Steel sheet pile vibration hammer and diesel hammer cooperative control method for deep silt stratum

Abstract

The present application relates to the steel sheet pile sinking construction technology field, especially relates to a kind of steel sheet pile vibration hammer and diesel hammer collaborative control method for deep silt stratum, comprising: in the process that vibration hammer implements initial sinking operation to steel sheet pile, real-time acquisition sinking process parameter, and determine whether current sinking interface has entered hard soil layer according to this;In the process that diesel hammer implements re-driving operation to steel sheet pile, based on the re-driving process parameter of real-time acquisition, the drop distance or hammering energy level of diesel hammer is dynamically adjusted, and vibration hammer is controlled to apply auxiliary vibration force to steel sheet pile in hammering gap;And based on the refusal hammer risk obtained by penetration degree trend prediction, or based on the stress of pile body is detected to be over limit, determine to execute automatic early warning and reduce drop distance or hammering energy level.The present application improves sinking efficiency and guarantees construction safety by the adaptive collaborative operation of vibration hammer and diesel hammer based on stratum working condition.

Description

Technical Field

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

[0002] Current sheet pile construction in deep silt strata relies solely on vibratory hammers or diesel hammers, or manual hammer changing, which easily leads to problems such as pile slippage, hammer refusal, pile damage, and low switching efficiency. Furthermore, the lack of quantitative assessment and dynamic collaborative management methods makes it difficult to consistently control construction quality, environmental protection, and safety. Commercially available integrated composite hammers only achieve hardware integration but lack customized adaptive control logic for highly sensitive silt strata, failing to solve the problem of load matching in layered pile driving.

[0003] Chinese Patent Application Publication No. CN117306524A discloses a double-layer guide frame and a method for driving sheet piles. The method includes a double-layer guide frame and a main body. The main body comprises two sets of frame bodies, which are vertically and parallelly arranged. Several pairs of limiting plates are connected between the two sets of frame bodies. Each pair of limiting plates is horizontally arranged, and a guide groove is formed between each pair of limiting plates. The limiting plates have two layers in the vertical direction. The sheet pile driving method involves driving the sheet piles in stages, initially using a vibratory hammer and then a diesel hammer. On the one hand, this application improves the stability of the sheet piles before driving by utilizing the inherent strength of the guide frame, enabling accurate positioning of longer sheet piles. On the other hand, the application uses a vibratory hammer and a diesel hammer to drive the sheet piles in stages, allowing for smooth and rapid driving.

[0004] However, the above technical solutions rely solely on manual judgment of soil layers and manual replacement of hammers, and cannot automatically switch operating modes based on real-time data of pile driving, making it difficult to balance construction efficiency and pile quality. Summary of the Invention

[0005] To address this issue, the present invention provides a method for coordinated control of a vibratory hammer and a diesel hammer for sheet piles in deep silt formations. This method overcomes the problem in the prior art where the soil layer is judged manually and the hammer is changed manually, making it impossible to automatically switch the operation mode based on real-time pile driving data, and thus difficult to balance construction efficiency and pile quality.

[0006] To achieve the above objectives, the present invention provides a method for coordinated control of a vibratory hammer and a diesel hammer for steel sheet piles in deep silt formations, comprising: During the initial driving operation of sheet piles with a vibratory hammer, the driving process parameters are collected in real time, including the driving rate and the excitation force of the vibratory hammer. The pile driving process parameters are compared with a preset set of switching trigger conditions to determine whether the current pile driving interface has entered the hard soil layer treated by the diesel hammer. The switching trigger conditions include the pile driving rate being less than the lower limit of the pile driving rate or the excitation force being greater than the upper limit of the excitation force within a number of consecutive first sampling periods. During the re-driving operation of the steel sheet pile by the diesel hammer, the re-driving process parameters are collected in real time. Based on the re-driving process parameters, the drop distance or hammering energy level of the diesel hammer is dynamically adjusted, and the vibratory hammer is controlled to apply auxiliary vibration force to the steel sheet pile within the hammering gap of the diesel hammer. The re-driving process parameters include penetration and rebound. Based on the penetration trend prediction, the risk of hammer failure is obtained, or based on the detection that the pile stress is greater than the safe upper limit of the pile stress, it is determined to implement collaborative safety management. The collaborative safety management includes automatic early warning and reduction of the dynamic adjustment drop distance or hammer energy level.

[0007] Furthermore, the process of real-time acquisition of parameters during pile driving includes: The time-domain acceleration signal of the steel sheet pile during the initial sinking operation is obtained by an acceleration sensor fixed to the top of the steel sheet pile within several consecutive first sampling periods. The low-frequency component introduced by the soil disturbance of the deep silt layer and the high-frequency component introduced by the vibration of the vibratory hammer itself are separated from the time-domain acceleration signal and integrated to determine the pile driving rate. The hydraulic signal is acquired by a hydraulic sensor installed in the hydraulic circuit of the vibratory hammer, and the excitation force is calculated by combining the eccentric block structural parameters of the vibratory hammer.

[0008] Furthermore, the vibratory hammer and the diesel hammer are mounted on the same pile frame, with the diesel hammer positioned above the vibratory hammer; The vibratory hammer has a through hole that extends vertically through the force transmission column, and the vibratory hammer is clamped to the top of the sheet pile by a bottom clamp. The lower end of the force transmission column abuts against the top of the sheet pile, and the upper end extends upward from the upper surface of the vibratory hammer. The hammer core of the diesel hammer falls and strikes the upper end of the force transmission column, which then transmits the hammering force to the top of the sheet pile.

[0009] Furthermore, upon determining that the machine has entered a hard soil layer treated by the diesel hammer, the machine is triggered to switch from operating the vibratory hammer alone to operating the diesel hammer and vibratory hammer in a coordinated manner. Specifically, the excitation force of the vibratory hammer is reduced to less than the initial excitation force of the initial sinking operation, and the hammer core of the diesel hammer is controlled to strike the top of the force transmission column, while the bottom clamping device maintains the clamping of the steel sheet pile.

[0010] Furthermore, the process of dynamically adjusting the drop height or hammering energy level of the diesel hammer based on the parameters of the re-strike process includes: Obtain the average value of the pile driving rate over several consecutive first sampling periods before the determination of entering the hard soil layer; The drop distance or the hammer impact energy level is determined based on the negative correlation between the average value of the pile driving rate and the pile driving rate.

[0011] Furthermore, the process of dynamically adjusting the drop height or hammering energy level of the diesel hammer based on the parameters of the re-strike process also includes: Obtain the penetration degree within a consecutive number of second sampling periods; Calculate the penetration difference between any two adjacent second sampling periods; Based on a series of consecutive negative penetration differences and the absolute value of the difference increasing periodically, the drop distance or the hammering energy level is adjusted accordingly. Based on a series of consecutive positive penetration differences and the absolute value of the difference increasing periodically, it is determined to reduce or adjust the drop distance or the hammering energy level.

[0012] Furthermore, the process of applying auxiliary vibration force to the sheet pile includes: After adjusting the drop distance or the hammering energy level, the hammering gap is determined based on the current drop distance or hammering energy level. The first applied amplitude corresponding to the auxiliary vibration force is determined based on the positive correlation between the adjusted drop distance and the hammering gap. The second applied amplitude corresponding to the auxiliary vibration force is determined based on the positive correlation between the adjusted hammering energy level and the hammering gap. Take the first applied amplitude or the second applied amplitude, and control the vibratory hammer to apply the auxiliary vibration force of the corresponding amplitude to the top of the steel sheet pile within the hammering gap.

[0013] Furthermore, the process of implementing collaborative security controls includes: Based on the fact that the penetration depth is less than the lower limit of penetration depth in several consecutive second sampling periods, it is determined that there is a risk of hammer failure. When the risk of hammer refusal is determined to exist, the dynamically adjusted drop height or hammer energy level is reduced and a hammer refusal warning signal is output simultaneously. If the penetration depth after reducing the drop height or hammering energy level remains below the lower limit of penetration depth for several consecutive second sampling periods, the hammering process of the diesel hammer will be suspended.

[0014] Furthermore, the process of implementing collaborative security controls also includes: When the pile stress is detected to be greater than the safe upper limit of the pile stress, the adjusted drop height or hammer energy level is reduced and a pile over-limit warning signal is output simultaneously. The reduction range is positively correlated with the value by which the pile stress exceeds the safe upper limit of the pile stress.

[0015] Furthermore, the springback penetration ratio is determined by calculating the ratio of the springback amount to the corresponding penetration within the same second sampling period; Based on a series of consecutive increases in the rebound penetration ratio, the applied amplitude of the auxiliary vibration force is adjusted upwards, and a hammering efficiency abnormality warning signal is output simultaneously.

[0016] Compared with existing technologies, the advantages of this invention are as follows: During the initial driving of sheet piles with a vibratory hammer, driving process parameters are collected in real time; these parameters are compared with a preset set of switching trigger conditions, including driving rates below the lower limit or excitation forces exceeding the upper limit for several consecutive first sampling cycles, to determine whether the current pile interface has entered the hard soil layer treated by the diesel hammer; during the re-driving of the sheet piles with the diesel hammer, re-driving process parameters are collected in real time, and the drop height or hammering energy level of the diesel hammer is dynamically adjusted based on these parameters, while the vibratory hammer applies auxiliary vibration force to the sheet piles within the hammering interval of the diesel hammer; and based on the penetration trend prediction of the risk of hammer rejection, or based on the detection that the pile stress exceeds the safe upper limit of the pile stress, an automatic warning is issued, while simultaneously reducing the dynamically adjusted drop height or hammering energy level. Thus, through the adaptive collaborative operation of the vibratory hammer and diesel hammer based on the geological conditions, pile driving efficiency is improved and construction safety is ensured.

[0017] Furthermore, this invention acquires time-domain acceleration signals of the sheet pile during the initial sinking process over several consecutive first sampling periods using an acceleration sensor fixed to the top of the sheet pile. The low-frequency components introduced by soil disturbance from the deep silt layer and the high-frequency components introduced by the vibration of the vibratory hammer itself are separated from the time-domain acceleration signals and integrated to determine the pile driving rate. Hydraulic signals are acquired using a hydraulic sensor installed in the hydraulic circuit of the vibratory hammer, and the excitation force is calculated by combining these signals with the eccentric block structural parameters of the vibratory hammer. Thus, by separating the interference from silt disturbance and vibration echo, integrating to reconstruct the pile driving displacement, and calculating the excitation force, the accuracy of obtaining the pile driving rate and excitation force is improved.

[0018] Furthermore, this invention obtains the average value of the pile driving rate over several consecutive first sampling periods before determining the entry point into the hard soil layer, and determines the drop height and hammer impact energy level based on the negative correlation of the average pile driving rate. Then, it obtains the penetration depth over several consecutive second sampling periods and calculates the penetration depth difference between any two adjacent second sampling periods. Based on this, it determines to increase the drop height or hammer impact energy level based on several consecutive negative penetration depth differences where the absolute value of the difference increases periodically; and it determines to decrease the drop height or hammer impact energy level based on several consecutive positive penetration depth differences where the absolute value of the difference increases periodically. Thus, by determining the initial drop height and hammer impact energy level based on the measured pile driving rate, and adjusting the hammer impact energy in real time according to the direction and magnitude of the penetration depth difference change, the continuity and stability of repeated pile driving are improved.

[0019] Furthermore, after adjusting the drop height or hammer impact energy level, the present invention determines the hammering gap based on the current drop height and hammer impact energy level; and determines the first application amplitude corresponding to the auxiliary vibration force based on the positive correlation between the adjusted drop height and hammer impact gap, and determines the second application amplitude corresponding to the auxiliary vibration force based on the positive correlation between the adjusted hammer impact energy level and hammer impact gap. Then, by taking either the first or second application amplitude, the vibratory hammer is controlled to apply an auxiliary vibration force of the corresponding amplitude to the top of the sheet pile within the hammering gap. In this way, by determining the application amplitude of the auxiliary vibration force through the drop height, hammer impact energy level, and hammer impact gap, the disturbed liquefaction state of the silt around the pile is maintained and the rebound of side friction is suppressed, thereby improving the utilization rate of the single hammer impact energy.

[0020] Furthermore, this invention determines the risk of hammer failure based on the penetration depth being less than the lower limit of penetration depth within several consecutive sampling periods. When a risk of hammer failure is determined, the dynamically adjusted drop height or hammering energy level is reduced, and a hammer failure warning signal is output simultaneously. Simultaneously, when the pile stress is detected to exceed the safe upper limit of pile stress, the adjusted drop height or hammering energy level is reduced, and a pile over-limit warning signal is output simultaneously. The reduction magnitude is positively correlated with the value by which the pile stress exceeds the safe upper limit of pile stress. The rebound penetration ratio is determined by calculating the ratio between the rebound amount and the corresponding penetration depth within the same second sampling period. Furthermore, based on the continuous increase of the rebound penetration ratio over several consecutive periods, the amplitude of the auxiliary vibration force is determined, and an abnormal hammering efficiency warning signal is output simultaneously. In this way, safety management ensures the structural safety of the pile and equipment, improving the overall safety of pile driving operations in deep silt strata. Attached Figure Description

[0021] Figure 1 This is a flowchart of a method for coordinated control of a vibratory hammer and a diesel hammer for sheet piles in deep silt formations, according to an embodiment of the present invention. Figure 2This is a schematic diagram of the integrated double hammer frame structure according to an embodiment of the present invention; Figure 3 This is a curve diagram for determining hard soil layers in an embodiment of the present invention; Figure 4 This is a time-series comparison diagram of the auxiliary vibration force during the hammering gap in an embodiment of the present invention; In the diagram: 1. Guide frame; 2. Diesel hammer; 3. Diesel hammer sliding bracket; 4. Force transmission column; 5. Vibratory hammer; 6. Vibratory hammer sliding support; 7. Clamp; 8. Steel sheet pile. 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 based on the specific circumstances.

[0026] Please see Figure 1 and Figure 2 As shown, Figure 1 This is a flowchart illustrating the method for coordinated control of a vibratory hammer and a diesel hammer for sheet piles in deep silt formations, as described in an embodiment of the present invention. Figure 2This is a schematic diagram of the integrated double-hammer structure according to an embodiment of the present invention. The guide frame 1 is vertically arranged above the top of the sheet pile 8, providing vertical support and guidance for the diesel hammer 2 and the vibratory hammer 5. The diesel hammer 2 is mounted on the guide frame 1 via a diesel hammer sliding bracket 3, which can slide up and down along the guide frame 1 to drive the diesel hammer 2 to rise and fall along the guide frame 1. The vibratory hammer 5 is mounted on the guide frame 1 via a vibratory hammer sliding support 6, which can slide up and down along the guide frame 1 to drive the vibratory hammer 5 to rise and fall along the guide frame 1.

[0027] The diesel hammer 2 is positioned above the vibratory hammer 5; the vibratory hammer 5 has a through hole extending vertically, and a force transmission column 4 is inserted through the through hole. The lower end of the force transmission column 4 abuts against the top of the sheet pile 8, and the upper end extends upward from the upper surface of the vibratory hammer 5. The vibratory hammer 5 is clamped to the top of the sheet pile 8 by the bottom clamp 7.

[0028] The method in this embodiment includes at least the following steps: Step S1: During the initial sinking operation of the sheet pile 8 by the vibratory hammer 5, the sinking process parameters are collected in real time, including the sinking rate and the excitation force of the vibratory hammer 5. Step S2: Based on the pile driving process parameters, compare with the preset switching trigger condition set to determine whether the current pile driving interface has entered the hard soil layer processed by the diesel hammer 2. The switching trigger conditions include the pile driving rate being less than the lower limit of the pile driving rate or the excitation force being greater than the upper limit of the excitation force within a number of consecutive first sampling cycles. Step S3: During the re-driving operation of the diesel hammer 2 on the sheet pile 8, the re-driving process parameters are collected in real time. Based on the re-driving process parameters, the drop distance or hammering energy level of the diesel hammer 2 is dynamically adjusted, and the vibratory hammer 5 is controlled to apply auxiliary vibration force to the sheet pile 8 within the hammering gap of the diesel hammer 2. The re-driving process parameters include penetration and rebound. Step S4: Based on the penetration trend prediction, the risk of hammer rejection is obtained, or based on the detection that the pile stress is greater than the safe upper limit of the pile stress, it is determined to implement collaborative safety management. The collaborative safety management includes automatic early warning and reducing the dynamic adjustment drop distance or hammer energy level.

[0029] In step S1, the vibratory hammer 5 performs initial sinking of the sheet pile 8, driving the sheet pile 8 through the thick silt layer and into the hard soil layer. During the initial sinking operation, the pile driving process parameters are collected in real time, including the pile driving rate and the excitation force of the vibratory hammer 5.

[0030] Specifically, the pile driving rate represents the depth to which the sheet pile 8 sinks into the soil per unit time. It reflects the work done by the vibratory hammer 5 to overcome the pile end resistance and pile side friction to drive the pile body down, and is the most direct process parameter for characterizing the current stratum bearing resistance. The pile driving rate is determined based on the real-time sinking displacement of the sheet pile 8 along the pile axis during the initial sinking operation.

[0031] Specifically, the time-domain acceleration signal of the sheet pile 8 during the initial sinking operation is obtained by an acceleration sensor fixed to the top of the sheet pile 8 within several consecutive first sampling periods. The time-domain acceleration signal is a direct representation of the change of the motion state of the sheet pile 8 over time. The acceleration signal changes accordingly every time the pile body undergoes a displacement change, and the displacement process of the pile body can be reconstructed by integrating it.

[0032] Specifically, the first sampling period is the time window for collecting parameters of the pile driving process during the initial sinking stage. During the initial sinking operation, the vibratory hammer 5 drives the sheet pile 8 to sink using high-frequency continuous vibration. The vibration phase and instantaneous disturbances on site cause significant fluctuations in the measured values ​​at any single point in time, making it difficult to stably reflect the true driving capacity of the pile. Therefore, the first sampling period is used as the acquisition unit to periodically collect and statistically analyze the time-domain acceleration signal and hydraulic signal, so that a driving rate and excitation force value that can represent the stable vibration state of the pile can be obtained within each first sampling period. The first sampling period is determined based on the vibration period corresponding to the rated operating frequency of the vibratory hammer 5, and the sampling period duration covers multiple vibration periods to completely include the pile driving motion process under stable vibration state.

[0033] Specifically, the duration of a single vibration cycle is first determined based on the rated operating frequency of the vibratory hammer 5, and then the duration of the first sampling cycle is set to cover multiple vibration cycles so that the sampling cycle contains a complete vibration cycle to smooth out instantaneous fluctuations. At the same time, the sampling cycle duration should not be too long to avoid masking the continuous changes in ground resistance as the pile driving depth advances.

[0034] For example, the rated operating frequency of the vibratory hammer is about 25 times per second, and the corresponding duration of a single vibration cycle is about 0.04 seconds. The duration of the first sampling cycle is more than ten times that of a single vibration cycle, and is exemplarily set to 0.5 seconds to 1 second, thereby covering multiple complete vibration cycles.

[0035] It should be noted that in the construction environment of deep silt strata, the time-domain acceleration signal inevitably contains two interference components: one is the low-frequency disturbance component caused by the loose covering of the pile body by the deep silt and the slight drift of the pile body in the mud; the other is the high-frequency component generated by the echo excited on the pile body by the rated working frequency of the vibratory hammer 5 itself.

[0036] Based on the difference between the rated operating frequency of the vibratory hammer 5 and the frequency band of silt disturbance, a filter cutoff frequency is preset. After the low-frequency and high-frequency components are separated from the time-domain acceleration signal, the net acceleration signal obtained by the separation is integrated to obtain the effective sinking displacement of the sheet pile 8. The effective sinking displacement is the net displacement of the sheet pile 8 actually sinking into the soil along the pile axis under the action of vibration, which directly reflects the pile driving process of the sheet pile 8. Then, the pile driving rate is determined based on the effective sinking displacement.

[0037] The filter cutoff frequency is used to remove low-frequency disturbance components and high-frequency echo components from the time-domain acceleration signal, retaining only the effective pile driving motion frequency band that reflects the actual sinking motion of the pile, thus ensuring the accuracy of subsequent displacement integration results. The filter cutoff frequency is determined based on the difference between the frequency band of the silt drift disturbance and the frequency band of the rated operating frequency of the vibratory hammer 5.

[0038] Specifically, the low-frequency range of the silt drift disturbance and the high-frequency range of the rated operating frequency of the vibratory hammer 5 are first determined respectively. Then, a low-frequency cutoff frequency is set above the upper limit of the low-frequency range of the silt disturbance to completely filter out the silt drift component. A high-frequency cutoff frequency is set between the effective motion frequency band of the pile and the echo frequency band of the vibratory hammer 5 to completely preserve the effective motion frequency band of the pile. Thus, the true pile driving motion information is not lost while filtering out the two types of interference.

[0039] For example, the sludge drift disturbance is concentrated in the low-frequency band below 1 Hz, and the vibratory hammer echo is concentrated in the high-frequency band near its rated operating frequency. The low-frequency cutoff frequency is set to about 1 Hz, and the high-frequency cutoff frequency is set to about 20 Hz, which is located between the upper limit of the effective movement frequency band of the pile and the lower limit of the vibratory hammer echo frequency band.

[0040] To ensure the accuracy of displacement measurement, a guy wire displacement sensor is further introduced as a calibration benchmark. The sensor body of the guy wire displacement sensor is fixed on the guide frame 1, and the guy wire end is fixed to the top of the sheet pile 8. The guide frame 1 remains stationary during construction and is not affected by the vibration of the vibratory hammer 5. The guy wire end sinks synchronously with the pile body, and the change in the length of the guy wire directly reflects the absolute sinking displacement of the sheet pile 8. The displacement measurement value of the guy wire displacement sensor is compared with the displacement obtained by acceleration integration. The allowable range is preset according to the drift characteristics of acceleration integration accumulated over time. When the deviation between the two exceeds the allowable range, the integration result is corrected by the displacement measurement value of the guy wire displacement sensor.

[0041] Specifically, the excitation force represents the periodic vibration force generated by the rotation of the eccentric block of the vibratory hammer 5 and applied to the sheet pile 8. Its amplitude reflects the current output vibration energy level of the vibratory hammer 5 and the load state of the vibratory hammer 5 during the initial sinking operation. The excitation force is determined by converting the hydraulic signal of the hydraulic system of the vibratory hammer 5 with the structural parameters of the eccentric block.

[0042] Specifically, hydraulic signals are collected by hydraulic sensors installed in the hydraulic circuit of the vibratory hammer 5. These hydraulic signals directly represent the working pressure of the vibratory hammer 5's hydraulic system; higher pressure values ​​indicate greater driving energy obtained by the eccentric block and a greater excitation force output by the vibratory hammer 5. The actual excitation force output by the vibratory hammer 5 is calculated by combining the eccentric block structural parameters, including the eccentric block mass, eccentricity, and rated speed, which are factory calibration constants for the vibratory hammer 5. Specifically, the angular velocity is first calculated from the rated speed (revolutions per second), where the rated speed is equal to the product of the rated speed and twice pi (radians per second). Then, the excitation force is determined based on the product of the eccentric block mass, eccentricity, and the square of the angular velocity.

[0043] It should be noted that the hydraulic signal is taken as the average value of the non-impact phase segments within multiple consecutive first sampling periods to eliminate instantaneous pressure fluctuations and ensure the stability of the excitation force conversion result.

[0044] In step S2, the real-time collected pile driving process parameters are compared with the preset switching trigger condition set to determine whether the current pile driving interface has entered the hard soil layer processed by the diesel hammer 2.

[0045] Specifically, a typical geological profile of deep silt strata consists of a thick, high-water-content silt layer at the top and a hard soil layer composed of silty clay, dense sand, or strongly weathered rock at the bottom. In silt layers, the vibratory hammer 5 utilizes high-frequency vibration to liquefy the soil, enabling efficient sinking. However, upon encountering hard soil layers, the soil no longer liquefies, and the vibration energy cannot be effectively transferred, resulting in a sharp drop in pile driving rate and a surge in excitation force. Based on this physical characteristic, the pile driving rate is compared with its lower limit, and the excitation force is compared with its upper limit. Based on the comparison results, it is accurately determined whether the pile has entered a hard soil layer.

[0046] Specifically, the lower limit of the pile driving rate is a quantitative benchmark for the stable pile driving rate that the vibratory hammer 5 can maintain in hard soil layers. Below this benchmark, it indicates that the vibratory hammer 5 has essentially lost its effective pile driving capability. The lower limit of the pile driving rate is determined based on the estimated stable pile driving rate that the vibratory hammer 5 can maintain at the top surface of the hard soil layer.

[0047] Specifically, the density of the top surface of the hard soil layer is first determined based on the geological survey report before construction. The denser the hard soil layer, the lower the stable pile driving rate that the vibratory hammer 5 can maintain in that stratum. Then, based on the correspondence between the density and the stable pile driving rate, the estimated value of the stable pile driving rate that the vibratory hammer 5 can maintain on the top surface of the hard soil layer is calculated. Finally, the estimated value is multiplied by a reliability coefficient of less than one to obtain the lower limit of the pile driving rate.

[0048] The relationship between compaction degree and stable pile driving rate is established in advance based on the equipment performance parameters of vibratory hammer 5 or construction experience data of the same type of stratum in the same area. For each increase in compaction degree, the stable pile driving rate decreases by a preset ratio, and the estimated value of stable pile driving rate is obtained accordingly.

[0049] The reliability coefficient is used to reserve a safety margin based on the estimated value, ensuring that the lower limit of the pile driving rate is slightly lower than the estimated stable pile driving rate. This prevents the lower limit of the pile driving rate from being too high due to estimation errors, thus avoiding premature switching before the hard soil layer is actually reached. The reliability coefficient is determined based on the reliability of the estimated stable pile driving rate.

[0050] Specifically, based on the degree of stratigraphic dispersion and the density of exploration points in the pre-construction geological survey report, the reliability of the estimated stable pile driving rate is assessed: when the stratigraphy is homogeneous and the exploration points are dense, the estimation result is highly reliable, and the reliability coefficient is taken as a larger value close to one; when the stratigraphy changes drastically and the exploration points are sparse, the estimation result is highly uncertain, and the reliability coefficient is taken as a smaller value to increase the margin for future expansion.

[0051] Specifically, the upper limit of the excitation force is a quantitative benchmark for the permissible excitation force of the vibratory hammer 5 under normal operating conditions. Exceeding this upper limit indicates that the vibratory hammer 5 has entered an overloaded no-load vibration state, which is used to prevent damage to the hammer body caused by long-term operation of the vibratory hammer 5 under full load or overload conditions. The upper limit of the excitation force is determined based on the ratio of the rated maximum excitation force of the vibratory hammer 5 to the load that allows continuous operation.

[0052] Specifically, first determine the rated maximum excitation force of the vibratory hammer 5. The rated maximum excitation force is the maximum instantaneous output capacity of the vibratory hammer 5. Due to the heat generation of the hydraulic system and the load-bearing capacity of the eccentric block bearing, the vibratory hammer 5 can only maintain short-term operation under the rated maximum excitation force. Then determine the load ratio that allows continuous operation. This ratio is the ratio of the excitation force of the vibratory hammer 5 during continuous operation to the rated maximum excitation force. It is the factory calibration value of the vibratory hammer 5. The longer the continuous operation time required at the work site, the lower the excitation force level that allows continuous operation, and the smaller the corresponding ratio. Finally, take the product of the rated maximum excitation force and this load ratio as the upper limit of the excitation force.

[0053] Please see Figure 3 As shown, this is a hard soil layer determination curve diagram according to an embodiment of the present invention. The horizontal axis represents pile driving depth, the left vertical axis represents pile driving rate, and the right vertical axis represents excitation force. The pile driving rate curve drops sharply at the hard soil layer interface and falls below the lower limit of the pile driving rate as the pile driving depth increases. The excitation force curve spikes at the hard soil layer interface and exceeds the upper limit of the excitation force. The two baselines are shown as dashed lines. The comparison process between the pile driving rate and the lower limit of the pile driving rate, and the excitation force and the upper limit of the excitation force, is as follows: In this embodiment, if the pile driving rate is less than the lower limit of the pile driving rate or the excitation force is greater than the upper limit of the excitation force in a number of consecutive first sampling periods, it indicates that the vibratory hammer 5 has basically lost its effective pile driving ability in the stratum and has fallen into an overloaded no-vibration state, and it is determined that the current pile driving interface has entered the hard soil layer.

[0054] Based on the fact that the pile driving rate is greater than or equal to the lower limit of the pile driving rate and the excitation force is less than or equal to the upper limit of the excitation force in several consecutive first sampling periods, it is determined that the vibratory hammer 5 can still maintain effective pile driving operation in this stratum and the excitation force is in the normal load range, and it is determined that the current pile driving interface has not entered the hard soil layer.

[0055] It should be noted that the number of consecutive first sampling periods in the above continuous determination is preset. This number, together with the duration of the first sampling period, determines the time span covered by the continuous determination, in order to achieve a balance between eliminating instantaneous disturbances and maintaining determination sensitivity.

[0056] The number of consecutive first sampling cycles is determined based on the duration of the sampling cycle: when the duration of the first sampling cycle is short, the number of consecutive sampling cycles is increased accordingly to ensure that the coverage time span is sufficient to eliminate false judgments caused by instantaneous sensor noise and random fluctuations of the pile body; when the duration of the first sampling cycle is long, the number is reduced accordingly to avoid excessive delay in judgment response and delay in response to changes in the stratum state.

[0057] Specifically, the duration of a single first sampling period is first determined. Then, based on the time span required for continuous determination, the number of sampling periods for continuous determination is calculated. The number of sampling periods for continuous determination is equal to the ratio of the time span required for continuous determination to the duration of a single first sampling period. This ensures that the time span includes a sufficient number of sampling points to smooth out instantaneous disturbances without masking the continuous changes in formation resistance. For example, the number of sampling periods for continuous determination is three to five.

[0058] The above value selection logic also applies to the continuous determination based on several consecutive second sampling periods during the repeat operation stage.

[0059] In step S3, after step S2 determines that the current pile driving interface has entered the hard soil layer, the operation mode of the vibratory hammer 5 working alone is switched to the collaborative operation mode of the diesel hammer 2 and the vibratory hammer 5, and the re-driving operation stage is entered.

[0060] The excitation force of the vibratory hammer 5 is reduced to a preset proportion of the excitation force output by the vibratory hammer 5 during the initial settling stage. This preset proportion is determined based on the minimum excitation force required to maintain the disturbed liquefaction state of the silt around the pile; for example, it is set to 50% to 70% of the initial settling excitation force. The reduced excitation force is sufficient to maintain the disturbed liquefaction state of the silt around the pile. Simultaneously, the hammer core of the diesel hammer 2 is controlled to fall to the upper end of the hammering force transmission column 4, and the hammering force is transmitted to the top of the sheet pile 8 via the force transmission column 4. During the switching process, the vibratory hammer 5 maintains its grip on the sheet pile 8, does not release the gripper 7, and continues to operate with the reduced excitation force.

[0061] It should be noted that if the vibratory hammer 5 stops completely during the switching interval, the thick silt will reconsolidate and cling to the pile body in a short time, causing the first hammer of the diesel hammer 2 to have to overcome a large amount of side friction resistance after recovery, which will seriously reduce the initial hammering efficiency. Maintaining vibration can prevent the silt from reconsolidating, so that the side friction resistance faced by the first hammer of the diesel hammer 2 is basically the same as that faced by the vibratory hammer 5 during the last vibration, achieving seamless connection.

[0062] At the start of the re-driving operation, the initial drop distance or initial hammer energy level is determined based on the pile driving process parameters collected by the vibratory hammer 5 before the determination time of the hard soil layer.

[0063] Specifically, a lower average pile driving rate indicates greater resistance encountered by the vibratory hammer 5 in the hard soil layer, and a denser soil layer. The average pile driving rate serves as the basis for determining the density of the hard soil layer. The hardness grade of the hard soil layer is determined by a negative correlation between the average pile driving rate and the hardness grade; a lower average rate corresponds to a higher hardness grade. Furthermore, the initial drop height and initial impact energy level of the diesel hammer 2 are determined by a positive correlation with the hardness grade; a higher hardness grade corresponds to a greater initial drop height and a higher initial impact energy level.

[0064] Specifically, the average pile driving rate over several consecutive first sampling periods before the determination of entering the hard soil layer is obtained as the basis for determining the hard soil layer hardness grade. The number of hardness grades represents the number of grades of the hard soil layer's compaction; the more grades, the more detailed the characterization of the changes in the hard soil layer's compaction. The number of hardness grades is determined based on the number of hammer energy levels included in the factory calibration of the diesel hammer 2. The number of hardness grades is equal to the number of hammer energy levels of the diesel hammer 2, meaning each hammer energy level corresponds to one hardness grade. For example, when the diesel hammer's factory calibration includes three hammer energy levels, the number of hardness grades is set to three.

[0065] The adjustable drop distance range and the hammering energy level adjustment range are evenly divided according to the number of hardness levels, resulting in the drop distance increment and energy level increment corresponding to each hardness level. The drop distance increment represents the difference in drop distance between adjacent hardness levels, and the energy level increment represents the difference in hammering energy level between adjacent hardness levels. Both the drop distance increment and the energy level increment serve as the minimum adjustment step size for dynamically adjusting the drop distance or hammering energy level during repeated striking.

[0066] Specifically, when the average pile driving rate is in a higher range, corresponding to a relatively soft soil layer with a lower hardness level, the initial drop distance should be the lowest drop distance specified by the manufacturer for the diesel hammer 2, and the initial hammering energy level should be the lowest energy level to ensure a smooth impact energy during the initial stage of re-driving. When the average pile driving rate is in a lower range, corresponding to an extremely dense hard soil layer with the highest hardness level, the initial drop distance should be the highest drop distance specified by the manufacturer for the diesel hammer 2, and the initial hammering energy level should be the highest hammering energy level specified by the manufacturer for the diesel hammer 2. For situations between the average pile driving rates corresponding to relatively soft and hard soil layers and extremely dense hard soil layers, the hardness grade is determined based on a negative correlation with the average pile driving rate. The initial drop distance and initial hammer impact energy level are then determined accordingly for each grade. Specifically, the lowest drop distance and lowest hammer impact energy level corresponding to the lowest hardness grade are used as benchmarks. For each increase in hardness grade, the initial drop distance increases by one drop distance increment, and the initial hammer impact energy level increases by one energy level increment. Specifically, the relative position of the average pile driving rate within the upper and lower limits of the average pile driving rate is first calculated, i.e., the ratio of the difference between the average pile driving rate and the lower limit of the average pile driving rate to the difference between the upper and lower limits of the average pile driving rate. Then, the difference between the highest and lowest hardness grades is multiplied by this ratio to obtain the correction amount for the hardness grade. Finally, the correction amount is subtracted from the highest hardness grade to obtain the corresponding hardness grade.

[0067] In this embodiment, after the re-penetration operation begins, re-penetration process parameters are collected, including penetration depth and rebound amount.

[0068] Specifically, penetration depth is the actual amount of settlement of the sheet pile 8 into the soil after each hammer blow. It directly reflects the effect of the single hammer impact energy on the penetration work of the stratum at the pile tip and is a core parameter characterizing the stratum resistance and hammering efficiency in re-driving operations. Rebound amount is the upward rebound amount of the sheet pile 8 under elastic action after each hammer blow. It reflects the portion of the single hammer impact energy absorbed by the elastic deformation of the soil and pile body and not converted into effective settlement. Penetration depth and rebound amount work together to completely depict the distribution of impact energy for each hammer blow. Penetration depth is obtained within several consecutive second sampling periods, and the penetration depth difference between any two adjacent second sampling periods is calculated based on the obtained penetration depth.

[0069] The second sampling period is the time window for collecting parameters of the re-driving process during the re-driving phase. In the re-driving operation, the diesel hammer 2 operates in a periodic hammering manner. The penetration and rebound of the sheet pile 8 both occur within a single hammering cycle. Therefore, the second sampling period is aligned with the hammering cycle, ensuring that each second sampling period completely covers one hammering process, thereby collecting the penetration depth and rebound amount corresponding to each hammering. The second sampling period is determined based on the time interval between two adjacent force peaks in the impact characteristic signal and is aligned with this complete time period.

[0070] Specifically, the impact characteristic signal is first obtained by the pile cap force sensor set between the lower end of the force transmission column 4 and the top of the sheet pile 8. The duration of a single hammering cycle is determined based on the time interval between two adjacent force peaks in the impact characteristic signal. Then, the duration of the second sampling cycle is aligned with the hammering cycle, and the penetration settlement and elastic rebound generated by the hammering are collected in each second sampling cycle.

[0071] The penetration and rebound amount are both obtained by displacement sensors installed on the top of the sheet pile 8. Specifically, the displacement change of the top of the sheet pile 8 during each hammering is monitored by a wire displacement sensor or a laser displacement meter. The net downward displacement of the pile top relative to the position before hammering after the hammering is the penetration. The upward rebound displacement of the pile top under elastic action after the hammering is the rebound amount.

[0072] It should be noted that in the initial settling operation, the vibratory hammer 5 operates continuously with high-frequency vibration, while in the re-sinking operation, the diesel hammer 2 operates intermittently with periodic hammering impacts. The energy application methods of the two operations are different, so the basis for setting the first sampling period and the second sampling period and the duration scale are also different, corresponding to the vibration cycle and the hammering cycle, respectively.

[0073] In this embodiment, the drop height or hammering energy level of the diesel hammer 2 is dynamically adjusted based on the penetration difference. The penetration difference is the difference in penetration between two adjacent second sampling periods; a positive value indicates increased penetration, increased sinking per hammer, and faster pile driving speed; a negative value indicates decreased penetration, decreased sinking per hammer, and slower pile driving speed; the absolute value of the difference reflects the drastic change in pile driving speed. The penetration difference directly characterizes the direction and magnitude of the change in ground resistance with pile driving depth, and is the core basis for dynamically adjusting the drop height and hammering energy level during re-driving.

[0074] In this embodiment, based on the fact that the penetration difference is negative and the absolute value of the difference increases periodically in several consecutive second sampling periods, it indicates that the sheet pile 8 is penetrating a denser soil layer, the penetration speed is continuously slowing down, and the stratum resistance is continuously increasing. Therefore, it is determined to increase the drop height or hammer energy level, increasing the drop height by one increment or the energy level by one increment. Among these, the hammer energy level is increased first, and the drop height is increased only after the hammer energy level has been increased to the highest energy level, so as to increase the hammer energy to adapt to the increased stratum resistance.

[0075] Based on the fact that the penetration difference is negative and the absolute value of the difference decreases cycle by cycle in several consecutive second sampling periods, it indicates that the penetration speed of the sheet pile 8 is still lower than the previous cycle, but the rate of decrease is gradually narrowing and the increasing trend of the stratum resistance is weakening. It is determined to maintain the current drop distance and hammer energy level unchanged, and make adjustments after the penetration difference further tends to stabilize.

[0076] Based on the fact that the penetration difference is positive and the absolute value of the difference increases periodically in several consecutive second sampling periods, it indicates that the sheet pile 8 is penetrating a relatively weak interlayer or the liquefaction of the soil around the pile is deepening, the penetration speed is continuously accelerating, and the stratum resistance is continuously decreasing. It is determined to reduce the adjustment drop height or hammer energy level, reducing the drop height increment or the energy level increment. Among them, the drop height is reduced first, and the hammer energy level is reduced only after the drop height has been reduced to the minimum drop height, so as to reduce the hammer energy and prevent the pile slippage and loss of control.

[0077] Based on the fact that the penetration difference is positive and the absolute value of the difference decreases cycle by cycle in several consecutive second sampling periods, it indicates that the penetration speed of the sheet pile 8 is still increasing compared to the previous cycle, but the increase is gradually narrowing and the decreasing trend of the stratum resistance is weakening. It is determined to maintain the current drop distance and hammer energy level unchanged to prevent blind adjustment from causing a mismatch between hammer energy and stratum resistance.

[0078] Based on the fact that the absolute value of the penetration difference remains basically unchanged in several consecutive second sampling periods, it indicates that the sheet pile 8 penetrates the current stratum at a basically constant penetration speed, and the stratum resistance matches the current hammering energy. Therefore, it is determined to maintain the current drop distance and hammering energy level, so that the re-driving operation can continue to advance under stable hammering energy.

[0079] The above adjustments are performed based on the initial drop distance and initial hammer energy level at the start of the repeating operation.

[0080] Please see Figure 4As shown, it is a time-series comparison diagram of the auxiliary vibration force during the hammer impact interval in an embodiment of the present invention. The horizontal axis represents time, and the vertical axis represents force. The upper part is the force-time waveform of the diesel hammer impact force, which presents as periodic sharp force peak pulses. The lower part is the force-time waveform of the auxiliary vibration force of the vibratory hammer. The auxiliary vibration force drops to a low amplitude at the moment of hammer impact and rises to an application amplitude that matches the current hammer impact energy within the hammer impact interval. After each adjustment of the drop distance or hammer impact energy level is completed, the auxiliary vibration force is applied within the hammer impact interval.

[0081] Specifically, the hammer gap is the time interval between two consecutive hammer impacts from the diesel hammer 2. It is an inherent physical parameter of the diesel hammer 2 under the condition that the drop distance and hammer energy level are determined, and can be predetermined before the hammering occurs. Specifically, the hammer gap is predetermined based on the currently adjusted drop distance and hammer energy level. The larger the drop distance, the longer the free fall stroke of the hammer core and the longer the fall time, resulting in a longer hammer gap; the higher the hammer energy level, the greater the fuel supply per unit time of the diesel hammer 2 and the higher the hammering frequency, resulting in a shorter hammer gap. Therefore, after adjusting the drop distance or hammer energy level, the hammer gap for the next hammering can be predetermined based on the adjusted drop distance and hammer energy level, and then the amplitude of the auxiliary vibration force can be determined based on this hammer gap.

[0082] The impact characteristic signal is the force-time waveform of each impact of the diesel hammer 2, recording the change of the single hammer impact force over time. It appears as a sharp force peak pulse on the waveform, and the magnitude of the force peak directly reflects the magnitude of the single hammer impact force. The impact characteristic signal is acquired by a pile cap force sensor located between the lower end of the force transmission column 4 and the top of the sheet pile 8. The time interval between two adjacent force peaks in the impact characteristic signal is used for aligning the acquisition window in the second sampling period.

[0083] The amplitude of the auxiliary vibration force is determined by the adjusted drop height or hammer energy level and the hammer gap, respectively. The application action occurs in the gap between the end of the current hammer impact and the arrival of the next hammer impact. Since the hammer gap has been predetermined based on the adjusted drop height and hammer energy level, the determination of the application amplitude is consistent with the application action in terms of timing.

[0084] Specifically, the first applied amplitude is determined based on the positive correlation between the adjusted drop distance and the hammer impact gap. Specifically, the first applied amplitude is determined based on the product of the adjusted drop distance and the hammer impact gap after normalization. The larger the drop distance, the higher the impact energy of the single hammer. The longer the hammer impact gap, the more sufficient the auxiliary vibration time window after each impact. Therefore, the first applied amplitude is larger.

[0085] The second applied amplitude is determined based on the positive correlation between the adjusted hammer energy level and the hammer gap. Specifically, the second applied amplitude is determined after normalization of the product of the adjusted hammer energy level and the hammer gap. The higher the hammer energy level, the higher the current diesel hammer 2 is in the high energy output range, and the greater the corresponding auxiliary vibration demand.

[0086] The first or second applied amplitude is taken as the final output auxiliary vibration force applied amplitude, and the vibratory hammer 5 is controlled to apply the corresponding amplitude of auxiliary vibration force to the top of the sheet pile 8 within the hammering interval.

[0087] It should be noted that the auxiliary vibration force serves to continuously vibrate the pile body during the interval between each hammer blow and the next, keeping the deep silt around the pile in a disturbed liquefied state and inhibiting the thixotropic reconsolidation of the silt within the hammering interval. Because deep silt exhibits significant thixotropy, the soil around the pile will rapidly reconsolidate and tightly wrap around the pile body after each hammer blow. The next hammer blow requires overcoming this recovered side friction resistance. Applying auxiliary vibration force maintains the liquefied state of the silt within the hammering interval, preventing the side friction resistance from rising again, thereby significantly improving the impact efficiency of each hammer blow.

[0088] In addition, the rebound data collected during the re-strike process is used for continuous evaluation of hammering efficiency.

[0089] Specifically, the rebound penetration ratio reflects the proportion of impact energy from each hammer blow that is consumed by the elastic deformation of the soil, manifested as rebound, and the proportion that is actually used to generate irreversible settlement displacement, manifested as penetration. It is a core parameter characterizing the energy utilization rate of a single hammer blow. The rebound penetration ratio is determined based on the ratio of the rebound amount to the corresponding penetration depth within the same second sampling period.

[0090] In this embodiment, based on the fact that the rebound penetration ratio increases in each of several consecutive second sampling cycles, indicating that the impact energy utilization rate continues to decline, the same hammering energy produces less and less effective sinking, and insufficient liquefaction of the soil around the pile leads to an increase in side friction, it is determined to increase the auxiliary vibration force. The increase is determined based on the positive correlation between the increase in the rebound penetration ratio and the amount of increase, and a hammering efficiency abnormality warning signal is output simultaneously.

[0091] The increase in the rebound penetration ratio is determined based on the difference between the rebound penetration ratios of adjacent second sampling periods. The greater the increase in the rebound penetration ratio, the greater the upward adjustment. The upward adjustment is equal to the product of the increase in the rebound penetration ratio and the preset adjustment coefficient.

[0092] The preset adjustment coefficient is used to convert the increase in rebound penetration ratio into the upward adjustment range of auxiliary vibration force. It is equal to the ratio of the adjustable range of auxiliary vibration force to the maximum value of the increase in rebound penetration ratio. The adjustable range of auxiliary vibration force is the difference between the maximum and minimum output values ​​of the auxiliary vibration force of vibratory hammer 5. The maximum value of the increase in rebound penetration ratio is determined in advance based on the construction experience data of the same type of stratum in the same region.

[0093] Based on the fact that the rebound penetration ratio remains stable or decreases with each sampling cycle in several consecutive second sampling periods, it indicates that the impact energy utilization rate remains stable or gradually improves, and the hammering energy can be effectively converted into sinking displacement. Therefore, it is determined to maintain the current auxiliary vibration force and not output an abnormal hammering efficiency warning signal.

[0094] It should be noted that the reason for increasing the auxiliary vibration force is that: increased rebound usually means that the soil around the pile is not sufficiently liquefied and the side friction is rising, which makes it impossible for the impact energy to be effectively transmitted to the pile end. Enhancing the auxiliary vibration in the gap can further liquefy the silt around the pile and reduce the side friction, so that the impact energy of the subsequent hammering can be used more effectively to promote sinking.

[0095] In step S4, the risk of hammer failure is obtained based on the penetration trend prediction, and collaborative safety control is determined.

[0096] Specifically, when the penetration depth is less than the lower limit of penetration depth for several consecutive second sampling periods, it is determined that the pile tip has encountered an impenetrable obstacle, such as a boulder, bedrock surface or abnormally dense interlayer, causing the diesel hammer 2 to continue hammering while the sheet pile 8 hardly sinks anymore. At this time, the risk of hammer refusal is predicted.

[0097] The lower limit of penetration is a quantitative benchmark for determining whether sheet pile 8 is still maintaining normal settlement. This value reflects the minimum settlement per hammer blow in the current hard soil layer under normal working conditions. The lower limit of penetration is determined based on the penetration statistics of sheet pile 8 under normal settlement conditions at the beginning of the re-driving operation.

[0098] Specifically, at the beginning of the re-driving operation of the diesel hammer 2, the penetration depth of the sheet pile 8 under normal sinking conditions is collected for several consecutive hammer blows. The collected results are statistically analyzed, and the lowest statistical value of the normal sinking penetration depth is taken as the lower limit of the penetration depth. The statistical lower value is taken as a certain proportion of the average value of the normal sinking penetration depth, for example, 80% of the average value, or the minimum value among the normal sinking penetration depths.

[0099] Specifically, when a risk of hammer refusal is predicted, an automatic warning is immediately issued, and the dynamically adjusted drop height or hammer energy level is reduced by one drop height increment or one energy level increment to mitigate the hammering intensity and prevent pile damage or pile tip curling under continuous high-energy impact. If, after reducing the drop height or hammer energy level, the penetration depth remains below the lower limit for several consecutive second sampling periods, the hammering process of diesel hammer 2 is suspended.

[0100] It should be noted that during the pause, the vibratory hammer 5 maintains the application of auxiliary vibration without stopping. Maintaining vibration can prevent the silt around the pile from reconsolidating and binding the pile body while waiting for the operator to inspect it. On the one hand, this facilitates the possible resumption of normal hammering later, and on the other hand, if it is determined that the pile location needs to be abandoned, the liquefied state of the silt soil is also conducive to the pile extraction operation.

[0101] Automatic warnings include, but are not limited to, audible and visual alarms in the driver's cab and text prompts on the control panel. After receiving a warning signal, the operator conducts on-site inspections, such as checking whether the pile is vertically skewed, whether the pile tip has hit a boulder or bedrock, etc. After the inspection is completed, the operator enters an inspection confirmation command through the control interface. After confirmation, the automatic hammering of the diesel hammer 2 is resumed, or other measures are taken based on the inspection results.

[0102] In step S4, based on the detection that the pile stress is greater than the safe upper limit of the pile stress, it is determined to perform collaborative safety control.

[0103] Specifically, the pile stress is the real-time stress borne by the sheet pile 8 during the repeated hammering process. It reflects the bearing capacity generated within the pile body after the hammering energy is transmitted to the pile body via the force transmission column 4, and is a direct measure of the pile structure's safety. The pile stress is determined based on signals collected by stress sensors located at the lower end of the force transmission column 4 or near the pile cap force sensor. These stress sensors are strain gauges that collect strain signals from the pile body and convert the strain signals into pile stress based on the elastic modulus of the sheet pile steel.

[0104] Specifically, the stress of the pile body is collected in real time by stress sensors installed at the lower end of the force transmission column 4 or near the pile cap force sensor; when the pile body stress is detected to be greater than the safe upper limit of the pile body stress, the coordinated safety control is determined to be implemented, the warning is automatically issued and the dynamic adjustment drop distance or hammer energy level is reduced, and the pile body over-limit warning signal is output simultaneously.

[0105] The upper limit of pile stress safety is the maximum stress level that the pile body is allowed to withstand, serving as the criterion for determining the safety of the pile structure. The upper limit of pile stress safety is determined based on the ratio of the yield strength of the sheet pile material to the safety factor. The safety factor is a conventional safety factor selected according to engineering structural design specifications, and its value can be directly determined based on the project's safety level.

[0106] The reduction rate is positively correlated with the value of the pile stress exceeding the safe upper limit of the pile stress. The excess value is the difference between the pile stress and the safe upper limit of the pile stress. For example, for every 10% of the excess value reaching the safe upper limit of the pile stress, the drop distance or hammering energy level is reduced by one energy level increment or one drop distance increment. The larger the excess value, the closer the pile bearing is to the material yield limit, and the greater the reduction rate, so as to reduce the stress to the safe range as soon as possible.

[0107] In summary, the collaborative control method provided in this embodiment, based on real-time collected pile driving process parameters and re-driving process parameters, achieves complete closed-loop control from automatic stratum perception and hard soil layer determination in the five stages of the vibratory hammer, to seamless switching of the integrated dual-hammer structure, to initial parameter configuration driven by prior measured data, to dynamic parameter adjustment based on real-time penetration trend, to precise application of auxiliary vibration force in the hammering gap, to automatic judgment and human-machine collaborative processing of hammer rejection risk, to over-limit graded protection of pile stress, and continuous monitoring of rebound penetration ratio and active correction of hammering efficiency.

[0108] 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 method for coordinated control of a vibratory hammer and a diesel hammer for steel sheet piles in deep silt formations, characterized in that, include: During the initial driving operation of sheet piles with a vibratory hammer, the driving process parameters are collected in real time, including the driving rate and the excitation force of the vibratory hammer. The pile driving process parameters are compared with a preset set of switching trigger conditions to determine whether the current pile driving interface has entered the hard soil layer treated by the diesel hammer. The switching trigger conditions include the pile driving rate being less than the lower limit of the pile driving rate or the excitation force being greater than the upper limit of the excitation force within a number of consecutive first sampling periods. During the re-driving operation of the steel sheet pile by the diesel hammer, the re-driving process parameters are collected in real time. Based on the re-driving process parameters, the drop distance or hammering energy level of the diesel hammer is dynamically adjusted, and the vibratory hammer is controlled to apply auxiliary vibration force to the steel sheet pile within the hammering gap of the diesel hammer. The re-driving process parameters include penetration and rebound. Based on the penetration trend prediction, the risk of hammer failure is obtained, or based on the detection that the pile stress is greater than the safe upper limit of the pile stress, it is determined to implement collaborative safety management. The collaborative safety management includes automatic early warning and reduction of the dynamic adjustment drop distance or hammer energy level.

2. The method for coordinated control of vibratory hammer and diesel hammer for steel sheet piles in deep silt formations according to claim 1, characterized in that, The process of real-time acquisition of parameters during pile driving includes: The time-domain acceleration signal of the steel sheet pile during the initial sinking operation is obtained by an acceleration sensor fixed to the top of the steel sheet pile within several consecutive first sampling periods. The low-frequency component introduced by the soil disturbance of the deep silt layer and the high-frequency component introduced by the vibration of the vibratory hammer itself are separated from the time-domain acceleration signal and integrated to determine the pile driving rate. The hydraulic signal is obtained by a hydraulic sensor installed in the hydraulic circuit of the vibratory hammer, and the excitation force is calculated by combining the structural parameters of the eccentric block of the vibratory hammer.

3. The method for coordinated control of vibratory hammer and diesel hammer for steel sheet piles in deep silt formations according to claim 2, characterized in that, The vibratory hammer and the diesel hammer are mounted on the same pile frame, with the diesel hammer positioned above the vibratory hammer. The vibratory hammer has a through hole that extends vertically through the force transmission column, and the vibratory hammer is clamped to the top of the sheet pile by a bottom clamp. The lower end of the force transmission column abuts against the top of the sheet pile, and the upper end extends upward from the upper surface of the vibratory hammer. The hammer core of the diesel hammer falls and strikes the upper end of the force transmission column, which then transmits the hammering force to the top of the sheet pile.

4. The method for coordinated control of vibratory hammer and diesel hammer for steel sheet piles in deep silt formations according to claim 3, characterized in that, Upon determining that the system has entered a hard soil layer processed by the diesel hammer, the system is triggered to switch from operating the vibratory hammer alone to operating the diesel hammer and vibratory hammer in a coordinated manner. Specifically, the excitation force of the vibratory hammer is reduced to less than the initial excitation force of the initial sinking operation, and the hammer core of the diesel hammer is controlled to strike the top of the force transmission column, while the bottom clamping device maintains the clamping of the steel sheet pile.

5. The method for coordinated control of vibratory hammer and diesel hammer for steel sheet piles in deep silt formations according to claim 4, characterized in that, The process of dynamically adjusting the drop height or impact energy level of the diesel hammer based on the parameters of the repeated striking process includes: Obtain the average value of the pile driving rate over several consecutive first sampling periods before the determination of entering the hard soil layer; The drop distance or the hammer impact energy level is determined based on the negative correlation between the average value of the pile driving rate and the pile driving rate.

6. The method for coordinated control of vibratory hammer and diesel hammer for steel sheet piles in deep silt formations according to claim 5, characterized in that, The process of dynamically adjusting the drop height or impact energy level of the diesel hammer based on the parameters of the repeated striking process also includes: Obtain the penetration degree within a consecutive number of second sampling periods; Calculate the penetration difference between any two adjacent second sampling periods; Based on a series of consecutive negative penetration differences and the absolute value of the difference increasing periodically, the drop distance or the hammering energy level is adjusted accordingly. Based on a series of consecutive positive penetration differences and the absolute value of the difference increasing periodically, it is determined to reduce or adjust the drop distance or the hammering energy level.

7. The method for coordinated control of vibratory hammer and diesel hammer for steel sheet piles in deep silt formations according to claim 6, characterized in that, The process of applying auxiliary vibration force to sheet piles includes: After adjusting the drop distance or the hammering energy level, the hammering gap is determined based on the current drop distance or hammering energy level. The first applied amplitude corresponding to the auxiliary vibration force is determined based on the positive correlation between the adjusted drop distance and the hammering gap. The second applied amplitude corresponding to the auxiliary vibration force is determined based on the positive correlation between the adjusted hammering energy level and the hammering gap. Take the first applied amplitude or the second applied amplitude, and control the vibratory hammer to apply the auxiliary vibration force of the corresponding amplitude to the top of the steel sheet pile within the hammering gap.

8. The method for coordinated control of vibratory hammer and diesel hammer for steel sheet piles in deep silt formations according to claim 7, characterized in that, The process of implementing collaborative security control includes: Based on the fact that the penetration depth is less than the lower limit of penetration depth in several consecutive second sampling periods, it is determined that there is a risk of hammer failure. When the risk of hammer refusal is determined to exist, the dynamically adjusted drop height or hammer energy level is reduced and a hammer refusal warning signal is output simultaneously. If the penetration depth after reducing the drop height or hammering energy level remains below the lower limit of penetration depth for several consecutive second sampling periods, the hammering process of the diesel hammer will be suspended.

9. The method for coordinated control of vibratory hammer and diesel hammer for steel sheet piles in deep silt formations according to claim 8, characterized in that, The process of implementing collaborative security control also includes: When the pile stress is detected to be greater than the safe upper limit of the pile stress, the adjusted drop height or hammer energy level is reduced and a pile over-limit warning signal is output simultaneously. The reduction range is positively correlated with the value by which the pile stress exceeds the safe upper limit of the pile stress.

10. The method for coordinated control of vibratory hammer and diesel hammer for steel sheet piles in deep silt formations according to claim 7, characterized in that, The springback penetration ratio is determined by calculating the ratio of the springback amount to the corresponding penetration within the same second sampling period. Based on a series of consecutive increases in the rebound penetration ratio, the applied amplitude of the auxiliary vibration force is adjusted upwards, and a hammering efficiency abnormality warning signal is output simultaneously.

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