The Study Of Utilization Of Dynamic Compaction To The Embankment Of Mountainous Area Expressway In Which Red Sandstone Gravelly Soil Is Used As Backfilling Materials

Red sandstone stratum,which has undesirable mechanical properties such as low strength,poor weathering resistance,water softening and filtration disintegration,widely distributes in southwest mountainous area of Hunan province.Scientific research must be conducted to the basic properties of red sandstone gravelly soil and filling technology before red sandstone gravelly soil is chosen as the backfilling material of mountainous expressway.Therefore,it has its theoretical and practical significance to carry out testing and research to the backfill embankment,which red sandstone gravelly soil is used,of mountainous area expressway,and put forward the workable dynamic compaction technology and efficient field testing method.To base on the results of field geological survey,combining the relevant documents and scientific articles at home and abroad,this thesis focus on an experimental section of backfilling embankment of Wu-Jing expressway in which located southwest mountainous area of Hunan province,to conduct the research and experiment to Dynamic Compaction used in mountainous area highway project on which red sandstone gravelly soil is utilized as backfilling materials for embankment.Firstly,to base on the waviness theory of Dynamic compaction method and the consolidation(strengthening)of saturated soil and non-saturated soil,conducting scientific research to consolidation mechanism of soil of red sandstone used as backfilling materials of embankment.At the meantime,to discuss the affecting factors of Dynamic compaction consolidation of red sandstone gravelly soil through construction parameters of Dynamic compaction and the physical properties of the soil.Secondly,to conduct experimental research of the outcome of Dynamic compaction to the backfilling embankment of mountainous area expressway in which red sandstone gravelly soil was used.To explore the feasibility of using red sandstone gravelly soil which is available in mountainous area as filling materials for the embankment through geological survey & Lab geotechnical test and integrating the former disposal experiences of similar sandstone works.To determine the disposal process of pre-disintegration of red sandstone gravelly soil,and established 800 kN·m,1000 kN·m,1200 kN·m,1400 kN·m and so on four different level of dynamic compaction reinforcement scheme and test plan.In the process of using dynamic compaction to strengthen the backfilling embankment with red sandstone gravelly soil as filling materials,to explore the result of Dynamic compaction strengthening method to backfilling embankment of the mountainous area expressway in which red sandstone gravelly soil was used by employing the load test,dynamic penetration test,surface wave test.And confirming the suitable techniques for the Dynamic compaction method are as follow: when the backfill soil thickness is 4 to 5 m,suggest the I1-2 area 1000 kN·m compaction process;When the backfill soil thickness is 5 to 6 m,recommended I1-3 area 1200 kN·m compaction process.Finally,to conduct the study of relativity between the field test through the design of field test and mathematical statistic method to discover the relativity existing among load test,dynamic penetration test and the transient Rayleigh wave test,and obtain the empirical equations of relativity which significantly simplify the testing plan facilitate the construction progress and save the investment in the later large scale.