Vibrator with DPT function

Abstract

The invention relates to a vibroflot with a DPT function, and belongs to the field of vibroflots. The vibroflot with the DPT function comprises a vibroflot body, the vibroflot body comprises an eccentric shaft and a motor used for driving the eccentric shaft, a shock absorber is connected to the upper portion of the motor, and a guide rod is connected to the upper portion of the shock absorber; the device is characterized in that a resistance sensor is installed at the conical tip of the vibroflot, a resistance sensor is installed on the side wall of the vibroflot, an attitude sensor is installed in the vibroflot, a first vibration sensor is installed in the conical tip of the vibroflot, a second vibration sensor is installed at the position, close to the shock absorber, of the vibroflot, and a third vibration sensor is installed on the guide rod. Soil layer data indexes are detected in real time in the working process of the vibroflot, and parameters of the vibroflot are adjusted in real time according to the data, so that the processed soil body finally meets the design requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of vibrators, in particular to a vibrator with a DPT function. Background Art

[0002] Vibratory compactors are used in vibro-compaction foundation reinforcement technology. During vibro-compaction construction, they densify loose sand foundations or replace weak soil layers with gravel to form gravel piles. The foundation's performance after compaction includes bearing capacity and settlement. The non-cohesive coarse aggregate used to form gravel piles accelerates drainage and settlement. The gravel piles, combined with the surrounding existing foundation soil, form composite piles, increasing the foundation's overall bearing capacity and, consequently, the seismic resistance of above-ground buildings.

[0003] Sand and gravel piles require a recorder and construction quality control system to monitor pile quality during construction. This system primarily records and controls data such as the infill current, vibration retention time, pile depth, and filler quantity, and then calculates the pile shape diagram. The varying soil properties in different undisturbed soil layers, such as looseness, fluidity, and particle size, influence the calculation of pile shape. Especially for uneven and stratified soils, layer-by-layer considerations are essential, rather than simply calculating based on a single soil property.

[0004] For compaction treatment, during the compaction and interlacing operation, due to the friction between the guide rod and the soil, the lifting and releasing speed is uneven, and part of the vibration energy may be dissipated in the non-compacted section, which may cause the compaction current to fail to accurately reflect the actual compaction degree at the compaction point.

[0005] For complex situations such as construction with deep piles, strata prone to collapse, or soft and hard interlayers, how to judge the conditions of each stratum, determine the location of the stuck points, and determine the reasons for the lack of advance (whether the guide rod is held by the soil layer, or there is a hard layer at the front end of the vibration head, or the vibrator is in a suspended state and cannot interact well with the soil), to provide help for targeted problem solving.

[0006] Based on this, the present invention is proposed. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the present invention provides a vibrator with DPT function, and its technical solution is as follows:

[0008] A vibrator with a DPT function includes the vibrator, the vibrator including a motor for driving an eccentric shaft, a vibration damper mounted on the motor, and a guide rod above the vibration damper; a resistance sensor is mounted at the cone tip of the vibrator, a posture sensor is mounted inside the vibrator, a first vibration sensor is mounted within the cone tip of the vibrator, a second vibration sensor is mounted near the vibration damper on the vibrator, and a third vibration sensor is mounted on the guide rod.

[0009] As a further solution of the present invention, the detection method of the vibrator with DPT function includes the following steps:

[0010] Step 1: Compare the phase of the eccentric block with the horizontal vibration phase, calculate the phase angle difference a, and calculate the force F1 between the vibrator and the soil;

[0011] Step 2: Measure the vibration amplitude using the first vibration sensor, compare it with the no-load vibration amplitude, and obtain the force F2 between the vibrator and the soil;

[0012] Step 3: Measure the electrical frequency f of the current based on the current signal 电 , according to the number of motor poles p, the synchronous frequency f of the motor is obtained s =f 电 / p, the vibration frequency f is measured by the first vibration sensor, and the slip rate of the motor s=1-f / f s ;

[0013] Step 4: Obtain the output power P of the vibrator at this time through the slip rate s and the frequency characteristic curve of the vibrator tested at the factory. g And output torque T; this output power P g is the energy density P transmitted to the soil by the vibrator in the form of vibration n ;

[0014] (Note: For hydraulic vibrators, the output torque value can be calculated by monitoring the pressure difference between the inlet and outlet of the vibrator hydraulic motor, or a torque sensor can be directly installed on the output shaft to directly measure the torque)

[0015] Step 5: Energy density P n And the soil density index is calculated based on the force F2 acting on the soil;

[0016] Step 6: Calculate the contact dynamic stress with the soil by the ratio of the soil force F2 to the lateral projection area S of the vibrator, convert it into the static penetration friction resistance of the soil, and then calculate the soil properties;

[0017] Step 7: Monitor the lifting and lowering speed u to ensure that the vibrator is in a hovering state within a normal speed, and monitor the vibration retention time t;

[0018] Step 8: Output the judgment result by comparing the data within the encrypted time period.

[0019] In step 9, resistance sensors at the cone tip and sidewalls dynamically monitor changes in soil resistance. Combined with triaxial vibration values, the relationship between soil resistance and penetration velocity under vertical quasi-static conditions, as well as under lateral dynamic loads, is calculated. This corresponds to data from static penetration and standard penetration.

[0020] Step 10: Detect the spatial posture of the vibrator and the verticality of the hole section using the average value of the three-axis acceleration or the orientation data of the posture sensor. Combined with the depth data, the spatial trajectory of the pile hole is calculated.

[0021] As a further solution of the present invention, during the vibratory construction process of the vibrator, when the vibrator encounters a hard layer, the load and the characteristic peak value change in a positive correlation.

[0022] As a further solution of the present invention, during the vibratory construction process of the vibrator, the spectral lines whose frequencies increase and decrease in proportion to the increase and decrease of the fundamental frequency are harmonics or multiples of the fundamental frequency.

[0023] As a further solution of the present invention, during the vibratory construction process of the vibrator, the trajectory of the horizontal vibration velocity vector diagram is elliptical, the lateral amplitude is greater than the longitudinal amplitude, and multiple circles of the trajectory are repeated, indicating that there is no torsional vibration.

[0024] As a further solution of the present invention, during the vibratory construction process of the vibrator, the trajectory of the horizontal vibration velocity vector diagram is elliptical and the axis of the ellipse is tilted, the lateral amplitude is greater than the longitudinal amplitude, and there is misalignment in multiple circles of the trajectory, indicating the existence of torsional vibration.

[0025] As a further solution of the present invention, during the vibratory construction process of the vibrator, the trajectory in the vibration velocity vector diagram is an inclined straight line, and the trajectories of multiple reciprocating vibrations are overlapped, indicating that there is no vibration jump phenomenon.

[0026] As a further solution of the present invention, during the vibratory construction process of the vibrator, the trajectory in the vibration velocity vector diagram is an inclined ellipse, and the trajectories of multiple reciprocating vibrations are not completely overlapped, indicating that there is no vibration jump phenomenon.

[0027] As a further solution of the present invention, during the vibratory construction process of the vibrator, the maximum exciting force F max , eccentric block mass m, eccentricity of eccentric block e, vibrator shell mass M;

[0028] The amplitude α of the vibrator:

[0029] Speed n and vibration angular frequency ω = 2πn / 60;

[0030] Soil resistance of the vibrator:

[0031] m—mass of eccentric block;

[0032] e—eccentricity of eccentric block;

[0033] ω—vibration angular frequency;

[0034] Phase difference angle and Angle relationship:

[0035] The output torque of the motor is T = F·a;

[0036] F—the resistance of the soil on the vibrator;

[0037] The power P transmitted by the vibrator to the soil:

[0038]

[0039] For a position with a distance r from the pile center, according to the vibration attenuation trend, there is the following vibration velocity peak value v max formula:

[0040] v max =A*r -b ;

[0041] A and b are the coefficients to be determined;

[0042] Calculate the energy absorption of the soil per unit volume at this time:

[0043]

[0044] in:

[0045] E—shear wave energy per unit volume of soil;

[0046] ρ—density of soil;

[0047] V s — shear wave velocity of soil medium;

[0048] v max —Peak vibration velocity of soil unit;

[0049] —Average absorption of wave energy by soil;

[0050] E in —The wave energy input to the soil element at a distance r from the vibration source;

[0051] E out —The wave energy output from the soil unit at a distance (r + Δr) from the vibration source;

[0052] Δr—thickness of soil unit;

[0053] The cumulative energy absorbed by the soil layer after the cumulative vibration time t is the cumulative energy W:

[0054] Calculate excess hydrostatic pressure u max :

[0055]

[0056] in,

[0057] u f —Excess pore pressure when soil liquefaction occurs;

[0058] W f —The accumulated energy absorbed when soil liquefies;

[0059] Finally, calculate the void ratio e of the soil after the water pressure dissipates after reinforcement i :

[0060] e i =e0-(1+e0)m v u max

[0061] e0—initial porosity ratio;

[0062] m v —Soil compression coefficient.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] The vibrator with DPT function described in the present invention improves upon existing vibrators and has a DPT function (Dynamic Penetration Test, or DPT; an in-situ testing method for determining the mechanical properties of soil layers). By using the installed first, second, and third vibration sensors, and analyzing the resulting spectrum to identify the components of chaotic vibration, potential faults in the vibrator or motor can be diagnosed. The relationship between the mechanical vibration phase of the vibrator and the rotational phase of the motor's eccentric block, as well as amplitude changes, is detected, and the force changes between the vibrator and the soil are then calculated. The soil's properties and density are then comprehensively determined by combining frictional resistance, lowering speed, and current data. The motor's slip rate is determined by measuring the mechanical vibration frequency and rotational speed of the vibrator and comparing them with the electrical frequency. The output torque and output power can then be determined based on the relationship between the slip rate and the power-torque efficiency obtained during factory testing of the motor (or vibrator). These data more accurately and comprehensively reflect the various states of the vibrator and their corresponding relationship with soil properties.

[0065] The core of this invention is the DPT function. Through its built-in DPT module, it calculates the confining pressure of the ground (the reaction force of the soil on the vibratory impactor) in real time during the piling process. Through data analysis, it calculates the density and bearing capacity of the pile. Furthermore, through the transmitter, other relevant parameters (such as backfill volume) can be determined after the piling is completed.

[0066] The DPT module generally consists of the following main parts:

[0067] Probe: A conical probe used to penetrate the soil. Its cone angle is generally 60°, and the cone base diameter varies depending on the type of equipment. For example, the cone base diameter of a lightweight dynamic penetration probe is 4.0 mm, with a cross-sectional area of 12.6 cm 2 The cone bottom diameter of the heavy-duty dynamic probe is 7.4 mm and the cross-sectional area is 43 cm 2 .

[0068] Probe: The rod that connects the probe to the hammer, transmitting the hammering force. The diameter and length of the probe are determined by the equipment type and test requirements.

[0069] Penetration hammer: This hammer provides the penetration force. Its mass, drop distance, and energy are key factors affecting penetration depth. For example, a light-duty power penetration hammer weighs 10 kg and has a drop distance of 50 cm, while a heavy-duty power penetration hammer weighs 63.5 kg and has a drop distance of 76 cm.

[0070] Guide rod: used to keep the probe rod vertical and prevent deflection. The diameter and length of the guide rod are determined according to the diameter and length of the probe rod.

[0071] Hammer pad: used to cushion the hammer force and reduce the impact between the hammer and the probe rod.

[0072] Control device: used to automatically control the hammering process and record data such as penetration depth and number of hammering times.

[0073] At present, in vibro-compaction construction, we can only estimate whether the vibro-compaction road is dense by using parameters such as density current, but we cannot determine the density and bearing capacity.

[0074] However, in the present invention, it can be calculated synchronously through the DPT module.

[0075] In addition, at the current stage, the amount of backfill required is estimated based on the amount of soil after the pile is driven. This is inaccurate and may require a second or even three backfill tests (such as driving a test pile). After the improvement, the calculation can be done simultaneously, and the data is accurate, which is convenient for subsequent backfilling, greatly reducing the number of test piles, reducing construction costs, and ensuring the technical qualification rate. For example, the existing external DPT will have a very large detection error. It may detect the strength of the pile body 20m below the soil layer, and it may display 0 when measured in certain intervals or positions; at this time, the actual situation in the interval or position is uncertain, so the strength of the entire pile is unclear.

[0076] The vibrator with built-in DPT module in the present invention determines the strength by testing the confining pressure, which can ensure the uniform strength of the whole pile.

[0077] In the early stages of a project, several groups of test piles are tested using a vibrator with a built-in DPT module to ensure the accuracy of the vibrator's built-in detection function and to calibrate it to ensure that the accuracy of subsequent pile density and bearing capacity measurements is consistent with the external DPT detection. The core innovation of this invention is that the vibrator with DPT function can replace the external DPT detection function. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 This is a schematic structural diagram of the vibrator with DPT function according to the present invention;

[0079] Figure 2 It is the instantaneous waveform of the vibration acceleration of the vibrator;

[0080] Figure 3 This is the vibration frequency distribution diagram of the vibrator when it is unloaded (harmonics can be ignored);

[0081] Figure 4 is the vibration frequency distribution in the soft soil layer (the harmonic energy is small);

[0082] Figure 5 This is the vibration frequency distribution diagram when the hard layer load is large;

[0083] Figure 6 It is the spectrum waterfall diagram of the vibrator startup process;

[0084] Figure 7 It is the spectrum waterfall diagram of the vibrator shutdown process;

[0085] Figure 8 is the horizontal vibration velocity vector diagram when there is no torsional vibration;

[0086] Figure 9 is the horizontal vibration velocity vector diagram that produces torsional vibration;

[0087] Figure 10 It is the vibration velocity vector diagram when there is no bounce vibration;

[0088] Figure 11 It is the vibration velocity vector diagram when jumping vibration occurs;

[0089] Figure 12 This is a graph showing the variation of the guide rod vibration amplitude with load during the operation of the vibrator;

[0090] Figure 13 This is the operation test diagram of the electric vibrator motor;

[0091] Figure 14 It is a waterfall diagram of the vibration spectrum of the electric vibrator motor;

[0092] Figure 15 It is the control flow chart of the encryption segment. DETAILED DESCRIPTION

[0093] The present invention is described in detail below with reference to specific embodiments. The embodiments described below are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0094] Example 1

[0095] like Figure 1 As shown in FIG, the structure of the vibrator generally includes a motor for driving an eccentric shaft, a vibration damper is installed on the motor, and a guide rod is placed above the vibration damper.

[0096] Installing a resistance sensor at the cone tip of the vibrator to detect the friction resistance at the cone tip or the resistance (tension or pressure) of the entire vibrator in front of the shock absorber will better control the vibrator construction.

[0097] Installing an attitude sensor inside the vibrator to monitor its spatial attitude, such as tilt and orientation, allows for better control of the vibrator, preventing pile hole deviation caused by ground tilt, large rock compression, or uneven ground density. Furthermore, the spatial shape of the pile hole trajectory can be determined based on attitude data and corresponding depth data recorded during the lifting and lowering process. This facilitates timely prediction, analysis, and adjustment of pile conditions, facilitates analysis and control of foundation treatment quality, and deepens understanding of vibratory construction.

[0098] A first vibration sensor is installed in the cone tip of the vibrator, a second vibration sensor is installed at a position of the vibrator close to the shock absorber, and a third vibration sensor is installed on the guide rod to monitor their vibration conditions.

[0099] The third rotation sensor on the guide rod can monitor the rotation situation to further determine whether there is a pipe holding situation.

[0100] The first vibration sensor and the second vibration sensor cooperate with each other to understand the distribution of vibration on the vibrator, determine the midpoint position, and the overall vibration state of the vibrator.

[0101] The first vibration sensor installed at the cone tip can diagnose potential faults of the vibrator or motor by analyzing the components of chaotic vibration through spectrum analysis.

[0102] An eccentric phase sensor installed in the vibrator detects the relationship between the mechanical vibration phase of the vibrator and the rotational phase of the eccentric, as well as changes in amplitude. This sensor then infers changes in the force acting on the vibrator and the soil. This is combined with frictional resistance, lowering speed, and current data to comprehensively assess the soil's properties and density. By measuring the vibrator's mechanical vibration frequency and speed and comparing them with the electrical frequency, the motor's slip ratio is determined. Based on the relationship between slip ratio and power-torque efficiency data obtained during factory testing of the motor (or vibrator), output torque and power can be calculated. These data more accurately and comprehensively reflect the relationship between the various states of the vibrator and soil properties.

[0103] Detection method process:

[0104] 1. Compare the phase of the eccentric block with the horizontal vibration phase, calculate the phase angle difference a, and calculate the force F1 between the vibrator and the soil based on the relationship between the force and the phase angle difference obtained in the test.

[0105] 2. The first vibration sensor is used to measure the vibration amplitude, and compared with the no-load vibration amplitude to obtain the force F2 between the vibrator and the soil.

[0106] 3. Measure the electrical frequency f of the current based on the current signal 电 According to the number of motor poles p, the synchronous frequency f of the motor is obtained s =f 电 / p, the vibration frequency f is measured by the first vibration sensor, which corresponds to the eccentric shaft rotation frequency f, and the motor slip rate s=1-f / f s .

[0107] 4. The output power P of the vibrator at this time is obtained by the slip rate s and the frequency characteristic curve of the vibrator in the factory test (Ms Ps). g And output torque T. This output power P g is the energy density P transmitted to the soil by the vibrator in the form of vibration n .

[0108] 5. Through energy density P n And the soil density and other indicators are calculated based on the force F2 acting on the soil.

[0109] 6. Calculate the dynamic contact stress with the soil by using the ratio of the soil force F2 to the lateral projection area S of the vibrator. Then, using the relationship between dynamic stress and static stress, calculate the static penetration friction resistance of the soil, and further calculate soil properties, including deformation modulus and bearing capacity.

[0110] 7. Monitor the lifting and lowering speed u to ensure that the vibrator is in a hovering state within the normal speed, and monitor the vibration retention time t.

[0111] 8. By comparing the data within the encrypted time period, the changes in the soil can be comprehensively reflected, and some characteristics of the soil can be further judged based on this.

[0112] Example 2

[0113] Different soils have different subsidence properties due to varying particle size distributions, porosity, and water content, as well as varying vibration intensities transmitted to the soil. Consequently, the rate of change in soil density during the vibration retention period varies. By analyzing the changing trends of the steady-state characteristic data accumulated during the densification process, we can make a comprehensive comparison and gain a more comprehensive understanding of soil characteristics.

[0114] 2.1. Monitor the bounce (vertical vibration) of the vibrator, so as to comprehensively reflect the soil characteristics.

[0115] When unloaded, the vibrator exhibits no torsional vibration or jumping vibration. However, when it contacts soil, due to the soil's composition (particle size ratio), mechanical properties (elasticity and plasticity), anisotropy, and inhomogeneity, the vibrator will experience jumping and torsional vibrations, as well as changes in amplitude in different orientations. An isolated jumping vibration may be caused by the momentary contact with a large piece of stone or a sudden hard layer. A prominent frequency band may indicate contact with stone or soil of a corresponding particle size, or resonance caused by the interaction of the elastic modulus of the soil layer and the vibrator. Because the dynamic destruction of soil has a threshold and nonlinear characteristics, it will excite a rich harmonic component or instantaneous jump.

[0116] exist Figure 2 In the figure, the horizontal axis represents time, and the vertical axis represents acceleration amplitude. The orange curve is the original waveform data, the red curve is the extracted main vibration waveform, and the blue curve is the remaining harmonic components. The figure shows that the vibrator vibration data contains a rich harmonic component. Observing the distribution of the harmonics, it is not uniform within a fundamental vibration cycle.

[0117] By recording waveform data and performing various identification and analysis, we can obtain various characteristic information and determine the operating status and soil characteristics. For example, spatial vibration shape analysis, time domain analysis, or frequency domain analysis.

[0118] Figure 3 This is a graph of the amplitude-frequency characteristics of the vibrator. The horizontal axis represents frequency, and the vertical axis represents the amplitude at that frequency. The graph shows that the energy is concentrated near the primary vibration frequency. Due to the inaccurate stiffness of the vibrator in both the vertical and horizontal directions, the vibration trajectory exhibits slight distortion and harmonics, which can be ignored.

[0119] Figure 4 This is a graph of the amplitude-frequency characteristics of the vibrator. The horizontal axis represents frequency, and the vertical axis represents the amplitude at that frequency. The graph shows that, in addition to the energy concentration near the main vibration frequency, two areas of high harmonic energy density appear in the high-frequency region. These characteristics are distinct, but their energy contribution is relatively small.

[0120] Figure 5 Multiple distinct frequency bands emerge. The amplitude-frequency characteristic diagram of this vibrator operation shows the distribution of the energy spectrum. Compared to the spectrum distribution in soft soil, this diagram shows a significantly increased energy spectrum density, a wider frequency distribution range, and a prominent characteristic peak near point 2000 on the horizontal axis.

[0121] Figure 6 In a waterfall chart, the horizontal axis is frequency, the vertical axis is time, and the amplitude-frequency curves are arranged in chronological order. This chart clearly shows how each characteristic spectral line changes over time. A characteristic spectral line with a constant center frequency in the chart may be the device's natural frequency, while a spectral line whose frequency increases or decreases proportionally with the fundamental frequency may be a harmonic or multiple of the fundamental frequency.

[0122] Figure 7 In the waterfall diagram, the horizontal axis is frequency, the vertical axis is time, and the amplitude-frequency curves are arranged in chronological order.

[0123] Figure 8 The horizontal axis represents horizontal front-to-back vibration, while the vertical axis represents horizontal left-to-right vibration (including a torsional component). In the figure, the trajectory is elliptical, with large lateral amplitude and small longitudinal amplitude. The axis of the ellipse is horizontal and vertical, and the trajectory repeats over multiple turns. This indicates that the vibration is stable when no external force is applied, with no torsional vibration.

[0124] Figure 9 The horizontal axis represents horizontal forward and backward vibration, while the vertical axis represents horizontal left and right vibration (including a torsional component). The trajectory in the figure is elliptical, with the axis of the ellipse tilted, and multiple trajectories are misaligned. This indicates that torsional vibration is generated by external forces acting on the soil.

[0125] Figure 10 The horizontal axis represents horizontal forward and backward vibration, while the vertical axis represents vertical vibration. The vibration trajectory in the figure appears as an inclined straight line, with the trajectories of multiple reciprocating vibrations overlapping. The tilt of the trajectory indicates oscillatory vibration. The vibrator as a whole vibrates in a conical pattern centered at a point above the axis, and the trajectory projected onto this plane exhibits pendulum-like vibration. The overlapping reciprocating vibration trajectories indicate stable no-load vibration, without bouncing.

[0126] Figure 11 The horizontal axis represents horizontal forward and backward vibration, while the vertical axis represents vertical vibration. The vibration trajectories in the figure are inclined ellipses, and the trajectories of multiple vibrations do not completely overlap. The ellipse indicates that in addition to the conical vibration, there is also vertical vibration, known as jump vibration. The incomplete overlap of the trajectories indicates that the jump vibration is irregular and the amplitude of the jump vibration varies continuously.

[0127] 2.2. By monitoring the vibration above the shock absorber, the working condition of the shock absorber can be judged and hidden dangers can be discovered in time.

[0128] The vibration of the guide rod above the shock absorber (monitored by the third vibration sensor) is directly related to the vibration reduction performance of the shock absorber, such as Figure 12 As shown in the figure, when unloaded, the vibration amplitude of the guide rod above the shock absorber remains within a small range. When the vibrator contacts the soil layer to create holes or densify, the vibration amplitude of the guide rod increases, but fluctuates within a reasonable range with the load. If the shock absorber performance deteriorates or is damaged, the guide rod amplitude will exceed the range and exhibit unstable vibration.

[0129] Data is accumulated during previous construction projects on the same or similar strata, and the distribution of characteristic data of vibration during normal operation is extracted and used for real-time monitoring of equipment during construction.

[0130] Figure 12 The middle horizontal axis is time, and the total axis is vibration amplitude. The left half shows that the guide rod's amplitude is stable and constant when unloaded. The right half shows that the guide rod's amplitude increases after the vibrator contacts the soil.

[0131] This method can also be used to monitor motors and bearings.

[0132] Figure 13 The horizontal axis represents the vibration frequency, and the vertical axis represents the vibration amplitude. In addition to the rotation frequency, there are also rich harmonic frequency components.

[0133] Figure 14 The horizontal axis is the frequency axis and the vertical axis is the time axis. Each waveform curve represents the amplitude of the corresponding frequency. From bottom to top, each amplitude-frequency curve shows the change of vibration harmonics over time.

[0134] 2.3. The soil characteristics can be further judged by the frequency spectrum distribution of vibration data.

[0135] Vibration data is collected using a first accelerometer at a frequency that meets the Nyquist sampling criteria. Smoothing filters are used to remove noise interference (e.g., time-domain synchronous averaging), discrete data points are windowed (e.g., using a Henning window), and then a Fast Fourier Transform (FFT) is performed to obtain amplitude-frequency and phase-frequency data. Frequency domain parameters (e.g., fundamental frequency and frequency of each harmonic, phase, peak value, and RMS value) are extracted, and further frequency domain statistics (e.g., center of gravity frequency, mean square frequency, root mean square frequency, frequency variance, and frequency standard deviation) are obtained. The distribution of energy-significant harmonics (e.g., energy spectral density distribution) is analyzed, and wavelet analysis can be further performed. Through the long-term accumulation of construction data, the distribution patterns of characteristic values for various soil types are determined.

[0136] 2.3.1. Method for calculating phase difference angle.

[0137] Because the eccentric shafts of the motor and vibrator rotate at the same speed, the two sets of signals have the same frequency. Therefore, the phase difference can be determined by correlation detection of the two sets of signals or by comparing the main frequency phase after Fourier transform. Motor phase detection uses a pulse at the zero phase point (a magnetic pulse or the Z pulse of a rotary encoder). The first accelerometer receives a continuous sinusoidal signal (or one containing high-frequency clutter and noise). In practice, one processing method uses the motor phase pulse as the trigger signal to start data acquisition for the vibration sensor. This can be simplified to performing a Fourier transform on only the first accelerometer. The phase angle corresponding to its main frequency is the phase difference angle, and this difference is the phase lag angle of the vibration.

[0138] 2.3.2. Use the phase difference angle to calculate the soil force between the vibrator and the soil.

[0139] Research has found that during the vibrating process of a vibrator, the phase lag angle is related to the damping force applied to the soil. The greater the damping force, the larger the phase lag angle. Simultaneously, the smaller the vibrator's amplitude, the energy transferred to the soil layer by the vibrator is related to the vibrator's linear velocity, resistance, and the angle between them. The greater the resistance and linear velocity, and the smaller the angle, the greater the output power. The linear velocity can be determined from the vibration sensor's acceleration, and the resistance and angle can be determined from the phase difference. Therefore, the power transferred by the vibrator to the soil can be calculated.

[0140] For a vibrator, the maximum exciting force F max , the mass m of the eccentric block, the eccentricity e of the eccentric block, and the mass M of the vibrator shell are all known quantities.

[0141] Through the rotational speed n and the vibration angular frequency ω=2πn / 60.

[0142] Do the following calculation:

[0143] The amplitude α of the vibrator:

[0144] Soil resistance of the vibrator:

[0145] m—mass of eccentric block

[0146] e—eccentricity of eccentric block

[0147] ω—vibration angular frequency

[0148] Phase difference angle and Angle relationship:

[0149] Output torque of the motor: T = F·a

[0150] F—the resistance of the soil on the vibrator

[0151] The power P transmitted by the vibrator to the soil:

[0152]

[0153] 2.3.3. According to the energy method of soil mechanics, the process of calculating soil density and other indicators through energy density P is as follows.

[0154] For a position with a distance r from the pile center, according to the vibration attenuation trend, there is the following vibration velocity peak value v max formula:

[0155] v max =A*r -b

[0156] In the formula, A and b are unknown coefficients. The value of b varies depending on the soil layer. A is related to the amplitude of the vibrator at that moment.

[0157] Calculate the energy absorption of the soil per unit volume at this time:

[0158]

[0159] in:

[0160] E—shear wave energy per unit volume of soil;

[0161] ρ—density of soil;

[0162] V s — shear wave velocity of soil medium;

[0163] v max —Peak vibration velocity of soil unit;

[0164] —Average absorption of wave energy by soil;

[0165] E in —The wave energy input to the soil element at a distance r from the vibration source;

[0166] E out —The wave energy output from the soil unit at a distance (r + Δr) from the vibration source;

[0167] Δr—thickness of soil unit;

[0168] The cumulative energy absorbed by the soil layer after the cumulative vibration time t is the cumulative energy W:

[0169] Calculate excess hydrostatic pressure u max :

[0170]

[0171] in,

[0172] u f —Excess pore pressure when soil liquefaction occurs;

[0173] W f —The accumulated energy absorbed when soil liquefies;

[0174] Finally, calculate the void ratio e of the soil after the water pressure dissipates after reinforcement i :

[0175] e i =e0-(1+e0)m v u max

[0176] e0—initial porosity ratio;

[0177] m v —soil compression coefficient;

[0178] Each vibro-compacted pile is constructed in the following order: hole making → cleaning → infilling. The several formation parameters on which the above-mentioned real-time detection process in the infilling project is based must be obtained before infilling.

[0179] Stratigraphic data can be obtained by obtaining stratigraphic sequence and depth range, as well as related stratigraphic parameters, from pre-construction geological reports. Some data can also be obtained by searching relevant design materials or conducting laboratory tests.

[0180] It can also be obtained through intelligent identification during the drilling process of vibro-pile construction. During the drilling process, the relevant construction data is collected, processed, decomposed and reconstructed, and the improved K-means method is used to perform real-time intelligent identification of the stratum to establish the stratum data sequence of the current pile position.

[0181] 2.4, the control flow of the encryption section is shown in Figure 15 :

[0182] After obtaining the depth of the densification section, read the formation data, lower the vibrator, and detect whether the densification current or the power P transmitted by the vibrator to the soil reaches the required value. If not, continue to lower the vibrator until it reaches it; if it reaches it, stop lowering, measure the vibration time, calculate the cumulative energy W at distance r based on the vibration data, and measure the excess hydrostatic pressure u max and porosity ratio e i ;

[0183] e i If the required value is reached, the process ends; e i If the required value is not reached, continue to observe.

[0184] Example 3

[0185] The main function of the DPT module is to penetrate the soil with hammer energy and evaluate the physical and mechanical properties of the soil based on the penetration depth and the number of hammer strikes. Specific functions include:

[0186] Data collection: Real-time collection of data such as penetration depth, number of hammer strikes, probe deflection, etc., and accurate measurement through sensors.

[0187] Data processing: Analyze and process the collected data to generate standardized reports, such as the relationship curve between penetration count and depth.

[0188] Remote control: Through the Internet of Things and Internet technologies, the test process can be viewed and controlled remotely to improve test efficiency.

[0189] Safety warning: The system is designed with a safety warning mechanism. When the probe rod deflection approaches or exceeds the specified upper limit of 2%, an early warning is triggered immediately to ensure the safety and controllability of the test.

[0190] The DPT module can be used to evaluate the physical and mechanical properties of soil, such as density, bearing capacity, deformation parameters, etc. Specific applications include:

[0191] Foundation bearing capacity testing: Through dynamic penetration tests, the bearing capacity of the foundation is evaluated to provide a basis for building design.

[0192] Soil stratification: Soil stratification is carried out based on the relationship curve between penetration number and depth to evaluate the uniformity and physical properties of the soil.

[0193] Soft soil evaluation: The free-fall dynamic penetration test (FFP) can be used to evaluate the undrained shear strength of shallow ultra-soft soil, serving as an effective supplement to the CPTU test or full-flow penetration test.

[0194] Marine engineering: Free-fall dynamic penetration technology is suitable for marine geotechnical engineering surveys to measure parameters such as acceleration, cone tip resistance, side wall friction and pore water pressure.

[0195] Example 4

[0196] The digital application of the DPT module

[0197] By integrating high-precision sensors and online transmission technology, it is possible to collect and record test data in real time, and perform data analysis and management through an intelligent software platform.

[0198] Mobile APP: A supporting mobile APP has been developed to realize mobile management of test data and improve on-site service efficiency.

[0199] Data processing software: such as Geovision geotechnical engineering data processing software, can import, analyze and automatically generate dynamic penetration test results in accordance with international standards.

[0200] In addition, it should be understood that those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A vibrator with a DPT function, comprising a vibrator, wherein the vibrator includes a motor for driving an eccentric shaft, a vibration damper connected to the motor, and a guide rod connected above the vibration damper; characterized in that: A resistance sensor is installed on the side wall of the vibrator, a posture sensor is installed inside the vibrator, a first vibration sensor is installed in the cone tip of the vibrator, a second vibration sensor is installed near the vibration absorber of the vibrator, and a third vibration sensor is installed on the guide rod; the vibrator also has a built-in DPT module, which is used for in-situ testing to evaluate the physical and mechanical properties of the soil.

2. The vibrator with DPT function according to claim 1, characterized in that: The detection method of the vibrator with DPT function comprises the following steps: Step 1: Compare the phase of the eccentric block with the horizontal vibration phase, calculate the phase angle difference a, and calculate the force F1 between the vibrator and the soil; Step 2: Measure the vibration amplitude using the first vibration sensor, compare it with the no-load vibration amplitude, and obtain the force F2 between the vibrator and the soil; Step 3: Measure the electrical frequency f of the current based on the current signal 电 , according to the number of motor poles p, the synchronous frequency f of the motor is obtained s =f 电 / p, the vibration frequency f is measured by the first vibration sensor, and the slip rate of the motor s=1-f / f s ; Step 4: Obtain the output power P of the vibrator at this time through the slip rate s and the frequency characteristic curve of the vibrator tested at the factory. g And output torque T; this output power P g is the energy density P transmitted to the soil by the vibrator in the form of vibration n ; Step 5: Energy density P n And the soil density index is calculated based on the force F2 acting on the soil; Step 6: Calculate the contact dynamic stress with the soil by the ratio of the soil force F2 to the lateral projection area S of the vibrator, convert it into the static penetration friction resistance of the soil, and then calculate the soil properties; Step 7: Monitor the lifting and lowering speed u to ensure that the vibrator is in a hovering state within a normal speed, and monitor the vibration retention time t; Step 8: Output the judgment result by comparing the data within the encrypted time period.

3. The vibrator with DPT function according to claim 1, characterized in that: During the vibratory construction process of the vibrator, when the vibrator encounters a hard layer, the load and the characteristic peak value show a positive correlation.

4. The vibrator with DPT function according to claim 1, characterized in that: During the vibratory construction process of the vibrator, the spectral lines whose frequencies increase or decrease proportionally with the increase or decrease of the fundamental frequency are harmonics or multiples of the fundamental frequency.

5. The vibrator with DPT function according to claim 1, characterized in that: During the vibratory construction process of the vibrator, the trajectory of the horizontal vibration velocity vector diagram is elliptical, the lateral amplitude is greater than the longitudinal amplitude, and the trajectory is repeated for multiple circles, indicating that there is no torsional vibration.

6. The vibrator with DPT function according to claim 1, characterized in that: During the vibratory construction process of the vibrator, the trajectory of the horizontal vibration velocity vector diagram is elliptical and the axis of the ellipse is tilted. The transverse amplitude is greater than the longitudinal amplitude, and there is misalignment in the multiple-circle trajectory, indicating the existence of torsional vibration.

7. The vibrator with DPT function according to claim 1, characterized in that: During the vibratory construction process of the vibrator, the trajectory in the vibration velocity vector diagram is an inclined straight line, and the trajectories of multiple reciprocating vibrations are overlapped, indicating that there is no vibration jump phenomenon.

8. The vibrator with DPT function according to claim 1, characterized in that: During the vibratory construction process of the vibrator, the trajectory in the vibration velocity vector diagram is an inclined ellipse, and the trajectories of multiple reciprocating vibrations are not completely overlapped, indicating the existence of vibration jumping.

9. The vibrator with DPT function according to claim 1, characterized in that: During the vibratory construction process, the maximum exciting force F max , eccentric block mass m, eccentricity of eccentric block e, vibrator shell mass M; The amplitude α of the vibrator: Speed n and vibration angular frequency ω = 2πn / 60; Soil resistance of the vibrator: m—mass of eccentric block; e—eccentricity of eccentric block; ω—vibration angular frequency; Phase difference angle and Angle relationship: The output torque of the motor is T = F·a; F—the resistance of the soil on the vibrator; The power P transmitted by the vibrator to the soil: For a position with a distance r from the pile center, according to the vibration attenuation trend, there is the following vibration velocity peak value v max formula: v max =A*r -b ; A and b are the coefficients to be determined; Calculate the energy absorption of the soil per unit volume at this time: in: E—shear wave energy per unit volume of soil; ρ—density of soil; V s — shear wave velocity of soil medium; v max —Peak vibration velocity of soil unit; —Average absorption of wave energy by soil; E in —The wave energy input to the soil element at a distance r from the vibration source; E out —The wave energy output by the soil unit at a distance (r + Δr) from the vibration source; Δr—thickness of soil unit; After the cumulative vibration time t, the cumulative energy absorbed by the soil layer, the cumulative energy Calculate excess hydrostatic pressure u max : in, u f —Excess pore pressure when soil liquefaction occurs; W f —The accumulated energy absorbed when soil liquefies; Finally, calculate the void ratio e of the soil after the water pressure dissipates after reinforcement i : e i =e0-(1+e0)m v u max e0—initial porosity ratio; m v —Soil compression coefficient.

Images