Packing Of Soft Rock In The High-speed Rail In The Applicability Analysis And Sedimentation Studies

There is plenty of soft rock distributed in the cutting position of New Wuhan-Guangzhou Passenger Railway. If they can be used as subgrade filling of this high-speed railway, social and economic benefits will be obviously obtained. As a representative soft rock, seriously-weakly weathering argillaceous siltstone at cretaceous and tertiary is the main research object in the thesis which is combined with the state natural science fund item. In order to validate argillaceous siltstone filling's suitability and feasibility in the high-speed railway and discuss the construction technology, a large number of indoor and outdoor experimentations were carried out. Since the settlement of subgrade is strictly controlled in ballastless tracks, the settlement of the embankment filled by soft rock is a research emphasis and the research is based on the system of settlement monitoring- prediction- evaluation.The main research means and the important conclusions in the thesis are the followings:(1) By means of collapse test, cyclic compaction test, large-scale triaxial test, CBR test, model test, water stability test in field and so on, make sure that argillaceous siltstone filling has characteristics of enough shear strength and stiffness, adequate rigidity, permanent volume stability, being prone to be compacted, and being sensitive to water. Argillaceous siltstone filling can be used under the bottom of bedding in high-speed railway but the water stability should be improved by some waterproof and drainage measures.(2) When the argillaceous siltstone filling was used in the substantiality embankment, it should be physically improved. The physically improved soil ought to be mixed centrally in field and the water content of construction should be controlled in the range of -2% to +2.5% of the optimum water content.Using vibratory roller with 20T to 25T and rolling by 6 to 8 times are suitable.(3) Through relativity analysis on the detecting indexes of compaction quality of the subgrade, discover that the mechanical detecting indexes are not much relative to the physical detecting indexes, but the mechanical detecting indexes are remarkably relative to each other, and the two kinds of detecting indexes should be adopted in the soft rock embankment. Furthermore, the physical detecting indexes which detect the compaction degree are more important than the mechanical detecting indexes which detect the stiffness, so the former are the prime detecting indexes.(4) The results of settlement monitoring show that creep is the main distortion of the argillaceous siltstone filling which is more affected by environment than load. The subsequent settlement is large.(5) By using multifold models of settlement prediction to fit the curves of settlement-time, find that Poisson curve is fitter than Asaoka method and GM(1,1) model but the final settlement prediction values is less by the former than the two latter which elicit the same results.(6) The results of settlement prediction show that the post-construction settlement of the soft foundation after being treated by CFG pile-net composite structure is small, and the post-construction settlement of the soft rock embankment mainly comes from the embankment itself. The post-construction settlement prediction value of the embankment itself is 0.091% to 0.183% of the height of the embankment.(7) Based on the theory of fuzzy-random reliability, the conclusions that the probability of the soft rock embankment which will lose stability because of post-construction settlement is small and the long-term stability of the embankment is highly ensured are drawn.