Research On The Vibration Stability Of TBM Hydraulic Straight Pipe

Abstract:Hard rock tunnel boring machine (TBM) is a large tunnel construction equipment, used in hard rock geology. Strong vibration is prominent during the process of rock breaking and excavation, which would exacerbate vibration of the pipeline which fixed on TBM, Causing instability of the pipeline. Substantial vibration and chaotic motion would be generated. The System stability and reliability of pipeline system were serious affected. In order to improve the stability of the pipeline in the vibration environment, the vibration characteristics and stability of the pipeline would be depth studied. This paper focuses on TBM hydraulic straight pipeline systems and expands research from the aspects of theory and experiment. The works carried out and responding conclusions of this paper are as follows:1. Based on Alembert principle and Newton’s law, the nonlinear differential equation of hydraulic straight pipeline conveying fluid was established, which was nondimensionalized and discretized by the Ritz-Galerkin. The first-order ordinary differential equations are gained though numerical calculations. The equivalent inherent vibration frequency of pipeline is gained basing on the equivalent linearization technique.2. The bifurcation characteristic and the correlation between bifurcation and equivalent natural frequency were depth studied. The results demonstrate that the pipe system has complex response with the variation of foundation excitation, and period motions, quasi-periodic motions, chaos are observed; There is good correlation between bifurcation point and equivalent natural frequency, the correlation coefficient is greater than0.85.3. On the basis of equivalent model of natural frequency, the effect of fluid parameters (velocity, pressure) and structural parameters (tube length, stiffness, diameter, wall thickness) on the instability of the pipeline were studied, and analyzed the sequence of impact through orthogonal experiment. The results showed that with the increasing of parameters, pipe length and diameter, the equivalent natural frequency decreases, the pipe more likely instability and bifurcation. With the increasing of stiffness and thickness, the equivalent natural frequency increases, the pipeline more stable; diameter and wall thickness is the most important factor affecting the equivalent natural frequency; on the basis of the above analysis to optimize the selection of traditional pipeline, a new selection criteria adapted to foundation vibration environment were proposed and a formula for calculating the pipeline installation tube length were deduced.4. The vibration test platform of hydraulic straight pipe was built, the basis for the dynamic response of the pipeline vibrations were studied experimentally. The correctness of the pipeline fluid-solid coupling mathematical model and analysis methods was verified, finally the generated reasons for the error between experiment and theory were analyzed.