Research On The Mechanism Of Differential Settlement In Embankment–Bridge Transition Section Of Permafrost Regions And Prevention Methods Of The Freezing Damage

The differential settlement in embankment–bridge transition section is an universal problem in railway and highway engineering. Especially, the settlement is more obvious under the dynamic action. In embankment–bridge transition section of permafrost regions, the roadbed could settle differentially. In addition, there are special engineering problems because of the underlying permafrost. Based on investigating data, the disease of embankment–bridge transition section along the Qinghai-Tibet Railway is wide-spread, and the differential settlement is serious. There is a space behind the abutment because of the differential settlement, and using the ballast to fill the space. At present, this is the main method. This method is effective in a short period, but basically, it is invalid. And it will create new diseases. Because the mechanism is different, the experience of talik do not apply to the permafrost. And there are very few studies in embankment–bridge transition section of permafrost regions. So, to study the mechanism prevention methods in embankment–bridge transition section of permafrost regions is meaningful. Through the experiment, observing the effect of groundwater, approach slab and different roadbed filling. And study the effect of thermal probe by ANSYS. Conclusions are as follows:(1) The mechanical properties of frozen soil can change, because the influence of Global warming and the dynamic change of groundwater. The structure and material of roadbde can also adjust the radiation, convection, conduction. So, the above three factors can affect the settlement of the embankment-bridge transition section.(2) In order to simulate the groundwater, setting the heat under the pile. Under this condition, the settlement of abutment and roadbed increased obviously. And the settlement of abutment is more serious, the steel pipe pile is more sensitive under the influence of groundwater.(3) Setting approach slab can reduce the differential settlement in some extent. And with the increasing of stiffness, the reduction of differential settlement is also more obvious. But once the basement settled, repairing is very difficult. Using different roadbed filling can also reduce the differential settlement, and with the increasing of stiffness, the differential settlement is smaller. But the stiffness of roadbed filling can not too strong. Filling grout is a good methed for old railway, it can improve the performance of roadbed. But thermal engineering diseases have improved very little.(4) Study the effect of thermal probe by ANSYS, after setting thermal probe along the roadbed can reduce the settlement of roadbed effectively. But the effect is very weak for the differential settlement in embankment–bridge transition section. From what has been discussed above, in order to to solve differential settlement,searching for the comprehensive prevention methods is very important.