Method for dividing pile end resistance and side friction in pile driving based on pile driving record

Abstract

The application discloses a method for dividing the end resistance and side friction of a pile foundation in a piling process based on piling records, and the method comprises the following steps: obtaining a curve of the hammering number changing with the depth in the piling process according to the field piling records; obtaining a curve of the relationship between the hammering number and the soil resistance; obtaining a curve of the soil resistance changing with the depth in the piling process by using the two curves; determining the upper and lower envelope lines of the curve of the soil resistance changing with the depth; drawing a straight line through the (0, 0) point and the lowest point of the lower envelope line; obtaining the curve of the soil resistance changing with the depth after eliminating the linear part by subtracting the straight line part from the curve of the soil resistance changing with the depth, and determining the new lower envelope line; fitting the side friction in the piling process by drawing a straight line through the original point, the lowest point and the final point of the new lower envelope line; and obtaining the end resistance of the pile foundation in the piling process by subtracting the side friction from the curve of the soil resistance changing with the depth. The end resistance and the side friction of the pile foundation can be conveniently obtained, and the calculation precision of the pile foundation drivability analysis is improved.

Description

Technical Field

[0001] This invention belongs to the fields of marine and civil engineering, and more specifically, it relates to a method for classifying the end resistance and side friction of pile foundations during the pile driving process based on pile driving records. Background Technology

[0002] With the rapid development of marine engineering, pile foundations have been widely used. Due to the complex marine environment and short construction window, pile installation is increasingly difficult. Pile driveability analysis is a crucial step in ensuring successful pile installation, and accurate analysis is essential for smooth pile driving. In practical engineering, if the driveability analysis fails to accurately predict events such as hammer rejection or pile slippage, it may lead to situations where the pile cannot be driven to the designed depth, or the pile bearing capacity fails to meet design requirements. These issues can delay the construction period, increase construction costs, damage the hammer, or even result in personnel injuries or fatalities.

[0003] Therefore, improving the accuracy of pile driveability analysis is a crucial part of pile foundation design calculations. To enhance this accuracy, accurately determining the end resistance and side friction of the pile during the driving process is essential. Currently, marine engineering projects often use high-strain dynamic testing methods to determine pile end resistance and side friction, calculating the data based on dynamic testing data. However, dynamic testing requires the installation of corresponding sensors, and due to the influence of the offshore construction environment, it can affect pile foundation construction and delay the project schedule. Furthermore, offshore dynamic testing is expensive, increasing the overall project cost. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies and obtain the end resistance and side friction resistance during the pile driving process without affecting on-site construction, this invention proposes a method for classifying the end resistance and side friction resistance of pile foundations based on pile driving records. Since pile driving records are obtained for each pile driving process, the method of this invention can conveniently obtain the end resistance and side friction resistance of the pile foundation, and use the obtained data to guide future construction, thereby improving the calculation accuracy of pile driveability analysis.

[0005] The objective of this invention is achieved through the following technical solutions.

[0006] This invention relates to a method for classifying pile end resistance and side friction during the pile driving process based on pile driving records. Based on the pile driving records, a trend line algorithm is used to classify the total soil resistance, thereby obtaining the pile end resistance and side friction separately. Specifically, the method includes the following steps:

[0007] (1) First, obtain the curve showing the relationship between the number of hammer blows and the depth during the pile driving process based on the on-site pile driving records;

[0008] (2) Based on the type of hammer used for pile driving, the relationship curve between the number of hammer blows and the soil resistance is calculated using the wave equation method;

[0009] (3) Using the curve of the relationship between the number of hammer blows and the depth obtained in step (1) and the curve of the relationship between the number of hammer blows and the soil resistance obtained in step (2), the curve of the relationship between the soil resistance and the depth during the pile driving process is obtained.

[0010] (4) Using the soil resistance variation curve obtained in step (3), determine the upper and lower envelopes of this soil resistance variation curve.

[0011] (5) Draw a straight line through the point (0,0) and the lowest point of the lower envelope of the curve showing the relationship between soil resistance and depth obtained in step (4) to obtain the equation of the straight line;

[0012] (6) Subtract the linear part obtained in step (5) from the soil resistance variation curve obtained in step (3) to obtain the soil resistance variation curve after eliminating the linear part.

[0013] (7) Using the soil resistance variation curve with depth obtained in step (6) after eliminating the linear part, determine its new lower envelope;

[0014] (8) Passing through the origin and the lowest and final points of the newly drawn envelope, use y = ax 2 The fitting process is performed using +b, and the fitted line represents the side friction resistance during the pile driving process; where y represents soil resistance, x represents depth, and a and b represent different fitting parameters, which are obtained using the least squares method.

[0015] (9) Subtract the side friction obtained in step (8) from the soil resistance change curve obtained in step (3) to obtain the pile end resistance during the pile driving process.

[0016] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0017] (1) Currently, the division of pile end resistance and pile side friction in the pile driving process requires the use of high-strain dynamic measurement methods. This method requires the installation of corresponding sensors on the pile foundation, which will have a certain impact on construction, increase the cost of pile foundation installation, and prolong the construction period. Moreover, this method is complex to calculate and has a high technical threshold. In contrast, this invention uses pile driving records as the basis for calculation, which is highly reliable, low-cost, and has a short cycle, and can greatly reduce manpower, material resources, and time. This has outstanding advantages for marine engineering.

[0018] (2) The method of the present invention conforms to engineering practice, is simple and clear, easy to calculate, and the parameters involved are easy to determine and reliable. Attached Figure Description

[0019] Figure 1 This is a schematic diagram showing the change in the number of hammer blows with depth.

[0020] Figure 2 This is a schematic diagram showing the relationship between soil resistance and the number of blows.

[0021] Figure 3 This is a schematic diagram showing how soil resistance varies with depth.

[0022] Figure 4 This is a schematic diagram of the upper and lower envelopes of soil resistance.

[0023] Figure 5 It is a schematic diagram of a straight line passing through the lowest point of the lower envelope.

[0024] Figure 6 This is a schematic diagram of soil resistance after eliminating the linear portion.

[0025] Figure 7 This is a schematic diagram of the upper and lower envelopes of soil resistance to eliminate the linear portion.

[0026] Figure 8 This is a schematic diagram of the side friction resistance during the pile driving process. Detailed Implementation

[0027] To further understand the invention's content, features, and effects, the following embodiments are provided, and the invention will be further described in conjunction with the accompanying drawings.

[0028] This invention relates to a method for classifying pile end resistance and side friction during the pile driving process based on pile driving records. Based on the pile driving records, a trend line algorithm is used to classify the total soil resistance, thereby obtaining the pile end resistance and side friction separately. Specifically, the method includes the following steps:

[0029] (1) First, obtain the curve showing the relationship between the number of hammer blows and the depth during the pile driving process based on the on-site pile driving records. For example... Figure 1 As shown.

[0030] (2) Based on the type of hammer used for pile driving, the relationship curve between the number of hammer blows and the soil resistance is calculated using the wave equation method. For example... Figure 2 As shown.

[0031] (3) Using the curve showing the relationship between the number of hammer blows and depth obtained in step (1) and the curve showing the relationship between the number of hammer blows and soil resistance obtained in step (2), the curve showing the relationship between soil resistance and depth during pile driving can be obtained. For example Figure 3 As shown.

[0032] (4) Using the soil resistance versus depth curve obtained in step (3), the upper and lower envelopes of this soil resistance versus depth curve can be obtained. For example Figure 4 As shown, to facilitate the drawing of the envelope, Figure 4 The horizontal axis represents the depth.

[0033] (5) Draw a straight line through the point (0,0) and the lowest point of the lower envelope of the soil resistance versus depth curve obtained in step (4) to obtain the equation of the straight line. For example Figure 5 As shown.

[0034] (6) Subtract the linear portion obtained in step (5) from the soil resistance variation curve obtained in step (3) to obtain the soil resistance variation curve after eliminating the linear portion. For example Figure 6 As shown.

[0035] (7) Using the soil resistance variation curve obtained in step (6) after eliminating the linear portion, determine its new lower envelope. For example... Figure 7 As shown.

[0036] (8) Passing through the origin and the lowest and final points of the newly drawn envelope, use y = ax 2 A fitting process is performed using +b, and the fitted line represents the side friction resistance during pile driving; where y represents soil resistance; x represents depth; and a and b represent different fitting parameters, obtained using the least squares method. For example... Figure 8 As shown.

[0037] (9) Subtract the side friction obtained in step (8) from the soil resistance change curve obtained in step (3) to obtain the pile end resistance during the pile driving process.

[0038] Although the functions and working processes of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific functions and working processes described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these are within the protection scope of the present invention.

Claims

1. A method for classifying pile end resistance and side friction during pile driving based on pile driving records, characterized in that, Based on pile driving records, the total soil resistance was divided using a trend line algorithm to obtain the end resistance and side skin resistance of the pile foundation; specifically... Includes the following processes: (1) First, obtain the curve showing the relationship between the number of hammer blows and the depth during the pile driving process based on the on-site pile driving records; (2) Based on the type of hammer used for pile driving, the relationship curve between the number of hammer blows and the soil resistance is calculated using the wave equation method; (3) Using the curve of the relationship between the number of hammer blows and the depth obtained in step (1) and the curve of the relationship between the number of hammer blows and the soil resistance obtained in step (2), the curve of the relationship between the soil resistance and the depth during the pile driving process is obtained. (4) Using the soil resistance variation curve obtained in step (3), determine the upper and lower envelopes of this soil resistance variation curve. (5) Draw a straight line through the point (0,0) and the lowest point of the lower envelope of the curve showing the relationship between soil resistance and depth obtained in step (4) to obtain the equation of the straight line; (6) Subtract the linear part obtained in step (5) from the soil resistance variation curve obtained in step (3) to obtain the soil resistance variation curve after eliminating the linear part. (7) Using the soil resistance variation curve with depth obtained in step (6) after eliminating the linear part, determine its new lower envelope; (8) Passing through the origin and the lowest and final points of the newly drawn envelope, use y = ax 2 The fitting process is performed using +b, and the fitted line represents the side friction resistance during the pile driving process; where y represents soil resistance, x represents depth, and a and b represent different fitting parameters, which are obtained using the least squares method. (9) Subtract the side friction obtained in step (8) from the soil resistance change curve obtained in step (3) to obtain the pile end resistance during the pile driving process.

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