The Dynamic Performance Of Subgrade Bed Structure Builded Of The Cement Stabilized Graded Aggregate

With the fast development of the high-speed railway, the request of subgrade raised increasingly. There are not only enough subgrade bed strength, but also appropriate subgrade bed stiffness to satisfy with the safety and comfort under the high-speed train loading. Suining-Chongqing high-speed railway is the first railway of 200 km/h for passenger and freight transportation in the southwest mountain area, and on which the double layer container train (120 km/h) will been planed to run. The stratum of Suining-Hechuan section is mainly red-layer soft rock, and the compaction degree of the top-filling of subgrade bed can't conform to the corresponding standard because of the gravel poorly-gradation. According to the above, the thesis tried to study the effect of graded aggregate improved by adding small proportion cement.The tests such as the compaction test, non-confining compression test, resilient modulus test and permeability test are done respectively. The 3% cement rate was proposed to use in graded aggregate as the top-filling of the subgrade bed structure according to these tests results. Three groups dynamic 1:1 model test were carried out to research the dynamic performance of the subgrade bed which builded of the cement stabilized graded aggregate and graded aggregate. In order to simulate the action of the high-speed railway's wheel load on the subgrade bed, the 4Hz cyclic loading is repeated 1 million times in every group of test. In order to compare the model tests, the finite element analyses in different work condition were carried out. The variation of dynamic deformation and dynamic stresses with the K30 value and height of the subgrade bed were obtained. Based on the result of the test, the test in situ and FE analysis, refer to the subgrade-bed builded of the graded aggregate, the dynamic performance of the subgrade-bed builded of the cement stabilized graded aggregate were improved, the stiffness of the subgrade bed was increased, the stress and the permanent deformation and the dynamic displaccment of the subgrade bed were decreased, the stability of the track structure have been improved. All the above conclusions indicate that the subgrade bed structure builded of the cement stabilized graded aggregate bed is feasible and reliable, which give someinstruction to the design of top subgrade in red-layer soft rock region, and also supply some advices to the building of railway soft subgrade.