Field Filling Test Of Full Weathering Soft Rock And Cement Modified Soil Subgrade In Monghua Heavy Haul Railway

Relying on the heavy haul railway construction of MengHua,In order to solve the filling problem of fully weathered soft phyllite fillings along the Yueyang Ji'an section,the basic physical and mechanical properties were analyzed through laboratory soil tests;Field tests of fully weathered soft rock and cement stabilized soil were carried out,the key control parameters and process of roller compaction construction are studied;the site settlement observation test was carried out,and the moisture content of the embankment and the settlement deformation of the foundation were obtained.The main conclusions of this paper are as follows:?1?Laboratory tests on fully weathered soft rock fillers are carried out,it is found that the main mineral compositions are quartz and iron-rich Muscovite,the optimal water content?_opt=17.5%,the maximum dry density?_dmax=1.61g/cm³,the particle density is 2.72g/cm³,the liquid limit W_L10=42.1%,the plasticity index I_p10=14.0,is the high liquid limit silty clay,belongs to the D group of fillers.?2?The laboratory cement Improvement Test concludes that,after the full weathering soft rock filler is mixed with 3.5%cement,when the compaction coefficient is 0.92,its 7-day unconfined compressive strength can meet the standard requirements,can be used directly as embankment filler below the base bed,the indoor compaction test shows that,after the full weathering soft rock filler is mixed with 3.5%cement,the maximum dry density?_dmax=1.62g/cm³,the optimal water content?_opt=17.1%,close to no improved compaction parameters.?3?In this paper,the site filling test of 0.3m,0.4m,0.5m and 0.6m for the full weathering soft rock filler with water content in 13.8%²1.5%was carried out,the test shows that the foundation coefficient K30 is the key control index for the compaction quality of the embankment,The increase of water content or loose thickness of filler will make K₃₀ difficult to meet the design requirements,the influence of water content and loose thickness of filler on K30 is analyzed,it is concluded that the filling water content of the whole weathered soft rock filler is controlled in the range of??(?_opt-3%,?_opt),and the embankment filler K₃₀ can meet the K₃₀?80MPa/m design requirements when the thickness of the loose layer is controlled within 0.35m.?4?This paper analyzes the relationship between the compaction coefficient K and the K₃₀ of foundation coefficient of the test index of embankment compaction quality,when the foundation coefficient K30 meet the design requirement of K₃₀?80MPa/m,the compaction coefficient of the filler is K?0.95,therefore,when the full weathering soft rock filler is used as the embankment below the base bed,the control value of the compaction coefficient of the filler should be increased to 0.95,so as to ensure the compaction quality of the soft rock embankment with full weathering.?5?The compaction effect of four kinds of rolling combination is compared,the whole weathering soft rock filler is crushed by static to weak and weak to strong foundation,by adding static pressure times,the compaction quality of embankment can be further improved,it is not advisable to increase vibration compaction times to improve the compaction quality of filler,therefore,it is recommended to use static pressure 2 times+weak vibration 1 times static pressure 1 times+strong vibration 1 times static pressure 1 times+static pressure 2times of the rolling combination method to fill the whole weathered soft rock filling.?6?Field filling test of modified soil filler from fully weathered soft rock,the control value of the loose thickness can be increased from 0.35m of the whole weathering soft rock to0.5m,the control range of filler water content can be relaxed to the range of??(?_opt-3%,?_opt+3%),Through static pressure 2 times+weak vibration 1 times static pressure 1 times+strong vibration 1 times static pressure 1 times after rolling,can reach K?0.92 and K₃₀?80MPa/m design requirements.?7?The settlement observation data collected in the test section indicate that,the settlement of the foundation in the field is filled with the 73%⁸5%of the total settlement when the embankment is completed,and the filling is slowly increased and stabilized gradually after the completion of the filling,the ground subsidence deformation is affected by groundwater in the reclaimed section,under the same embankment height,the subsidence of the groundwater development section is obviously larger than that of the undeveloped section,and the water content of the filling of the lower embankment has a tendency to increase slowly,the increasing trend of embankment is more significant,in order to prevent the leaching of groundwater and infiltration of rainwater into soft rock embankment,it is necessary to increase the aquiclude thickness of graded crushed stone in the filling section of soft rock,and to adopt waterproof covering measures in the course of embankment filling.