| Recent years, high-speed railway in our country has made major development, long-term stability of the high-speed railway tunnel issue has caused widespread concern in the engineering sector gradually, and also has become extremely important when doing research on how vibration load of high-speed train affects the dynamic properties and fatigue damage of the basal soft rock. This article takes the basal soft rock in Jinshazhou tunnel of Wuguang high speed railway as research object, based on the National Nature Science Foundation of China (NO:51278121), by using methods of laboratory test and finite element analysis to carry the research.By use of similar materials to simulate the basal soft rock in the tunnel of the high speed railway. Characteristic of fatigue damage in the tunnel of high speed railway basal soft rock has been obtained.After tests analysis and on the basis of the cumulative damage theory, fatigue failure of soft rock mainly has two modes which are the tension-shear on the end and the compression-shear on the central of specimen. The polynomial model with three parameters to calculate the fatigue life curve is established for the different strength of soft rock-mass(S-LgN curve). The results turned out that the fatigue curve of soft rock-mass in different strength showed similar variation. Combined with elastic damage theory and nonmetal ultrasonic testing method, soft rock in different circumstances were tested, the polynomial model of the soft rock with four parameters to calculate the cumulative damage were obtained. And with the coMParison analysis between the accumulated vibration times and dynamic strain curves, it is considered that there is a good correlation between the two. According to the relationship between ultrasonic velocity and vibration damage test times, ultrasonic wave mode and velocity can be used as an indicator of the soft rock damage critical evaluation.Base on the three dimensional finite element analysis platform of MIDAS, the dynamic response characteristics of high-speed train tunnel soft rock basement have been discussed in detail. Having analyzed the dynamic response characteristics of different strength soft rock under different train speeds, the primary conclusion was made:the influence of the train speed on the basement of tunnel in the high speed railway is obvious. Through analyzing dynamic stress calculation results under different circumstances combined with fatigue damage test, corresponding fatigue longevity have been obtained. On the condition of weaker soften basement rock-mass, the reinforcing measure must be adopted to improve the fatigue life of the base of tunnel in high speed railway and estimated the fatigue life of Jinshazhou basement tunnel soft rock-mass.The research result in this thesis will not only have important significance towards the long-term dynamic stability and fatigue life prediction under train loads, but also can be used as an important reference when making the design and construction of the high-speed railway in soft soil field. |
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