Method for calculating and controlling the sonic effect of pile driving at sea

Abstract

The application discloses a method for calculating and controlling the influence of sound waves on offshore piling. The calculation method adopts an impact force model and a transverse vibration model caused by the poisson effect of a steel casing under the action of the impact force. In addition, a fiber cloth is wound around the steel casing to improve the transverse deformation resistance of the steel casing and reduce the poisson effect of the steel casing, so that the influence on surrounding fish is reduced.

Description

Technical Field

[0001] This invention relates to the field of environmental impact of offshore piling construction, specifically to a method for calculating and controlling the acoustic impact of offshore piling. Background Technology

[0002] Currently, large bridge pile foundations generally adopt the design of large-diameter bored piles, which require the use of large-diameter steel casings during construction. When constructing bridge pile foundations in water, steel casings need to be driven underwater for drilling, and the steel casing is the most important auxiliary structure in bored pile construction.

[0003] In existing technologies, hammering a steel casing into the seabed soil or rock layer and then pouring concrete is a common method for constructing bridge piers for cross-sea bridges. However, when hammering the steel casing longitudinally, the Poisson effect of the casing radiates sound waves into the seawater, which can affect fish. Therefore, methods for calculating and controlling the sound wave impact of offshore piling are needed to address the problems and find solutions for offshore piling. Summary of the Invention

[0004] The purpose of this invention is to provide a method for calculating and controlling the acoustic effects of offshore piling, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] The calculation method for the acoustic impact of offshore piling includes the following steps:

[0007] Step 1: Calculate the sound pressure of the impact force. The sound pressure meter value is: P(t) = 2.1 * 1e8 * exp(-t / 0.004), where the unit of P(t) is Pa.

[0008] Step 2: Calculate the impact force. The impact force decreases with time. The impact force is calculated as: F = P(t) * A.

[0009] Step 3: Set the time waveform of the impact force as F(t), and the outer diameter of the pile as... Take 0.8 m, Poisson's ratio is Taking 0.33, the radial displacement of the steel pipe pile is... for: In the formula, A and E are the cross-sectional area and longitudinal elastic coefficient of the pile, respectively;

[0010] Step 4: Calculate the radial velocity. The radial velocity of the pile is the time derivative of u, expressed as:

[0011]

[0012] In the formula, Z represents the mechanical resistance of the steel pipe. = AE / Cp;

[0013] Step 5: Establish the hammerhead velocity model:

[0014]

[0015] It is the velocity of the particle vibration caused by the impact force;

[0016] Step Six: Obtain the sound power. The sound power is:

[0017]

[0018] The density of water is 1000 kg / m³. 3 The product of the sound velocity in water (1500 m / s) and the sound impedance is the acoustic impedance.

[0019] Since the impact force decreases monotonically with time, we only need to consider the interference of the sound pressure at the moment of impact on the fish school. We take the maximum value of W as the control value, and the formula is as follows:

[0020]

[0021] Step 7: The longitudinal strain caused by the longitudinal impact is:

[0022]

[0023] Step 8: The transverse strain generated by the Poisson effect in the steel pipe is:

[0024]

[0025] Step Nine: The transverse stress generated by the Poisson effect in the steel pipe is:

[0026]

[0027] Step 10: Due to the continuity of transverse stress at the interface of the fiber cloth wrapping, the stress in the fiber cloth is also... Therefore, the transverse strain after being constrained by the fiber cloth is:

[0028]

[0029] Step 11: Therefore, the equivalent Poisson's ratio of the steel sleeve after being constrained by the fiber cloth is: .

[0030] This invention also provides a method for controlling the acoustic effects of offshore piling, comprising the following steps:

[0031] Step 1: Cut the fiber cloth strips. Cut fiber cloth strips with a width of 200mm according to the design, and coil the corresponding fiber cloth strips according to the length that can be constructed at one time.

[0032] Step 2: Grinding the steel pipe. Use a polishing machine to grind and remove rust from both the inner and outer surfaces of the steel pipe. Use a blower to clean the surface of the ground steel pipe.

[0033] Step 3: Marking and positioning. Use a non-water-washable pen to mark and position the steel pipe on its outer surface. The marking position is determined according to the design drawings, starting from the water inlet end of the steel pipe.

[0034] Step 4: Impregnate the fiber cloth strips with resin. Prepare the epoxy resin required for impregnation on site. The amount of resin prepared is the amount required for the minimum construction unit. The site temperature should be 20-30℃. Impregnate the strips required for one construction.

[0035] Step 5: Wrap the fiber cloth. According to the positioning lines, attach and wrap the impregnated fiber cloth strips to the surface of the steel pipe.

[0036] Step 6: Curing. Cur at room temperature for 24 hours, avoiding contact with water.

[0037] Preferably, the fiber cloth is unidirectional carbon fiber cloth.

[0038] Preferably, the winding method in step five is either 45-degree continuous winding or horizontal circumferential segmented winding.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] This invention, by calculating and controlling the impact range of acoustic waves generated during offshore piling, is crucial for the environmental assessment of cross-sea bridge construction. The invention proposes an impact force model and a lateral vibration model induced by the Poisson effect of the steel casing under impact force. Furthermore, it employs fiber cloth wrapping around the steel casing to enhance its lateral resistance to deformation, reduce the Poisson effect, and thus minimize the impact on surrounding fish populations. This invention's approach has a profound impact on the environmental impact of offshore piling construction. Attached Figure Description

[0041] Figure 1 This is a flowchart of the control method in Embodiment 2 of the present invention;

[0042] Figure 2 This is a graph showing the change in sound pressure with distance in Embodiment 2 of the present invention when no treatment measures were taken;

[0043] Figure 3 This is a graph showing the change in sound pressure with distance when the treatment measures are adopted in Embodiment 2 of the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1: This invention provides a technical solution: a method for calculating the acoustic impact of offshore piling, comprising the following steps:

[0046] Step 1: Calculate the sound pressure of the impact force. The sound pressure meter value is: P(t) = 2.1 * 1e8 * exp(-t / 0.004), where the unit of P(t) is Pa.

[0047] Step 2: Calculate the impact force. The impact force decreases with time. The impact force is calculated as: F = P(t) * A.

[0048] Step 3: Set the time waveform of the impact force as F(t), and the outer diameter of the pile as... Take 0.8 m, Poisson's ratio is Taking 0.33, the radial displacement of the steel pipe pile is... for: In the formula, A and E are the cross-sectional area and longitudinal elastic coefficient of the pile, respectively;

[0049] Step 4: Calculate the radial velocity. The radial velocity of the pile is the time derivative of u, expressed as:

[0050]

[0051] In the formula, Z represents the mechanical resistance of the steel pipe. = AE / Cp;

[0052] Step 5: Establish the hammerhead velocity model:

[0053]

[0054] It is the velocity of the particle vibration caused by the impact force;

[0055] Step Six: Obtain the sound power. The sound power is:

[0056]

[0057] The density of water is 1000 kg / m³. 3 The product of the sound velocity in water (1500 m / s) and the sound impedance is the acoustic impedance.

[0058] Since the impact force decreases monotonically with time, we only need to consider the interference of the sound pressure at the moment of impact on the fish school. We take the maximum value of W as the control value, and the formula is as follows:

[0059]

[0060] Step 7: The longitudinal strain caused by the longitudinal impact is:

[0061]

[0062] Step 8: The transverse strain generated by the Poisson effect in the steel pipe is:

[0063]

[0064] Step Nine: The transverse stress generated by the Poisson effect in the steel pipe is:

[0065]

[0066] Step 10: Due to the continuity of transverse stress at the interface of the fiber cloth wrapping, the stress in the fiber cloth is also... Therefore, the transverse strain after being constrained by the fiber cloth is:

[0067]

[0068] Step 11: Therefore, the equivalent Poisson's ratio of the steel sleeve after being constrained by the fiber cloth is: .

[0069] In this embodiment, based on the above calculation method, a steel casing with a diameter of 4.4m, a thickness of 3.6cm, and a length of approximately 100m is used. During construction, the casing is driven into the bedrock under an impact of approximately 800 tons at the top, generating shock waves that spread in the water and affect fish. It is necessary to coat or attach wave-absorbing material to the submerged portion of the casing to control the wave's influence range in the water to no more than 400m, ideally within 200m.

[0070] The implementation parameters are as follows:

[0071] Density of water: 1000 kg / m³ 3 ;

[0072] Speed ​​of sound in water: 1500 m / s;

[0073] Steel pipe diameter: 4.4 m;

[0074] Steel pipe thickness: 3.6cm;

[0075] Poisson's ratio for steel pipe: 0.33;

[0076] Longitudinal elastic modulus of steel pipe: 200 GPa;

[0077] Length of the steel pipe protruding above the seabed: 100m;

[0078] Longitudinal wave velocity Cp inside the steel pipe: 5900 m / s;

[0079] Hammer weight: 800 tons;

[0080] Initial velocity of the hammer when it strikes the steel pipe: 6 m / s;

[0081] Model experiments showed that the sound wave sensitivity frequencies for 1-month-old fry and 8-month-old fry are 800Hz and 600Hz, respectively, with direct lethal sound pressure thresholds of approximately 40Pa and 4kPa. The sound wave sensitivity frequency for 13-month-old fish is also 600Hz, but when the sound pressure reaches 4kPa, the fish are clearly startled, but not directly killed.

[0082] The sound pressure pressure variation curve with distance is as follows: Figure 2 As shown:

[0083] Based on this, it can be concluded that without any treatment measures, the lethal range for 8-month-old fish fry is 164m.

[0084] Example 2: The scheme of Example 2 is an implementation method that controls the calculation results of Example 1.

[0085] The control implementation process is as follows:

[0086] On-site, fiber strips were wrapped around the steel pipe using a wet epoxy resin method. The strips were 200mm wide, spaced 150mm apart, and consisted of two layers. Two wrapping methods were used: continuous wrapping at a 45° angle and horizontal circumferential segmented wrapping (with an overlap length of 150mm).

[0087] like Figure 1 As shown, the specific construction steps are as follows:

[0088] Step 1: Cut the fiber cloth strips: Cut fiber cloth strips with a width of 200mm according to the design, and coil the corresponding fiber cloth strips according to the length that can be constructed at one time;

[0089] Step 2: Grinding the steel pipe: Use a polishing machine to grind and remove rust from both the inner and outer surfaces of the steel pipe, and use a blower to clean the surface of the ground steel pipe.

[0090] Step 3: Marking and positioning: Mark and position the steel pipe on the outer surface using a non-water-washable pen. The marking position is determined according to the design drawings, starting from the water inlet end of the steel pipe.

[0091] Step 4: Impregnate fiber cloth strips with resin: Prepare the epoxy resin required for impregnation on site. The amount of resin prepared is the minimum amount required for the construction unit. The site temperature should be 20-30℃. Impregnate the strips required for one construction.

[0092] Step 5: Wrap the fiber cloth: According to the positioning lines, attach and wrap the impregnated fiber cloth strips to the surface of the steel pipe;

[0093] Step 6: Curing: Curing at room temperature for 24 hours, avoiding contact with water.

[0094] Based on the control method of Example 2, and after repeating the above calculations (calculations of Example 1), the experiment shows that:

[0095] When treatment measures are adopted, the lethal range for 8-month-old fish fry is expanded to 204m (e.g. Figure 3 (As shown).

[0096] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for calculating and controlling the acoustic impact of offshore piling, characterized in that, Including the following steps: Step 1: Calculate the sound pressure of the impact force. The sound pressure meter value is: P(t) = 2.1 * 1e8 * exp(-t / 0.004), where the unit of P(t) is Pa. Step 2: Calculate the impact force. The impact force decreases with time. The impact force is calculated as: F = P(t) * A; where A is the cross-sectional area of ​​the pile. Step 3: Set the time waveform of the impact force as F(t), and the outer diameter of the pile as... Take 0.8m, Poisson's ratio is Taking 0.33, the radial displacement of the steel pipe pile is... for: In the formula, E is the longitudinal elastic coefficient; Step 4: Calculate the radial velocity. The radial velocity of the pile is the time derivative of u, expressed as: ； In the formula, Z represents the mechanical resistance of the steel pipe. = AE / Cp; Cp is the longitudinal wave velocity inside the steel pipe; Step 5: Establish the hammerhead velocity model: ； It is the velocity of the particle vibration caused by the impact force; Step Six: Obtain the sound power. The sound power is: ； The density of water is 1000 kg / m³. 3 The product of the sound velocity in water (1500 m / s) and the sound impedance is the acoustic impedance. Since the impact force decreases monotonically with time, we only need to consider the interference of the sound pressure at the moment of impact on the fish school. We take the maximum value of W as the control value, and the formula is as follows: ； Step 7: The longitudinal strain caused by the longitudinal impact is: ； Step 8: The transverse strain generated by the Poisson effect in the steel pipe is: ； Step Nine: The transverse stress generated by the Poisson effect in the steel pipe is: ； Step 10: Due to the continuity of transverse stress at the interface of the fiber cloth wrapping, the stress in the fiber cloth is also... Therefore, the transverse strain after being constrained by the fiber cloth is: ； Step 11: Therefore, the equivalent Poisson's ratio of the steel sleeve after being constrained by the fiber cloth is: .

2. The method for calculating and controlling the acoustic impact of offshore piling as described in claim 1, characterized in that: This also includes controlling the implementation process, with the specific construction steps as follows: Step (1): Cut the fiber cloth strips. Cut the fiber cloth strips with a width of 200mm according to the design. Coil the corresponding fiber cloth strips according to the length that can be constructed at one time. Step (2): Grind the steel pipe. Use a polishing machine to grind and remove rust from both the inner and outer surfaces of the steel pipe. Use a blower to clean the surface of the ground steel pipe. Step (3): Marking and positioning. Use a non-water-washable pen to mark and position the steel pipe on the outer surface. The marking position is based on the design drawings and starts from the water inlet end of the steel pipe. Step (4): Impregnate the fiber cloth strips with resin. Prepare the epoxy resin required for impregnation on site. The amount of resin prepared is the minimum amount required for the construction unit. The site temperature is 20-30℃. Impregnate the strips required for one construction. Step (5): Wrap the fiber cloth. According to the positioning line, stick and wrap the impregnated fiber cloth strips to the surface of the steel pipe. Step (6): Curing, cure at room temperature for 24 hours, avoid contact with water.

3. The method for calculating and controlling the acoustic impact of offshore piling according to claim 2, characterized in that: The fiber cloth is a unidirectional carbon fiber cloth.

4. The method for calculating and controlling the acoustic impact of offshore piling according to claim 2, characterized in that: In step (5), the winding method can be either 45-degree continuous winding or horizontal circumferential segmented winding.

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