A method for improving the bonding effect of shotcrete based on the spraying speed

Abstract

The present invention discloses a method for improving the bonding effect of shotcrete based on the spraying speed, constructing a correlation function between the spraying speed of the spraying equipment and the amount of concrete bonded in the wall; obtaining the porosity of the wall at the engineering construction site and the initial parameters of the equipment of the spraying equipment; inputting the initial parameters of the equipment and the porosity into the correlation function, solving the correlation function to obtain the optimal spraying speed; setting the spraying equipment according to the optimal spraying speed. By studying that when concrete is sprayed onto the wall at a certain spraying speed and collides with the wall, a part of the concrete will enter the wall, and the spraying speed will affect the amount of shotcrete entering the wall, constructing a correlation function between the spraying speed of the spraying equipment and the amount of concrete bonded in the wall, improving the bonding effect between the concrete and the wall, and reducing the rebound rate.

Description

Technical Field

[0001] The present invention relates to the technical field of shotcrete simulation calculation, and specifically relates to a method for improving the bonding effect of shotcrete based on the spraying speed. Background Art

[0002] Generally, it is considered that when shotcrete ejected from spraying equipment at a certain spraying speed moves onto a wall, the spraying speed only affects the rebound rate of the shotcrete on the wall. And generally, the greater the spraying speed, the greater the rebound rate, the more concrete rebounds from the wall, and the less the amount of concrete bonded on the wall, resulting in a poor bonding effect. Therefore, it is considered that the greater the spraying speed, the less conducive to bonding. In this analysis, it is not considered that after the concrete collides with the wall at a certain speed, part of the concrete will enter the wall and adhere to the pores in the wall, and this part is not considered in the calculation of the amount of concrete bonding. In fact, the relationship between the spraying speed and the bonding amount is not a simple linear relationship. The greater the spraying speed, the more the amount of concrete bonding, or the smaller the spraying speed, the more the amount of concrete bonding. Generally, after the concrete impacts the wall, at different spraying speeds, the depth of the concrete entering the wall is different. Naturally, the greater the speed of the concrete, the greater the depth of the concrete entering the wall. Then the space for the concrete to adhere to inside the wall becomes larger, which means that the amount of concrete entering the wall is also relatively large, and then the actual bonding amount will also increase. However, when the spraying speed reaches a certain threshold, increasing the speed further will not increase the amount of concrete bonding.

[0003] Therefore, how to reasonably set the spraying speed to reduce the waste of concrete while meeting the bonding effect is a problem to be solved. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for improving the bonding effect of shotcrete based on the spraying speed, and to increase the bonding effect of the shotcrete on the wall by reasonably setting the spraying speed of the spraying equipment.

[0005] Based on the above purpose, the present application proposes the following solutions:

[0006] A method for improving the bonding effect of shotcrete based on the spraying speed specifically includes the following steps:

[0007] S1. Construct a correlation function between the spraying speed of the spraying equipment and the amount of concrete bonding in the wall;

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

[0009] S3. Input the initial parameters of the equipment and the porosity into the correlation function, solve the correlation function, and obtain the optimal spraying speed;

[0010] S4. Set the spraying device according to the optimal spraying speed.

[0011] In some specific embodiments, the initial parameters of the device include the cross-sectional area of the nozzle pipeline of the spraying device, the horizontal distance between the nozzle and the wall, and the initial spraying angle of the nozzle with respect to the horizontal plane.

[0012] In some specific embodiments, the specific process of step S1 is as follows:

[0013] S11. Construct the first correlation relationship between the spraying speed of the shotcrete ejected from the nozzle and the angle between the overall movement of the shotcrete ejected from the nozzle and the wall when it reaches the wall. The first correlation relationship is used to solve the angle between the overall movement of the shotcrete and the wall when it reaches the wall;

[0014] S12. Construct the motion equation for the distance that the shotcrete enters the wall when it collides with the wall after moving to the wall at the spraying speed. The motion equation is used to solve the distance that the shotcrete enters the wall after colliding with the wall;

[0015] S13. Construct the correlation function between the spraying speed of the spraying device and the amount of concrete adhesion in the wall according to the first correlation relationship and the motion equation.

[0016] In some specific embodiments, the specific process of step S3 is as follows:

[0017] S31. Input the cross-sectional area S of the nozzle pipeline of the spraying device, the horizontal distance between the nozzle and the wall l 水 and the initial spraying angle a of the nozzle with respect to the horizontal plane into the first correlation relationship to obtain the angle b between the overall movement of the shotcrete and the wall when it reaches the wall;

[0018] S32. Input the initial spraying angle a of the nozzle with respect to the horizontal plane into the motion equation to solve and obtain the distance that the shotcrete enters the wall after colliding with the wall X max ;

[0019] S33. Input the angle b between the overall movement of the shotcrete and the wall when it reaches the wall, the distance that the shotcrete enters the wall after colliding with the wall X max and the porosity R of the wall into the correlation function to solve and obtain the optimal spraying speed v 喷 .

[0020] In some specific embodiments, the calculation method of the first correlation relationship is:

[0021] .

[0022] In some specific embodiments,X max The calculation method is as follows:

[0023]

[0024] Where k is a constant related to the friction coefficient of the wall.

[0025] In some specific embodiments, the correlation function f( v 喷 ) is as follows:

[0026]

[0027] Where Q represents the rebound rate and dx represents the thickness of the wall.

[0028] In some specific embodiments, before step S4, there are also steps:

[0029] S41. Calculate the concrete flow per unit time ejected from the nozzle of the spraying device according to the optimal spraying speed;

[0030] S42. Determine the moving speed of the nozzle according to the concrete flow per unit time and the preset concrete amount per unit area that can adhere to the unit area of the wall;

[0031] S43. Set the spraying device according to the optimal spraying speed and the moving speed.

[0032] In some specific embodiments, the moving speed of the nozzle determined in step S42 v 移 The calculation method is as follows:

[0033]

[0034] Where L represents the distance that the nozzle moves per unit time, v 喷 represents the optimal spraying speed, S represents the cross-sectional area of the nozzle pipeline of the spraying device, v 喷 *S represents the concrete flow per unit time; Y represents the preset concrete amount per unit area that can adhere to the unit area of the wall.

[0035] The inventive concept of the present invention is:

[0036] In the existing situation, after shotcrete is ejected from the nozzle and impacts the wall, part of the concrete adheres to the wall, part of the concrete enters the wall, and part of the concrete rebounds and drops after colliding with the wall, resulting in waste. Therefore, in the existing situation, when studying the bonding effect between shotcrete and the wall, generally, the amount of concrete that adheres to the wall after being ejected and the amount of concrete that rebounds after colliding with the wall are considered, and these two amounts are used to measure the bonding amount of shotcrete on the wall. According to this analysis process, it can be easily obtained that the greater the spraying speed, the greater the rebound rate after colliding with the wall, the more concrete rebounds from the wall, and the less the bonding amount of concrete on the wall, resulting in a poor bonding effect. However, in this analysis method, only the amount of concrete that adheres to the wall when the concrete collides with the wall is considered, and the amount of concrete that enters the wall after the concrete collides with the wall is not considered. The spraying speed obtained according to the above process cannot achieve the best bonding effect.

[0037] This application takes into account that after shotcrete moves to the wall at a certain speed and collides with the wall, part of the concrete will enter the wall due to inertia and the pores in the wall. In this way, even if the speed is a little larger, it is actually beneficial for the concrete to enter the deep part of the wall, increasing the amount of concrete that adheres to the wall, thereby improving the bonding effect. However, the spraying speed cannot be increased infinitely. Therefore, this application studies the relationship between the spraying speed and the bonding amount of concrete in the wall, and reasonably sets the spraying speed to increase the bonding effect between shotcrete and the wall.

[0038] The beneficial effects of the present invention are:

[0039] This application studies that when concrete is sprayed onto the wall at a certain spraying speed and collides with the wall, part of the concrete will enter the wall, and the spraying speed will affect the amount of shotcrete that enters the wall. A correlation function between the spraying speed of the spraying equipment and the bonding amount of concrete in the wall is constructed. By inputting the initial parameters of the equipment and data such as the porosity of the wall collected at the construction site into the correlation function, the optimal spraying speed can be obtained, and then the spraying equipment can be controlled to work at the optimal spraying speed, improving the bonding effect between the concrete and the wall and reducing the rebound rate. Description of the Drawings

[0040] Figure 1 It is a flowchart of a method for improving the bonding effect of shotcrete based on the spraying speed provided by an embodiment of the present invention;

[0041] Figure 2 It is a flowchart of constructing a correlation function between the spraying speed of the spraying equipment and the bonding amount of concrete in the wall provided by an embodiment of the present invention;

[0042] Figure 3Flowchart of the method for setting the nozzle moving speed provided by the embodiments of the present invention. Detailed implementation manners

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. The description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

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

[0045] Meanwhile, it should be understood that, for the sake of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships.

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

[0047] The techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and devices should be regarded as part of the authorization specification.

[0048] In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0049] Embodiment 1

[0050] As Figure 1 shown, this embodiment provides a method for improving the bonding effect of shotcrete based on the spraying speed, specifically including the following steps:

[0051] S1. Establish an association function between the spraying speed of the spraying device and the amount of concrete bonded in the wall;

[0052] As Figure 2 shown, the specific process of step S1 is as follows:

[0053] S11. Construct the first correlation relationship between the spraying speed of the shotcrete ejected from the nozzle and the angle between the overall movement of the shotcrete ejected from the nozzle and the wall when it reaches the wall. The first correlation relationship is used to solve the angle between the overall movement of the shotcrete and the wall when it reaches the wall;

[0054] S12. Construct the motion equation of the distance that the shotcrete enters the wall after colliding with the wall when it moves to the wall at the spraying speed. The motion equation is used to solve the distance that the shotcrete enters the wall after colliding with the wall;

[0055] S13. Construct the correlation function between the spraying speed of the spraying equipment and the amount of concrete adhesion in the wall according to the first correlation relationship and the motion equation.

[0056] S2. Obtain the porosity of the wall at the engineering construction site and the initial parameters of the spraying equipment;

[0057] The initial parameters of the equipment include the cross-sectional area of the nozzle pipeline of the spraying equipment, the horizontal distance between the nozzle and the wall, and the initial spraying angle of the nozzle with the horizontal plane.

[0058] S3. Input the initial parameters of the equipment and the porosity into the correlation function, solve the correlation function, and obtain the optimal spraying speed;

[0059] The specific process of step S3 is as follows:

[0060] S31. Input the cross-sectional area S of the nozzle pipeline of the spraying equipment, the horizontal distance l 水 between the nozzle and the wall, and the initial spraying angle a of the nozzle with the horizontal plane into the first correlation relationship to obtain the angle b between the overall movement of the shotcrete and the wall when it reaches the wall;

[0061] The calculation method of the first correlation relationship is:

[0062] 。

[0063] S32. Input the initial spraying angle a of the nozzle with the horizontal plane into the motion equation to solve and obtain the distance X max ;

[0064] X max The calculation method of is:

[0065]

[0066] where k is a constant related to the friction coefficient of the wall.

[0067] S33. The angle b between the overall movement of the shotcrete and the wall when it reaches the wall, and the distance that the shotcrete enters the wall after colliding with the wall X max , the porosity R of the wall is input into the correlation function, and the optimal spraying speed is obtained by solving v 喷 .

[0068] The correlation function f( v 喷 ) is as follows:

[0069]

[0070] Among them, Q represents the rebound rate, and dx represents the thickness of the wall.

[0071] S4. Set the spraying equipment according to the optimal spraying speed.

[0072] Embodiment 2

[0073] The difference between this Embodiment 2 and Embodiment 1 is that when the nozzle sprays shotcrete, it does not spray statically at one position. The nozzle moves and sprays at a certain speed according to a set path, and it is necessary to ensure that the amount of concrete received by each area after the concrete is sprayed on the wall is uniform. The amount of concrete sprayed on the wall is not only related to the spraying speed of the concrete, but also related to the moving speed of the nozzle. Therefore, after obtaining the optimal spraying speed, it is also necessary to further set the moving speed of the nozzle. As Figure 3 shown, the method for setting the moving speed of the nozzle is as follows:

[0074] S41. Calculate the concrete flow rate per unit time sprayed by the nozzle of the spraying equipment per unit time according to the optimal spraying speed v 喷 *S;

[0075] S42. Determine the moving speed of the nozzle according to the concrete flow rate per unit time and the preset amount of concrete that can be bonded per unit area on the wall per unit area;

[0076] S43. Set the spraying equipment according to the optimal spraying speed and the moving speed.

[0077] In some specific implementation schemes, step S42 determines the moving speed of the nozzle v 移 The calculation method is as follows:

[0078]

[0079] Among them, L represents the distance that the nozzle moves per unit time, v 喷represents the optimal injection speed, S represents the cross-sectional area of the nozzle pipe of the injection device, v 喷 *S represents the concrete flow rate per unit time; Y represents the preset amount of concrete per unit area that can be bonded per unit area of the wall.

[0080] It can be understood that in order to obtain the first correlation relationship between the injection speed of the shotcrete ejected from the nozzle and the angle between the overall movement of the shotcrete ejected from the nozzle to the wall and the wall in the above-mentioned embodiments, the following is the specific derivation process:

[0081] Assume that the horizontal distance between the nozzle and the wall is l 水 , and the angle between the nozzle and the horizontal plane is a. Assume that the speed of the shotcrete when it is ejected from the nozzle is v 喷 , the cross-sectional area of the concrete ejected from the nozzle is S, and the ejected concrete is regarded as a cylinder. Generally, it is considered that when the shotcrete impacts the wall, the magnitude of the speed should be controlled, and the depth to which the shotcrete can enter the wall determines whether it can finally adhere to the wall. Therefore, only the horizontal speed is considered after the impact, and the vertical speed is not considered. According to Newton's second law, it is not difficult to obtain that when the overall movement of the shotcrete reaches the wall, the horizontal speed v 水 and the vertical speed are respectively:

[0082] ,

[0083]

[0084] (where g is the local acceleration due to gravity, generally taken as )

[0085] The calculation idea of the above horizontal speed is that since the shotcrete is mainly affected by gravity work from being ejected to hitting the wall, however, the work done by gravity does not affect the horizontal speed, so the horizontal speed v 喷 *cos a, for the calculation of the vertical speed, it can be calculated according to the calculation method of the oblique projectile motion with the known horizontal distance. Further, according to the horizontal speed and vertical speed of the concrete when it reaches the wall, the angle with the wall surface can be obtained as b:

[0086]

[0087] Assume that the wall is vertically placed, then the contact area between the concrete and the wall at this time is (S is the cross-sectional area of the concrete, and S is a fixed value related to the cross-sectional area of the pipeline). When the sprayed concrete impacts the wall, since the hardness of the wall can be regarded as extremely high, that is, the behavior of the concrete impacting the wall will not cause the wall to displace.

[0088] Then, the sprayed concrete fluid is regarded as countless micro-elements for analysis to examine the motion of each micro-element after contacting the wall surface. After the micro-element contacts the wall, there will be collisions and frictions with the wall. The collision of the micro-element with the wall only changes the direction of the micro-element's velocity and does not reduce the energy of the micro-element. However, after the micro-element penetrates into the wall, the friction with the wall will cause kinetic energy loss. The study believes that during the impact of the sprayed concrete with the wall, the depth of penetration into the wall is extremely small compared to the thickness of the entire wall. Therefore, it can be considered that the part of the sprayed concrete in contact with the wall has uniform pores and consistent other properties such as strength and hardness. According to the common sense of physical mechanics, the frictional force received by a moving object is positively correlated with its mass. In this study, the concrete sprayed into the wall will generate a frictional force with the contacting wall. Therefore, it can be considered that the frictional force exerted by the wall on the moving concrete micro-element (with a mass of m) is k*m, where k is a constant related to the properties of the sprayed concrete and the wall itself.

[0089] If it is assumed that the maximum depth of penetration of a certain micro-element into the wall is X, since only the frictional force will do work during the movement of the concrete in the wall and it does negative work, so when the frictional force of the wall does work

[0090] at this time,

[0091] where m is the mass of the micro-element. This is because the maximum depth of the micro-element in the wall is X, and then the sum of the horizontal distances of the micro-element from entering the wall to leaving the wall does not exceed 2X, and the work done by the frictional force on this distance cannot offset all the kinetic energy of the micro-element. In this way, the micro-element will leave the wall.

[0092] Now consider the maximum depth after the micro-element enters the wall. When the micro-element reaches the maximum displacement in the wall, if the speed does not decrease to 0 at this moment, it means that the micro-element has rebounded due to collision at this moment. Since as long as the micro-element collides in the wall, its speed will reverse. So this collision point is the maximum displacement point.

[0093] Since the part of the wall involved in the motion is uniform, the concept of the rebound rate Q is defined: in a partial area of the wall with a thickness of dx, the total mass of the concrete that collides divided by the sum of the mass of the concrete that passes through plus the mass of the concrete that collides.

[0094] Referring to the calculation method of probability theory, the amount of concrete that can reach a depth of X in the wall accounts for the total amount of the injected concrete as , the total injection volume is calculated by multiplying the sum of the volumes of the pores in all the walls contacted during the collision process by the density of the shotcrete. The principle is that if the volume of the concrete hitting the wall exceeds the sum of the volumes of all the pores in the wall contacted during the impact process, then after the concrete fills all the pores in the wall, the remaining part will not enter the wall (because there is no space for them to occupy), so the total injection volume is considered to be the total pore volume passed through by the concrete during its movement.

[0095] Define the wall porosity R as the volume of pores per unit volume of the wall. Then the pore volume for the entire collision process is . Among them X max is defined as the maximum depth of entry among all the shotcrete entering the wall. When the horizontal displacement of a certain microelement in the wall reaches X max , at this time its velocity must be 0, then the kinetic energy throughout the process is consumed by the work done by friction. From the mechanical energy conservation equation, we can know that:

[0096]

[0097]

[0098] So the amount of concrete finally bonded in the wall is:

[0099] .

[0100] Among them, the method for determining R is to take out a part of the wall and measure its porosity according to the relevant standard methods. To ensure the accuracy of the measured results, several groups should be taken for experiments.

[0101] In engineering practice, the coefficient k of the wall, the porosity Q of the wall, the nozzle spraying angle a, and the horizontal distance of the nozzle from the wall should be determined first l 水 , input these fixed quantities into the computer, and according to

[0102]

[0103]

[0104] calculate the v 喷 that makes the value of this formula the largest. This is the recommended optimal spraying speed in this case. Here m is the mass of the microelement.

[0105] However, since the spraying speed is to ensure that the most concrete adheres to the wall, that is, the maximum amount of concrete adhesion, the optimal spraying speed is such that the wall can adhere to the maximum amount of concrete. If you want to change the amount of concrete sprayed on the wall, you can only start from the nozzle moving speed. Assume that the expected amount of concrete per unit area that can adhere to the wall per unit area is Y (even if the change in spraying speed causes a change in flow rate, ensure that the amount of concrete received in each area is the same as expected).

[0106] Assume that in actual engineering, it is necessary to spray concrete with an amount of Y per square meter area on the wall. In the previous description, in order to achieve the maximum possible adhesion amount of concrete on the wall, an optimal speed v was selected 喷 , then the flow rate of the sprayed concrete can be expressed as v 喷 *S. Assume that the nozzle moves a distance of L within a unit time T, then T = L / v 移 , then within this distance, the amount of sprayed concrete received per unit area is L*v 喷 *S / v 移 , when L, S, and v 最佳 are all fixed, the amount of concrete received per unit area can be made equal to the expected value of the project by changing the nozzle moving speed.

[0107] The above is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Based on the technical essence of the present invention, within the spirit and principle of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for improving the bonding effect of shotcrete based on injection speed, characterized in that, Specifically, it includes the following steps: S1. Construct a correlation function between the spraying speed of the spraying equipment and the amount of concrete adhesion in the wall; The specific process of step S1 is as follows: S11. Construct a first correlation relationship between the spraying speed of the sprayed concrete ejected from the nozzle and the angle between the whole movement of the sprayed concrete ejected from the nozzle to the wall and the wall, and the first correlation relationship is used to solve the angle between the whole movement of the sprayed concrete to the wall and the wall; S12. Construct a motion equation for the distance that the sprayed concrete enters the wall when it collides with the wall after moving to the wall at the spraying speed, and the motion equation is used to solve the distance that the sprayed concrete enters the wall after colliding with the wall; S13. Construct a correlation function between the spraying speed of the spraying equipment and the amount of concrete adhesion in the wall according to the first correlation relationship and the motion equation; S2. Obtain the porosity of the wall at the construction site of the project and the initial parameters of the spraying equipment; S3. Input the initial parameters of the equipment and the porosity into the correlation function, solve the correlation function, and obtain the optimal spraying speed; The initial parameters of the equipment include the cross-sectional area of the nozzle pipeline of the spraying equipment, the horizontal distance between the nozzle and the wall, and the initial spraying angle between the nozzle and the horizontal plane; The specific process of step S3 is as follows: S31. Input the cross-sectional area S of the nozzle pipeline of the spraying device, the horizontal distance of the nozzle from the wall l 水 and the initial spraying angle α of the nozzle with the horizontal plane into the first correlation relationship to obtain the angle b between the sprayed concrete as a whole and the wall when it moves to the wall; S32. Input the initial injection angle α between the nozzle and the horizontal plane into the motion equation to solve for the distance that the shotcrete enters the wall after colliding with the wall. X max ; S33. The angle b between the overall movement of the shotcrete and the wall when it reaches the wall, and the distance that the shotcrete enters the wall after colliding with the wall X max . Input the porosity R of the wall into the correlation function to solve for the optimal spraying speed v 喷 ; S4. Set the spraying equipment according to the optimal spraying speed.

2. A method for improving the bonding effect of shotcrete based on the injection speed, characterized in that, The calculation method of the first correlation relationship is: 。 3. A method for improving the bonding effect of shotcrete based on the injection speed according to claim 1, characterized in that, X max The calculation method is as follows: where k is a constant related to the friction coefficient of the wall.

4. A method for improving the bonding effect of shotcrete based on injection speed according to claim 1, characterized in that, Associated function f( v 喷 ) is as follows: where Q represents the rebound rate and dx represents the thickness of the wall.

5. A method for improving the bonding effect of shotcrete based on the injection speed, characterized in that, Before step S4, there is also a step: S41. Calculate the concrete flow rate per unit time ejected from the nozzle of the spraying equipment per unit time according to the optimal spraying speed; S42. Determine the moving speed of the nozzle according to the concrete flow rate per unit time and the preset amount of concrete that can be adhered per unit area on the unit area of the wall; S43. Set the spraying equipment according to the optimal spraying speed and the moving speed.

6. A method for improving the bonding effect of shotcrete based on the injection speed, characterized in that, Step S42 determines the moving speed of the nozzle v 移 The calculation method is as follows: where, L represents the distance that the nozzle moves within a unit time, v 喷 represents the optimal spraying speed, S represents the cross-sectional area of the nozzle pipeline of the spraying device, v 喷 *S represents the concrete flow rate per unit time; Y represents the preset amount of concrete per unit area that can be adhered to per unit area of the wall.

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