Research On Compaction Quality Control And Stability Of Soil-rock Mixed Subgrade

In the southwestern region of my country,due to its complex terrain,high mountains and valleys are everywhere,so transportation is extremely inconvenient.With the continuous expansion of infrastructure construction in my country,road transportation has become the main mode of transportation in the region.In order to enhance the bearing capacity,stability and durability of highway subgrades,soil and stone mixed fillers are often used to build subgrades in engineering.However,due to the complexity of material and structure of soil-rock mixed filler,the roadbed filled with it often encounters problems such as difficult to guarantee the compaction quality,difficult to control the strength of the roadbed,and unpredictable settlement after construction.In order to solve the above problems and improve the construction quality of highway subgrade,this paper proposes a method of using the software FLAC^3D to simulate and calculate the compaction settlement of soil,combined with a random aggregate generating program,a variety of soil-rock mixture subgrade,soil-rock mixture and soil-rock mixture subgrade slope models are established,and numerical simulations are performed on them.On this basis,the relationship between compaction settlement and compaction degree of soil-rock mixed roadbed,uneven settlement of soil-rock mixed roadbed under pressure,shear strength of soil-rock mixture,stability of soil-rock mixed roadbed slope and its possible failure mode are studied and analyzed.（1）The"FLAC^3D Modulus Variation Method"is proposed:By establishing the relationship between rock and soil porosity,strain and elastic modulus,the elastic modulus value of the unit body is changed in real time according to the strain of the unit body in the software FLAC^3D calculation process,so as to simulate the change of the porosity of the soil-rock body.（2）The program of generating random aggregate is used to establish a variety of soil-rock mixed subgrade models,and the"FLAC^3D Modulus Variation Method"is used to simulate the compaction process of subgrade.The relationship between compaction settlement and compaction degree of various soil-rock mixed subgrade,the uneven settlement of subgrade surface under pressure and the loss of vertical stress of subgrade under multi-layer compaction are obtained.（3）The model of soil-rock mixture was established by the program of random aggregate generation and the FLAC^3D triaxial compression test was simulated,the overall shear strength parameters of soil-rock mixture with different compaction degree,different internal friction Angle of soil（rock）and different cohesive force of soil（rock）were measured,and the sensitivity of single factor was analyzed.The influence of shear strength parameters of soil and rock on the overall shear strength of soil-rock mixture is obtained.（4）Combined with practical engineering cases,the rationality of the relationship between compaction settlement and compaction degree of soil-rock mixed roadbed simulated by"FLAC^3D modulus change method"is verified.At the same time,the simplified model of the typical soil-rock embankment slope in engineering is established,and the stability and failure modes of the soil-rock embankment slope and the homogeneous soil embankment slope are compared.The results show that the soil-rock embankment slope has higher strength and better stability than the homogeneous soil embankment slope.