CN-121992767-A - Dynamic frequency tracking-based self-adaptive resonance compaction method for alluvial foundation

CN121992767ACN 121992767 ACN121992767 ACN 121992767ACN-121992767-A

Abstract

The invention belongs to the technical field of foundation treatment, and discloses a alluvial foundation self-adaptive resonance compaction method based on dynamic frequency tracking. The problem of resonance frequency drift of a yellow river downstream alluvial powder foundation caused by rigidity time-varying property in the resonance compaction process is solved. The method comprises the steps of S1, equipment positioning and initial penetration, S2, real-time response monitoring, S3, bottom vibration remaining and instantaneous frequency analysis, S4, dynamic frequency tracking and self-adaptive resonance in the vibration rod lifting process, S5, lifting the vibration rod to the ground to finish construction of a single point location, S6, moving the resonance compacting equipment to the next construction point location, and repeating the steps S1-S5 until foundation treatment of all areas is finished. The invention solves the problem of resonance frequency drift caused by the rigidity time-varying property of the alluvial powder soil at the downstream of the yellow river fundamentally by analyzing the instantaneous natural frequency of the soil body in real time and dynamically tracking and matching.

Inventors

GAO CHANGHUI
TAN XIANFENG
LIU SONGYU
DU GUANGYIN
YANG YONG
MA CHUANYI
ZOU GUOCHUN
DUAN WEI
BAI MEI

Assignees

山东科技大学

Dates

Publication Date: 20260508
Application Date: 20260407

Claims (10)

1. The self-adaptive resonance compaction method for the alluvial powder soil foundation based on dynamic frequency tracking is characterized by comprising the following steps of: S1, aligning a vibrating rod of resonance compacting equipment to a preset construction point, starting a vibrating hammer of the resonance compacting equipment, and penetrating the vibrating rod to a design depth at an initial scanning frequency higher than the upper limit of a predicted resonance frequency range; s2, after the vibrating rod reaches the design depth, acquiring vibration response signals of the vibrating hammer, the vibrating rod and the foundation soil coupling system in real time through a data acquisition device arranged on the vibrating rod; s3, receiving a vibration response signal by a control system of the resonance compacting equipment, analyzing and identifying the instantaneous natural frequency of the foundation soil in the current compacting state in real time, and adjusting the output frequency of the vibration hammer in real time by taking the instantaneous natural frequency as a target to enable the output frequency to be matched with the instantaneous natural frequency, so as to ensure that the vibration hammer, the vibration rod and the soil mass system enter a resonance state at a designed depth; S4, starting a vibration rod lifting program, continuously collecting vibration response signals in real time by a control system, continuously analyzing the instantaneous natural frequencies of soil bodies with different depths, and adjusting the output frequency of a vibration hammer in real time, so that the output frequency always follows and matches the instantaneous natural frequency of the soil body with the current depth, the vibration hammer, the vibration rod and the soil body system are always in or approach to a resonance state in the whole lifting process, and meanwhile, adaptively adjusting the output amplitude according to the response amplitude change of the soil body monitored in real time, so that uniform encryption of the full-hole depth range is realized; s5, after the vibrating rod is lifted to the ground, completing construction of a single point location; S6, moving the resonance compacting equipment to the next construction point, and repeating the steps S1-S5 until the foundation treatment of all areas is completed.
2. The method of adaptive resonance compaction of a alluvial foundation based on dynamic frequency tracking according to claim 1, wherein in step S1, the initial scanning frequency is 10% -30% higher than the upper limit of the estimated resonance frequency range.
3. The method for adaptively compacting the alluvial foundation based on dynamic frequency tracking according to claim 1, wherein in step S2, the data acquisition device comprises an acceleration sensor and an impedance monitoring device, and the sampling frequency is not lower than 200Hz.
4. The dynamic frequency tracking-based alluvial foundation adaptive resonance compaction method of claim 1, wherein the vibration response signal comprises at least one of an acceleration response signal, a vibration energy dissipation ratio, and a vibration rod impedance change signal of the vibration rod.
5. The method for adaptively compacting the alluvial foundation based on dynamic frequency tracking according to claim 3 or 4 is characterized in that in the step S3 and the step S4, the analysis of the instantaneous natural frequency is realized based on the fast Fourier transform spectrum analysis or the amplitude-frequency characteristic curve peak search of the vibration rod acceleration response signal, and a sliding time window algorithm is adopted to process continuous signals in real time, wherein the time window length is 0.5-2S.
6. The dynamic frequency tracking-based alluvial foundation self-adaptive resonance compaction method according to claim 1, wherein in step S3, the preset duration of bottom vibration is 1-5min.
7. The dynamic frequency tracking-based alluvial foundation self-adaptive resonance compacting method of claim 1, wherein in step S4, the lifting speed of the vibrating rod is controlled to be 1.0-2.0m/min.
8. The self-adaptive resonance compaction method for the alluvial foundation based on dynamic frequency tracking according to claim 1, wherein in step S4, the specific mode of self-adaptive adjustment is that the amplitude of the acceleration of the vibration rod is monitored in real time, and when the amplitude of the acceleration continuously decreases or reaches an amplitude threshold corresponding to a preset compactness, the amplitude is automatically reduced or the output power is reduced.
9. The dynamic frequency tracking-based alluvial foundation self-adaptive resonance compaction method is characterized in that construction points are arranged in a quincuncial or square grid, and the distance between adjacent construction points is 1.5-3.0m.
10. The dynamic frequency tracking-based alluvial foundation adaptive resonance compaction method according to claim 1, which is suitable for treating a alluvial foundation downstream of a yellow river.

Description

Dynamic frequency tracking-based self-adaptive resonance compaction method for alluvial foundation Technical Field The invention belongs to the technical field of foundation treatment, and particularly relates to a alluvial foundation self-adaptive resonance compaction method based on dynamic frequency tracking. Background Due to periodic flooding of rivers (e.g., yellow river) and high sedimentation rates, recently deposited silt with unique engineering properties is widely distributed in areas. Compared with common silt, the fluvial silt at the downstream of the river has the characteristics of high particle roundness, high particle content (generally more than 80%), poor grading (C u is generally less than 5), low liquid limit and plasticity index, severe capillary action, lack of consolidation and the like, so that the fluvial silt is difficult to compact, and is extremely easy to liquefy under the dynamic actions of earthquake, traffic load and the like. Thus, the yellow river downstream alluvial foundation treatment is a significant challenge in engineering construction. Currently, the construction scale of infrastructures in the fluvial plain area at the downstream of a river is continuously enlarged, but the traditional foundation treatment technology faces serious challenges such as insufficient deep treatment capacity, high carbon emission, large vibration influence and the like. The resonance compaction method is to adjust the vibration frequency of a 'vibration hammer-vibration rod-foundation soil' system to enable the system to reach a resonance state, and utilize resonance energy to rearrange soil particles and reduce pores, so that the compaction degree and liquefaction resistance of the foundation soil are improved. The method does not need extra filler, the unit area cost of the method is saved by more than 50 percent compared with that of a gravel pile method, the carbon emission intensity is only 1/5 of that of a reinforced soil pile method, the construction safety distance is less than 10m, the treatment depth can reach more than 15m, and the method has great application potential in the construction of infrastructures in plain areas of downstream alluvial and alluvial rivers. However, when the method is applied to a foundation of river down-stream alluvial powder soil, a special technical problem is faced, namely resonance frequency drift caused by rigidity time-varying property. Specifically, under the action of vibration load, the shear modulus and the rigidity of the fluvial silts at the downstream of the river can be obviously changed along with the gradual compaction of the soil body, so that the natural frequency of the soil body shifts in real time. The traditional resonance compacting method adopts a mode of fixed-frequency vibration or frequency conversion according to a preset curve, and can not track the frequency drift caused by the self-change of the soil body in real time. In the construction process, most of the time, the vibrating hammer-vibrating rod-soil mass system is in a detuned state, the energy utilization efficiency is low, the deep soil mass reinforcing effect is uneven, and meanwhile, if energy is continuously input in the detuned state, the soil mass structure is possibly damaged (over-vibrating), and the reinforcing effect is reduced. In the prior art, although a report about a vibration hammer frequency adjusting device (such as the Chinese patent of publication No. CN 211698727U) is provided, the adjusting logic is mainly based on the running parameters of the device, and does not relate to dynamic frequency tracking based on the real-time response of soil, so that the problem of frequency drift caused by the time-varying stiffness of the drift-deposited silt in the downstream of the river can not be solved. Therefore, an adaptive resonance compacting method capable of tracking the frequency change of the soil body in real time and dynamically matching the excitation frequency is urgently needed to realize efficient and uniform reinforcement of the foundation of the river downstream alluvial powder soil. Disclosure of Invention The invention aims to provide a dynamic frequency tracking-based self-adaptive resonance compaction method for a alluvial foundation, which effectively solves the problem of resonance frequency drift of the alluvial foundation caused by rigidity time-varying property in the resonance compaction process of a river downstream alluvial foundation. In order to solve the technical problems, the self-adaptive resonance compaction method for the foundation of the alluvial powder soil based on dynamic frequency tracking comprises the following steps of S1, aligning a vibrating rod of resonance compaction equipment to a preset construction point, starting a vibrating hammer of the resonance compaction equipment, and penetrating the vibrating rod to a designed depth at an initial scanning frequency higher than the upper limit of a predicted re