Vibration pile sinking drillability analysis method for hydraulic vibration hammer

Abstract

The invention provides a method for analyzing the vibratory pile sinking drivability of a hydraulic vibratory hammer. The method comprises the steps that the initial amplitude of the hydraulic vibratory hammer and the mass of the vibratory hammer without a clamp are obtained on the basis of working parameters of the hydraulic vibratory hammer; the total mass of a clamp needing to be clamped by the hydraulic vibration hammer is obtained; according to the characteristics of the land where the hydraulic vibration hammer works, the dynamic friction resistance and the dynamic end resistance of the hydraulic vibration hammer during working are obtained; the final amplitude of the hydraulic vibration hammer at the vibration pile sinking limit is calculated through the obtained data, and on the basis of the method for calculating the final amplitude of the hydraulic vibration hammer, when the final amplitude of the hydraulic vibration hammer is calculated, the dynamic friction resistance and the dynamic end resistance during vibration pile sinking of the hydraulic vibration hammer are introduced, so that the final amplitude of the hydraulic vibration hammer is calculated. The resistance encountered by the hydraulic vibration hammer during working and the characteristics of different soil properties are considered, the relevance with the measured data of the sensor is relatively high, and compared with the amplitude obtained by calculation in the prior art, the amplitude obtained by calculation is more accurate and real.

Description

Technical Field

[0001] The invention relates to the technical field of vibration pile driving, and in particular to a method for analyzing the driveability of vibration pile driving with a hydraulic vibration hammer. Background Art

[0002] Driveability analysis is a very important task before pile foundation construction, which is crucial to the selection of pile hammer type, vibratory hammer model, exciting force and other parameters. However, vibration pile driving is a very complex mechanical process, and its pile driving mechanism has not yet been fully clarified.

[0003] The commonly used pile analysis methods can be roughly divided into the following categories:

[0004] The first category is based on equations of kinematics, energy conservation equations, momentum conservation equations, or quasi-static processes;

[0005] The second type is an analysis method based on one-dimensional stress wave theory. The most common GRLWEAP pile analysis software on the market is designed based on this theory.

[0006] The third type is the amplitude analysis method, which predicts the necessary amplitude ultimately required for different soil conditions based on the necessary amplitude theory.

[0007] According to the kinematic process analysis of vibration pile driving and previous experimental tests, the mechanical process of vibration pile driving is essentially different from that of hammer pile driving. The force of hammer pile driving acts directly on the pile top and propagates to the pile bottom in the form of one-dimensional stress wave, while vibration pile sinking mainly drives the eccentric block through the gear box to make the vibration hammer produce reciprocating motion. The vibration hammer is connected to the pile through a clamp. Therefore, the former directly acts on the pile in the form of force, while the latter produces a forced motion on the pile through mechanical motion. Therefore, the equation established based on the one-dimensional stress wave theory is actually applicable to hammer pile driving, which is essentially different from vibration pile sinking. For the first type of pile driving analysis method, the above problems also exist. At present, most of the quasi-static methods are realized by applying a sinusoidal impact vibration force on the pile top. More importantly, for this type of analysis method, its mechanical process and motion process are not well coordinated and integrated. From the basic mechanics and motion process, it can be seen that the amplitude of the vibration hammer is a movement generated by the vibration hammer driven by the eccentric block to overcome the soil resistance. Therefore, its mechanical process and movement process are actually organically and closely linked together. The current necessary amplitude analysis method only studies the necessary amplitude of various soil types, but does not explain the actual amplitude of the final movement form of the vibrating hammer. Summary of the invention

[0008] In view of the shortcomings and deficiencies in the calculation of the actual amplitude of the final form of the vibratory hammer in the above-mentioned prior art, the technical problem to be solved by the present application is to provide a method for analyzing the drivability of hydraulic vibratory hammer vibration pile driving.

[0009] In order to solve the above technical problems, the present invention provides a hydraulic vibration hammer vibration pile driving feasibility analysis method, the hydraulic vibration hammer vibration pile driving feasibility analysis method comprises:

[0010] Based on the working parameters of the hydraulic vibration hammer, the initial amplitude of the hydraulic vibration hammer and the mass of the vibration hammer without the clamp are obtained;

[0011] Obtaining the total mass of the fixture required to be clamped by the hydraulic vibration hammer;

[0012] According to the characteristics of the land on which the hydraulic vibratory hammer works, the dynamic friction resistance and dynamic end resistance of the hydraulic vibratory hammer when working are obtained;

[0013] The final amplitude of the hydraulic vibration hammer at the vibration pile sinking limit is calculated using the above data. The formula is as follows:

[0014]

[0015] In the formula, A T is the final amplitude of the hydraulic vibratory hammer at the limit of pile sinking, M is the vibration of the vibration system driven by the eccentric moment, m c Initial mass of the vibration system, m z F is the mass of the fixture held by the vibrating hammer, s F is the dynamic friction during vibration pile driving, c is the moving end resistance during vibration pile driving,

[0016] Finally, according to A T ≥A N The relationship between the final amplitude and the necessary amplitude is analyzed. N is the necessary amplitude.

[0017] The hydraulic vibration hammer vibration pile driving feasibility analysis method provided by the present invention may also have the following characteristics: the calculation formula of M in the calculation of the final amplitude is:

[0018] M=A0m c

[0019] Where A0 is the initial amplitude of the hydraulic vibration hammer, m c Initial mass of the vibration system.

[0020] The hydraulic vibratory hammer vibration pile driving feasibility analysis method provided by the present invention may also have the following feature: the initial amplitude is the maximum amplitude of the hydraulic vibratory hammer when it is vibrating in vacant vibration.

[0021] The hydraulic vibratory hammer vibration pile driving feasibility analysis method provided by the present invention may also have the following characteristics: when the vibratory hammer generates vibration, its exciting force must be greater than the dynamic friction resistance between the pile and the soil, and the dynamic friction resistance is calculated and predicted using this size relationship with reference to the soil characteristics.

[0022] The hydraulic vibration hammer vibration pile driving feasibility analysis method provided by the present invention may also have the following characteristics: the dynamic friction resistance is related to the static friction between the pile and the soil, and the calculation formula thereof is:

[0023] F s =μF

[0024] In the formula, F s is the dynamic friction resistance; the friction of soil particles is reduced after being vibrated by the vibrating hammer, μ is the reduction rate; F is the static friction between the pile and the soil.

[0025] The hydraulic vibratory hammer vibration pile driving feasibility analysis method provided by the present invention may also have the following characteristics: the size of μ is related to the vibration acceleration of the vibratory hammer and decreases as the vibration acceleration increases.

[0026] The hydraulic vibratory hammer vibration pile driving feasibility analysis method provided by the present invention may also have the following characteristics: the vibratory hammer and the fixture form a vibration system, and the mass of the vibration system is greater than the moving end resistance.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In the driveability analysis method for hydraulic vibratory hammer vibration pile driving provided by the present invention, first, the initial amplitude of the hydraulic vibratory hammer and the mass of the vibratory hammer without a clamp are obtained according to the working parameters of the hydraulic vibratory hammer; then, the total mass of the clamp clamped by the hydraulic vibratory hammer when working is detected; thereafter, the dynamic friction resistance and dynamic end resistance of the hydraulic vibratory hammer when working are obtained according to the properties of the land on which the hydraulic vibratory hammer works, and finally, the final amplitude of the hydraulic vibratory hammer is determined according to the above-obtained data.

[0029] Based on the above method for calculating the final amplitude of the hydraulic vibratory hammer, the dynamic friction resistance and dynamic end resistance of the hydraulic vibratory hammer during pile sinking are introduced when calculating the final amplitude of the hydraulic vibratory hammer. The resistance encountered by the hydraulic vibratory hammer during operation and the characteristics of different soils are taken into account to obtain the calculation formula for the final amplitude of the present application:

[0030]

[0031] The final amplitude is then calculated using the above formula. The calculated final amplitude is compared with the amplitude measured by the sensor when the vibrating hammer is actually working, and the correlation is relatively high, which proves that the final amplitude obtained by this method is more accurate and true than the amplitude calculated by the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a real-time amplitude data diagram of the vibration hammer detected by the sensor in this embodiment;

[0033] Figure 2 4 is a curve diagram showing the relationship between vibration acceleration and the reduction degree of soil friction resistance in this embodiment. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] The driveability analysis method for hydraulic vibratory hammer pile driving in this embodiment is used to calculate the final amplitude of the hydraulic vibratory hammer, obtain the final amplitude based on the calculation, and then compare it with the necessary amplitude to analyze the driveability of the soil.

[0036] In the current existing technology, the necessary amplitude analysis methods for vibration pile driving analysis mainly include the Japanese Kobe Construction and Adjustment Co., Ltd. method, the American ICE vibration pile driving analysis method and the French PTC necessary amplitude analysis method. Taking the French PTC necessary amplitude analysis theory as an example, the necessary amplitudes in various soils are summarized as follows:

[0037] Necessary amplitude under different soil conditions

[0038]

[0039] The necessary amplitude theory holds that the system vibration amplitude A at the final moment of vibration pile sinking is T Should be greater than its necessary amplitude A N .

[0040] However, almost all current analysis methods mistakenly regard the initial amplitude of the system as the final amplitude. According to the mechanical principle of vibratory hammer piling, the eccentric moment M of the vibratory hammer is equal to the product of the mass m of the eccentric block and the eccentric moment r. The eccentric moment drives the vibration of the vibration system:

[0041] M=A0m c

[0042] Where A0 is the initial amplitude, m cis the initial mass of the vibration system, mainly the mass of the vibrating hammer. During the vibration piling process, the mass of the vibrating hammer changes due to the clamping of the pile. Therefore, if the pile is clamped and vibrates in the air, the amplitude at that time is as follows:

[0043]

[0044] Where m z It is the mass of the pile (including the clamp) clamped by the vibratory hammer.

[0045] Taking the piling of 12 YZ-400L vibratory hammers as an example, its main technical parameters are as follows:

[0046] Eccentric moment: 200KGM

[0047] Maximum speed: 1400RPM

[0048] Rated exciting force: 4300KN

[0049] Maximum exciting force: 4980KN

[0050] Maximum pile pulling force: 2500KN

[0051] Maximum amplitude: 37MM

[0052] Maximum oil flow: 1220L / MIN

[0053] Dimensions (length, width and height without fixture): 4710×840×2600MM

[0054] Weight (without clamp): 21T

[0055] Hydraulic clamp: double clamp, quad clamp

[0056] Supporting hydraulic power station: 1200P hydraulic power station

[0057] Based on the above parameters, it can be known that the maximum amplitude is 37mm. After the 12 hammers are linked, the total mass of the system is 1469 tons. When the pile is sunk to the limit, the total dynamic end resistance and dynamic friction resistance is 4800 tons.

[0058] Then, using the calculation method in the prior art, the final amplitude of the vibrating hammer without considering the moving end resistance and dynamic friction resistance is:

[0059]

[0060] The calculation formula for the final amplitude used in this implementation is:

[0061]

[0062] In the formula, AT is the final amplitude of the hydraulic vibratory hammer at the limit of pile sinking, M is the vibration of the vibration system driven by the eccentric moment, m c Initial mass of the vibration system, m z F is the mass of the fixture held by the vibrating hammer, s F is the dynamic friction during vibration pile driving, c It is the moving end resistance during vibration pile driving.

[0063] After substituting the above parameters into the formula, the final amplitude is calculated as:

[0064]

[0065] Afterwards, the acceleration of the vibrating hammer is monitored in real time by using a sensor, and converted into amplitude data. The real-time amplitude data obtained is as follows: Figure 1 As shown, according to its amplitude, it can be known that the real-time amplitude data is more closely related to the amplitude calculation method of the present embodiment which refers to the dynamic end resistance and dynamic friction resistance than the calculation method of the prior art, and the calculated data is more accurate and reliable.

[0066] Finally, the final amplitude A obtained by the calculation method in this embodiment is T With the necessary amplitude A N For comparison, refer to A T >A N The relationship between the system and the soil is determined, and the amplitude of the system is predicted to be greater than the necessary amplitude at the final moment, so as to analyze the compressibility of the soil.

[0067] In addition, the calculation of the dynamic end resistance and dynamic friction resistance of the soil can refer to the calculation methods in the prior art.

[0068] For example, Japan Construction Machinery Research Co., Ltd. believes that the friction reduction rate μ is related to the parameters of the vibration system itself (weight of the vibration system, eccentric moment, vibration frequency, etc.) and soil parameters. The French PTC company's empirical formula directly gives the empirical value of the dynamic side resistance based on soil properties, N value and other parameters. The empirical value of the dynamic side resistance is directly substituted into the calculation during analysis. The American ICE company believes that the pile side friction reduction rate μ is related to soil parameters, and provides reference values ​​of μ for different soils.

[0069] Take Japan’s calculation method as an example:

[0070] To make the pile vibrate, the exciting force P0 must be greater than the dynamic resistance between the pile and the soil. Assuming the static friction between the pile and the soil is T, after the forced vibration, the friction is reduced due to the vibration between the soil particles. At this time, the friction between the pile and the soil is set to the dynamic friction T v , let the reduction rate be μ, that is, the requirement is:

[0071] P0≥Tv =μT

[0072] The size of μ is determined by the vibration acceleration. As the vibration acceleration increases, soil liquefaction will occur. When the vibration acceleration exceeds 10g, the reduction rate of soil friction becomes very small. Therefore, after exceeding this limit, even if the vibration acceleration is infinitely increased, the soil friction will not be reduced to 0. Therefore, it has a limit value T. vmin Let η be the ratio of the maximum vibration acceleration to the gravitational acceleration,

[0073] η=a / g=(A0ω 2 ) / g

[0074] Where a is the maximum acceleration of vibration, A0 is the maximum amplitude of the vibration system, and ω is the angular velocity of vibration.

[0075] According to Newton's second law, the exciting force P0 is calculated:

[0076] P0=ma=Q0·a=Q0·A0ω 2

[0077] Where P0 is the exciting force of the vibration system, and Q0 is the total mass of the vibration system.

[0078] At the same time, due to

[0079]

[0080] K——Maximum eccentric moment of vibration system (N·m).

[0081] Arranging the above formulas, we can get

[0082] P0=η·Q0

[0083] Right now:

[0084]

[0085] In addition, the construction company provides an empirical formula

[0086] μ=μ min +(1-μ min ) -βη

[0087] β is the reduction coefficient, which is 0.52 for steel piles and 0.77 for large cylinders and steel sheet piles.

[0088] μ min ——The minimum value of the reduction rate is 0.05 for sandy soil, 0.06 for silty clay, and 0.13 for clay.

[0089] The relationship curve between vibration acceleration and soil friction reduction is shown in the figure below: Figure 2 shown.

[0090] Based on the above method, the dynamic friction resistance of different soils during vibration can be obtained, and then the model of the vibrating hammer to be used can be preliminarily selected or planned based on the relationship that the exciting force must be greater than the dynamic side resistance between the pile and the soil. Then, the parameters and performance data of the vibrating hammer and the type of soil to be vibrated can be used to estimate and test whether the vibrating hammer can overcome the dynamic end resistance of the pile and sink to the required length by referring to the empirical formula. That is, the weight of the vibration system must be greater than the dynamic end resistance of the pile.

[0091] According to the driveability analysis method of hydraulic vibratory hammer vibration pile driving in the above embodiment, first, the initial amplitude of the hydraulic vibratory hammer and the mass of the vibratory hammer without the clamp are obtained according to the working parameters of the hydraulic vibratory hammer; then, the total mass of the clamp clamped by the hydraulic vibratory hammer when working is detected; thereafter, according to the properties of the land on which the hydraulic vibratory hammer works, the dynamic friction resistance and dynamic end resistance of the hydraulic vibratory hammer when working are obtained, and finally, the final amplitude of the hydraulic vibratory hammer is determined according to the above-mentioned data.

[0092] Based on the above method for calculating the final amplitude of the hydraulic vibratory hammer, the dynamic friction resistance and dynamic end resistance of the hydraulic vibratory hammer during pile sinking are introduced when calculating the final amplitude of the hydraulic vibratory hammer. The resistance encountered by the hydraulic vibratory hammer during operation and the characteristics of different soils are taken into account to obtain the calculation formula for the final amplitude of the present application:

[0093]

[0094] The final amplitude is then calculated using the above formula. The calculated final amplitude is compared with the amplitude measured by the sensor when the vibrating hammer is actually working, and the correlation is relatively high, which proves that the final amplitude obtained by this method is more accurate and true than the amplitude calculated by the prior art.

[0095] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and the equivalent technology, the present application is also intended to include these modifications and variations.

Claims

1. A hydraulic vibratory hammer vibration pile driving feasibility analysis method, characterized in that: include: Based on the working parameters of the hydraulic vibration hammer, the initial amplitude of the hydraulic vibration hammer and the mass of the vibration hammer without the clamp are obtained; Obtaining the total mass of the fixture required to be clamped by the hydraulic vibration hammer; According to the characteristics of the land on which the hydraulic vibratory hammer works, the dynamic friction resistance and dynamic end resistance of the hydraulic vibratory hammer when working are obtained; The final amplitude of the hydraulic vibration hammer at the vibration pile sinking limit is calculated using the above data. The formula is as follows: In the formula, A T is the final amplitude of the hydraulic vibratory hammer at the limit of pile sinking, M is the vibration of the vibration system driven by the eccentric moment, m c Initial mass of the vibration system, m z F is the mass of the fixture held by the vibrating hammer, s F is the dynamic friction during vibration pile driving, c is the moving end resistance during vibration pile driving, Finally, according to A T ≥A N The relationship between the final amplitude and the necessary amplitude is analyzed. N The necessary amplitude.

2. The hydraulic vibration hammer vibration pile driving feasibility analysis method according to claim 1 is characterized by: The calculation formula of M in the calculation of the final amplitude is: M=A0m c Where A0 is the initial amplitude of the hydraulic vibration hammer, m c Initial mass of the vibration system.

3. The hydraulic vibration hammer vibration pile driving feasibility analysis method according to claim 2 is characterized by: The initial amplitude is the maximum amplitude of the hydraulic vibration hammer when it vibrates in the air.

4. The hydraulic vibration hammer vibration pile driving feasibility analysis method according to claim 1 is characterized by: When the vibrating hammer generates vibration, its exciting force must be greater than the dynamic friction resistance between the pile and the soil. The dynamic friction resistance is calculated and predicted by using this magnitude relationship with reference to the soil characteristics.

5. The hydraulic vibration hammer vibration pile driving feasibility analysis method according to claim 1 is characterized by: The dynamic friction resistance is related to the static friction between the pile and the soil, and its calculation formula is: F s =μF In the formula, F s is the dynamic friction resistance; the friction of soil particles is reduced after being vibrated by the vibrating hammer, μ is the reduction rate; F is the static friction between the pile and the soil.

6. The hydraulic vibration hammer vibration pile driving feasibility analysis method according to claim 5 is characterized by: The size of μ is related to the vibration acceleration of the vibration hammer, and decreases as the vibration acceleration increases.

7. The hydraulic vibration hammer vibration pile driving feasibility analysis method according to claim 1 is characterized by: The vibration hammer and the fixture form a vibration system, and the mass of the vibration system is greater than the moving end resistance.

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