Crawler crane load-based roadbed box construction method

Abstract

This invention provides a method for constructing roadbed boxes based on crawler crane load, comprising: obtaining the maximum load on one side of the target crane's crawler track, and obtaining the maximum stress at the bottom of the crawler track based on the maximum load; comparing the maximum stress with the bearing capacity of the foundation in the target area and obtaining a first comparison result; predicting the number of roadbed box layers to be laid on the foundation based on this result, and obtaining the maximum ground stress at the bottom of the roadbed box; comparing the maximum ground stress with the foundation bearing capacity and obtaining a second comparison result, and adjusting the number of roadbed box layers to be laid on the foundation based on this result until the maximum ground stress at the bottom of the roadbed box is less than the foundation bearing capacity, thus determining the actual number of roadbed box layers; and constructing the roadbed boxes according to the actual number of layers. The maximum ground stress distribution of the roadbed boxes obtained using this invention is closer to the actual engineering situation, and the determined roadbed box laying method is also more accurate.

Description

Technical Field

[0001] This invention relates to the field of steel structure construction technology, and more specifically, to a method for constructing roadbed boxes based on crawler crane load. Background Technology

[0002] With the rapid development of the construction industry, the application scope of large steel structures continues to expand, and the size and weight of their components are showing a significant upward trend. This also gradually increases the requirements for the lifting capacity of crawler cranes. During construction, crawler cranes are often equipped with roadbed boxes to reduce ground stress and ensure that they do not overturn. There are various ways to lay roadbed boxes. To determine the appropriate crawler crane laying method for different types of crawler cranes, it is necessary to determine the ground stress at the bottom of the roadbed box under the load of the crawler crane.

[0003] Currently, when using crawler cranes for construction, the common method for laying roadbed boxes is to lay a single layer of roadbed boxes perpendicular to the length of the crawler track. When a single layer of roadbed boxes cannot meet the bearing capacity requirements of the foundation, a two-layer roadbed box is used. The lower layer is laid in the same way as the single layer, while the upper layer is laid with the length of the roadbed box parallel to the crawler track.

[0004] It is known that the determination of the grounding stress at the bottom of the existing roadbed box is usually a simplified algorithm. It often directly adds the total weight of the crawler crane to the lifting weight and divides it by the bottom area of ​​the roadbed box under one side of the crawler to obtain the grounding stress. The stress parameters obtained by this method have a large deviation from the actual values.

[0005] Therefore, there is an urgent need for a stress calculation scheme for roadbed boxes under crawler crane loads, so as to determine the grounding stress at the bottom of the roadbed box more accurately and improve construction safety. Summary of the Invention

[0006] In view of the above problems, the purpose of this invention is to provide a roadbed box construction method based on crawler crane load, so as to solve the problems of poor accuracy in existing roadbed box laying schemes.

[0007] The present invention provides a method for constructing roadbed boxes based on crawler crane load, comprising: Step 1: Obtain the maximum load on one side of the track of the target crane, and obtain the maximum stress at the bottom of the track on one side based on the maximum load; Step 2: Compare the maximum stress with the bearing capacity of the foundation in the target area and obtain the first comparison result; Step 3: Based on the first comparison result, predict the number of roadbed boxes that need to be laid on the foundation, and obtain the maximum grounding stress at the bottom of the roadbed box according to the predicted number of roadbed box laying layers; Step 4: Compare the maximum grounding stress with the foundation bearing capacity numerically, and obtain a second comparison result; Step 5: Adjust the number of roadbed boxes to be laid on the foundation according to the second comparison result, and repeat Step 3 and Step 4 above until the maximum ground stress at the bottom of the roadbed box is less than the bearing capacity of the foundation, and determine the actual number of roadbed box layers. Step Six: Carry out the roadbed box laying construction according to the actual number of laying layers.

[0008] Alternatively, an optional technical solution is to obtain the maximum stress at the bottom of a single track based on the maximum load, including: Obtain the lifting parameters, maximum lifting weight, and operating radius of the target crane; Based on the maximum load, the lifting parameters, the maximum lifting weight, and the operating radius, the maximum stress at the bottom of the single-sided track is determined.

[0009] Alternatively, the lifting parameters may include track bottom area, lifting speed, dynamic load coefficient, safety redundancy, and construction counterweight.

[0010] In addition, an optional technical solution is to obtain the maximum grounding stress at the bottom of the roadbed box, including: establishing a unit model of the roadbed box using finite element analysis software; The maximum stress at the bottom of the single-sided track is set on the top plate of the unit model, and an elastic constraint support is set on the bottom plate of the unit model. Based on the maximum stress at the bottom of the single-sided track and the stiffness of the elastic constraint support, the maximum grounding stress at the bottom of the roadbed box is determined using the finite element analysis software.

[0011] In addition, an optional technical solution is to predict the number of layers of roadbed boxes that need to be laid on the foundation based on the first comparison result, including: Obtain the difference between the maximum stress and the foundation bearing capacity; When the difference is less than a preset threshold, the predicted number of roadbed box layers is determined to be one layer; otherwise, when the difference is not less than the preset threshold, the predicted number of roadbed box layers is determined to be two layers.

[0012] In addition, an optional technical solution is that when the actual number of layers of the roadbed box is greater than the preset number of layers, it also includes: changing the hoisting scheme, reducing the hoisting weight or the working radius, or performing special treatment on the foundation.

[0013] Alternatively, the special treatment may include compacting the foundation with grout, reinforcing it, or applying dynamic compaction.

[0014] In addition, an alternative technical solution is that when the number of roadbed boxes is not less than two layers, the distribution patterns of adjacent roadbed boxes are different.

[0015] Alternatively, the technical solution is to rigidly connect two adjacent roadbed boxes in the Z-axis direction and elastically connect them in the X and Y-axis directions.

[0016] In addition, alternatively, the distribution method may include horizontal, vertical, and diagonal.

[0017] By utilizing the above-mentioned construction method for roadbed boxes based on crawler crane load, the influence of the roadbed box and the bearing capacity of the foundation can be fully considered. The maximum ground stress distribution of the roadbed box obtained is closer to the actual engineering situation. Based on this, the laying method of the roadbed box can be determined more accurately, thereby ensuring the construction safety and accuracy of the crawler crane and reducing unnecessary waste of manpower and material resources.

[0018] To achieve the foregoing and related objectives, one or more aspects of the invention include the features that will be described in detail below. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0019] Other objects and results of the invention will become more apparent and readily understood with reference to the following description taken in conjunction with the accompanying drawings. In the drawings: Figure 1 This is a schematic flowchart of a roadbed box construction method based on crawler crane load according to an embodiment of the present invention; Figure 2 A schematic diagram illustrating the principle of laying a layer of roadbed box according to the roadbed box construction method based on crawler crane load according to an embodiment of the present invention; Figure 3 A schematic diagram illustrating the principle of laying two layers of roadbed boxes according to the roadbed box construction method based on crawler crane load according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the roadbed box according to an embodiment of the present invention; Figure 5 This is a detailed flowchart of a roadbed box construction method based on crawler crane load according to an embodiment of the present invention.

[0020] Reference numerals: 1. Roadbed box; 2. Track; 3. Roadbed box; 11. Roadbed box top plate; 12. Roadbed box bottom plate. Detailed Implementation

[0021] In the following description, numerous specific details are set forth for illustrative purposes and to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may also be implemented without these specific details. In other instances, well-known structures and devices are shown in block diagram form for ease of description of one or more embodiments.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate structural component; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] To describe in detail the roadbed box construction method based on crawler crane load provided by the present invention, it will be described in detail below with reference to the accompanying drawings.

[0024] Figure 1 A schematic flow diagram of a roadbed box construction method based on crawler crane load according to an embodiment of the present invention is shown; as shown in Figures 2 to 3. Figure 4 The schematic principles of the roadbed box construction method based on crawler crane load according to embodiments of the present invention are shown from different perspectives.

[0025] like Figures 1 to 4 As shown in the figure, the roadbed box construction method based on crawler crane load in this embodiment of the invention includes the following steps: Step 1 (S100): Obtain the maximum load on one side of the track of the target crane, and obtain the maximum stress at the bottom of the track on one side based on the maximum load.

[0026] Specifically, firstly, the lifting parameters, maximum lifting weight, and operating radius of the target crane are obtained. Then, based on the maximum load, lifting parameters, maximum lifting weight, and operating radius, the maximum stress on the bottom of one side of the track is determined. The lifting parameters include the track bottom area, lifting speed, dynamic load coefficient, safety redundancy, and construction counterweight.

[0027] After determining the maximum stress at the bottom of one side of the track, it is possible to determine whether the current foundation can meet the construction requirements of the crawler crane based on the bearing capacity of the foundation supporting the target crane. If the construction requirements cannot be met, the bearing capacity of the foundation can be further adjusted, such as by adding a roadbed box, or by adjusting the lifting of the target crane, such as by reducing the operating radius and controlling the lifting weight.

[0028] Step 2 (S200): Compare the maximum stress with the bearing capacity of the foundation in the target area and obtain the first comparison result.

[0029] After determining the maximum stress at the bottom of a single track, it can be compared with the bearing capacity of the foundation in the target area of ​​the crane's operation to determine the relationship between the maximum stress and the foundation bearing capacity, thus ensuring the safety of subsequent construction.

[0030] Step 3 (S300): Based on the first comparison result, predict the number of roadbed boxes that need to be laid on the foundation, and obtain the maximum grounding stress at the bottom of the roadbed box according to the predicted number of roadbed box laying layers.

[0031] Specifically, the number of roadbed boxes can be 0, 1, 2… natural numbers. For example, if the first comparison result shows that the foundation bearing capacity is greater than the maximum stress at the bottom of one side of the track, it means that the current roadbed can meet the construction requirements of the crawler crane. In this case, the number of roadbed box layers is 0, meaning that the lifting operation can be carried out directly by the crane without laying additional roadbed boxes. Otherwise, if the maximum stress at the bottom of one side of the track is not less than the foundation bearing capacity, it means that the roadbed in the current target area cannot meet the construction requirements of the crawler crane, and the bearing capacity of the foundation needs to be adjusted.

[0032] As a specific example, predicting the number of roadbed boxes to be laid on the foundation based on the first comparison result may further include: obtaining the difference between the maximum stress and the foundation bearing capacity. Since no additional roadbed boxes are needed when the foundation bearing capacity is greater than the maximum stress, this difference mainly represents the difference between the foundation bearing capacity and the maximum stress. When the difference is less than a preset threshold, it indicates that the range of roadbed bearing capacity adjustment is small, and the predicted number of roadbed box layers can be determined to be one layer. Otherwise, when the difference is not less than the preset threshold, it indicates that the range of roadbed box bearing capacity adjustment is large, and the predicted number of roadbed box layers can be determined to be two layers. By setting the preset threshold, the number of roadbed box layers can be directly predicted, and then the predicted number of layers can be verified, avoiding the process of adding roadbed boxes layer by layer and verifying them, and reducing unnecessary roadbed box laying calculations.

[0033] Step 4 (S400): Compare the maximum grounding stress with the foundation bearing capacity numerically, and obtain a second comparison result.

[0034] This step mainly involves obtaining the maximum ground stress at the bottom of the roadbed box based on the predicted number of roadbed box laying layers, and then comparing the maximum ground stress with the foundation bearing capacity to obtain a second comparison result. If the second comparison result meets the requirements of crawler crane construction, that is, the maximum ground stress is less than the foundation bearing capacity, it means that the prediction of the number of roadbed box laying layers is correct, and the roadbed box can be laid directly according to this number of layers for hoisting operations. Otherwise, it means that the number of roadbed box laying layers needs to be adjusted.

[0035] Step 5 (S500): Adjust the number of roadbed boxes to be laid on the foundation according to the second comparison result, and repeat Step 3 and Step 4 above until the maximum ground stress at the bottom of the roadbed box is less than the bearing capacity of the foundation, and determine the actual number of roadbed box layers. Step 6 (S600): Carry out the roadbed box laying construction according to the actual number of laying layers.

[0036] In addition, in obtaining the maximum grounding stress at the bottom of the roadbed box, a unit model of the roadbed box is established using finite element analysis software. Then, the maximum stress at the bottom of the track on one side is set or applied on the top plate (top plate of the roadbed box) of the unit model, and an elastic constraint support is set on the bottom plate (floor plate of the roadbed box) of the unit model. The stiffness of the elastic constraint support can be calculated based on the machine tool coefficient obtained from engineering measurements. Finally, based on the maximum stress at the bottom of the track on one side and the stiffness of the elastic constraint support, the maximum grounding stress at the bottom of the roadbed box is determined using finite element analysis software.

[0037] By constructing a unit model of the roadbed box and using finite element analysis software for mechanical analysis, not only can the accuracy and efficiency of calculation be improved, but also the maximum ground stress parameter at the bottom of the roadbed box can be directly obtained without the need for manual conversion or calculation of parameters such as load, stress, and stiffness.

[0038] It should be noted that, based on the second comparison results, the number of roadbed boxes to be laid on the foundation is adjusted, and steps three and four above are repeated until the maximum ground stress at the bottom of the roadbed box is less than the bearing capacity of the foundation, thus determining the actual number of roadbed box layers. However, as the number of roadbed box layers increases, the corresponding construction cost also increases, and the lifting operation of the crawler crane does not allow for an unlimited increase in the number of roadbed boxes.

[0039] Therefore, in the roadbed box construction method based on crawler crane load in this embodiment of the invention, a preset number of layers is set. When the actual number of roadbed box layers exceeds the preset number, other methods besides increasing the number of roadbed box layers can be used to handle the situation, such as changing the hoisting scheme, reducing the hoisting weight or operating radius, or performing special treatment on the foundation. The preset number of layers can be set to 2 or 3 layers, etc., depending on the construction site and the size of the roadbed box.

[0040] Specifically, the aforementioned special treatment of the foundation includes operations such as compaction grouting, reinforcement, or dynamic compaction to increase the overall structural strength of the foundation and improve its bearing capacity.

[0041] Furthermore, in one specific embodiment of the present invention, when the number of roadbed boxes is not less than two layers, the distribution of adjacent roadbed boxes is different. The adjacent roadbed boxes are rigidly connected in the Z-axis direction and elastically connected in the X and Y-axis directions to improve the accuracy of the unit model and make the finite element analysis software more closely resemble the actual construction situation during the processing.

[0042] The difference in the distribution of adjacent layers of roadbed boxes mainly refers to the difference in their arrangement. For example, when one layer of roadbed boxes is arranged laterally, the adjacent layer can be arranged longitudinally or diagonally to improve the overall stability and strength of the roadbed boxes. These distribution methods include laterally, longitudinally, and diagonally.

[0043] As a specific example Figure 5 A detailed flowchart of a roadbed box construction method based on crawler crane load according to an embodiment of the present invention is shown.

[0044] like Figure 5 As shown, the roadbed box construction method based on crawler crane load in this embodiment includes: 1. Obtain the maximum load on one side of the crawler crane (i.e., crawler 2). The maximum stress P0 at the bottom of the crawler can be obtained through mechanical calculation based on the actual selection of the crawler crane, the maximum lifting weight, and the working radius.

[0045] 2. Compare the maximum stress P0 at the bottom of a single track with the bearing capacity of the foundation [P].

[0046] If the maximum stress P0 at the bottom of a single track is less than the bearing capacity of the foundation [P], it indicates that the current bearing capacity of the foundation meets the hoisting requirements. In this case, the roadbed box does not need to be laid and the hoisting operation can be carried out directly. If the maximum stress P0 at the bottom of a single track is not less than the bearing capacity of the foundation [P], then the calculation should be performed first based on laying one layer of roadbed box to see if it can meet the requirements of the hoisting operation.

[0047] 3. Calculate the grounding stress P1 when laying one layer of roadbed box: (1) First, establish the element model of the first-layer roadbed box 1 using finite element analysis software; (2) Set the maximum stress P0 at the bottom of the track on one side on the top plate 11 of the roadbed box; (3) An elastic constraint support is set on the bottom plate 12 of the roadbed box. The stiffness of the elastic constraint support is calculated based on the subgrade coefficient obtained by engineering measurement. (4) Run the finite element analysis software and, based on the maximum stress P0 at the bottom of the single track and the elastic constraint support, obtain the maximum grounding stress P1 at the bottom of the roadbed box.

[0048] 4. Compare the maximum ground stress P1 at the bottom of the roadbed box obtained in step 3 with the foundation bearing capacity [P]: (1) If the maximum ground stress P1 at the bottom of the roadbed box is less than the bearing capacity of the foundation [P], it indicates that the bearing capacity of the current roadbed box can meet the hoisting requirements. In this case, no additional roadbed box is required, and hoisting operations can be carried out directly on the basis of the first roadbed box. (2) If the maximum ground stress P1 at the bottom of the roadbed box is not greater than the bearing capacity of the foundation [P], then two layers of roadbed boxes need to be laid and the calculation should be performed.

[0049] 5. Calculate the grounding stress P2 when laying two layers of roadbed boxes: (1) Using finite element analysis software, first establish a unit model of two-layer roadbed boxes (a certain gap is left between the two-layer roadbed boxes, including the roadbed box 1 located in the lower layer and the roadbed box 3 located in the upper layer). (2) The connection between the two roadbed boxes includes rigid connection in the Z-axis direction and elastic connection in the X-axis and Y-axis directions. The stiffness of the elastic connection depends on the coefficient of friction. (3) Set the maximum stress P0 at the bottom of the track on one side on the top plate 11 of the upper roadbed box; (4) An elastic constraint support is set on the bottom plate 12 of the lower roadbed box. The stiffness of the elastic constraint support is calculated based on the subgrade coefficient obtained by engineering measurement. (5) Run the finite element analysis software and obtain the maximum grounding stress P2 at the bottom of the roadbed box.

[0050] 6. Compare the maximum ground stress P2 at the bottom of the roadbed box obtained in step 5 with the bearing capacity of the foundation [P]: (1) If the maximum ground stress P2 at the bottom of the roadbed box ② is less than the bearing capacity of the foundation [P], it indicates that the plan of laying two layers of roadbed boxes is feasible. At this time, the on-site construction can be carried out according to the plan of two layers of roadbed boxes, and the hoisting operation can be carried out on the basis of the two layers of roadbed boxes after construction. (2) If the maximum ground stress P2 at the bottom of the roadbed box is not less than the bearing capacity of the foundation [P], it means that the load-bearing capacity of the two roadbed boxes is still insufficient to meet the requirements of the hoisting operation. In this case, the measures shown in step 7 can be taken to solve the problem. In other words, the number of roadbed boxes can be increased, or other methods can be used besides increasing the number of roadbed box layers, such as changing the hoisting plan, reducing the hoisting weight or the working radius, or performing special treatment on the foundation.

[0051] Step 7: If laying two layers of roadbed boxes still cannot meet the foundation bearing capacity requirements, the following measures can be taken: (1) Continue to increase the number of roadbed boxes to reduce ground stress. (2) Change the crane scheme, reduce the lifting weight or working radius, and make the crane load distribution more uniform. (3) Perform special treatment on the foundation (such as compaction grouting, etc.) to improve the foundation bearing capacity, etc.

[0052] It is known that the choice of roadbed box laying method under crawler crane load depends on whether the ground stress at the bottom of the roadbed box exceeds the bearing capacity limit of the foundation. After the crawler crane load is transferred to the roadbed box, the ground stress at the bottom of the roadbed box may be unevenly distributed and locally excessive under the combined action of the roadbed box stiffness and the elastic foundation. According to the roadbed box construction method based on crawler crane load provided by the present invention, the influence of roadbed box stiffness and foundation stiffness on ground stress distribution can be fully considered. The obtained ground stress distribution is closer to the actual engineering situation. The obtained maximum ground stress is also more accurate when used to evaluate the bearing capacity of the foundation. It not only has a small amount of calculation but also higher accuracy, and can be applied to crawler hoisting operations in various construction scenarios.

[0053] The method for constructing roadbed boxes based on tracked crane load according to the present invention has been described above by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various modifications can be made to the method for constructing roadbed boxes based on tracked crane load according to the present invention without departing from the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the contents of the appended claims.

Claims

1. A method for constructing roadbed boxes based on crawler crane load, characterized in that, include: Step 1: Obtain the maximum load on one side of the track of the target crane, and obtain the maximum stress at the bottom of the track on one side based on the maximum load; Step 2: Compare the maximum stress with the bearing capacity of the foundation in the target area and obtain the first comparison result; Step 3: Based on the first comparison result, predict the number of roadbed boxes that need to be laid on the foundation, and obtain the maximum grounding stress at the bottom of the roadbed box according to the predicted number of roadbed box laying layers; Step 4: Compare the maximum grounding stress with the foundation bearing capacity numerically, and obtain a second comparison result; Step 5: Adjust the number of roadbed boxes to be laid on the foundation according to the second comparison result, and repeat Step 3 and Step 4 above until the maximum ground stress at the bottom of the roadbed box is less than the bearing capacity of the foundation, and determine the actual number of roadbed box layers. Step Six: Carry out the roadbed box laying construction according to the actual number of laying layers.

2. The method for constructing roadbed boxes based on crawler crane load as described in claim 1, characterized in that, The maximum stress at the bottom of a single track is obtained based on the maximum load, including: Obtain the lifting parameters, maximum lifting weight, and operating radius of the target crane; Based on the maximum load, the lifting parameters, the maximum lifting weight, and the operating radius, the maximum stress at the bottom of the single-sided track is determined.

3. The method for constructing roadbed boxes based on crawler crane load as described in claim 2, characterized in that, The lifting parameters include track bottom area, lifting speed, dynamic load coefficient, safety redundancy, and construction counterweight.

4. The method for constructing roadbed boxes based on crawler crane load as described in claim 1, characterized in that, Obtaining the maximum grounding stress at the bottom of the roadbed box includes: A unit model of the roadbed box was established using finite element analysis software; The maximum stress at the bottom of the single-sided track is set on the top plate of the unit model, and an elastic constraint support is set on the bottom plate of the unit model. Based on the maximum stress at the bottom of the single-sided track and the stiffness of the elastic constraint support, the maximum grounding stress at the bottom of the roadbed box is determined using the finite element analysis software.

5. The method for constructing roadbed boxes based on crawler crane load as described in claim 1, characterized in that, Based on the first comparison results, the number of roadbed boxes that need to be laid on the foundation is predicted, including: Obtain the difference between the maximum stress and the foundation bearing capacity; When the difference is less than a preset threshold, the predicted number of roadbed box layers is determined to be one layer; otherwise, when the difference is not less than the preset threshold, the predicted number of roadbed box layers is determined to be two layers.

6. The method for constructing roadbed boxes based on crawler crane load as described in claim 1, characterized in that, When the actual number of layers of the roadbed box is greater than the preset number of layers, the method also includes: changing the hoisting scheme, reducing the hoisting weight or the working radius, or performing special treatment on the foundation.

7. The method for constructing roadbed boxes based on crawler crane load as described in claim 6, characterized in that, The special treatments include compaction grouting, reinforcement, or dynamic compaction of the foundation.

8. The method for constructing roadbed boxes based on crawler crane load as described in claim 1, characterized in that, When the number of roadbed boxes is not less than two, the distribution patterns of adjacent roadbed boxes are different.

9. The method for constructing roadbed boxes based on crawler crane load as described in claim 8, characterized in that, The adjacent roadbed boxes are rigidly connected in the Z-axis direction and elastically connected in the X and Y-axis directions.

10. The method for constructing roadbed boxes based on crawler crane load as described in claim 8, characterized in that, The distribution methods include horizontal, vertical, and diagonal.

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