Evaluation and Mechanism Study of Vibration Compaction State of Graded Gravel under Different Moisture Content
When the optimal moisture content in the heavy hammer compaction method is used as the standard for deter-mining the moisture content in the vibratory compaction method for graded aggregates for high speed railway subgrade,the phenomenon of"mud bubbling"during vibratory compaction deteriorates the compaction quality of the graded aggre-gates.In order to study the effect and mechanism of moisture content on vibration compaction method,the graded crushed stones with different soil structure types were taken as the research object.Through large-scale indoor vibratory compaction and triaxial tests,the change law of compaction state was discussed and analyzed.The results show that:The extreme dry density first decreases before increasing with the increase of water content,with a wave trough and high moisture content.During vibration compaction,phenomena such as coarse aggregate adhesion and mud bubbling will oc-cur.When the critical moisture content after compaction and drying is used as the water addition amount for the vibration compaction method,no mud bubbling phenomenon occurs during compaction,with the dry density meeting the require-ments of on-site compaction.The critical water content keeps CEI and TDI in the optimal range,with the lowest particle breakage rate,and the maximum stiffness and strength of the compacted filler.Based on the theory of soil mechanics in the critical state,the effect of pore water on the vibration compaction of the filler is explained.That is,when the mois-ture content exceeds the critical moisture content and the total external stress remains unchanged,the pore water pressure increases and the effective earth pressure decreases,resulting in a decrease in the strength of the filler after molding.The research results can provide a theoretical reference for the control of high-speed rail coarse-grained soil fill-ing.
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