Indoor model experiment device for bearing capacity of tubular foundation of bored secant pile and implementation method

Abstract

The invention discloses a drilling secant pile cylindrical foundation bearing capacity indoor model experiment device and an implementation method. The experiment device comprises a bearing platform foundation; an anchor bolt cage is embedded in the center position of the bearing platform foundation; a tower drum is arranged in the center of the anchor bolt cage; the peripheral edge of the bottom of the bearing platform foundation is connected with the top of the model pile structure; the model pile structure comprises a plurality of model piles; the plurality of model piles comprise a plurality of meat piles and plain piles, and the meat piles and the plain piles are alternately distributed and engaged with each other; the bottom of the model pile structure is fixedly connected with the pile bottom circular hoop fixing bottom plate; the anchor bolt cage comprises an anchor bolt cage main body; a bearing platform top anchor plate is arranged at the top of the anchor bolt cage body; a plurality of anchor bolts are distributed on the anchor bolt cage main body; the anchor bolt cage body is connected with a bearing platform top anchor plate and a bearing platform foundation through anchor bolts. According to the invention, the connection state between different pile foundations is simulated by changing the roughness (friction force) between the reinforced piles and the plain piles; and an anchor bolt is arranged in the middle of the bearing platform foundation to check the force transmission path of the real cylindrical foundation.

Description

Technical Field

[0001] The invention relates to the technical field of onshore wind power, and in particular to an indoor model test device for bearing capacity of a bored interlocking pile barrel foundation and an implementation method thereof. Background Art

[0002] There are various types of onshore wind power foundation structures. The barrel foundation is the main foundation type in the wind power field in recent years. Among them, the bored interlocking pile barrel foundation is a new type of barrel foundation with a simple structure, small footprint, high bearing capacity, and strong anti-overturning ability, which can meet the requirements of large wind turbines.

[0003] At present, simplified cylindrical foundation model experimental devices are often used in simple indoor experimental models. However, in actual experiments, it is found that the multi-dimensional loads on the existing simplified cylindrical foundation model experimental devices are different from the loads on the actual engineering devices. After repeated experiments, it is found that the existing simplified cylindrical foundation model experimental devices have the following problems:

[0004] Problem 1: There are differences between the pile foundation of the simplified cylindrical experimental device and the pile foundation of the actual project. There are non-negligible cold joints between the pile foundations in the actual project device. 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 the skirt piles does not conform to 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 difference in stiffness between the piles with steel bars (cooked piles) and the plain concrete piles (plain piles) in the cylindrical skirt of the actual engineering device. This makes the simplified cylindrical foundation model experimental device inconsistent with the actual engineering device in stiffness, which lacks rigor.

[0006] Question 3: In the simplified cylindrical foundation model, the bottom of the loading tower is directly rigidly connected to the top of the foundation, ignoring the existence of the anchor cage in the actual project, so that its transfer path is tower-cap top-cap-cap bottom-pile foundation-soil; while in the actual engineering device, the anchor cage runs through the top and bottom of the cap, and its actual transfer path is tower-anchor-cap bottom-cap-pile foundation-soil; the difference in load transfer path between the simplified cylindrical foundation model and the actual engineering device causes distortion in the model test results.

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

[0008] The purpose of the present invention is to provide a bored interlocking pile cylindrical foundation bearing capacity indoor model test device and implementation method in view of the technical defects existing in the prior art.

[0009] To this end, the present invention provides a bored interlocking pile barrel foundation bearing capacity indoor model experimental device and implementation method, which includes a cap foundation;

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

[0011] A vertically distributed tower is provided at the center of the anchor cage so as to protrude upward;

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

[0013] The model pile structure includes a plurality of model piles;

[0014] A plurality of model piles, including a plurality of meat piles and a plurality of plain piles, wherein the meat piles and the plain piles are alternately distributed and interlocked with each other;

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

[0016] Wherein, the anchor cage comprises an anchor cage body which is distributed around;

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

[0018] On the anchor bolt cage body, a plurality of vertically arranged anchor bolts are evenly distributed along the circumference;

[0019] The anchor cage body is connected to the anchor plate at the top of the cap and the cap foundation through anchor bolts.

[0020] In addition, the present invention also provides an implementation method of the aforementioned bored interlocking pile cylindrical foundation bearing capacity indoor model test device, comprising the following steps:

[0021] The first step is to vertically place the bored interlocking pile cylindrical foundation bearing capacity indoor model test device in a soil test box with an opening at the top, bury the part of the model pile structure below the bottom surface of the cap foundation into the soil layer in the soil test box, and compact the soil layer;

[0022] The second step is to add water to the soil test box. When water seeps out from the top soil layer of the soil test box, stop adding water and maintain it for 24 hours.

[0023] The third step is to carry out loading tests of vertical and horizontal loads after the maintenance is completed.

[0024] It can be seen from the technical solution provided by the present invention that, 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 foundation, which is scientifically designed. The experimental device provided by the present invention can truly simulate the adhesion and friction between bored interlocking piles (i.e., meat piles and plain piles), and has great practical significance.

[0025] In addition, the present invention can also truly simulate the relative stiffness of meat piles and plain piles in actual engineering projects. Through the principle of model similarity, the overall size of the model can be reduced, and the size and direction of the model load and stiffness can be kept similar, so that it is easy to place it indoors and conduct indoor experiments on bored interlocking pile barrel foundations. It is beneficial to verify the actual force transmission path of the model experiment by loading multiple loads, which has great practical significance.

[0026] In addition, the present invention simulates the connection state between different pile foundations by changing the roughness (i.e., friction) between the raw piles and the plain piles; at the same time, through the theory of model similarity principle, it is determined that the relative stiffness between the raw piles and the plain piles is consistent with the stiffness of the pile foundation in actual engineering; in addition, the present invention also verifies the force transmission path of the actual barrel foundation by setting anchor bolts (i.e., pedestal fixing bolts) in the middle of the pedestal foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a cross-sectional view of an indoor model test device for bearing capacity of a bored interlocking pile barrel foundation provided by the present invention;

[0028] Figure 2 It is a front view of an indoor model test device for bearing capacity of a bored interlocking pile barrel type foundation provided by the present invention;

[0029] Figure 3a It is a bottom side view of the indoor model experimental device for bearing capacity of bored interlocking pile barrel type foundation provided by the present invention;

[0030] Figure 3b It is an upper side view of an indoor model test device for bearing capacity of a bored interlocking pile barrel type foundation provided by the present invention;

[0031] Figure 4 It is a top view of the indoor model experimental device for the bearing capacity of the bored interlocking pile barrel type foundation provided by the present invention;

[0032] Figure 5 It is a schematic diagram of the stiffness of the raw pile and the plain pile in the indoor model experimental device for the bearing capacity of the bored interlocking pile barrel foundation provided by the present invention;

[0033] Figure 6 It is a schematic diagram of the connection gap between the raw pile and the plain pile in the indoor model experimental device for the bearing capacity of the bored interlocking pile barrel type foundation provided by the present invention;

[0034] Figure 7 It is a schematic diagram of a cap foundation anchor bolt cage in an indoor model test device for bearing capacity of a bored interlocking pile barrel type foundation provided by the present invention;

[0035] Figure 8It is a schematic diagram of a bottom plate fixed by a circular hoop at the bottom of a pile in an indoor model test device for bearing capacity of a bored interlocking pile barrel type foundation provided by the present invention;

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

[0037] 6-anchor plate at the top of the cap; 71-first bolt; 72-second bolt; 73-third bolt;

[0038] 8-anchor cage; 80-anchor cage body; 81-anchor bolt (i.e., cap fixing bolt), 82-fastening nut; 801-tower embedding hole;

[0039] 9-round hoop at the bottom of the pile to fix the bottom plate; 901-screw hole for fixing the bottom plate; 10-screw hole on the upper part of the model pile;

[0040] 12-Plinth foundation. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0043] In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, it can be fixedly connected or set, or it can be detachably connected or set, or connected or set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0044] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0045] See also Figure 1 to Figure 2 , Figure 3a to Figure 3b , Figures 4 to 8 The present invention provides a borehole interlocking pile barrel type foundation bearing capacity indoor model experimental device, which is a borehole interlocking pile barrel type foundation device suitable for onshore wind power, and involves the field of tensile and compressive tests after entering the soil, and includes: a cap foundation 12;

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

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

[0048] The bottom edges of the cap 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 a plurality of model piles;

[0050] A plurality of model piles, including a plurality of meat piles 4 and a plurality of plain piles 5, wherein the meat piles 4 and the plain piles 5 are alternately distributed and interlocked with each other;

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

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

[0053] Among them, see also Figure 7 As shown, the anchor cage 8 comprises an anchor cage body 80 distributed around;

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

[0055] On the anchor bolt cage body 80, a plurality of vertically arranged anchor bolts 81 are evenly distributed along the circumference;

[0056] The anchor bolt cage body 80 is connected to the anchor plate 6 at the top of the cap and the cap foundation 12 through the anchor bolts 81 .

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

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

[0059] The upper and lower ends of the anchor bolt 81 are respectively threadedly fixedly connected with a fastening nut 82 after passing through the upper screw hole 2 of the pedestal and the through hole of the pedestal base.

[0060] In a specific implementation, the anchor cage body 80 is a body formed by pouring concrete.

[0061] It should be noted that, for the present invention, the anchor cage 8 ensures that the experimental device has a correct force transmission path, specifically: tower 1-anchor 81-base bottom (i.e., the bottom of the base foundation 12)-base (i.e., the entire base 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 anchor plate 6 at the top of the cap through the screw hole 2 at the top of the cap, so as to connect the tower 1 and the cap foundation 12.

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

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

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

[0066] In specific implementation, on the cap foundation 12, there are multiple cap outer edge screw holes 3 vertically penetrating evenly distributed along the circumference;

[0067] A model pile is provided just below the screw hole 3 on the outer edge of each cap;

[0068] A model pile upper screw hole 10 is provided at the top center of each model pile;

[0069] The screw hole 10 on the upper part of the model pile is arranged correspondingly to the screw hole 3 on the outer edge of the cap;

[0070] The first bolt 71 passes through the outer screw hole 3 of the cap foundation 12 from top to bottom, and is threadedly fixedly connected with the upper screw hole 10 of the model pile at the corresponding position.

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

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

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

[0074] After the second bolt 72 passes through the screw hole 901 of the fixing base plate from bottom to top, it is threadedly fixedly connected with the screw hole at the lower part of the model pile at the corresponding position.

[0075] In the present invention, the specific implementation is as follows: Figure 1 , Figure 2 , Figure 3a to Figure 3b As shown, the model pile structure is fixedly connected to the lower four side walls of the cap foundation 12 by a plurality of third bolts 73;

[0076] The lower part of the cap foundation 12 has a model pile installation groove (circular in cross section) opening downward;

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

[0078] The cap foundation 12 is evenly provided with a plurality of side wall through holes connected to the model pile installation groove around the model pile installation groove;

[0079] Each model pile is provided with a third bolt butt-jointed threaded hole at a 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 cap foundation 12, it is threadedly fixedly connected with the third bolt threaded hole at the corresponding position.

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

[0082] In the present invention, in a specific implementation, the meat pile 4 and the plain pile 5 have the same radius of the circular cross section;

[0083] The height of each meat pile 4 is the same as that of each plain pile 5, ensuring the stability of the barrel foundation.

[0084] In the present invention, in a specific implementation, the plain pile 5 is provided with a concave groove on one side opposite to each adjacent meat pile 4;

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

[0086] In the present invention, in a specific implementation, the contact surfaces between the meat pile 4 and the plain pile 5 are bonded.

[0087] In the present invention, in a specific implementation, the contact surface between the meat pile 4 and the plain pile 5 is a smooth surface.

[0088] It should be noted that due to the specific connection method between the meat piles and the vegetarian piles (i.e., the bite connection), a gap appears between the two adjacent piles.

[0089] For the present invention, the gap can change the roughness between the meat pile 4 and the plain pile 5 in the following ways:

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

[0091] 2. Use glue with different bonding strengths to reinforce the connection between the meat piles and the plain piles;

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

[0093] The above three methods can reduce the gap between the steel piles and the plain piles, thereby simulating the connection state of the pile foundation under different conditions.

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

[0095] In the present invention, in a specific implementation, the cross-sectional shape and size of the pile bottom circular hoop fixing bottom plate 9 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 base plate 9 at the bottom of the pile is consistent with the overall cross-section of the arranged model pile structure. The lower screw hole of the model pile structure (i.e. the lower screw hole of the model pile) and the second bolt 72 are used to reinforce the cylindrical foundation, ensuring that no deformation or offset occurs between the meat pile and the plain pile, thereby further narrowing the gap between the pile foundations.

[0097] In the present invention, the model piles (meat piles 4 and plain piles 5) in the experimental device (i.e., experimental model) of the present invention can be derived through the formula of similarity principle (geometric similarity, load similarity, physical similarity), and then the load application position, relative stiffness of the material and consistency of the actual engineering device of the model piles (meat piles 4 and plain piles 5) in the experimental device (i.e., experimental model) of the present invention can be determined.

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

[0099] The model piles (the meat piles 4 and the plain piles 5) in the experimental device (i.e., the 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 length, width, and height of the structure, respectively;

[0102] 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;

[0103] l m , b m 、h m , are respectively the linear dimensions of the model pile (meat pile 4 or plain pile 5) in the experimental model (i.e. the experimental device of the present invention) in three directions of length, width and height. The length is obtained by a tape measure and is kept similar to the prototype (i.e. the actual engineering device) to ensure the scientific rigor of the experiment;

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

[0105] S l is the geometric similarity constant.

[0106] In specific implementation, the consistency between the load application position of the model piles (meat piles 4 and plain piles 5) in the experimental device (i.e., the experimental model) of the present invention and the actual engineering device is determined by the load similarity principle formula;

[0107] The so-called load application position refers to the application position of various loads of the simulated prototype under extreme conditions. In the experiment, since the load is often applied to the upper area of ​​the tower 1, the load application position is usually the upper area of ​​the tower 1;

[0108] The model piles (the meat piles 4 and the plain piles 5) in the experimental device (i.e., the experimental model) of the present 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, σ are load, cross-sectional area, and stress, respectively;

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

[0113] S l 2 is the area similarity constant, which is the force-bearing area of ​​the applied load and is obtained through measurement. The area similarity constant is the constant proportional to the force-bearing area of ​​the experimental model and the force-bearing area of ​​the prototype.

[0114] S P is the concentrated load similarity constant, which is obtained by the ratio between the prototype and the experimental model (specifically the size ratio), or is equal to S σ and S l 2 By finding S σ and S l 2 The product is obtained;

[0115] It should be noted that, by using formula (2), the load directions of the experimental device (ie, the experimental model) of the present invention and the prototype (ie, the actual engineering device) can be consistent and proportional.

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

[0117] The model piles (the meat piles 4 and the plain piles 5) in the experimental device (i.e., the experimental model) of the present 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 bored interlocking pile barrel foundation (i.e., the experimental model) provided by the present invention and the pile foundation of the actual engineering device (i.e., the prototype) can be kept consistent;

[0120] In formula (3) to formula (5), S σ , S E , S ε , S τ , S G , S γ , S μ, which are the similarity constants of 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] The elastic modulus is the stress under uniaxial stress divided by the strain in that direction;

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

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

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

[0126] Shear strain is the degree of deformation at each point in the body when an object is deformed by force;

[0127] Poisson's ratio is the ratio of the transverse normal strain to the axial normal strain when the Poisson's ratio material is subjected to unidirectional tension or compression.

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

[0129] Where σ in formula (3) m , σ p 、E m 、E p , ε m , ε p They 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 They represent 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 They represent the model Poisson's ratio and the prototype Poisson's ratio respectively.

[0132] All the above parameters are used in the above formulas. Normal stress, normal strain, shear stress and shear strain are obtained through sensors installed on the experimental model later. The elastic modulus, shear modulus and Poisson's ratio are input according to the corresponding data of the materials used in the experiment (their parameters are fixed constant properties and do not need to be measured).

[0133] In summary, for the present invention, through the principles of geometric similarity, load similarity, physical similarity and referring to the relative stiffness of raw piles and plain piles in actual engineering projects, after many experiments, it was determined that raw piles made of aluminum alloy and plain piles made of acrylic material were used as the cylindrical foundation materials for the indoor model experiment of bearing capacity, which ensured the consistency of the relative stiffness of the bored interlocking pile cylindrical foundation (i.e., the experimental device of the present invention) and the actual engineering device in the pile foundation relative stiffness.

[0134] In order to more clearly understand the technical solution of the present invention, the working principle of the present invention is explained below.

[0135] The present invention completes the assembly of the bored occlusal pile barrel foundation (i.e., the experimental device of the present invention), and then conducts different working condition experiments on the bored occlusal pile barrel foundation, and simulates the state between different pile foundations by changing the friction between the piles, thereby further solving the problem 1 mentioned in the background technology part;

[0136] In addition, according to the actual engineering device, the pile foundation material suitable for indoor experiments is selected through similarity theory, so that the relative stiffness between the meat pile 4 and the plain pile 5 is consistent with the engineering device, further solving the problem 2 mentioned in the background technology part;

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

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

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

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

[0141] It should be noted that, in view of the fact that in actual engineering, an inevitable gap is formed between the meat pile 4 and the plain pile 5, and the existing simplified cylindrical foundation model experimental device does not take this gap problem into consideration, the present invention solves the gap problem by means of a bored interlocking pile cylindrical foundation indoor experimental device.

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

[0143] Method 1: After completing step S1, each meat pile 4 and the plain pile 5 is polished by sandpaper to make the surface smooth, and the polished meat pile 4 and the plain pile 5 are used to complete step S2, thereby reducing the internal friction between the meat pile 4 and the plain pile 5, thereby reducing the gap between the pile foundations, and strengthening the connection between the meat pile 4 and the plain pile 5;

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

[0145] Step S11: When the first pile 4 is inserted into the foundation 12, a layer of hot melt adhesive coating is applied on the left and right sides of the circumferential cylindrical surface (i.e., the arc surface) of the first pile 41 by a hot melt gun;

[0146] Step S12: insert two adjacent plain stakes 5 immediately on both sides of the first meat stake 41;

[0147] Step S13: applying a hot melt adhesive coating to the groove portions (i.e., the outer sides of the depressions) on the sides of the two plain piles 5;

[0148] Step S14: Repeat the above steps S11 to S13 for the remaining meat piles 4 and plain piles 5 in sequence and arrange them alternately, and reduce the gap between the meat piles 4 and the plain piles 5 (i.e., the gap of the drilled bite pile barrel foundation) by the bonding force of the hot melt adhesive;

[0149] Therefore, after step S14, when the hot melt adhesive cools down, the meat piles 4 and the plain piles 5 can be connected to the base foundation 12 through the first bolts 71 and the second bolts 72 and the screw holes 3 on the outer edge of the base.

[0150] In the present invention, in order 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 tests are repeatedly carried out, and various working conditions are recorded.

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

[0152] Step S3, according to FIG. 3, Figure 8 As shown, the second bolt 72 is used to connect the circular hoop fixing base plate 9 at the bottom of the pile to the lower screw holes of the model pile at the bottom of the meat pile 4 and the plain pile 5, thereby achieving a fixed connection, thereby reinforcing the bottom of the experimental device of the present invention (i.e., the bored interlocking pile barrel foundation) and reducing the gap between the pile foundation (specifically, the meat pile 4 and the plain pile 5).

[0153] Through the above three working conditions (i.e., three modes), the present invention simulates the connection state of adjacent piles of the bored interlocking pile barrel foundation under various conditions, and reduces the gap between the piles by changing the friction between the meat piles 4 and the plain piles 5, thereby solving the problem 1 mentioned in the background technology part.

[0154] In the present invention, in specific implementation, the material of the meat pile 4 is preferably aluminum alloy;

[0155] The material of the pile 5 is preferably acrylic.

[0156] It should be noted that, for the present invention, in order to ensure the consistency between indoor experiments and actual projects, through the principles of geometric similarity, load similarity, and physical similarity, pile foundations of various materials with different stiffness, such as aluminum alloy, acrylic, wood, and plastic, were used for repeated experiments. After multiple experimental screenings, the experiments finally determined the meat piles 4 made of aluminum alloy and the plain piles 5 made of acrylic, so that the relative stiffness of the indoor model experimental device of the bearing capacity of the interlocking pile cylinder foundation provided by the present invention is unified with the actual engineering device, which solves the stiffness problem of the simplified cylinder experimental device, that is, solves the problem 2 mentioned in the background technology part.

[0157] After solving the problems under the background conditions, based on the borehole interlocking pile barrel type foundation bearing capacity indoor model test device provided by the present invention, the present invention also provides an implementation method of the borehole interlocking pile barrel type foundation bearing capacity indoor model test device, which includes the following steps for carrying out the bearing capacity indoor model test:

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

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

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

[0161] It should be noted that, for the present invention, the soil is removed according to the corresponding size of the cylinder foundation (i.e., the experimental device of the present invention), and part of the soil is added to the inside of the cylinder foundation. Then, a crane is used to place the bored interlocking pile cylinder foundation (i.e., the experimental device of the present invention) in the soil experimental box, and the inclination of the foundation is manually adjusted. The angles in the xy directions of the horizontal coordinate system are controlled within 0.2°. The removed soil is placed back in the experimental box, and the soil layer is compacted.

[0162] The second step is to add water to the soil test box. When water seeps out from the top soil layer of the soil test box, stop adding water and maintain it for 24 hours.

[0163] It should be noted that, for the present invention, after the first step, a water pipe can be connected to the soil test box to drain water. When a small amount of water seeps out of the top soil layer of the soil test box, stop adding water and maintain it for 24 hours.

[0164] The third step is to carry out loading tests of vertical and horizontal loads after the maintenance is completed.

[0165] It should be noted that based on the above Figure 1 to Figure 2 , Figure 3a to Figure 3b as well as Figures 4 to 8 The experimental device of the present invention shown in the figure can be used to carry out the well-known vertical compressive loading test (vertical bearing capacity loading test, i.e. vertical load loading test) and the horizontal bearing capacity loading test (i.e. horizontal load loading test) which are mature in the prior art.

[0166] It should be noted that before the vertical compressive loading test, all equipment and instruments must be correctly connected, and all sensors and acquisition instruments must be checked for normal operation. The load is applied through the hydraulic system, and the reading of the soil pressure sensor is observed through the data acquisition instrument. After the top cover soil pressure sensor has a reading, sampling and loading are started, and the entire structure is kept horizontal. After loading to the ultimate bearing capacity or the maximum bearing capacity of the reaction beam, stop loading and record real-time data.

[0167] Among them, it should be noted that after the vertical bearing capacity loading test is completed, the horizontal bearing capacity loading test is carried out, the vertical loading test instrument inspection work is repeated, the horizontal force transmission vertical rod is fixed on the model, and the bored interlocking pile barrel foundation is vertically inserted into the soil. When the reading of the soil pressure sensor on the cap changes, the horizontal loading can be prepared, and the barrel wall soil pressure sensor and the horizontal force hydraulic system are kept in the same direction, and the hydraulic cylinder is just against the pressure sensor. During the loading process, keep the two from shifting. Observe the change of the cap soil pressure, and start horizontal loading and sampling when the contact between the cap and the soil is stable. When the displacement of the model barrel changes rapidly (the inclination angle is about 6°), stop loading and sampling.

[0168] The above-mentioned vertical compressive loading test (vertical bearing capacity loading test) and the implementation equipment and method of the horizontal bearing capacity loading test are mature and well-known knowledge in the prior art and will not be elaborated here.

[0169] In terms of specific implementation, in order to ensure the scientific nature of the experiment, multiple groups of experiments must be completed. By changing the vertical and horizontal load forces and the height of the loading point, the active and passive earth pressure laws on the inside and outside of the cylinder wall can be measured to realize foundation loading experiments under different load combinations.

[0170] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Indoor model test device and implementation method for bearing capacity of bored interlocking pile barrel foundation, characterized in that: Including the cap foundation (12); An anchor cage (8) is embedded in the center of the cap foundation (12); A vertically distributed tower (1) is provided at the center of the anchor cage (8) so as to protrude upward; The bottom edges of the cap foundation (12) are connected to the tops of the surrounding model pile structures; The model pile structure includes a plurality of model piles; A plurality of model piles, including a plurality of meat piles (4) and a plurality of plain piles (5), wherein the meat piles (4) and the plain piles (5) are alternately distributed and interlocked; The bottom of the model pile structure is fixedly connected to the pile bottom circular hoop fixing bottom plate (9); Wherein, the anchor cage (8) comprises an anchor cage body (80) distributed around; The top of the anchor cage body (80) is provided with a cap top anchor plate (6); A plurality of vertically arranged anchor bolts (81) are evenly distributed along the circumference of the anchor bolt cage body (80); The anchor bolt cage body (80) is connected to the anchor plate (6) at the top of the cap and the cap foundation (12) through anchor bolts (81).

2. The indoor model test device for bearing capacity of bored interlocking pile barrel foundation according to claim 1, characterized in that: The anchor plate (6) at the top of the pedestal is provided with a screw hole (2) at the top of the pedestal at a position corresponding to each anchor bolt (81); A cap foundation through hole is respectively provided at the lower end of the cap foundation (12) at a position corresponding to each anchor bolt (81); The upper and lower ends of the anchor bolt (81) are respectively threadedly fixedly connected with a fastening nut (82) after passing through the upper screw hole (2) of the cap and the through hole of the base of the cap.

3. The indoor model test device for bearing capacity of bored interlocking pile barrel foundation according to claim 1, characterized in that: A tower embedding hole (801) is provided at the center of the anchor cage body (80); The tower is embedded in the hole (801) and embedded in the lower end of the tower (1).

4. The indoor model test device for bearing capacity of bored interlocking pile barrel foundation according to claim 1, characterized in that: A cap foundation (12) is fixedly connected to the top of the model pile via a plurality of first bolts (71); On the cap foundation (12), a plurality of cap outer edge screw holes (3) are evenly distributed along the circumference and vertically penetrate the cap; A model pile is respectively arranged directly below the screw hole (3) on the outer edge of each cap; A model pile upper screw hole (10) is arranged at the top center of each model pile; The screw hole (10) on the upper part of the model pile is arranged correspondingly to the screw hole (3) on the outer edge of the cap; After the first bolt (71) passes through the outer screw hole (3) of the cap foundation (12) from top to bottom, it is threadedly fixedly connected with the upper screw hole (10) of the model pile at the corresponding position.

5. The indoor model test device for bearing capacity of bored interlocking pile barrel foundation according to claim 1, characterized in that: The model pile structure is fixedly connected to the pile bottom circular hoop fixing base plate (9) via a plurality of second bolts (72); A model pile lower screw hole is arranged at the bottom center of each model pile; The pile bottom circular hoop fixing bottom plate (9) is provided with a fixing bottom plate screw hole (901) at a position corresponding to the screw hole at the bottom of each model pile; The second bolt (72) passes through the screw hole (901) of the fixed bottom plate from bottom to top, and is threadedly fixedly connected with the screw hole at the lower part of the model pile at the corresponding position; and / or, The model pile structure is fixedly connected to the lower peripheral side walls of the cap foundation (12) via a plurality of third bolts (73); The lower part of the cap foundation (12) has a model pile installation groove opening downward; The top end of the model pile is located in the model pile installation groove and is arranged correspondingly to the screw hole (3) on the outer edge of the cap foundation (12); The cap foundation (12) is evenly provided with a plurality of side wall through holes connected to the model pile installation groove around the model pile installation groove; Each model pile is provided with a third bolt butt-jointed threaded hole at a position corresponding to the through hole in the side wall; After the third bolt (73) passes through a side wall through hole on the bearing platform foundation (12), it is threadedly fixedly connected with a third bolt butt threaded hole at a corresponding position.

6. The indoor model test device for bearing capacity of bored interlocking pile barrel foundation according to claim 1, characterized in that: The meat pile (4) and the plain pile (5) have the same radius of the circular cross section; Each meat pile (4) has the same height as each vegetarian pile (5); and / or, The plain pile (5) is provided with a concave groove on one side opposite to each adjacent meat pile (4); The shape and size of the groove correspond to the shape and size of the cylindrical surface of the meat pile (4); and / or, The contact surfaces between the meat pile (4) and the plain pile (5) are bonded; and / or, The contact surface between the meat pile (4) and the plain pile (5) is a smooth surface; and / or, The cross-sectional shape and size of the pile bottom circular hoop fixing bottom plate (9) are the same as those of the model pile structure; and / or, The material of the meat pile (4) is aluminum alloy; The material of the plain pile (5) is acrylic material.

7. The indoor model test device for bearing capacity of bored interlocking pile barrel foundation according to claim 1, characterized in that: The assembly process includes the following steps: Step S1, passing the anchor bolt cage (8) through the screw hole (2) and anchor bolt (81) on the upper part of the pedestal, and connecting the anchor plate (6) on the top of the pedestal; Step S2, alternately inserting the meat piles (4) and the plain piles (5) into the screw holes (3) on the outer edge of the pedestal, and then rotating the first bolt (71) to achieve fixed connection between the meat piles (4), the plain piles (5) and the pedestal foundation (12).

8. The borehole interlocking pile cylindrical foundation bearing capacity indoor model test device according to claim 7, characterized in that: During the assembly process, the roughness between the meat pile (4) and the plain pile (5) is changed by at least one of the following methods, thereby reducing the gap between the meat pile (4) and the plain pile (5): Method 1: After completing step S1, each of the meat piles (4) and the plain piles (5) is polished with sandpaper to make their surfaces smooth, and the polished meat piles (4) and the plain piles (5) are used to complete step S(2), thereby reducing the internal friction between the meat piles (4) and the plain piles (5), thereby reducing the gap between the pile foundations, and strengthening the connection between the meat piles (4) and the plain piles (5); Method 2: After completing step S1, perform the following operations: Step S11: When inserting the first pile (4) on the foundation (12), a layer of hot melt adhesive coating is applied on the left and right sides of the circumferential cylindrical surface of the first pile (41) by a hot melt gun; Step S12: insert two adjacent plain stakes (5) immediately on both sides of the first meat stake (41); Step S13: applying a hot melt adhesive coating to the grooves on the sides of the two plain piles (5); Step S14: Repeat the above steps S11 to S13 for the remaining meat piles (4) and plain piles (5) in sequence and arrange them alternately, so as to reduce the gap between the meat piles (4) and the plain piles (5) by the bonding force of the hot melt adhesive; Method 3: After step S1 and step S2, the following steps are further included: Step S3, through the second bolt (72), the circular hoop fixing base plate (9) at the bottom of the pile is connected to the lower screw holes of the model pile at the lower parts of the meat pile (4) and the plain pile (5), so as to achieve a fixed connection, thereby reinforcing the bottom of the experimental device and reducing the gap between the meat pile (4) and the plain pile (5).

9. A method for implementing the indoor model test device for bearing capacity of bored interlocking pile cylindrical foundation according to any one of claims 1 to 8, characterized in that: The following steps are involved: The first step is to vertically place the bored interlocking pile cylindrical foundation bearing capacity indoor model test device in a soil test box with an opening at the top, bury the part of the model pile structure below the bottom surface of the cap foundation (12) in the soil layer in the soil test box, and compact the soil layer; The second step is to add water to the soil test box. When water seeps out from the top soil layer of the soil test box, stop adding water and maintain it for 24 hours. The third step is to carry out loading tests of vertical and horizontal loads after the maintenance is completed.

10. The implementation method of the indoor model test device for bearing capacity of bored interlocking pile barrel foundation according to claim 9 is characterized in that: Through the geometric similarity principle formula, the consistency between the size of the model pile in the experimental device and the actual engineering device is determined; The model satisfies the geometric similarity principle formula, which is as follows: In formula (1), m and p represent the experimental device and prototype respectively. The experimental device is the experimental model, and the prototype is the actual engineering device. l m , b m 、h m , are the linear dimensions of the model pile in the experimental device in the length, width and height directions respectively; l p , b p 、h p , are the linear dimensions of the length, width and height of the meat pile or the plain pile in the prototype respectively; S l is the geometric similarity constant; and / or, Through 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 is determined; The model pile in the experimental device satisfies the load similarity principle formula, which is as follows: In formula (2), m and p represent the experimental model and prototype, respectively; P, A, σ are load, cross-sectional area, and stress, respectively; S σ is the stress similarity constant, that is, the stresses at corresponding points on the prototype and the model are proportional to each other in time; S l 2 is the area similarity constant, which is the area of ​​the experimental model and the prototype. A constant that represents the proportionality between areas; S P is the concentrated load similarity constant, equal to S σ and S l 2 By finding S σ and S l 2 The product is obtained; and / or, Through the formula of physical similarity principle, the relative stiffness of the material of the model pile in the experimental device is determined to be consistent with the actual engineering device; The model pile in the experimental device satisfies the physical similarity principle formula, which is as follows: In formula (3) to formula (5), S σ , S E , S ε , S τ , S G , S γ , S μ , which are the similarity constants of normal stress, elastic modulus, normal strain, shear stress, shear modulus, shear strain and Poisson's ratio respectively.

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