Research On Dynamic Response And Damage Characteristics Of Tunnel Lining Structure Under Train Vibration Load

The concrete structure design code of 2010 version has been implemented for many years in China, but there is no application in the field of engineering structure calculation by using the constitutive relation of concrete damage, which is a kind of shortcomings and deficiencies in the engineering design. This paper, adopting the theoretical analysis and numerical calculation methods, established the differential form of corresponding damage evolution equation in tension and compression according to the constitutive relation of concrete damage in the new code;and writed corresponding calculating program for the elastoplastic damage constitutive model of concrete by using C++ language,and extend function for secondary development based on FLAC3 D finite difference software platform. And analyzed the dynamic response and figure out the distribution of damage in lining structure of China’s high-speed railway tunnel under different vehicle speed and different classes of surrounding rock by using the concrete damage model that has developed; studied the dynamic characteristics, strength deterioration process, the distribution and developing curve of damage of the lining structure, found out the dangerous parts of the structure intuitively. The calculation results show that:(1) lining structure dynamic response(displacement, acceleration and dynamic stress) and damage value decreases with the departure of the increase of the source distance and position under vibration loads of train, the damage is small above the sidewall, while it is relatively large in the junction part of sidewall and inverted arch; a damage concentrated area occurred on the concrete foundation under track slab and inverted arch, which is the most dangerous areas of lining structure that is possiblely damaged.(2) lining structure dynamic response and the value of damage increased with the train speed, to which the acceleration is the most sensitive; the level of surrounding rock has significant influence to the dynamic response, the value and distribution of damage of the lining structure(especially in the damage concentrated area), thedamage degree of the structure is relatively larger while surrounding rock level is poor; the growth of damage value presents a step effect.