An optimization method to improve the bonding effect of shotcrete

Abstract

The present invention discloses an optimization method for improving the bonding effect of shotcrete, including constructing a correlation function model between the spraying angle of a spraying device and the wall bonding performance, obtaining the initial equipment parameters and the wall bonding force of the spraying device at the construction site; inputting the initial equipment parameters and the wall bonding force into the correlation function model, judging whether the current initial equipment parameters meet the preset conditions; if not, adjusting the initial equipment parameters, repeating the above steps until the preset conditions are met, and obtaining the optimal equipment parameters; setting the spraying device according to the optimal equipment parameters. The bonding performance of the shotcrete on the wall is increased by only reasonably setting the spraying method, especially the spraying angle of the nozzle.

Description

Technical Field

[0001] The invention relates to the technical field of shotcrete simulation calculation, and in particular to an optimization method for improving the bonding effect of shotcrete. Background Art

[0002] Shotcrete is widely used in daily tunnel engineering due to its advantages such as short setting time, simple process, convenient transportation, easy construction operation and flexible operation method.

[0003] Since the bonding effect of shotcrete and the wall will affect the construction quality, how to improve the bonding effect of shotcrete and the wall has been a problem that has been studied for a long time. The bonding effect of concrete and the wall is generally manifested in the rebound rate of concrete after being sprayed onto the wall, and some rebound rates often exceed 30%. There are many factors that affect the bonding effect of shotcrete, such as the mix design of concrete, inaccurate concrete spraying equipment, or inadequate spraying methods, which will affect the rebound rate of shotcrete. Among these influencing factors, the parameters of the spraying equipment are easy to control, and among these parameters, if the speed is adjusted, the pressure at the starting point of the spraying equipment may be changed, the distance between the spraying equipment and the wall may be changed, and it is necessary to consider whether the construction space at the construction site can be adjusted, and it is possible to cause excess shotcrete liquid to fall during the spraying process. And adjusting the spraying angle only requires rotating the spraying equipment, which is easier to control and does not require many restrictions. Therefore, how to improve the bonding effect of concrete and the wall by adjusting the spraying angle when the spraying equipment sprays concrete onto the wall is a problem that needs to be solved in this application. Summary of the invention

[0004] The object of the present invention is to provide an optimization method for improving the bonding effect of shotcrete, by only reasonably setting the spraying mode, especially the spraying angle of the nozzle, so as to increase the bonding performance of the shotcrete on the wall.

[0005] Based on the above objectives, this application proposes the following solutions:

[0006] An optimization method for improving the bonding effect of shotcrete, specifically comprising the following steps:

[0007] S1. Construct a correlation function model between the spraying angle of the spraying equipment and the wall bonding performance.

[0008] S2. Obtaining the initial parameters of the spraying equipment and the wall adhesion at the construction site;

[0009] S3, inputting the initial parameters of the device and the wall adhesion into the correlation function model to determine whether the current initial parameters of the device meet the preset conditions;

[0010] S4. If not, adjust the initial parameters of the device and repeat step S3 until the preset conditions are met to obtain the optimal device parameters;

[0011] S5. Set the injection equipment according to the optimal equipment parameters.

[0012] In some specific embodiments, the initial parameters of the equipment include the cross-sectional area of ​​the nozzle pipe of the spraying equipment, the initial velocity of concrete sprayed from the nozzle, the horizontal distance of the nozzle from the wall, and the initial spraying angle of the nozzle to the horizontal plane.

[0013] In some specific implementations, the specific process of step S3 is:

[0014] S31, calculating the speed of the shotcrete when it moves as a whole to the wall surface according to the horizontal distance between the nozzle and the wall, the initial spraying angle between the nozzle and the horizontal plane, and the initial speed of the concrete sprayed from the nozzle;

[0015] S32, calculating the angle between the shotcrete and the wall surface when the shotcrete moves as a whole to the wall surface according to the speed of the shotcrete when the shotcrete moves as a whole to the wall surface;

[0016] S33, inputting the cross-sectional area of ​​the nozzle pipe of the spraying equipment, the speed of the sprayed concrete when it moves as a whole to the wall, the angle between the sprayed concrete and the wall when it moves as a whole to the wall, the wall adhesion, and the initial spraying angle between the nozzle and the horizontal plane into the correlation function model to determine whether the preset conditions are met, where the preset conditions are preset correlation relationships.

[0017] In some specific implementations, the process of step S32 is:

[0018] S321, performing vector decomposition on the velocity of the shotcrete when it moves to the wall surface as a whole, and obtaining the vertical velocity and the horizontal velocity;

[0019] S322, solving the inverse tangent function for the ratio of the vertical velocity to the horizontal velocity, and obtaining the angle θ between the shotcrete and the wall surface when the shotcrete moves as a whole to the wall surface.

[0020] In some specific implementations, the specific process of step S321 is:

[0021] The sprayed concrete is sprayed from the nozzle at an initial spray angle. α , initial velocity v 1 moves to a horizontal distance from the nozzle of l 1 wall, according to Newton's second law, the velocity of the shotcrete when it moves to the wall is vector-decomposed to obtain the vertical velocity v 竖直1 and horizontal speed v 水平1 They are:

[0022]

[0023]

[0024] Here, g is the local acceleration due to gravity.

[0025] In some specific implementations, the preset association relationship is:

[0026]

[0027] Where S represents the cross-sectional area of ​​the nozzle pipe of the injection equipment, and the wall adhesion , k 1 is a fixed value.

[0028] In some specific implementations, adjusting the initial parameters of the device in step S4 is to only adjust the initial spray angle between the nozzle and the horizontal plane until the adjusted spray angle meets the preset conditions.

[0029] In some optional implementations, the specific process of step S3 is: the preset condition is the nozzle spray angle range, and it is determined whether the initial spray angle between the nozzle and the horizontal plane is within the nozzle spray angle range, if not, the initial spray angle between the nozzle and the horizontal plane is adjusted.

[0030] In some specific implementations, solving the nozzle spray angle range α Method 1 is:

[0031] The cross-sectional area S of the nozzle pipe of the injection equipment and the initial velocity of the concrete ejected from the nozzle v 1. Horizontal distance between the nozzle and the wall l 1. Wall Adhesion Input into the correlation function model to solve the nozzle spray angle range α 1, where the correlation function model calculation formula is:

[0032]

[0033] Where g is the local gravitational acceleration, k 1 is a fixed value.

[0034] The inventive concept of the present invention is:

[0035] In order to improve the bonding effect of shotcrete spraying and wall surface, the prior art generally takes into account the influence of various factors that affect the concrete spraying effect, such as analyzing the spraying distance from the nozzle to the wall surface, the spraying path, the nozzle movement speed, the movement route, the concrete particle size, the spraying speed, the spraying angle and the spraying distance, and comprehensively considering multiple factors to determine the target working parameters for improving the bonding effect. However, these analysis methods generally obtain working parameters through comprehensive consideration, among which there are many variables that need to be adjusted, and the variables will affect each other, and the analysis is complicated. For example, if you want to adjust the spraying speed of the nozzle (such as reducing the speed), then you need to consider that after changing the spraying speed, after the concrete is sprayed from the nozzle, the horizontal speed and the vertical speed thereof will also decrease during the process of moving to the wall surface, which may cause the shotcrete to fail to be sprayed to the original position. This is because the vertical speed has changed and the spraying height is also different, so the subsequent analysis process is invalid. Therefore, if you want to change the parameters so that the concrete can still be sprayed to the original position, you cannot increase the horizontal and vertical speeds at the same time.

[0036] In addition, from the nature of movement, it is generally believed that bonding is the bonding of two objects after contact. When the wall bonding force is the same, the factor that affects the bonding effect is the "collision speed" of the two objects at the moment of bonding. When the shotcrete hits the wall, the faster the collision speed, the shorter the contact time will be, and the natural bonding will be poor. The speed in the vertical direction will affect the sliding effect of the concrete after it contacts the wall, and the concrete can slide down appropriately after contacting the wall to increase the contact area. Therefore, in this application, by studying the influence of the speed in the vertical direction on the bonding effect, the movement speed after spraying is divided into horizontal and vertical directions for separate research.

[0037] The present application also simplifies the adjustment process of concrete. For the spraying equipment itself, the more intuitive and easy-to-adjust method is to directly adjust the spraying angle of the nozzle, and only change the spraying angle of the nozzle. As the spraying angle changes, the horizontal speed and vertical speed of the concrete in the air after being sprayed from the nozzle will not change monotonically. For example, if the spraying angle is adjusted higher, the horizontal speed will be reduced, which means that the movement time of the sprayed concrete from the nozzle to the wall has become longer, and the vertical speed after the spraying has become higher accordingly. Vertically upward, wait for its vertical speed to decrease to 0, and then the time for the direction to grow is more. In this case, since the time required for horizontal movement and vertical movement to the same position has increased, as long as the spraying angle is adjusted, the concrete can still be sprayed to the original position. In addition, due to different impact angles, the contact area between the sprayed concrete and the wall will be different. If it hits obliquely, the impact surface is an inclined surface, which increases the contact area, thereby improving the bonding effect.

[0038] The present invention has the beneficial effects:

[0039] This application studies the relationship between the change of the spraying angle of the spraying equipment and the adhesion of the sprayed concrete, explores the influence of the impact angle on the rebound rebound rate of the sprayed concrete after hitting the wall, and thus constructs a correlation function model between the spraying angle of the spraying equipment and the wall adhesion performance. By inputting data such as the initial parameters of the equipment and the wall adhesion force collected at the construction site into the correlation function model, the optimal spraying angle can be obtained, and then the spraying equipment is controlled to work at the optimal spraying angle, thereby improving the bonding effect between the concrete and the wall and reducing the rebound rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart of an optimization method for improving the bonding effect of shotcrete provided by an embodiment of the present invention;

[0041] Figure 2 A flow chart of a method for determining whether the initial parameters of a current device meet preset conditions provided by an embodiment of the present invention;

[0042] Figure 3 A flow chart of another optimization method for improving the bonding effect of shotcrete provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] 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, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. 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.

[0044] The relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0045] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0046] Additionally, descriptions of well-known structures, functions, and configurations may be omitted for clarity and conciseness.One of ordinary skill in the art will recognize that various changes and modifications may be made to the examples described herein without departing from the spirit and scope of the present disclosure.

[0047] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0048] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0049] The concrete and shotcrete described in this application are nanocrystalline polymer shotcrete. Current research on the bonding and rebound of shotcrete sprayed on the wall is often based on experience.

[0050] Example 1

[0051] like Figure 1 As shown, this embodiment provides an optimization method for improving the bonding effect of shotcrete, which specifically includes the following steps:

[0052] S1. Construct a correlation function model between the spraying angle of the spraying equipment and the wall bonding performance.

[0053] S2. Obtaining the initial parameters of the spraying equipment and the wall adhesion at the construction site;

[0054] The initial parameters of the equipment include the cross-sectional area of ​​the nozzle pipe of the spraying equipment, the initial velocity of concrete sprayed from the nozzle, the horizontal distance between the nozzle and the wall, and the initial spraying angle between the nozzle and the horizontal plane.

[0055] S3, inputting the initial parameters of the device and the wall adhesion into the correlation function model to determine whether the current initial parameters of the device meet the preset conditions;

[0056] like Figure 2 As shown, the specific process of step S3 is:

[0057] S31, calculating the speed of the shotcrete when it moves as a whole to the wall surface according to the horizontal distance between the nozzle and the wall, the initial spraying angle between the nozzle and the horizontal plane, and the initial speed of the concrete sprayed from the nozzle;

[0058] S32, calculating the angle between the shotcrete and the wall surface when the shotcrete moves as a whole to the wall surface according to the speed of the shotcrete when the shotcrete moves as a whole to the wall surface;

[0059] The process of step S32 is:

[0060] S321, performing vector decomposition on the velocity of the shotcrete when it moves to the wall surface as a whole, and obtaining the vertical velocity and the horizontal velocity;

[0061] The specific process of step S321 is:

[0062] The sprayed concrete is sprayed from the nozzle at an initial spray angle. α , initial speed v 1 moves to a horizontal distance from the nozzle of l 1 wall, according to Newton's second law, the velocity of the shotcrete when it moves to the wall is vector-decomposed to obtain the vertical velocity v 竖直1 and horizontal speed v 水平1 They are:

[0063]

[0064]

[0065] Here, g is the local acceleration due to gravity.

[0066] S322, solving the inverse tangent function for the ratio of the vertical velocity to the horizontal velocity, and obtaining the angle θ between the shotcrete and the wall surface when the shotcrete moves as a whole to the wall surface.

[0067] S33, inputting the cross-sectional area of ​​the nozzle pipe of the spraying equipment, the speed of the sprayed concrete when it moves as a whole to the wall, the angle between the sprayed concrete and the wall when it moves as a whole to the wall, the wall adhesion, and the initial spraying angle between the nozzle and the horizontal plane into the correlation function model to determine whether the preset conditions are met, where the preset conditions are preset correlation relationships.

[0068] The default conditions are:

[0069]

[0070] Where S represents the cross-sectional area of ​​the nozzle pipe of the injection equipment, and the wall adhesion , k 1 is a fixed value.

[0071] S4. If not, adjust the initial parameters of the device and repeat step S3 until the preset conditions are met to obtain the optimal device parameters;

[0072] When adjusting the equipment parameters, the nozzle spray angle has a greater impact on the bonding effect. Therefore, the initial parameters of the equipment are adjusted to only adjust the initial spray angle between the nozzle and the horizontal plane until the adjusted spray angle meets the preset conditions.

[0073] S5. Set the injection equipment according to the optimal equipment parameters.

[0074] Example 2

[0075] like Figure 3As shown, the difference between this embodiment and embodiment 1 is that the specific process of step S3 in this embodiment is: the preset condition is the nozzle spray angle range, and it is determined whether the initial spray angle between the nozzle and the horizontal plane is within the nozzle spray angle range, if not, the initial spray angle between the nozzle and the horizontal plane is adjusted.

[0076] Get the nozzle spray angle range α Method 1 is:

[0077] The cross-sectional area S of the nozzle pipe of the injection equipment and the initial velocity of the concrete ejected from the nozzle v 1. Horizontal distance between the nozzle and the wall l 1. Wall Adhesion Input into the correlation function model to solve the nozzle spray angle range α 1, where the correlation function model calculation formula is:

[0078]

[0079] Where g is the local gravitational acceleration, k 1 is a fixed value.

[0080] It can be understood that in order to obtain the correlation function model between the spraying angle of the spraying device and the wall bonding performance proposed in the above embodiment, the specific derivation process is as follows:

[0081] Assume that the horizontal distance between the nozzle and the wall is l 1. The angle between the nozzle and the horizontal plane is α The speed of concrete spraying out of the nozzle is v 1, then according to Newton's second law, it is not difficult to deduce that when the shotcrete moves to the wall as a whole, the speed is,

[0082] (1)

[0083] (2)

[0084] (where g is the local gravity acceleration, generally 9.8m / s 2 )

[0085] This time

[0086] but (3)

[0087] Here we study the movement of the concrete part in contact with the wall (the thickness is considered to be 0), assuming that the wall is placed vertically, and that changing the nozzle angle only changes the contact area between the contact part and the wall, without changing the mass of the contact part.

[0088] Assuming that the mud flow after the sprayed concrete is a cylinder with a cross-sectional area of ​​S (this is a constant value related to the cross-sectional area of ​​the pipe), the contact area between the concrete and the wall is , assuming that the bonding force between concrete and wall per unit area is .

[0089] The adhesive force of the contact part is ,

[0090] During the impact, we know from the empirical formula of physics that the rebound force is proportional to the square of the impact velocity, so we assume , k is a constant value related to the properties of concrete and the wall itself, and v is the horizontal impact velocity. For the entire concrete under study, the set horizontal velocity value is entered, that is,

[0091] (k1 is a constant value)

[0092] After the concrete hits the surface, it is subjected to work done by the bonding force and elastic force in the horizontal direction, and it is obvious that both are doing negative work.

[0093] According to the momentum theorem formula: Column format:

[0094]

[0095] After simplifying, we get:

[0096]

[0097] X is the horizontal distance from the deepest point of the concrete to the surface, and m is the mass of this part of the concrete.

[0098] Since the researchers hope that the concrete will not fall off the wall, they consider the critical case, that is, when the concrete stops moving, it stops on the wall surface, which is equivalent to the displacement from contacting the wall to stopping moving being 0. In this case, during the entire movement of the concrete, the work done by the rebound force is 0 (the direction of the rebound force remains unchanged, and the concrete displacement is 0), and the distance worked by the bonding force is 2X (the direction of the bonding force is always opposite to the direction of concrete movement).

[0099] From the mechanical energy conservation equation, we know that the work done by the bonding force is equal to the change in the kinetic energy of the concrete. The simplified formula is:

[0100]

[0101] Simplifying, we get:

[0102] (4)

[0103] The above equation is a critical case. In general, researchers need to ensure that the work done by the adhesive force is sufficient to consume the horizontal velocity, that is:

[0104] (5)

[0105] Now, by substituting (1) and (3), we can get a solution with only α The formula of , after calculation by a calculator, can be obtained α The value range of is the reasonable nozzle angle range.

[0106] In order to verify the above inference, the researchers used molecular dynamics simulation methods to simulate the collision process and verify the proposed correlation function model:

[0107] First, the molecular dynamics simulation of the collision process is carried out. In order to simplify the calculation process, the velocity of the shotcrete when it hits can be fixed as v 2. Change the angle of impact.

[0108]

[0109] In the formula, , bring in 10 v 2 value, solve the corresponding 10 θ values ​​and record them as (i=1, 2, 3...10), and at the same time establish the following microelement, the volume of the microelement is V, the density is fixed, and the vertical cross-sectional area is , where s1 is a constant value in the entire simulation process. The horizontal width is , ensuring that the lateral width is extremely small. A force field is set up next to the right side of the microelement, which has a horizontally distributed load to the left, J, with a magnitude of , v is the horizontal velocity of the material entering the area. Let a force field Q be set, the direction of the force in the force field is always opposite to the direction of the object's movement, and the force field is also a distributed load with a constant value q. The horizontal velocity of the concrete microelement is .

[0110] The simulation process is as follows: 10 of v 2 Set to simulate v 2 values. Starting from 0 degrees, change the value of θ in increments of 0.5 degrees each time to simulate until two θ values ​​are obtained, so that the concrete corresponding to one angle remains in the wall and the concrete corresponding to the other angle leaves the wall. At this time, record the smaller θ value. Record as .

[0111] Repeat the operation to get 10 . And calculate The size is recorded as p i . p i The results are shown in Table 1:

[0112] Table 1 Ratio of simulated values ​​from molecular dynamics simulation to theoretical values ​​calculated by the algorithm

[0113] <![CDATA[ P 1 ]]> <![CDATA[ P 2 ]]> <![CDATA[ P 3 ]]> <![CDATA[ P 4 ]]> <![CDATA[ P 5 ]]> <![CDATA[ P 6 ]]> <![CDATA[ P 7 ]]> <![CDATA[ P 8 ]]> <![CDATA[ P 9 ]]> <![CDATA[ P 10 ]]> Proportional value 0.987 1.054 1.098 0.943 0.955 1.121 1.084 0.932 0.994 1.052

[0114] It is found that the simulated values ​​​​of the researchers are close to the theoretical solution values, which shows that the proposed algorithm is effective.

[0115] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. An optimization method for improving the bonding effect of shotcrete, characterized in that: The specific steps include: S1. Construct a correlation function model between the spraying angle of the spraying equipment and the wall bonding performance. S2. Obtaining the initial parameters of the spraying equipment and the wall adhesion of the construction site; the initial parameters of the equipment include the cross-sectional area of ​​the nozzle pipe of the spraying equipment, the initial velocity of the concrete sprayed from the nozzle, the horizontal distance between the nozzle and the wall, and the initial spraying angle between the nozzle and the horizontal plane; S3, inputting the initial parameters of the device and the wall adhesion into the correlation function model to determine whether the current initial parameters of the device meet the preset conditions; The preset condition is the nozzle spray angle range, and it is determined whether the initial spray angle between the nozzle and the horizontal plane is within the nozzle spray angle range, and if not, the initial spray angle between the nozzle and the horizontal plane is adjusted; Solving the nozzle spray angle range α Method 1 is: The cross-sectional area S of the nozzle pipe of the injection equipment and the initial velocity of the concrete ejected from the nozzle v 1. Horizontal distance between the nozzle and the wall l 1. Wall Adhesion Input into the correlation function model to solve the nozzle spray angle range α 1, where the correlation function model calculation formula is: Where g is the local gravitational acceleration, k 1 is a fixed value; S4. If not, adjust the initial parameters of the device and repeat step S3 until the preset conditions are met to obtain the optimal device parameters; S5. Set the injection equipment according to the optimal equipment parameters.

2. The optimization method for improving the bonding effect of shotcrete according to claim 1, characterized in that: The specific process of step S3 is: S31, calculating the speed of the shotcrete when it moves as a whole to the wall surface according to the horizontal distance between the nozzle and the wall, the initial spraying angle between the nozzle and the horizontal plane, and the initial speed of the concrete sprayed from the nozzle; S32, calculating the angle between the shotcrete and the wall surface when the shotcrete moves as a whole to the wall surface according to the speed of the shotcrete when the shotcrete moves as a whole to the wall surface; S33, inputting the cross-sectional area of ​​the nozzle pipe of the spraying equipment, the speed of the sprayed concrete when it moves as a whole to the wall, the angle between the sprayed concrete and the wall when it moves as a whole to the wall, the wall adhesion, and the initial spraying angle between the nozzle and the horizontal plane into the correlation function model to determine whether the preset conditions are met, where the preset conditions are preset correlation relationships.

3. The optimization method for improving the bonding effect of shotcrete according to claim 2, characterized in that: The process of step S32 is: S321, performing vector decomposition on the velocity of the shotcrete when it moves to the wall surface as a whole, and obtaining the vertical velocity and the horizontal velocity; S322, solving the inverse tangent function for the ratio of the vertical velocity to the horizontal velocity, and obtaining the angle θ between the shotcrete and the wall surface when the shotcrete moves as a whole to the wall surface.

4. The optimization method for improving the bonding effect of shotcrete according to claim 3, characterized in that: The specific process of step S321 is: The sprayed concrete is sprayed from the nozzle at an initial spray angle. α , initial velocity v 1 moves to a horizontal distance from the nozzle of l 1 wall, according to Newton's second law, the velocity of the shotcrete when it moves to the wall is vector-decomposed to obtain the vertical velocity v 竖直1 and horizontal speed v 水平1 They are: Here, g is the local acceleration due to gravity.

5. The optimization method for improving the bonding effect of shotcrete according to claim 4, characterized in that: The default association relationship is: Where S represents the cross-sectional area of ​​the nozzle pipe of the injection equipment, and the wall adhesion , k 1 is a fixed value.

6. The optimization method for improving the bonding effect of shotcrete according to claim 5, characterized in that: In step S4, the initial parameters of the device are adjusted to only adjust the initial spray angle between the nozzle and the horizontal plane until the adjusted spray angle meets the preset conditions.

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