节点文献
液压振动桩锤沉桩动力学及调频调矩控制研究
【作者】 罗春雷；
【作者基本信息】 中南大学 ， 机械设计及理论， 2005， 博士
【摘要】 液压振动桩锤是一种以油压力为驱动力产生偏心激振、强迫桩土振动,使沙土液化以实现轻松沉桩的新型环保型桩工机械。国内振动桩锤设计理论很落后,也没有自己成熟的产品;国外液压振动锤问世已有二十多年历史,产品相对成熟,但对沉桩理论、尤其对沉桩阻力研究还远远不够。国内外液压振动桩锤产品存在着这样的共同问题:一方面,目前各种液压振动桩锤液压控制技术水平低下,功能普遍比较简单,另一方面,调频调矩机构复杂,导致机械故障率普遍较高,制约了设备向高性能的发展。 本文在研究振动沉桩过程地质特性的基础上,深入研究了桩—土作用机理,形成了一种面向地基土的液压振动桩锤研究设计新方法,提出新型四轴振动锤结构,其调矩机构不需齿轮传动,针对这种新型机构,研究了新型机电液控制方案,研究设计了频率调节控制、在线辩识近共振频率实现近共振沉桩及相位差在线调节实现偏心矩柔性调节的控制系统,并且深入研究了这种新型四轴惯性振动机的同步特性,完成了较系统的调频调矩动力学及其控制的研究与设计。论文进行了大量的仿真研究,针对局部问题进行了现场实验研究。论文主要研究内容如下: 论文首先研究了沉桩过程地质特性和土的阻力问题。在研究对比静载荷、非液化低振幅振动载荷和振动液化载荷这三种情况下的地质特性基础上,借助于动力地基刚度经验算法、土动力学对土的应力—
【Abstract】 A hydraulic vibratory pile hammer is a new type of environmental-friendly pile machine which depends on oil pressure to generate eccentric vibration and forces the soil to vibrate so that the soil can be liquefied to realize easy pile sinking. The domestic theory of vibratory pile hammer falls behind and there are no mature products of our own; In overseas, the hydraulic vibratory hammer have came out for more than 20 years ,their products are much more mature ,but their researches for the theory of pile sinking especially for the resistance of pile sinking are not enough. The domestic and foreign hydraulic vibratory pile hammers have common problems: on one hand, at present the hydraulic control engineering level of various hydraulic vibratory pile hammers is prevalently low and the functions are all simple; On the other hand, its frequency and amplitude modulation frameworks are complex, so that the machinery failure rate is prevalently high, therefore, the direction towards high performance of facilities is restricted.In the foundation of researching the geological characteristics of ground soil, the paper goes deep into the mechanism of the pile-soil function, forms a new hydraulic vibratory hammer design method orienting to the ground soil, designs a new type of 4-shafted vibratory hammer which can modulate the moment according to the gearless self-readjustment phase difference modulation, explores a new type of mechanical-electrical scheme and a control system which can control frequency modulation, on-line identify the frequency of near-resonant vibration to realize near-resonant pile sinking and the on-line eccentric moment self-readjustment modulation, and then researches the synchronism of this machine ,completes the design and research of its frequency and amplitude modulation dynamics and its control systematically . The paper runs large amounts of simulation researches and field experiments aiming at solving local problems. The main contents of this paper are:At first, the paper researches the geological characteristics of groundsoil and the resistance of it during the pile sinking process, presents a new concept of geologic characteristics and pile sinking resistance orienting to the ground soil. When the ground soil is loaded with steady load, non-liquefied low amplitude vibration load or liquefied load, the geologic properties are different, the paper compares the three different circumstances, with the help of classic dynamics force ground rigidity algorithm, the new research and experiment achievements based on the soil’s stress-strain relation and the field experiment data, the paper gets a newly practical formula and a theoretical model whose soil dynamic rigidity and dynamic damp are determined by the type of ground soil, the structure and the depth of the pile; Considering the effects of the inner friction coefficient and viscous force caused by the vibration pile sinking, going from the utmost dynamic stress state of the soil and the theory of shear dynamic intensity, the paper researches the resistance at the pile tip and the pile side. With the help of the name, the depth, the physical mechanics of the soil (the steady load friction angle, viscous force of the soil), the size of the pile and the coefficient of the pile hammer presented by the report of geologic survey, we can get any soil foundation’s dynamic rigidity, dynamic damp and dynamic resistance during the pile sinking process.Then the paper researches the load problem of the pile machine’s hydraulic system orienting to the ground soil. With the help of the linear vibration theory, the paper deduces a series of models showing the relations among the force exerted by the pile tip, the inertia force of the pile, the vibration frequency and the phase difference. Also with the help of the new Case formula and the dynamic rigidity, the dynamic damp and the dynamic resistance formula which the paper researched before, the paper establishes a mechanical condition which can guarantee the pile to sink in order to determine the vibration frequency and eccentric force moment. By researching the characteristic of the load force moment caused by the vibration of the hydraulic motor, the paper gets the model showing the relations among the load pressure of the hydraulic system, the power, the vibration frequency, the phase difference, the structure of the pile hammer and the geologic characteristics, also it gets the vibrationcondition which can guarantee the resonance vibration and non-resonance vibration pile sinking under special condition, so that we can determine the coefficient of the structure of pile hammer and the coefficient of its control. At last, the paper sums up a set of new method of researching and designing the hydraulic vibration hammer orienting to the ground soil.The paper applies the research method of the parameters of the pile hammer orienting the ground soil into predicting pile sinking of a special ground soil, researches the geological characteristics, load properties, and frequency modulation properties during the pile sinking process, and the paper predicts the depth of the pile sinking, gets the rule of the parameters’ change and the rule of modulation control; By running the simulation of the pile sinking process of the newly zzyyl60 hydraulic vibration machine and researching the dynamic response, the paper gets the vibration frequency, the rigidity of the ground soil, the damp parameters, and the properties which affect the displacement, the acceleration and the force at the pile tip.In the foundation of the research of the pile-soil functioning and load property of the pile hammer mentioned above, the paper designs a new type of mechanical-electrical control scheme of the gearless moment modulation pile hammer, considers such functions as electric-hydraulic proportion frequency modulation, prevention of motor absorbing the air, energy conservation and so on, then determines to adopt fuzzy control strategy to modulate the frequency and the moment and adopt the control scheme to on-line search the pile-soil resonance frequency.Kinematics and dynamics model building and simulation analysis has been carried out comprehensively for the newly frequency modulation system, in which motor is controlled by high-pressure and heavy-flow electric-hydraulic proportional flow modulation valve. And the velocity modulation characteristics of system can be known. General PID controller and fuzzy PID controller have been designed for frequency modulation system. Controlling parameters of general PID controller and fuzzy PID controller has been designed and adjusted by the debugging of simulation experiment. The simulation result indicates that fuzzy PID controller is better. In the foundation of fuzzy frequency modulation,general fuzzy PID controller and parameter self-adjusting fuzzy PID controller have been designed to search for the pile-soil’s near-resonant frequency. The simulation result indicates that parameter self-adjusting online fuzzy PID controller is better than general fuzzy PID controller. And it leads to a control system which can on-line modulate frequency intelligently and realize the pile sinking at the near-resonant frequency.In order to design the control system which can realize self readjustment of the phase difference, a mechanical electrical hydraulic coupling model has been developed at the beginning, and then synchronicity mechanism and synchronizing characteristics of mechanic system and hydraulic system have been studied without monitoring the phase difference. By carrying the dynamic simulation of the mechanical-electrical hydraulic coupling model, we know the interaction between parameters of the synchronizing system, which includes mechanical parameter, hydraulic parameter, characteristic parameter of the ground soil and the modulation of frequency and vibration amplitude, etc. And synchronous stability and synchronous transition characteristics have been studied. Stable average mathematic model of control system without monitoring the phase difference has been developed for vibratory machine. And the condition of stable synchronization can be deduced, which provides method for the design of mechanical-electrical and hydraulic system on gearless self-readjustment synchronizing machine. Measures to improve synchronization have been put forward. The preceding study of mechanical electrical hydraulic coupling relating to the synchronization of hydraulic vibratory machine fills in the gap between our nation and foreign countries.The preceding study focuses mainly on synchronization of mechanical electrical and hydraulic system with electric-hydraulic frequency modulation and the system is not monitored with the phase difference. Based on this, the control system with flexible adjustment of amplitude has been developed, which is achieved by parameter self-adjusting fuzzy control for phase difference modulation. Fuzzy controller has been designed. So parameter self-adjusting fuzzy controller for phase difference has been optimized and checked in simulation. Simulationstudies the characteristics of change of parameter in fuzzy regulation, including vibration amplitude, load moment and pressure, etc. Simulation result shows that parameter self-adjusting fuzzy control system for phase difference is what we expect in the construction process without the resonance of pile and bay and in the process of the self-adjusting control during pile sinking.The new method for the selection of parameters of hydraulic vibration pile hammer and the prediction of the load characteristics in pile sinking can be used to predict the load characteristics in pile sinking process and the depth of pile sinking on condition of resonance and non-resonance, which is based on geological survey report. And field experiment has been carried out to demonstrate it. The result shows that this new project is feasible.The paper presents a relatively intact theory and method for designing and researching the hydraulic vibratory pile hammer and its dynamic characteristics. The research achievements relating to the characteristics of the synchronism can be extended to the application of the general vibratory machine driven by hydraulic pressure.The dissertation includes 90 thousand words and 107 diagrams.