| With the implementation of"the Belt and Road"and the strategy of the development of the western region in China,the construction of expressways has gradually entered the remote mountainous areas of western China,and the terrain and geological conditions are becoming more and more complex,the vast areas of the west are dominated by plateaus,mountains and basins.Due to the wide source and easy access of soil-rock mixture,it has gradually become the primary choice of subgrade filling materials.However,the nature of soil-rock mixture is unstable,which is different from pure soil filler or pure rock filler.At present,the research on the soil-rock mixture is mostly based on its mechanical properties and engineering properties,and the scope of application of the project is mainly low-fill subgrade.The research on the compaction and stability of high fill subgrade with super large particle rock filler under the condition of steep slope terrain is relatively less,and the targeted compaction detection standard and construction technology can not be formed.Therefore,based on the construction sites K16+700,K16+920 and K12+280 of the second section of Jianshui-Yuanyang Expressway,this thesis delimits the corresponding test section according to the on-site filling characteristics and construction conditions,carries out the continuous compaction control test and dynamic elastic modulus test of soil-rock mixed subgrade in steep slope section,and carries out the subgrade settlement,inclinometer and stress monitoring of anti-slide pile steel bar meter,the main results are as follows:（1）The index of vibration compaction value（VCV）can reflect the overall structural resistance of subgrade filling layer,while the index of dynamic resilient modulus(Evd)can only reflect the compaction degree within the depth of 500mm below the surface of filling layer,and the uniformity degree of VCV index is higher than that of Evd.（2）Steep slope,rock content of filling material and rolling times all have an important impact on the compaction quality of soil-rock mixed subgrade in steep slope section,the steep slope has the greatest impact on the compaction quality of subgrade.With the increase of steep slope,the compaction quality of subgrade decreases significantly,but when the rolling times are too many,the compaction effect of subgrade becomes worse.Generally speaking,the correlation of VCV and Evdincreases with the decrease of the loose paving thickness or the steep slope.（3）Through the calculation and analysis of the numerical simulation of the compaction process of the soil-rock mixed subgrade in the steep slope section,the priority of the three factors affecting the compaction quality of the subgrade in the steep slope section is:steep slope>stone content>the number of times of cyclic load application,the conclusion of the simulation of the compaction process of the soil-rock mixed subgrade in the steep slope section is basically consistent with that of the field subgrade compaction test.（4）The stability of soil-rock mixed subgrade in steep slope section decreases with the increase of steep slope and subgrade filling height,and increases with the increase of cohesion and internal friction angle of soil-rock mixture,the influence of filler cohesion on subgrade stability is relatively small.（5）Based on the long-term monitoring of the soil-rock mixed subgrade in steep slope section,it is found that the subgrade settlement,lateral displacement of slope and steel bar meter stress change slowly and tend to be stable gradually in the later period of monitoring,the steep slope has an important impact on the stability of subgrade slope.With the increase of steep slope,the stability of subgrade slope decreases.（6）The slope stability of K16+700,K16+920 and K12+280 is good,which can optimize the supporting conditions of subgrade slope and save the project cost.The anti-slide pile size of K16+700 is changed to 1.25×1.5m,K16+920 to 1.25×1.75m,and K12+280to 1.75×2m. |
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