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Study on the Stability of Bridge Pile Foundation at Permafrost Regions under the Locomotive Load

Author: HuoYuanKun
Tutor: ChenBo；WuZhiJian
School: Lanzhou Jiaotong University
Course: Structural Engineering
Keywords: Qinghai-Tibet Railway Bridge Vibration transmission Dynamic Response Finite Element Analysis
CLC: U443.15
Type: Master's thesis
Year: 2011
Downloads: 43
Quote: 0
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Abstract

Thermal disturbances caused by the impact of external factors in the gradual global warming and human engineering activities, the permafrost of the Qinghai-Tibet railway will be faced with the problem of the degradation, and thus a threat to the safe operation of the Qinghai-Tibet Railway. To ensure the safety of the Qinghai-Tibet Railway extremely unstable by high temperature and high ice content permafrost railway \Decide this \Recent decades, global temperatures generally increased the Tibetan Plateau year average temperatures generally increased by 0.2-0.4 ° C annual temperature decreases year by year, resulting in the area of ??permafrost showed mostly emerged in the state of regional degradation. At the same time, the permafrost ground temperature rise also caused a decrease in intensity of the permafrost. With the opening and operation of the Qinghai-Tibet Railway, and from dozens of trains a day, high-frequency vibration of train bridge foundation structure will be the effects of vibration, affect the stability of the bridge foundation, and thus a threat to the safe operation of the Qinghai-Tibet Railway. Select the high temperature of the Qinghai-Tibet Railway is extremely unstable permafrost regions \Inspection of the site visits and literature to determine the engineering geology and climate of the study area environmental data; in Qingshuihe Bridge to carry out a strong vibration and temperature test locomotives through real-time on-site master locomotive loads under the bridge foundation vibration response characteristics, attenuation the regularity and vibration energy distribution and temperature variation; Finally, two-dimensional transient dynamic finite element analysis methods, combined with field measurement data to analyze the characteristics of the the locomotive load, the bridge foundation vibration response. The innovation of this paper and the main conclusions can be summarized as follows: 1. Locomotive through the bridge foundation vibration response. Vibration acceleration for the pile foundation pass by the bridge, there is a significant attenuation effect. The response intensity of the vibration tripartite upward different vibration response in the vertical direction of the most strongly, but the attenuation of substantially the same magnitude. Locomotive vibration energy is more concentrated in the 50Hz-60Hz, and the energy attenuation in the frequency range of the most significant, the vibration energy when the surface of the pile is reached for about 10% of the original. Found through analysis of the on-site temperature monitoring data, locomotives real-time by locomotive vibration of bridge pile temperature field disturbance, but due to the relatively short duration of action, the instantaneous temperature field warming amplitude is only about 0.02 ℃. 3 Numerical calculations show that under the load of the locomotive, the vibration energy from the deck to the bottom pile is about 2% of the original. The basis of maximum subsidence occurred in a pile near the upper part of the soil, the largest settlement 0.085mm. The settlement size decreases with increasing distance from the pile, and decreases as the depth increases. Stress concentration in the bottom of the bridge foundation, pile-soil contact portion is in close contact with the state, no cracking, dislocation of the situation.

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CLC: > Transportation > Road transport > Bridges and Culverts > Bridges constructed > Bridge Foundation > Pile
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