Steel sheet pile vibration hammer and diesel hammer combined driving device for deep silt stratum

Abstract

The present application relates to barge steel sheet pile construction technology field, especially to the steel sheet pile vibration hammer and diesel hammer combined driving device for deep silt stratum, including: pile frame, vibration hammer assembly, diesel hammer assembly, detection assembly and control assembly. Pile frame is provided with several groups of guide clamps; vibration hammer assembly is provided with frequency conversion driving unit; diesel hammer assembly is provided with fuel supply adjusting unit; detection assembly includes laser positioner, strain force sensor, impact acceleration sensor and ground vibration monitor. Control assembly adjusts the clamping force of guide clamp according to the pile top offset of steel sheet pile, adjusts the excitation frequency of vibration hammer body according to the penetration resistance vibration ratio, and adjusts the fuel supply frequency of diesel hammer body according to the hammer energy transmission efficiency. The present application solves the problems of pile body leakage sand, silt layer over thixotropic liquefaction and sinking pile efficiency reduction, and improves the sinking pile quality and construction safety of steel sheet pile in deep silt stratum.

Description

Technical Field

[0001] This invention relates to the field of barge sheet pile construction technology, and in particular to a combined vibratory hammer and diesel hammer driving device for sheet piles in deep silt formations. Background Technology

[0002] Deep silt strata are widely distributed in coastal areas, river deltas, and inland lacustrine areas. Steel sheet piles, as a type of interlocking steel pile with a straight web or Z-shaped cross-section, have advantages such as high strength, good water-stopping performance, and fast construction speed. They are a commonly used support structure in deep foundation pit support, cofferdam, and wharf construction projects in such soft soil areas. Currently, vibratory hammers or diesel hammers are mainly used for driving steel sheet piles. Vibratory hammers use high-frequency vibration to cause thixotropic liquefaction of the soil around the pile, thereby reducing penetration resistance. They have the advantages of fast construction speed and minimal impact on the surrounding environment, and are especially suitable for soft soil and silty clay layers. Diesel hammers rely on impact energy to overcome pile end resistance, have strong penetration ability, and are suitable for conditions that require passing through hard interlayers or ensuring that the pile end reaches the design bearing capacity. In actual engineering, to balance construction efficiency and pile driving quality, vibratory hammers and diesel hammers are often used in combination: the steel sheet pile is first driven to a certain depth with a vibratory hammer, and then a diesel hammer is used for re-driving to ensure that the pile reaches the design elevation. However, this combined driving method still faces many technical challenges in deep silt strata. First, the silt layer is prone to thixotropic liquefaction under vibration excitation, which drastically reduces the pile's perimeter resistance. However, the degree of liquefaction fluctuates significantly with the vibration frequency and duration, making precise control difficult. When the vibration frequency is inappropriate, excessive liquefaction may lead to uncontrolled pile sinking, or insufficient liquefaction may result in excessive penetration resistance, preventing further driving. Second, the impact energy of the diesel hammer is significantly dissipated during its transmission to the sheet pile through the vibratory hammer body due to poor rigid contact between the hammer bodies. This results in the actual effective impact energy transmitted to the pile being far lower than the nominal output energy of the diesel hammer. Furthermore, the bearing capacity of deep silt layers is extremely low and uneven, making sheet piles prone to instability issues such as pile top displacement, pile tilting, and even "lifting" deformation during driving. Existing guiding devices are mostly fixed structures, unable to dynamically adjust the clamping force according to the actual pile top displacement, making it difficult to effectively constrain the driving direction in complex strata with alternating soft and hard surfaces.

[0003] Chinese Patent Publication No. CN117947772B discloses a method for driving composite sheet piles and its vibratory hammer. The method includes: first, setting up a guide frame at the location to be driven, coordinating the composite sheet pile with the guide frame, and driving the composite sheet pile by vibration using a vibratory hammer; second, stopping the vibration and dismantling the guide frame when the composite sheet pile is at least 0.5m above the guide frame, and then using a pile hammer to drive the composite sheet pile; wherein, if driving difficulties are encountered during the process, a water flushing device is used in conjunction with the composite sheet pile to flush the soil and backflow to remove gravel from the pile, thereby reducing driving resistance. This invention can reduce the difficulty of driving composite sheet piles in geological conditions with high penetration depth.

[0004] As can be seen from the above, the existing technology lacks a combined driving device that can coordinate the vibration frequency of the vibratory hammer, the fuel supply frequency of the diesel hammer, and the guiding clamping force based on real-time detection data. This makes it difficult to effectively address multiple coupled problems such as fluctuations in the degree of thixotropic liquefaction, loss of hammer energy transmission, and pile attitude deviation in deep silt strata. Summary of the Invention

[0005] To address this issue, the present invention provides a combined vibratory hammer and diesel hammer driving device for sheet piles in deep silt formations, which overcomes the risk of leakage and sand inrush caused by the tilting of sheet piles in the existing technology, thereby causing the deep silt layer to undergo thixotropic liquefaction under vibration excitation.

[0006] To achieve the above objectives, the present invention provides a combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations, comprising: A pile frame is vertically installed on a construction platform. The top of the pile frame is equipped with a guide pulley group, and the pile frame is provided with several sets of guide clamps at intervals along the height direction to constrain the driving direction of the steel sheet piles. The vibratory hammer assembly includes a vibratory hammer body slidably disposed on the pile frame, a hydraulic clamp disposed at the bottom of the vibratory hammer body for clamping the top of the sheet pile, and a vibration transmission seat disposed between the vibratory hammer body and the hydraulic clamp. The vibratory hammer body is provided with a frequency conversion drive unit for adjusting the excitation frequency. The diesel hammer assembly includes a diesel hammer body slidably disposed on the pile frame and located above the vibratory hammer body, a replacement hammer device disposed at the bottom of the diesel hammer body for transmitting impact energy to the vibratory hammer body or the sheet pile, and a fuel supply regulating unit disposed on the diesel hammer body. The detection assembly includes a laser positioning device mounted on the top of the pile frame for monitoring the three-dimensional spatial position of the top of the sheet pile, a strain gauge force sensor mounted on the guide clamp for detecting the penetration resistance of the sheet pile, an impact acceleration sensor mounted between the vibratory hammer and the diesel hammer for detecting the hammering energy transfer efficiency, and a surface vibration monitoring device mounted on the construction platform for detecting the vibration response of the silt layer. A control component, which is connected to the vibratory hammer assembly, the diesel hammer assembly and the detection component respectively, is used to adjust the clamping force of the guide clamp according to the offset of the top of the sheet pile, to adjust the excitation frequency of the vibratory hammer body according to the penetration resistance vibration ratio, and to adjust the fuel supply frequency of the diesel hammer body according to the hammer energy transfer efficiency.

[0007] Furthermore, the control component also includes: The offset determination module is used to determine whether the risk of seepage and sand inrush in the deep silt layer where the sheet pile is located does not meet the requirements if the offset of the top of the sheet pile is greater than the critical offset of the top of the pile. The clamping adjustment module is used to increase the clamping force of the guide clamp if the risk of sand leakage in the deep silt layer where the sheet pile is located does not meet the requirements. The increase in the clamping force is positively correlated with the difference between the pile top offset and the critical pile top offset.

[0008] Furthermore, the pile top offset is the square root of the sum of the squares of the displacement components of the steel sheet pile top in two mutually perpendicular directions in the horizontal plane, which are collected in real time by the laser positioning instrument.

[0009] Furthermore, the variable frequency drive unit further includes: The resistance determination module is used to determine whether the degree of thixotropic liquefaction of the deep silt layer under vibration excitation does not meet the requirements, based on the fact that the penetration resistance vibration response ratio is less than the penetration resistance critical vibration response ratio. The frequency adjustment module is used to reduce the excitation frequency of the vibrating hammer body if the degree of thixotropic liquefaction of the deep silt layer under vibration excitation is deemed unsatisfactory.

[0010] Furthermore, the penetration resistance vibration response ratio is the ratio of the steel sheet pile penetration resistance to the vibration response of the silt layer, which is determined by the ratio of the real-time penetration resistance value detected by the strain gauge force sensor to the peak ground acceleration detected by the ground vibration monitor.

[0011] Furthermore, the reduction in the excitation frequency of the vibrating hammer is positively correlated with the difference between the penetration resistance vibration ratio and the critical penetration resistance vibration ratio.

[0012] Furthermore, the fuel supply regulating unit also includes: The energy determination module is used to determine that the energy dissipation of the impact energy of the diesel hammer body during the process of transmitting the impact energy through the vibrating hammer body to the steel sheet pile due to poor rigid contact between the vibrating hammer body and the replacement device does not meet the requirements, based on the fact that the hammer energy transmission efficiency is less than the hammer energy critical transmission efficiency. The fuel supply adjustment module is used to increase the fuel supply frequency of the diesel hammer if the energy dissipation of the impact energy during the transmission process does not meet the requirements. The increase in the fuel supply frequency is positively correlated with the difference between the critical transfer efficiency of the hammer energy and the transfer efficiency of the hammer energy.

[0013] Furthermore, the hammer energy transfer efficiency is the ratio of the peak value of the impact acceleration transmitted to the vibrating hammer after a single hammering by the diesel hammer, as detected by the impact acceleration sensor, to the peak value of the no-load impact acceleration of the diesel hammer.

[0014] Furthermore, as the fuel supply frequency of the diesel hammer increases, the vibration acceleration of the vibrating hammer is continuously monitored. If the vibration acceleration exceeds the critical vibration acceleration, it is determined that the impact energy of the diesel hammer is too large, which may cause resonance damage to the vibrating hammer and does not meet the requirements. The diesel hammer hammering operation is then suspended.

[0015] Furthermore, the guide clamp consists of two sets of hydraulic clamping arms spaced apart along the height of the pile frame. The clamping force of the upper and lower sets of hydraulic clamping arms is independently adjustable, and the clamping force of the upper set of hydraulic clamping arms is greater than that of the lower set of hydraulic clamping arms.

[0016] Compared with existing technologies, the advantages of this invention are as follows: By real-time monitoring of the spatial position of the sheet pile top, penetration resistance, and hammer energy transfer efficiency, and by adjusting the clamping force of the guide clamp, the excitation frequency of the vibratory hammer, and the fuel supply frequency of the diesel hammer based on the detection data, this invention achieves coordinated construction operations of the vibratory hammer and diesel hammer in deep silt strata. When the pile top offset exceeds the limit, the clamping force is increased to constrain the pile driving direction, effectively suppressing the disturbance of the surrounding soil and the formation of seepage and sand inflow channels caused by the tilting of the sheet pile; when the penetration resistance-to-vibration ratio is low, the excitation frequency is reduced to avoid excessive thixotropic liquefaction of the silt layer induced by high-frequency vibration; when the hammer energy transfer efficiency is insufficient, the fuel supply frequency is increased to compensate for energy dissipation caused by poor contact, thereby maintaining the verticality of the sheet pile and the stability of the strata throughout the pile driving process, overcoming the technical defects of single construction methods in soft strata that are prone to displacement and liquefaction.

[0017] Furthermore, this invention compares the real-time spatial position of the pile top collected by the laser positioning instrument with the critical offset of the pile top through an offset determination module. When the offset exceeds the critical value, it is determined that the risk of seepage and sand inrush does not meet the requirements. Subsequently, the clamping force of the guide clamp is increased through the clamping adjustment module, and the increase is positively correlated with the deviation, thereby actively suppressing the tilting trend of the pile. Compared with the traditional method that relies on manual observation and experience to correct the offset, this invention can adjust the constraint force in real time according to the degree of offset. This avoids the continuous accumulation of offset due to insufficient clamping force, and also prevents damage to the pile or jamming of the clamp due to excessive clamping force. This improves the verticality control accuracy and seepage prevention reliability of sheet pile driving in deep silt layers.

[0018] Furthermore, this invention compares the penetration resistance vibration response ratio with the critical penetration resistance vibration response ratio using a resistance determination module. When this ratio is lower than the critical value, it is determined that the thixotropic liquefaction degree of the silt layer does not meet the requirements. Subsequently, the frequency adjustment module reduces the excitation frequency of the vibratory hammer, and the reduction is positively correlated with the difference between the two. Based on the real-time ratio of penetration resistance to surface vibration response, the softening state of the silt layer under vibration excitation is accurately identified. By actively reducing the excitation frequency, excessive disturbance of vibration energy to the soil structure is reduced, allowing the silt layer to maintain necessary residual strength and shear capacity during pile driving. This effectively avoids the problem of a sudden drop in the bearing capacity of the sheet pile and instability of the surrounding foundation caused by thixotropic liquefaction induced by high-frequency vibration.

[0019] Furthermore, this invention compares the hammering energy transfer efficiency with a critical value using an energy determination module. When the transfer efficiency is lower than the critical value, it is determined that the impact energy of the diesel hammer is excessively dissipated between the vibratory hammer and the replacement device due to poor rigid contact. Subsequently, the fuel supply adjustment module increases the fuel supply frequency of the diesel hammer, and the increase is positively correlated with the efficiency difference. This control mechanism effectively compensates for the energy loss at the contact interface, ensuring that the impact energy of the diesel hammer is fully transferred to the top of the sheet pile, avoiding the decrease in pile driving efficiency and difficulty in pile penetration caused by energy attenuation. At the same time, by monitoring the vibration acceleration of the vibratory hammer in real time and suspending the hammering operation when it exceeds the limit, it prevents resonance damage to the vibratory hammer caused by excessive impact energy, thus achieving synergistic optimization of the diesel hammer impact strength and the structural safety of the vibratory hammer.

[0020] Furthermore, the guide clamp in this invention consists of two sets of hydraulic clamping arms spaced apart along the height of the pile frame, with the clamping forces of the upper and lower sets independently adjustable. The clamping force of the upper set is greater than that of the lower set. This differentiated clamping strategy provides a stronger corrective torque to the upper part of the pile while maintaining moderate constraint on the lower part to avoid increased pile friction and penetration resistance caused by excessive clamping. This ensures guiding accuracy while minimizing the adverse effects of clamping resistance on pile driving efficiency. In addition, the surface vibration monitoring instrument provides real-time feedback on the vibration response of the silt layer, enabling the control components to dynamically assess the impact of vibration energy on the strata. This provides comprehensive data support for the joint adjustment of the excitation frequency and fuel supply frequency, further enhancing the adaptability and robustness of this invention under different geological conditions and construction conditions. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the combined vibratory hammer and diesel hammer driving device for sheet piles according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating the process of determining the risk of seepage and sand inrush using the offset determination module in an embodiment of the present invention. Figure 3 This is a flowchart illustrating the process of determining the degree of thixotropic liquefaction using the resistance determination module in an embodiment of the present invention. Figure 4 This is a flowchart illustrating the energy dissipation determination process of the energy determination module in an embodiment of the present invention. In the diagram: 1. Pile frame; 2. Construction platform; 3. Guide pulley block; 4. Guide clamp; 41. Upper hydraulic clamping arm; 5. Vibratory hammer; 51. Hydraulic clamp; 52. Vibration transmission seat; 6. Diesel hammer; 61. Replacement hammer device; 42. Lower hydraulic clamping arm. Detailed Implementation

[0022] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0025] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 medium; 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 according to the specific circumstances.

[0026] Please see Figure 1 As shown, it is a schematic diagram of the overall structure of the combined vibratory hammer and diesel hammer driving device for steel sheet piles in an embodiment of the present invention.

[0027] This invention provides a combined vibratory hammer and diesel hammer driving device for sheet piles in deep silt formations, comprising: The pile frame 1 is vertically set on the construction platform 2. The top of the pile frame 1 is provided with a guide pulley group 3. The pile frame 1 is provided with several sets of guide clamps 4 at intervals along the height direction to constrain the driving direction of the steel sheet piles. The vibratory hammer assembly includes a vibratory hammer body 5 slidably disposed on the pile frame 1, a hydraulic clamp 51 disposed at the bottom of the vibratory hammer body 5 for clamping the top of the sheet pile, and a vibration transmission seat 52 disposed between the vibratory hammer body 5 and the hydraulic clamp 51. The vibratory hammer body 5 is provided with a frequency conversion drive unit for adjusting the excitation frequency. The diesel hammer assembly includes a diesel hammer body 6 slidably disposed on the pile frame 1 and located above the vibratory hammer body 5, a replacement hammer device 61 disposed at the bottom of the diesel hammer body 6 for transmitting impact energy to the vibratory hammer body 5 or the sheet pile, and a fuel supply regulating unit disposed on the diesel hammer body 6. The detection components include a laser positioning device mounted on the top of the pile frame 1 for monitoring the three-dimensional spatial position of the top of the sheet pile; a strain gauge force sensor mounted on the guide clamp 4 for detecting the penetration resistance of the sheet pile; an impact acceleration sensor mounted between the vibratory hammer 5 and the diesel hammer 6 for detecting the hammering energy transfer efficiency; and a ground vibration monitoring device mounted on the construction platform 2 for detecting the vibration response of the silt layer. The above detection instruments are not shown in the figure; they only need to be able to output corresponding image results based on the monitoring data. A control component, which is connected to the vibratory hammer assembly, the diesel hammer assembly and the detection component respectively, is used to adjust the clamping force of the guide clamp 4 according to the offset of the top of the sheet pile, to adjust the excitation frequency of the vibratory hammer body 5 according to the penetration resistance vibration ratio, and to adjust the fuel supply frequency of the diesel hammer body 6 according to the hammer energy transmission efficiency.

[0028] In this embodiment, the guide clamp 4 consists of two sets of hydraulic clamping arms spaced apart along the height direction of the pile frame 1. The clamping force of the upper and lower sets of hydraulic clamping arms is independently adjustable, and the clamping force of the upper set of hydraulic clamping arms 41 is greater than that of the lower set of hydraulic clamping arms 42. Several sets of guide clamps 4 are spaced apart along the height direction of the pile frame 1. The upper set of hydraulic clamping arms 41 is used to provide a stronger corrective torque on the upper part of the pile body, while the lower set of hydraulic clamping arms 42 maintains appropriate restraint to avoid increased pile body friction and increased penetration resistance caused by over-clamping. The clamping force of the hydraulic clamping arms is adjusted in real time by the proportional relief valve of the hydraulic station. Each hydraulic clamping arm is equipped with a pressure sensor for detecting the actual clamping force, and the control component adjusts according to the deviation between the pressure sensor feedback signal and the target clamping force.

[0029] In this embodiment, the frequency conversion drive unit of the vibratory hammer 5 uses a frequency converter to drive an asynchronous motor, and the excitation frequency is adjusted by changing the output frequency of the frequency converter. The vibration transmission seat 52 is equipped with a damping spring and a guide column, which are used to transmit the high-frequency vibration energy of the vibratory hammer 5 to the hydraulic clamp 51 and the steel sheet pile, while isolating the damage to the internal eccentric block of the vibratory hammer 5 caused by the instantaneous high amplitude impact load generated during the impact of the diesel hammer.

[0030] In this embodiment, the replacement device 61 consists of a replacement body and a replacement pad block disposed at the bottom of the replacement body. The replacement pad block is made of high-strength wear-resistant steel, and its lower end face abuts against the upper end face of the vibratory hammer body 5. When the diesel hammer body 6 starts hammering, the lower piston of the diesel hammer body 6 impacts the replacement device 61, and the replacement device 61 transmits the impact energy to the vibratory hammer body 5, and then transmits it to the top of the sheet pile through the vibration transmission seat 52 and the hydraulic clamp 51. The replacement device 61 and the vibratory hammer body 5 are fitted with a clearance, allowing the vibratory hammer body 5 to produce a small axial reciprocating motion relative to the replacement device 61 under vibration conditions, avoiding excessive dissipation of impact energy caused by rigid connection.

[0031] Please see Figure 2 As shown, this is a flowchart illustrating the process of determining the risk of seepage and sand inrush by the offset determination module in an embodiment of the present invention. The control component further includes: The offset determination module is used to determine whether the risk of seepage and sand inrush in the deep silt layer where the sheet pile is located does not meet the requirements if the offset of the top of the sheet pile is greater than the critical offset of the top of the pile. The clamping adjustment module is used to increase the clamping force of the guide clamp 4 if the risk of sand leakage in the deep silt layer where the sheet pile is located does not meet the requirements.

[0032] In this embodiment, the clamping force of the guide clamp 4 is increased to strengthen the constraint on the direction of the sheet pile driving, thereby suppressing the tendency of the pile body to tilt due to the offset of the pile top and avoiding the opening of the interlocks caused by tilting, which allows soil particles to seep in along the opening gaps and form a seepage and sand inrush channel. When the offset of the sheet pile top is extremely low and uneven due to the extremely low bearing capacity of the deep silt layer, the pile body is subjected to uneven lateral forces during the driving process and deviates. The tilting of the pile body will increase the interlocking gap between adjacent sheet piles. Under pressure, silt and groundwater seep into the foundation pit along the gaps, forming a risk of seepage and sand inrush.

[0033] Specifically, the offset determination module calculates the current offset value of the pile top based on the three-dimensional spatial position data of the steel sheet pile top collected in real time by the laser positioning instrument, and compares it with the critical offset value of the pile top. When the offset of the steel sheet pile top is greater than the critical offset value, it is determined that the risk of seepage and sand inrush in the deep silt layer where the steel sheet pile is located does not meet the requirements, thereby triggering the clamping adjustment module to increase the clamping force of the guide clamp 4. The adjustment of the clamping force of the guide clamp 4 aims to resist the deviation moment generated by the uneven strata by enhancing the lateral constraint force on the upper part of the pile body, so that the pile axis returns to the design direction and avoids the failure of the interlock and the formation of seepage channels due to the accumulation of tilt.

[0034] Specifically, based on the varying relationships between the verticality deviation of sheet piles and the interlock sealing performance under different geological conditions, the critical offset of the pile top is defined as the amount of offset that allows the sheet pile to maintain effective interlocking without creating leakage channels throughout the entire pile driving process. Those skilled in the art can make adaptive adjustments based on the water content, sensitivity, lateral earth pressure coefficient of the silt layer, as well as the interlock type and pile length of the sheet pile.

[0035] It should be noted that the clamping force reference range of the guide clamp 4 can be calibrated based on the section modulus and yield strength of the sheet pile, with the criterion being to effectively restrain pile deviation without causing local buckling of the pile. In practical applications, adjustments can be made up or down based on this reference range. For example, according to the instructions of the control component, a certain percentage can be floated up or down from the preset reference range as the maximum adjustment range. Under the premise of ensuring basic guiding function, adjustments can be made flexibly according to specific working conditions such as actual deviation, pile driving rate, and soil resistance fluctuations to ensure that the clamping force matches the degree of deviation. In this embodiment, the clamping force of the guide clamp 4 is set in the range of 50-200N.

[0036] It is understood that increasing the clamping force of the guide clamp 4 can be achieved by adjusting the command current of the proportional relief valve connected to the hydraulic clamping arm. Those skilled in the art can select the corresponding adjustment strategy according to the actual hydraulic system and control method, without further limitations.

[0037] In this embodiment, the pile top offset is the square root of the sum of the squares of the displacement components of the top of the steel sheet pile in two mutually perpendicular directions in the horizontal plane, which are collected in real time by the laser positioning instrument. The greater the offset of the top of the sheet pile, the more significant the uneven lateral force on the pile body during the pile driving process, the more serious the tilt of the pile body, and the higher the risk of seepage and sand inrush, which is not conducive to the water-stopping effect and construction safety of the foundation pit cofferdam.

[0038] Specifically, the increase in the clamping force is positively correlated with the difference between the pile top offset and the critical pile top offset. It is understood that the positive correlation can be linear or nonlinear, and there is no specific limitation. Similarly, the slope of the linear positive correlation is not specifically limited and can be set according to the actual fabrication conditions. The only requirement is that the greater the difference between the pile top offset and the critical pile top offset, the greater the increase in the clamping force.

[0039] Please see Figure 3 As shown, it is a flowchart of the resistance determination module for determining the degree of thixotropic liquefaction in an embodiment of the present invention. The frequency conversion drive unit further includes: The resistance determination module is used to determine whether the degree of thixotropic liquefaction of the deep silt layer under vibration excitation does not meet the requirements, based on the fact that the penetration resistance vibration response ratio is less than the penetration resistance critical vibration response ratio. The frequency adjustment module is used to reduce the excitation frequency of the vibrating hammer 5 if the degree of thixotropic liquefaction of the deep silt layer under vibration excitation is deemed unsatisfactory.

[0040] In this embodiment, by reducing the excitation frequency of the vibratory hammer 5, the continuous disturbance of vibration energy to the silt layer structure is reduced, thereby avoiding excessive thixotropic liquefaction of the soil layer caused by high-frequency vibration, and ensuring that the silt layer maintains the necessary residual strength and shear capacity during pile driving. When the penetration resistance vibration-to-response ratio decreases due to the excessively high excitation frequency of the vibratory hammer 5, resulting in the continuous accumulation of vibration energy in the silt layer, the continuous increase of pore water pressure, a significant reduction in the effective stress of the soil, and an intensification of thixotropic liquefaction, the soil around the pile loses its bearing capacity, the penetration resistance drops sharply, while the surface vibration response continues to increase, and the penetration resistance vibration-to-response ratio decreases accordingly.

[0041] Specifically, the resistance determination module calculates the current penetration resistance vibration-to-response ratio based on the real-time penetration resistance value detected by the strain gauge force sensor and the peak ground acceleration detected by the surface vibration monitor, and compares it with the critical penetration resistance vibration-to-response ratio. When the penetration resistance vibration-to-response ratio is less than the critical penetration resistance vibration-to-response ratio, it is determined that the degree of thixotropic liquefaction of the deep silt layer under vibration excitation does not meet the requirements, thereby triggering the frequency adjustment module to reduce the excitation frequency of the vibratory hammer 5. The adjustment of the excitation frequency of the vibratory hammer 5 aims to reduce the input intensity of vibration energy, reduce the accumulation rate of pore water pressure, and allow the soil sufficient time to complete drainage consolidation during the vibration interval, recover some shear strength, and avoid uncontrolled pile settlement and instability of the surrounding foundation due to excessive liquefaction.

[0042] Specifically, based on the varying relationships between vibration frequency and thixotropic liquefaction under different geological conditions, the critical vibration-response ratio for penetration resistance is defined as the ratio at which the silt layer maintains necessary residual strength and does not undergo excessive liquefaction during vibratory pile driving. Those skilled in the art can make adaptive adjustments based on the silt layer's sensitivity, sensitivity index, water content, and the amplitude of the vibratory hammer's excitation force.

[0043] It should be noted that the excitation frequency reference range of the vibratory hammer 5 can be calibrated according to the model and rated power of the vibratory hammer, with the criterion of overcoming pile side friction without causing excessive soil liquefaction. In practical applications, adjustments can be made up or down based on this reference range. For example, according to the instructions of the control component, a certain percentage can be floated up or down from the preset reference range as the maximum adjustment range. Under the premise of ensuring basic pile driving efficiency, adjustments can be made flexibly according to specific working conditions such as actual penetration resistance, surface vibration response, and pore water pressure monitoring data to ensure that the excitation frequency matches the soil liquefaction state. In this embodiment, the excitation frequency of the vibratory hammer 5 is set in the range of 15 to 50 Hz.

[0044] It is understood that the excitation frequency of the vibrating hammer 5 can be reduced by adjusting the output frequency of the variable frequency drive unit. Those skilled in the art can select the corresponding adjustment method according to the actual variable frequency drive model and control protocol, without further limitations.

[0045] In this embodiment, the penetration resistance vibration response ratio is the ratio of the steel sheet pile penetration resistance to the silt layer vibration response, which is determined by the ratio of the real-time penetration resistance value detected by the strain gauge force sensor to the peak ground acceleration detected by the ground vibration monitor. The smaller the penetration resistance-to-vibration ratio, the more significant the strength attenuation of the soil around the pile under vibration excitation, the more severe the degree of thixotropic liquefaction, and the higher the risk of a decrease in the bearing capacity of the pile foundation. This is not conducive to the stable control of the pile driving process and the safety protection of the surrounding environment.

[0046] Specifically, the reduction in excitation frequency is positively correlated with the difference between the penetration resistance vibration ratio and the critical penetration resistance vibration ratio. This positive correlation can be linear or nonlinear, and the slope of the linear correlation is also not limited; it can be set according to the actual preparation conditions. The key requirement is that the greater the difference between the penetration resistance vibration ratio and the critical penetration resistance vibration ratio, the greater the reduction in excitation frequency. The units for the penetration resistance vibration ratio and the critical penetration resistance vibration ratio are kg. That is, for every 1 kg increase in the difference between the penetration resistance vibration ratio and the critical penetration resistance vibration ratio, the excitation frequency decreases by 0.5 Hz. Specific values ​​can be adjusted according to the rated parameters of the vibratory hammer and the on-site geological conditions. When the penetration resistance vibration ratio rises back to a level greater than or equal to the critical penetration resistance vibration ratio, the reduction in excitation frequency stops. The current frequency can be maintained or gradually restored to the reference frequency range depending on the current pile driving conditions, balancing pile driving efficiency and soil stability control requirements.

[0047] Please see Figure 4 As shown, this is a flowchart illustrating the energy dissipation determination process of the energy determination module in an embodiment of the present invention. The fuel supply adjustment unit further includes: The energy determination module is used to determine that the energy dissipation of the impact energy of the diesel hammer 6 during the process of passing through the vibrating hammer 5 to the steel sheet pile due to poor rigid contact between the vibrating hammer 5 and the replacement hammer device 61 does not meet the requirements, based on the fact that the hammer energy transmission efficiency is less than the hammer energy critical transmission efficiency. The fuel supply adjustment module is used to increase the fuel supply frequency of the diesel hammer 6 if the energy dissipation of the impact energy during the transmission process does not meet the requirements.

[0048] In this embodiment, the single impact energy of the diesel hammer 6 is increased by increasing the fuel supply frequency of the diesel hammer 6, thereby compensating for the insufficient effective impact energy caused by energy dissipation at the contact interface. This ensures that the impact energy of the diesel hammer is fully transferred to the top of the sheet pile, avoiding a decrease in pile driving efficiency and difficulty in pile penetration due to energy attenuation. When the impact energy of the diesel hammer 6 is transmitted to the sheet pile through the vibratory hammer 5, due to the gap or insufficient contact stiffness at the contact surface between the vibratory hammer 5 and the replacement device 61, the shock wave is reflected and refracted at the interface. Some energy is dissipated into the surrounding medium in the form of elastic waves. When the actual effective impact energy transferred to the sheet pile is much lower than the nominal output energy of the diesel hammer, the hammering energy transfer efficiency decreases accordingly.

[0049] Specifically, the energy determination module calculates the current impact energy transfer efficiency based on the peak impact acceleration transmitted to the vibrating hammer 5 after a single impact by the diesel hammer 6, detected by the impact acceleration sensor, and the peak impact acceleration of the diesel hammer 6 under no-load conditions. This efficiency is then compared to the critical impact energy transfer efficiency. When the impact energy transfer efficiency is less than the critical efficiency, it is determined that the energy dissipation during the transmission of impact energy from the diesel hammer 6 does not meet requirements, thus triggering the fuel supply adjustment module to increase the fuel supply frequency of the diesel hammer 6. Adjusting the fuel supply frequency of the diesel hammer 6 aims to increase the impact velocity and impact energy of the lower piston by increasing the fuel injection quantity and combustion explosion pressure, allowing more effective impact energy to overcome interface dissipation and be transferred to the sheet pile, ensuring the pile receives sufficient penetration energy.

[0050] Specifically, based on the differences in energy transfer efficiency under different hammer types and contact conditions, the critical energy transfer efficiency of the diesel hammer 6 under normal working conditions, which is required to overcome interface energy loss and ensure effective pile driving, is taken as the critical energy transfer efficiency. Those skilled in the art can make adaptive adjustments based on the model of the diesel hammer, the rated impact energy, the structural form of the replacement hammer 61, and the mass of the vibrating hammer 5.

[0051] It should be noted that the reference range for the fuel supply frequency of the diesel hammer 6 can be calibrated according to the model and rated power of the diesel hammer, with the criterion of providing sufficient impact energy without causing equipment overload. In practical applications, adjustments can be made up or down based on this reference range. For example, according to the instructions of the control component, a certain percentage can be added or subtracted from the preset reference range as the maximum adjustment range. Under the premise of ensuring basic pile driving efficiency, adjustments can be made flexibly according to specific working conditions such as actual penetration resistance, hammer energy transfer efficiency, and pile penetration rate to ensure that the fuel supply frequency matches the degree of energy dissipation.

[0052] It is understood that increasing the fuel supply frequency of the diesel hammer 6 can be achieved by adjusting the actuator execution frequency of the fuel supply adjustment unit of the diesel hammer 6. Those skilled in the art can select the corresponding adjustment strategy according to the actual fuel system and control method, without further limitations.

[0053] In this embodiment, the hammer energy transfer efficiency is the ratio of the peak value of the impact acceleration transmitted to the vibrating hammer 5 after a single hammering by the diesel hammer 6, as detected by the impact acceleration sensor, to the peak value of the no-load impact acceleration of the diesel hammer 6. The lower the energy transfer efficiency of the hammer, the more severe the dissipation of the impact energy of the diesel hammer body 6 in the transmission path, the less energy is effectively transferred to the steel sheet pile, the lower the pile driving efficiency, and the less conducive it is to ensuring that the pile body reaches the design elevation and bearing capacity.

[0054] Specifically, the increase in the fuel supply frequency is positively correlated with the difference between the critical hammer energy transfer efficiency and the hammer energy transfer efficiency. It is understood that the positive correlation can be linear or nonlinear, and there is no specific limitation. Similarly, the slope of the linear positive correlation is not specifically limited and can be set according to the actual preparation conditions. The only requirement is that the greater the difference between the critical hammer energy transfer efficiency and the hammer energy transfer efficiency, the greater the increase in the fuel supply frequency.

[0055] In this embodiment, as the fuel supply frequency of the diesel hammer 6 increases, the vibration acceleration of the vibrating hammer 5 is continuously monitored. If the vibration acceleration exceeds the critical vibration acceleration, it is determined that the impact energy of the diesel hammer 6 is too large, resulting in a risk of resonance damage to the vibrating hammer 5 that does not meet the requirements, and the hammering operation of the diesel hammer 6 is suspended.

[0056] It should be noted that as the fuel supply frequency of the diesel hammer 6 increases, the single impact energy also increases, and the peak impact acceleration transmitted to the vibratory hammer 5 also increases accordingly. When the vibration acceleration exceeds the critical vibration acceleration, it indicates that the eccentric blocks, bearings, and damping springs inside the vibratory hammer 5 have been subjected to impact loads exceeding the design threshold. Long-term operation under this condition will lead to fatigue damage or even structural failure. Suspending the hammering operation of the diesel hammer 6 allows the vibratory hammer 5 to temporarily escape the impact load. Operation can be resumed after the vibration acceleration drops below the safe threshold, thus ensuring pile driving efficiency while protecting the structural integrity of the vibratory hammer 5.

[0057] The specific value of the critical vibration acceleration is determined by comprehensively considering the structural strength of the vibratory hammer body 5, the rated load of the bearing, and the fatigue life of the damping spring. It is usually obtained by combining the technical parameters provided by the equipment manufacturer with finite element analysis. When the model or maintenance status of the vibratory hammer body 5 changes, the critical value needs to be recalibrated to ensure the accuracy of the judgment.

[0058] In this embodiment, a detection component consisting of a laser positioning device, a strain gauge force sensor, an impact acceleration sensor, and a ground vibration monitor collects multi-source data in real time, including the offset of the top of the steel sheet pile, the penetration resistance, the hammer energy transfer efficiency, and the vibration response of the silt layer. The control component makes comprehensive decisions based on the above data and coordinates the execution of three control actions: adjusting the clamping force of the guide clamp 4, adjusting the excitation frequency of the vibrating hammer 5, and adjusting the fuel supply frequency of the diesel hammer 6.

[0059] Specifically, in the initial stage of pile driving, high-frequency vibration of the vibratory hammer 5 is the main method for pile driving. The control component dynamically adjusts the excitation frequency according to the penetration resistance-vibration ratio to avoid excessive liquefaction of the silt layer. When the pile approaches the design elevation or encounters a hard interlayer and needs to enhance its penetration ability, the diesel hammer 6 is activated for impact re-driving. The control component dynamically adjusts the fuel supply frequency according to the hammer energy transfer efficiency to compensate for energy dissipation. Throughout the entire pile driving process, the control component continuously monitors the pile top offset and dynamically adjusts the clamping force of the guide clamp 4 according to its changes to maintain the verticality of the pile. The three components work together through the coordinated scheduling of the control components. The reduction of the excitation frequency changes the contact state between the vibratory hammer 5 and the replacement device 61, thus affecting the hammering energy transfer efficiency. The increase of the fuel supply frequency changes the impact acceleration of the diesel hammer 6, thus triggering the vibration acceleration over-limit protection. The increase of the clamping force changes the constraint state of the pile body, thus affecting the transmission path of the penetration resistance. The various control actions are coupled and influence each other. The control components detect the changes of various parameters in real time and coordinate the action sequence and adjustment range of each actuator accordingly. This achieves coordinated and optimized construction operations of the vibratory hammer and diesel hammer in deep silt strata, effectively overcoming the technical defects of single construction methods in soft strata, such as easy deviation and easy liquefaction.

[0060] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations, characterized in that, include: A pile frame is vertically installed on a construction platform. The top of the pile frame is equipped with a guide pulley group, and the pile frame is provided with several sets of guide clamps at intervals along the height direction to constrain the driving direction of the steel sheet piles. The vibratory hammer assembly includes a vibratory hammer body slidably disposed on the pile frame, a hydraulic clamp disposed at the bottom of the vibratory hammer body for clamping the top of the sheet pile, and a vibration transmission seat disposed between the vibratory hammer body and the hydraulic clamp. The vibratory hammer body is provided with a frequency conversion drive unit for adjusting the excitation frequency. The diesel hammer assembly includes a diesel hammer body slidably disposed on the pile frame and located above the vibratory hammer body, a replacement hammer device disposed at the bottom of the diesel hammer body for transmitting impact energy to the vibratory hammer body or sheet pile, and a fuel supply regulating unit disposed on the diesel hammer body. The detection assembly includes a laser positioning device mounted on the top of the pile frame for monitoring the three-dimensional spatial position of the top of the sheet pile, a strain gauge force sensor mounted on the guide clamp for detecting the penetration resistance of the sheet pile, an impact acceleration sensor mounted between the vibratory hammer and the diesel hammer for detecting the hammering energy transfer efficiency, and a surface vibration monitoring device mounted on the construction platform for detecting the vibration response of the silt layer. A control component, which is connected to the vibratory hammer assembly, the diesel hammer assembly and the detection component respectively, is used to adjust the clamping force of the guide clamp according to the offset of the top of the sheet pile, to adjust the excitation frequency of the vibratory hammer body according to the penetration resistance vibration ratio, and to adjust the fuel supply frequency of the diesel hammer body according to the hammer energy transfer efficiency.

2. The combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations according to claim 1, characterized in that, The control component also includes: The offset determination module is used to determine whether the risk of seepage and sand inrush in the deep silt layer where the sheet pile is located does not meet the requirements if the offset of the top of the sheet pile is greater than the critical offset of the top of the pile. The clamping adjustment module is used to increase the clamping force of the guide clamp if the risk of sand leakage in the deep silt layer where the sheet pile is located does not meet the requirements. The increase in the clamping force is positively correlated with the difference between the pile top offset and the critical pile top offset.

3. The combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations according to claim 2, characterized in that, The offset of the pile top is the square root of the sum of the squares of the displacement components of the steel sheet pile top in two mutually perpendicular directions in the horizontal plane, which are collected in real time by the laser positioning instrument.

4. The combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations according to claim 3, characterized in that, The frequency converter drive unit also includes: The resistance determination module is used to determine whether the degree of thixotropic liquefaction of the deep silt layer under vibration excitation does not meet the requirements, based on the fact that the penetration resistance vibration response ratio is less than the penetration resistance critical vibration response ratio. The frequency adjustment module is used to reduce the excitation frequency of the vibrating hammer body if the degree of thixotropic liquefaction of the deep silt layer under vibration excitation is deemed unsatisfactory.

5. The combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations according to claim 4, characterized in that, The penetration resistance vibration response ratio is the ratio of the penetration resistance of the sheet pile to the vibration response of the silt layer. The penetration resistance vibration ratio is determined by the ratio of the real-time penetration resistance value detected by the strain gauge force sensor to the peak ground acceleration detected by the ground vibration monitor.

6. The combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations according to claim 5, characterized in that, The reduction in the excitation frequency of the vibrating hammer is positively correlated with the difference between the penetration resistance vibration ratio and the critical penetration resistance vibration ratio.

7. The combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations according to claim 6, characterized in that, The fuel supply regulating unit also includes: The energy determination module is used to determine that the energy dissipation of the impact energy of the diesel hammer body during the process of transmitting the impact energy through the vibrating hammer body to the steel sheet pile due to poor rigid contact between the vibrating hammer body and the replacement device does not meet the requirements, based on the fact that the hammer energy transmission efficiency is less than the hammer energy critical transmission efficiency. The fuel supply adjustment module is used to increase the fuel supply frequency of the diesel hammer if the energy dissipation of the impact energy during the transmission process does not meet the requirements. The increase in the fuel supply frequency is positively correlated with the difference between the critical transfer efficiency of the hammer energy and the transfer efficiency of the hammer energy.

8. The combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations according to claim 7, characterized in that, The hammer energy transfer efficiency is the ratio of the peak impact acceleration transmitted to the vibrating hammer after a single hammering by the diesel hammer, as detected by the impact acceleration sensor, to the peak impact acceleration of the diesel hammer under no-load conditions.

9. The combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations according to claim 8, characterized in that, During the process of increasing the fuel supply frequency of the diesel hammer, the vibration acceleration of the vibrating hammer is continuously monitored. If the vibration acceleration exceeds the critical vibration acceleration, it is determined that the impact energy of the diesel hammer is too large, which may cause resonance damage to the vibrating hammer and does not meet the requirements. The diesel hammer hammering operation is then suspended.

10. The combined vibratory hammer and diesel hammer driving device for steel sheet piles in deep silt formations according to claim 9, characterized in that, The guide clamp consists of two sets of hydraulic clamping arms spaced apart along the height of the pile frame. The clamping force of the upper and lower sets of hydraulic clamping arms can be adjusted independently, and the clamping force of the upper set of hydraulic clamping arms is greater than that of the lower set of hydraulic clamping arms.

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