Settlement. Railway Embankment Earthquake Shaking Table Model Test Study

China, which is situated on the intersection of the Circum-Pacific seismic zone and Eurasian seismic zone, suffers from earthquake disaster greatly. It is a very common phenomenon that embankments subside during the earthquake. In 2008, Wenchuan great earthquake damaged lots of embankments and about 9 railways embankments subsided severely including Guanghan-Yuejiashan Railway, Baoji-Chengdu Railway, Chengdu-Dujiangyan Railway, Chengdu-Wenchuan Railway, and so on. Because of the seismic subsidence of embankments, the railway and highway in most areas could not be used and transportation was broken off. The national economy was suffered enormous losses and the safety of people's lives and property was under great threat. Therefore, based on project supported by railway ministry:seismic design and standard of railway embankments (No:2008G010-A), the method for the prevention of seismic subsidence were researched by field investigation, large-scale shaking table model test and theoretical analysis. The main researches carried out were as follows:(1) Field investigation was conducted on railway and road embankments, and reinforced embankments in heavy disaster area of Wenchuan earthquake.(2) Large-scale shaking table tests of embankments were designed. The similarity relation and similar material for shaking table tests were proposed and described in detail. At the same time, test equipments, the location of measuring points, the input seismic waves and loading rules for tests were presented.(3) A series of large-scale triaxial tests for the filler of embankments were carried out. The strength and deformation behavior of the filler of different compaction degrees and different patterns of reinforcement forms were obtained.(4) Shaking table tests of embankments with four compaction degrees (95%,91%,87%and 83%) and two types of reinforcement forms(2 or 4 layers of reinforcements) were carried out. And the dynamic behavior and seismic subsidence characteristics of embankments were studied. The measures for preventing seismic subsidence by improving compaction degree or reinforcing were compared.(5) According to the shaking table tests, it was showed that the compaction degree affected seismic subsidence of embankments greatly, when the compaction degree of embankment is less than 90%, with the decrease of compaction, embankment seismic subsidence increase significantly. Meanwhile, when the compaction of embankment is greater than 90%, with the increase of compaction, the seismic subsidence reduce not obviously. Therefore,90%was a key compaction degree for seismic subsidence prevention. The relationship between the seismic subsidence and compaction degree can be fit by cubic polynomial.(6) According to the shaking table tests, the seismic subsidence caused by lateral deformation played great role when the peak acceleration of input seismic waves is more than 0.6g. And therefore, in order to prevent the damage of seismic subsidence in the region of high earthquake intensity, the measures should be taken to constraint the lateral deformation of embankment as well as the high compaction degrees should be insured, such as reinforcement.