Study On Compaction Evaluation Method And Deformation Performance Of Rockfill Materials

In the construction of highways in mountainous areas,the excavation of roadbeds and tunnels will produce a large amount of rock filling materials.Filling stone has high strength and adaptive deformation performance,its excellent physical and mechanical properties and adaptive deformation performance,can be used for high embankment and subgrade pavement deformation coordination structure.However,it is very difficult to determine the standard dry density by laboratory test and evaluate the strength and deformation performance of rockfill materials according to the predetermined density.At present,compaction control can only be carried out by rolling times and qualitative methods in engineering,and it is admitted that the road performance of rockfill subgrade can be guaranteed by meeting the requirements of rolling times.In this study,similar gradation and equivalent compaction work method were used to establish a compaction control method based on compression deformation rate.The strength and deformation properties of the stone filling material were studied according to the predetermined compression deformation rate,and the adaptive deformation properties of the stone filling material were further studied according to the control conditions.The main research results are as follows:(1)The compaction control of rock-filled subgrade can be quantitatively evaluated by compression ratio method,and similar gradation only needs similar content of skeleton particles and filling particles.The maximum compression rate obtained under the action of heavy standard forming work can be used as the standard compression rate.The compaction density,compaction degree and porosity can be measured by using the standard compression ratio,and the compaction effect can be quantitatively evaluated.(2)Based on the contact mechanics method,a formula for calculating the California bearing ratio(CBR)of rockfill materials is proposed,and the calculated values are basically consistent with the experimental values.The CBR strength of the filling stone is only related to the strength of the parent rock and the filling density within a certain range.Similar gradation can be used to evaluate the strength and deformation properties of the filling stone.(3)The rock-fill material has excellent adaptive deformation performance,and its adaptive deformation performance comes from the looseness of the rockfill material.The loose rock-fill material has large volume deformation and still has sufficient CBR strength.The content of fine-grained soil and plasticity index have an adverse effect on the adaptive deformation performance of rockfill materials.With the increase of fine-grained soil content,plasticity index and plasticity product,the looseness and adaptive deformation performance of rockfill materials decrease.(4)The rock filling material has low compressibility and good pressuresensitivity.The compression index increases with the increase of the crushing rate,increases with the increase of the plasticity index,and decreases with the increase of the plastic product,indicating that the compressibility of the rockfill is mainly controlled by the crushing rate and the plasticity index,and the finegrained soil content is beneficial to reduce the compressibility.The K value of the Janbu model increases with the increase of the crushing rate and decreases with the increase of the plastic product.The law of n value is opposite to that of K value,indicating that the compressive hardness of rockfill mainly comes from fragmentation,and the plastic product of fine-grained soil is sensitive to the change of pressure-sensitivity parameters.The compaction control method of rockfill and the evaluation method of strength and deformation performance of rockfill proposed in this study can improve the quantitative level of compaction control and performance evaluation of rockfill,quantitatively evaluate the compaction effect of rockfill roadbed,give full play to the strength and deformation performance of rockfill,effectively use the adaptive deformation performance of rockfill,and solve the complex roadbed pavement deformation coordination problem.