| The load of subgrade becomes larger, and the aciont times become more with the improvement of transition capacity of the Daqin Railway. This paper has made an assessment to the bearing capacity of the subgrade through the on-site research , field test, dynamic load test of the train, regular laboratory soil test, dynamic triaxial test, slaking test and slaking test with flowing water. The principal work is as follow:Firstly, the Daqin Railway subgrade was researched and its problems were analyzed. The bearing capacity of the subgrade was measured with field tests, and combined with the laboratory tests, the basic characteristics of the subgrade soil was analyzed. Some kinds of sensors were buried in the subgrade surface to measure the factors of the stress and the acceleration of subgrade when trains passed.Secondly, the dynamic triaxial test was carried in the laboratory to simulate the pressure of subgrade soil under 5000t, 10000t, 20000t train, and the pore pressure of silt and silty clay was analyzed. The result is that effective stress of the silt clay after 20000t train is reduced 7% than that after 5000t train. Triaxial compression test was taken after the dynamic triaxial test, the change of the bearing capacity under it was analyzed and the result was that the bearing capacity after 20000t train is reduced 8.7% than that after 5000t train, and the relation curve between the load action times when the soil failed and load grade of silt was given.Finally, the outwash of the road shoulder and slope were researched. Through slaking test, the influence of the soil characteristics and the degree of compaction on the outwash resistance of the soil were analyzed. The subgrade outwash under the rain was simulated, and it was found that the degree of compaction had an obvious influence on the resistance outwash of the soil. The slaking test with flowing water was carried. Compared with the regular slaking test, the slaking test with flowing water was more accord to the fact.
|
PDF Full Text Request