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An indoor model experimental device for the bearing capacity of drilled interlocking pile tube foundations, characterized in that, Including pile cap foundation (12); An anchor cage (8) is embedded in the center of the foundation (12); At the center of the anchor cage (8), a vertically distributed tower tube (1) is provided; The bottom edges of the foundation (12) are connected to the top of the surrounding model pile structure; The model pile structure includes multiple model piles; Multiple model piles, including multiple solid piles (4) and multiple plain piles (5), with solid piles (4) and plain piles (5) alternating and interlocking with each other; The bottom of the model pile structure is fixedly connected to the pile bottom circular hoop fixing base plate (9); Among them, the anchor cage (8) includes the anchor cage body (80) distributed around it; The top of the anchor cage body (80) is provided with a top anchor plate (6); On the main body (80) of the anchor cage, there are multiple vertically arranged anchor bolts (81) evenly distributed along the circumference; The anchor cage body (80) is connected to the top anchor plate (6) of the foundation and the foundation foundation (12) of the foundation via anchor bolts (81); The foundation (12) is fixedly connected to the top of the model pile by multiple first bolts (71); On the foundation (12), there are multiple vertically penetrating screw holes (3) evenly distributed along the circumference; A model pile is set directly below each of the screw holes (3) on the outer edge of the pile cap; Each model pile has a screw hole (10) at the top center of its top; The bolt holes (10) on the upper part of the model pile are set in direct correspondence with the bolt holes (3) on the outer edge of the pile cap; After the first bolt (71) passes through the outer edge screw hole (3) on the foundation (12) from top to bottom, it is threadedly fixed to the upper screw hole (10) of the model pile corresponding to the position. The model pile structure is fixedly connected to the pile bottom circular hoop fixing plate (9) by multiple second bolts (72); At the center of the bottom end of each model pile, there is a screw hole at the bottom of the model pile; The circular hoop fixing base plate (9) at the bottom of the pile is provided with a fixing base plate screw hole (901) at the position corresponding to the screw hole at the bottom of each model pile; After the second bolt (72) passes through the screw hole (901) of the fixed base plate from bottom to top, it is threadedly fixed to the screw hole at the bottom of the model pile corresponding to the position. The model pile structure is fixedly connected to the lower four sides of the foundation (12) by multiple third bolts (73); The lower part of the foundation cap (12) has a downward-opening groove for mounting model piles; The top of the model pile is located in the model pile installation groove and is set directly corresponding to the screw hole (3) on the outer edge of the foundation (12); The foundation (12) has multiple side wall through holes that are connected to the model pile installation groove evenly arranged around the model pile installation groove. Each model pile has a third bolt threaded hole at the position corresponding to the through hole in the side wall; After the third bolt (73) passes through a side wall through hole on the foundation (12), it is threadedly fixed to the corresponding third bolt threaded hole; The radii of the circular cross sections of the meat pile (4) and the plain pile (5) are the same; Each meat-filled stake (4) is the same height as each vegetarian stake (5); On the side opposite to each adjacent solid pile (4), the plain pile (5) is provided with a concave groove; The shape and size of the groove correspond to and match the shape and size of the cylindrical surface of the pile (4); The contact surfaces between the meat pile (4) and the plain pile (5) are bonded together, or the contact surfaces between the meat pile (4) and the plain pile (5) are smooth surfaces; The cross-sectional shape and size of the circular hoop fixing base plate (9) at the bottom of the pile are the same as the cross-sectional shape and size of the model pile structure; The material of the meat pile (4) is aluminum alloy; The material of the plain pile (5) is acrylic.

2. The indoor model experimental device for bearing capacity of drilled interlocking pile tube foundation as described in claim 1, characterized in that, The anchor plate (6) at the top of the pier cap is provided with a screw hole (2) at the top of the pier cap at the position corresponding to each anchor bolt (81); At the lower end of the foundation (12), a foundation through hole is provided at the position corresponding to each anchor bolt (81); The upper and lower ends of the anchor bolt (81) are threadedly connected to a fastening nut (82) after passing through the upper screw hole (2) of the bearing platform and the through hole of the bearing platform foundation.

3. The indoor model experimental device for bearing capacity of drilled interlocking pile tube foundation as described in claim 1, characterized in that, A tower insertion hole (801) is provided at the center of the anchor cage body (80); The tower is embedded in the hole (801) at the lower end of the tower (1).

4. The indoor model experimental device for bearing capacity of drilled interlocking pile tube foundation as described in claim 1, characterized in that, Its assembly process includes the following steps: Step S1: Connect the anchor cage (8) to the top anchor plate (6) of the foundation through the upper screw hole (2) and the anchor (81); In step S2, the rough pile (4) and plain pile (5) are alternately inserted into the screw hole (3) on the outer edge of the foundation, and then the first bolt (71) is rotated to fix the rough pile (4) and plain pile (5) to the foundation (12).

5. The indoor model experimental device for bearing capacity of drilled interlocking pile tube foundation as described in claim 4, characterized in that, During the assembly process, the roughness between the rough stake (4) and the plain stake (5) is changed by at least one of the following methods, thereby reducing the gap between the rough stake (4) and the plain stake (5): Method 1: After completing step S1, each of the rough piles (4) and plain piles (5) is sanded with sandpaper to make their surfaces smooth. The sanded rough piles (4) and plain piles (5) are then used to complete step S2, thereby reducing the internal friction between the rough piles (4) and plain piles (5), thus narrowing the gap between the pile foundations and strengthening the connection between the rough piles (4) and plain piles (5). Method 2: After completing step S1, perform the following operations: Step S11: When inserting the first pile (4) into the foundation (12), apply a layer of hot melt adhesive coating to the left and right sides of the circumferential cylindrical surface of the first pile (4) using a hot melt gun. Step S12: Immediately insert two adjacent plain stakes (5) on both sides of the first plain stake (4); Step S13: Apply hot melt adhesive coating to the grooved parts on the sides of the two plain stakes (5); Step S14: Repeat steps S11 to S13 and alternate the remaining raw stakes (4) and plain stakes (5) in sequence to reduce the gap between the raw stakes (4) and plain stakes (5) by the adhesive force of hot melt adhesive. Method 3: After steps S1 and S2, the following steps are also included: In step S3, the bottom circular hoop fixing plate (9) is connected to the lower screw hole of the model pile at the bottom of the solid pile (4) and the plain pile (5) by the second bolt (72), thereby achieving a fixed connection and reinforcing the bottom of the experimental device, reducing the gap between the solid pile (4) and the plain pile (5).

6. A method for implementing an indoor model experimental device for the bearing capacity of drilled interlocking pile cylindrical foundations as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The first step is to vertically place the borehole interlocking pile tube foundation bearing capacity indoor model test device in the soil test box with the top opening, and bury the part of the model pile structure below the bottom surface of the foundation (12) into the soil layer in the soil test box, and compact the soil layer. The second step is to fill the soil test chamber with water. When water seeps out from the top soil layer of the soil test chamber, stop adding water and allow it to cure for 24 hours. The third step is to conduct loading tests on vertical and horizontal loads after the curing is completed.

7. The implementation method of the indoor model test device for the bearing capacity of drilled interlocking pile cylindrical foundation as described in claim 6, characterized in that, The consistency between the dimensions of the model piles in the experimental setup and the actual engineering setup was determined using the formula based on the principle of geometric similarity. The model satisfies the geometric similarity principle formula, which is as follows: In formula (1), m and p represent the experimental device and the prototype, respectively. The experimental device is the experimental model, and the prototype is the actual engineering device. l m b m h m These are the linear dimensions of the model pile in the experimental setup, representing the length, width, and height in three directions. l p b p h p These are the linear dimensions of the prototype's stub or blank stub in the three directions of length, width, and height. S l It is a geometric similarity constant; And / or, By using the load similarity principle formula, the consistency between the load application position of the model pile in the experimental device and the actual engineering device was determined. The model piles in the experimental setup satisfy the load similarity principle formula, which is as follows: In formula (2), m and p represent the experimental model and the prototype, respectively; P, A, and σ represent the load, cross-sectional area, and stress, respectively. S σ It is the stress similarity constant, meaning that the stress at corresponding points in the prototype and the model is instantaneously proportional in time. S l 2 It is the area similarity constant, which is the constant that represents the ratio between the force-bearing area of ​​the experimental model and the force-bearing area of ​​the prototype. S P It is the similarity constant for concentrated loads, equal to S. σ and S l 2 The product of S is obtained by finding S. σ and S l 2 The product is obtained; And / or, The relative stiffness of the model pile in the experimental setup was determined using the formula based on the principle of physical similarity, ensuring its consistency with the actual engineering setup. The model piles in the experimental setup satisfy the physical similarity principle formula, which is as follows: In formulas (3) to (5), S σ S E S ε S τ S G S γ S μ These are the similarity constants for normal stress, elastic modulus, normal strain, shear stress, shear modulus, shear strain, and Poisson's ratio, respectively.

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