High-speed Railway Improvement Of Soft Rock Soil Test And Construction Technology Research

Along the Wu-Guang special passenger transport line, There are lots of Fully-heavily Weathered argillite slate and phylite slate. Putting those soft rock to use for express railway embankment material, we can save more then millon yuan for the project investment.meanwhile, which can decrease discarding soil and benefit for environment. Therefore, economic and social effects are very considerable. Based on the present research on soft rock fillings at home and abroad and the integrated analysis, the dissertation combines the research projects supported by railway ministry,by means of theory analysis,indoor test and site test, the research work has been accomplished with following achievements:(1) Weakly-weathered argillite slate rock is so weak that it could be broken into fine grains easily in the process of compacting.So we can not use those material directly. By adding medium-coarse sand to improve it, The results of the strength and permeability experiments show that the effect of physical modification method is not significant.(2) Indoor tests show that the property of mined fully-heavily weathered argillaceous slate is unstable.The maximum dry density of the soft rock is related to its gradation and weathering degree and changed with time of storage prolonging. It is hard for us to get the subgrade compactness because of the uncertainty of maximum dry density. In this dissertation I suggest other methods to estimate the effectiveness of compaction.(3) Adding cement and lime to fully-heavily weathered argillite slate seperately to improve its strength.Indoor tests show that the unconfined compressive strength of cement-improved soft rock is superior to lime-improved soft rock. On the basis of this conclusion,I make a further study on the mechanism of the two modified soil technique.(4) Indoor tests shows that enlarge the maximum grain size properly is beneficial to gradation of the improved soil,which make it can be campacted easily,at the same time,the void ratio of filling is decreased. Site test proved that with the coarse grain contents increasing,the strength and water-stability of the improved soft rock are not weaken obviously, which can meet the technical requirements of the express railway.(5) Field tests show that the chemical analysis method of current specifications is not suitable for modified weathered soft rock,Based on the study of indoor test and field test,this dissertation put forward a improved chemical analysis method,which is applied to site inspection successfully.