Study On Improvement Of Subgrade Filling Of Fluvioglacial Deposits On Chengle Expressway

Fluvioglacial deposits are widely distributed in southwest China,but they have not been used as subgrade filler for engineering projects because of their special origin and complex composition.With the continuous development of transportation construction in the west of China,the problem of bad soil quality will inevitably be encountered in the construction of engineering projects.Due to the high altitude and complex terrain in the west of China,it is impossible to fundamentally solve the problem by simply using the replacement filling method.To this end,this thesis on G0512 line expansion and the chengdu-leshan highway construction project bid E2,through a series of indoor test of fluvioglacial deposits as subgrade filling modified treatment plan to carry out the experimental study,by adding different solution such as cement,lime,shale soil to improvement of water deposit,deposit obtained in ice water and compaction characteristics in different improvement schemes and strength performance trends,and sums up the deposit in ice water and improvement of soil dynamic modulus of resilience.(1)The basic physical characteristics and mechanical properties of fluvioglacial deposits in this area were explored based on laboratory tests by sampling three soil collection points on the site.The test results show that the fluvioglacial deposits have the basic conditions of being used as subgrade filler after a long period of precipitation and accumulation,but because of its high natural moisture content and low strength,it must be improved and treated in engineering application before it can be used as subgrade filler.(2)In view of the shortcoming that the fluvioglacial deposits do not meet the requirements of subgrade filling,different amounts of cement,lime and shale soil are added into the fluvioglacial deposits to study the change rule of its compaction characteristics and strength performance.The results show that cement has the best improvement effect on strength performance,followed by lime and shale soil.Lime is the best,cement is the second,and shale soil is the worst.(3)At present,there is almost no research on the dynamic rebound modulus of fluvioglacial deposits.The relationship between dynamic resilience modulus and confining pressure,deviatoric stress and content of improved soil with different amount of admixtures was obtained through laboratory dynamic triaxial tests.The results show that the dynamic resilience modulus of the improved soil is positively correlated with the confining pressure and negatively correlated with the deviatancy stress,and the influence of the deviatancy stress gradually decreases under the high confining pressure.