Research On The Cumulative Plastic Deformation Of High-speed Railway Subgrade Composed Of Stone Packing To Class A/B

ABSTRACT:The natural A, B group of packing is very scarce along Wuhan-guangzhou high-speed rail, but the hard rock, calcium cementation sandstone, marl and not easily weathered soft stone is abundant. In recent years, they are famous for the high strength, fast construction and economic beneficial, and are widely used in high speed railway subgrade engineering. Engineer called it stone class A, B group of packing; At the same time, due to their size distribution of discontinuous, strength is affected by factors such as geological conditions. These rocks with the current defined in the specification of A, B group of packing is different, this leads to their corresponding construction and detection technology standard is quite incomplete and lack of systemic, and quality evaluation index is vulnerable to big error of the actual situation, which often cause improper control of compaction, and large embankment settlement, even subgrade damage, etc.Through extensive research, indoor and outdoor testing and theoretical analysis, we study the stone class A, B group of packing’s quality control standards, engineering mechanics, filling process parameters and roadbed quality testing methods, and in the long train loads, whether its deformation characteristics can meet the design requirements, the main research results are as follows:Saturated uniaxial compressive strength of Rb(>)15MPa, the coefficient of softening η(?)0.45, the largest particle size should be controlled within the63mm, the non-uniform coefficient Cu≥5, the curvature coefficient Cc＝1～3, less than0.075mm of the fine particle content control within5～10%of group A and group B control within15～20%, and appropriate for the low liquid limit silt or low liquid limit clay powder.Bed bottom quality control indicators:K30≥150MPa/m, Evd≥35MPa, Ev2≥60MPa, Ev2/Evl≤2.5, Compacting factor Kh≥0.95; Subgrade ontology:K30≥130MPa/m, Ev2≥45MPa, Ev2/Evl≤2.6, Compacting factor Kh≥0.92.Stone class A, group B in the packing of plastic dynamic strength as the confining pressure, degree of compaction, increases with the increase of confining pressure and roughly quasi linear relationship; Along with the load frequency increase, the plastic dynamic strength in turn reduce; After flooding, the dynamic strength decreased7～8%, the limit of the dynamic strength under flooding condition about plastic dynamic strength of1.46-1.82times, without a frantic jumble roadbed structure with plastic in the dynamic strength as control index, a frantic jumble roadbed structure limit dynamic strength as the control target.Considering density, moisture content, lateral stress and dynamic stress amplitude and frequency on stone class A, B group of the accumulation of filling subgrade deformation characteristics, the influence of100trains under cyclic loading, stone class A, B group of packing bed (2.3m) and bottom (3.0m) the cumulative plastic deformation of subgrade ontology forecast of3.25mm and3.60mm respectively.