A Calculation Method for Crane Support Based on CAE Simulation Model

Abstract

This invention relates to a crane support calculation method based on a CAE simulation model, belonging to the field of civil engineering technology. The method mainly consists of four steps: establishing a single-pile computer simulation model for reinforced foundation, determining the effectiveness of the foundation and adjusting the load; establishing a pile-slab unit computer simulation model for reinforced foundation, and determining the effectiveness of the reinforcement slab and adjusting its span. The method first determines the ultimate load value of a single pile using the single-pile computer simulation model. P lim Then, the ultimate load value of a single pile P lim Within a defined range, a reasonable span is determined using a computer simulation model of pile-slab units. L y Its advantages include simple and convenient simulation model establishment for foundation reinforcement calculation, high efficiency in mechanical calculation of piles and slabs, simple safety judgment of reinforced foundation, and applicability to the calculation needs of crane foundation reinforcement schemes for different specifications and lifting weight steel cages.

Description

Technical Field

[0001] This invention relates to a crane support calculation method based on a CAE simulation model, belonging to the field of civil engineering technology. Background Technology

[0002] In underground engineering construction, the hoisting of reinforcing cages is a crucial step in diaphragm wall construction. One characteristic of reinforcing cages is their large span and overall weight, placing significant pressure on the foundation supporting the crane during hoisting. Because the soil's bearing capacity is relatively weak, it often cannot withstand the crane's weight, easily leading to the risk of crane overturning. This necessitates proper reinforcement of the crane foundation, and the specific reinforcement plan requires accurate and effective calculation methods.

[0003] Most existing patents mentioning foundation reinforcement methods that focus on structural improvements, with few analyzing actual loads and soil shear strength to arrive at the optimal reinforcement method. For example, patent application CN2019112676376, entitled "A Foundation Reinforcement Method," describes a foundation reinforcement process, mentioning drilling multiple vertical holes in the pre-reinforced surface at predetermined intervals. However, this patent does not specify how to set these intervals or the hole depths, nor does it provide criteria for determining whether the reinforcement meets requirements. Similarly, patent application CN2020115625171, entitled "Bridge Foundation Reinforcement Method," describes a bridge foundation reinforcement method, directly specifying the width and depth of the pre-embedded holes without offering a method for obtaining the most suitable data. Patent application CN202110599297.8, entitled "A Multi-Layer Reinforcement Technology for Pile-Bearing Embankments Based on Numerical Simulation," discloses a multi-layer reinforcement technology for pile-bearing embankments based on ABAQUS. This method uses ABAQUS to simulate the model and then modifies the strength grade of the reinforcement body according to stress-strain laws, focusing on optimizing the pile body through simulation. This patent, however, establishes two different reinforcement models based on actual loads and soil conditions, and performs simulation calculations. It processes the simulation data according to soil shear strength theory and material strength theory to obtain relevant parameters for the piles and slabs used in foundation reinforcement. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a crane support calculation method based on a CAE simulation model, a method for calculating the necessary support for the reinforced foundation required for hoisting steel cages, applicable to the needs of crane foundation reinforcement calculation for different specifications and lifting weights of steel cages.

[0005] The technical solution of the present invention is as follows: A calculation method for crane support based on a CAE simulation model is disclosed. This method is used to determine the reasonable span of the reinforcing piles when designing the pile-slab foundation for supporting the crane. The method is characterized by the following steps: (a) Establish a computer simulation model of a single pile for reinforced foundation, and obtain the maximum shear stress value of the foundation soil in the model under the preset initial load through simulation analysis. t max ; (b) Apply the effective foundation criterion to determine whether the soil bearing capacity of the model is effective. If the determination result is failure, reduce the load and repeat the calculation until the determination result is effective; if the determination result is effective, increase the load and repeat the calculation until the determination result is failure. Take the maximum effective load as the ultimate load value of a single pile that the soil can bear. P lim ; (c) Based on the weight of the crane (including the lifting of the steel cage) W Tracked surface area S and the ultimate load value of a single pile that the soil can withstand. P lim Calculate the maximum allowable span of the reinforced plate. L max A computer simulation model of the pile-slab unit for the reinforced foundation is established based on the maximum allowable span of the reinforcing slab, and the weight of the crane is considered. W The ground area of ​​the crane's tracks S Determine the uniform load that the reinforced plate of the model should bear. P a (Crane weight) W Evenly distributed on the ground area of ​​the track S The magnitude of the load (the load formed on the surface of the reinforced plate) is then determined through simulation analysis, which yields the maximum principal stress value of the reinforced plate under uniform load in the model. s max ; (d) Apply the effective judgment criteria for the reinforced plate to determine whether the supporting capacity of the reinforced plate in the model is effective. If the judgment result is failure, reduce the span and repeat the calculation until the judgment result is effective. Take the maximum effective span as the reasonable span of the reinforced plate. L y .

[0006] Furthermore, step (a) specifically includes the following sub-steps: (a-1) Establish a computer simulation model of a single pile including the foundation soil and the reinforcing pile. The model consists of a reinforcing pile, a square reinforcing plate at the top of the reinforcing pile, and the foundation soil surrounding the reinforcing pile below the square reinforcing plate. The cross-sectional dimensions of the reinforcing pile, the depth of its embedment in the soil, and the thickness of the reinforcing plate are given by the preliminary design. When the designed reinforcing pile is not cylindrical, it is equivalent to a cylinder with an equal cross-section. The side length of the square reinforcing plate is... sd equal to the diameter of the reinforcing pile jR The dimensions of the foundation soil are to be 2-3 times larger in the transverse direction than the size of the reinforcement plate, and 2-3 times larger in the longitudinal direction than the embedment depth of the reinforcement piles; the model is constrained by fixing the soil around its perimeter and bottom, and the surface in contact with the piles is defined according to the mechanical contact model; the model's expected initial load is... P 0 Based on crane weight W Assuming that 1 / 10 to 1 / 15 of the material is evenly applied to the square reinforcing plate, according to the formula... P 0= W / n sd 2 The calculation shows that, in the formula, n = 10~15; (a-2) Perform nonlinear finite element static analysis on the model established in step (a-1), and take the maximum shear stress value in the soil from the analysis results. t max .

[0007] Furthermore, step (b) specifically includes the following sub-steps: (b-1) The criterion for determining the effectiveness of the foundation is based on inequality (i): t max ≤ [ t 0] indicates that in the formula [ t 0] represents the ultimate bearing capacity of the foundation soil; when the value of the maximum shear stress satisfies inequality (I), it indicates that the bearing capacity of the foundation soil is effective; otherwise, it indicates that the bearing capacity of the foundation soil is ineffective. (b-2) The stress value obtained in step (a-2) t max Applying this to the validity criterion of inequality (I), if the initial load... P If the maximum shear stress at 0 satisfies inequality (a), then increase the load and repeat step (a-2) until the inequality is no longer satisfied; if the initial load... P If the maximum shear stress at 0° does not satisfy inequality (i), then reduce the load and repeat step (a-3) until inequality (i) is satisfied. Take the maximum load that satisfies the inequality as the ultimate load value that the foundation soil can withstand for a single pile. P lim .

[0008] The magnitude of the load increase or decrease can be a fixed value, such as 0.1 MPa or 0.5 MPa. The smaller the value, the better the final ultimate load value of the single pile, but the more times the analysis model needs to be repeated. Alternatively, it can be estimated based on the difference between the analysis results and the ultimate bearing capacity of the foundation soil. When the difference is large, a larger increase or decrease magnitude should be chosen; if the difference is small, a smaller increase or decrease magnitude should be chosen.

[0009] Furthermore, step (c) specifically includes the following sub-steps: (c-1) Establish a computer simulation model of a pile-slab unit including foundation soil, reinforcing piles, and reinforcing slab. It consists of two reinforcing piles, a rectangular reinforcing slab at the top of the reinforcing piles, and foundation soil surrounding the reinforcing piles below the rectangular reinforcing slab. The dimensions of the reinforcing piles and the thickness of the reinforcing slab are the same as in step (a-1), and the width of the reinforcing slab is... rd Equal to the span of the reinforcing plate L ,length rl equal to width rd Twice the span of the reinforced plate L The initial value is the maximum allowable span of the reinforcing plate. L max Take the formula m sd 2 P lim The smallest integer value of m for W, and the maximum allowable span of the reinforcing plate. L max According to the formula L max =( S / m) 1 / 2 Calculations show that the dimensions of the foundation soil are 2-3 times larger in the transverse direction than the size of the reinforcing plate and 2-3 times larger in the longitudinal direction than the pile embedment depth. The model is constrained by fixing the soil around its perimeter and bottom. The contact surfaces between the soil and the pile / plate are defined according to the mechanical contact model. The load on the model is taken as the uniform load that the reinforcing plate should bear. P a According to the formula P a = W / S Calculated; (c-2) Perform nonlinear finite element static analysis on the model established in step (c-1), and take the maximum principal stress value in the plate from the analysis results. s max .

[0010] Furthermore, step (d) includes the following sub-steps: (d-1) The criterion for determining the effectiveness of the reinforcement plate is inequality (II): s max ≤ [ s0] indicates that in the formula [ s [0] represents the allowable stress of the material; when the reinforcing plate is made of concrete, the allowable stress is taken as the tensile strength of the concrete. Satisfying inequality (ii) indicates that the reinforcing plate's supporting capacity is effective; otherwise, it indicates that the reinforcing plate's supporting capacity is ineffective. (d-2) The maximum principal stress value obtained in step (c-2) s max The validity criterion of inequality (II) is applied to determine whether the analysis results satisfy inequality (II) under the initial reinforcement plate span. If the analysis results satisfy inequality (II), then the span of the reinforcement pile is increased. L (Width of the reinforcing plate) rd and length rl (and so on), repeat step (c-2) until the inequality is no longer satisfied, and take the maximum span that satisfies inequality (ii) as the reasonable span of the reinforcement plate. L y .

[0011] Similarly, the reduction in span can also be a fixed value, such as 500mm or 100mm. The smaller the value, the better the final reasonable span value, but the more times the analysis model needs to be repeated. Alternatively, it can be estimated based on the difference between the analysis results and the allowable stress of the material. When the difference is large, a larger reduction range is chosen; if the difference is small, a smaller reduction range is chosen.

[0012] When using the calculation method of this invention, designers need to first determine the cross-sectional area and length of the reinforcing pile, as well as the thickness of the reinforcing plate, based on general experience. Additionally, when using this method, attention must be paid to the dimensions of each physical quantity; that is, the dimensions must be consistent. If the International System of Units (SI) is adopted, with the basic dimensions being millimeters (mm), kilograms (kg), and seconds (s), then the dimension of force is Newtons (N), and the modulus of elasticity... E With stress s The dimension is MPa (N / mm). 2 Poisson's ratio m It is dimensionless. Sometimes it is also expressed in kPa (10). 3 Pa).

[0013] The beneficial effects of this invention are: the simulation model for foundation reinforcement calculation is simple to establish and easy to use; the mechanical calculation efficiency of reinforcement piles and reinforcement plates is high; the safety judgment of foundation reinforcement is simple; and it can be applied to the needs of crane foundation reinforcement calculation for different specifications and lifting weight steel cages. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a single pile and soil block.

[0015] Figure 2 This is a schematic diagram of a single pile model.

[0016] Figure 3 These are the simulation results of normal stress on a soil block in a single pile model.

[0017] Figure 4 This is the simulation result of the normal stress of the soil block in the adjusted single pile model.

[0018] Figure 5 This is a schematic diagram of a pile slab model.

[0019] Figure 6 These are the simulation results of equivalent stress in the pile-slab model. Detailed Implementation

[0020] The technical solution of the present invention will be further explained in detail below through a specific embodiment and in conjunction with the accompanying drawings.

[0021] In this case, the weight of the crane (including the lifting of the steel cage) is W = 818t. The two tracks of the crane are in contact with the bottom surface. The length of the tracks... l 1 = 12250mm, the sum of the widths of the two tracks. l 2=3000mm, the preliminary design of the reinforcement pile is a cylindrical pile with a diameter of 850mm and an embedment depth of 2000mm. The square reinforcement plate is 850mm wide and 300mm thick. The tensile strength of the reinforcement plate concrete material is 1.71MPa. In addition, it is known that the allowable bearing capacity of cohesive soil is […]. t 0]=57.22 E a 0.57 In this example, the compressibility modulus of clay E a Taking 40 MPa as an example, the allowable bearing capacity of the soil in this example can be calculated to be 469 kPa.

[0022] The following are the specific calculation steps for this case.

[0023] (a) Establish a computer simulation model of a single pile for reinforced foundation.

[0024] (a-1) Dimensions of a single pile model: The reinforced pile is a cylindrical pile with a square plate, and the diameter of the cylinder is... jR =850mm, embedment depth 2000mm, square plate width sd=850mm, thickness 300mm, square soil depth 4000mm, side length 2600mm. The model is constrained by fixing the soil around the perimeter and bottom, and the surface in contact with the pile is defined according to the mechanical contact model. For example Figure 1 , Figure 2 As shown.

[0025] Based on general experience, approximately 6 to 15 reinforcing piles can support the weight of the aforementioned 818t crane and reinforcing cage. In this example, we will first assume n = 12, according to the formula...P 0= W / n sd 2 Calculation yielded: P 0=818*1000*10 / 12*850*850=0.94MPa.

[0026] (a-2) A nonlinear finite element static analysis was performed on the model, and the maximum stress value in the soil was taken from the analysis results. Under the above loading conditions, the maximum shear stress value of the soil was 746 kPa. Figure 3 As shown.

[0027] (b) Apply the effective foundation criterion to obtain the ultimate load value of a single pile. P lim .

[0028] According to the inequality (one) of the foundation validity determination criteria: t max ≤ [ t [0] Since 746 kPa > 469 kPa, it indicates that the bearing capacity of the foundation soil has failed. Therefore, the load is reduced, and a new nonlinear finite element static analysis is performed on the model. In this example, the load reduction is set to a fixed value of 0.2 MPa. After two load reductions, when the load is reduced to 0.54 MPa, the maximum shear stress value of the soil is obtained as 435 kPa. Figure 4 As shown, if the first load is less than 469 kPa, then the ultimate load value of a single pile is... P lim= 0.54 MPa. Calculations determine that the formula m is satisfied. sd 2 P lim The minimum value of m for W is 22.

[0029] (c) Establish a computer simulation model of the pile-slab unit for reinforced foundation.

[0030] (c-1) Model Composition: The model consists of two reinforced piles and one reinforced plate. The center-to-center distance between the two piles is taken from the preliminary design value (referred to as pile span L). The span of the reinforced plate is... L The initial value is the maximum allowable span of the reinforcing plate. L max Maximum allowable span of the reinforcing plate L max According to the formula L max =( S / m) 1 / 2The calculations yielded the following initial values: L = 1292 mm; the width of the reinforcing plate was taken as equal to the span, rd = 1292 mm; the length of the reinforcing plate was taken as 2L, i.e., rl = 2584 mm; and the thickness of the reinforcing plate was the same as that of the monopile model plate, taken as 300 mm. The soil dimensions were taken as 5500 mm in length, 3000 mm in width, and 2000 mm in depth. Model loads... P Take initial value P a According to the formula P a = W / S P was calculated a =818*1000*10 / 12250*3000=0.22MPa, obviously P a ≤ P lim The requirements are met.

[0031] (c-2) Perform nonlinear finite element static analysis on the model, and take the maximum principal stress value in the plate from the analysis results. s max Under the above loading conditions, the maximum principal stress is 1.26 MPa.

[0032] (d) Apply the effective judgment criteria for reinforcement plates to determine the reasonable span of the reinforcement plates. L y .

[0033] The effective determination criterion for reinforced plates uses inequality (II): s max ≤ [ s [0] Since 1.26MPa < 1.71MPa, it indicates that the supporting capacity of the reinforcing plate is effective. Therefore, the reasonable span of the reinforcing plate is determined. L y =1292mm.

[0034] Based on the above-described preferred embodiments of the present invention, and through the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims. Because there are certain deviations between the ideal state and the actual situation, such as different sand content in the foundation soil, the presence of impurities such as garbage in the foundation soil, and errors in the ground area of ​​the crane tracks, a safety factor should be added when using the method of the present invention to ensure safety. It is recommended to use 1.2-1.5 times the actual weight as the weight of the crane and the lifting steel cage. W .

Claims

1. A calculation method for crane support based on a CAE simulation model, which is used to determine the reasonable span of the reinforcing piles when designing the pile-slab reinforced foundation for supporting the crane, characterized in that... Includes the following steps: (a) Establish a computer simulation model of a single pile for reinforced foundation, and obtain the maximum shear stress value of the foundation soil in the model under the preset initial load through simulation analysis. τ max ; (b) Apply the effective foundation criterion to determine whether the soil bearing capacity of the model is effective. If the determination result is failure, reduce the load by the set range and repeat the calculation until the determination result is effective; if the determination result is effective, increase the load by the set range and repeat the calculation until the determination result is failure. Take the maximum effective load as the ultimate load value of a single pile that the soil can bear. P lim ; (c) Based on the weight of the crane W Tracked surface area S and the ultimate load value of a single pile that the soil can withstand P lim Calculate the maximum allowable span of the reinforced plate. L max ; A computer simulation model of the pile-slab unit for the reinforced foundation is established based on the maximum allowable span of the reinforcing slab, and the weight of the crane is considered. W The ground area of ​​the crane's tracks S Determine the uniform load that the reinforced plate of the model should bear. P a The size of the stress is determined; then, through simulation analysis, the maximum principal stress value of the reinforced plate under uniform load in the model is obtained. σ max ; (d) Apply the effective judgment criteria for the reinforcement plate to determine whether the support capacity of the reinforcement plate in the model is effective. If the judgment result is failure, reduce the span by a set amount and repeat the calculation until the judgment result is effective. Take the maximum effective span as the reasonable span of the reinforcement plate. L y ; Step (a) includes the following sub-steps: (a-1) Establish a computer simulation model of a single pile including the foundation soil and the reinforcing pile. The model consists of a reinforcing pile, a square reinforcing plate located on top of the reinforcing pile, and the foundation soil surrounding the reinforcing pile below the square reinforcing plate. The cross-sectional dimensions of the reinforcing pile, the depth of its embedment in the soil, and the thickness of the reinforcing plate are given by the preliminary design. The side length of the square reinforcing plate is... sd The diameter of the reinforcing pile is equal to jR; the dimensions of the foundation soil are taken to be 2-3 times larger in the transverse dimension than the reinforcing plate dimension and 2-3 times larger in the longitudinal dimension than the embedment depth of the reinforcing pile; the model is constrained by fixing the soil around its perimeter and bottom, and the surface in contact with the pile is defined according to the mechanical contact model; the model's expected initial load is... P 0 Based on crane weight W Assuming that 6 to 1 / 15 of the material is evenly applied to the square reinforcing plate, according to the formula... P 0= W / n sd 2 The calculation shows that n = 6~15; (a-2) Perform nonlinear finite element static analysis on the model established in step (a-1), and take the maximum shear stress value in the soil from the analysis results. τ max .

2. The crane support calculation method based on CAE simulation model according to claim 1, characterized in that, Step (b) includes the following sub-steps: (b-1) The criterion for determining the effectiveness of the foundation is based on inequality (i): τ max ≤ [ τ 0] indicates that in the formula [ τ 0] represents the ultimate bearing capacity of the foundation soil; when the value of the maximum shear stress satisfies inequality (I), it indicates that the bearing capacity of the foundation soil is effective; otherwise, it indicates that the bearing capacity of the foundation soil is ineffective. (b-2) The stress value obtained in step (a-2) τ max Applying this to the validity criterion of inequality (I), if the initial load... P If the maximum shear stress at 0 satisfies inequality (a), then increase the load and repeat step (a-2) until the inequality is no longer satisfied; if the initial load... P If the maximum shear stress at 0° does not satisfy inequality (i), then reduce the load and repeat step (a-3) until inequality (i) is satisfied. Take the maximum load that satisfies the inequality as the ultimate load value that the foundation soil can withstand for a single pile. P lim .

3. The crane support calculation method based on CAE simulation model according to claim 2, characterized in that, Step (c) includes the following sub-steps: (c-1) Establish a computer simulation model of a pile-slab unit including foundation soil, reinforcing piles, and reinforcing slab. It consists of two reinforcing piles, a rectangular reinforcing slab at the top of the reinforcing piles, and foundation soil surrounding the reinforcing piles below the rectangular reinforcing slab. The dimensions of the reinforcing piles and the thickness of the reinforcing slab are the same as in step (a-1), and the width of the reinforcing slab is... rd Equal to the span of the reinforcing plate L ,length rl equal to width rd Twice the span of the reinforced plate L The initial value is the maximum allowable span of the reinforcing plate. L max Take the formula m sd 2 P lim The smallest integer value of m for W, and the maximum allowable span of the reinforcing plate. L max According to the formula L max =( S / m) 1 / 2 Calculations show that the dimensions of the foundation soil are 2-3 times larger in the transverse direction than the size of the reinforcing plate and 2-3 times larger in the longitudinal direction than the pile embedment depth. The model is constrained by fixing the soil around its perimeter and bottom. The contact surfaces between the soil and the pile / plate are defined according to the mechanical contact model. The load on the model is taken as the uniform load that the reinforcing plate should bear. P a According to the formula P a = W / S Calculated; (c-2) Perform nonlinear finite element static analysis on the model established in step (c-1), and take the maximum principal stress value in the plate from the analysis results. σ max .

4. The crane support calculation method based on CAE simulation model according to claim 3, characterized in that, Step (d) includes the following sub-steps: (d-1) The criterion for determining the effectiveness of the reinforcement plate is inequality (II): σ max ≤ [ σ 0] indicates that in the formula [ σ 0] is the allowable stress of the material; when the reinforcing plate is made of concrete, the allowable stress is taken as the tensile strength of the concrete. If inequality (ii) is satisfied, it means that the supporting capacity of the reinforcing plate is effective; otherwise, it means that the supporting capacity of the reinforcing plate is ineffective. (d-2) The maximum principal stress value obtained in step (c-2) σ max The validity criterion of inequality (II) is applied to determine whether the analysis results satisfy inequality (II) under the initial reinforcement plate span. If the analysis results satisfy inequality (II), then the span of the reinforcement pile is increased. L Repeat step (c-2) until the inequality is no longer satisfied. Take the maximum span that satisfies inequality (ii) as the reasonable span of the reinforcement plate. L y .

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