Planar geomechanical model is adopted to simulate construction and post construction settlement characteristics of soil and rock aggregate mixture embankment. All the results can provide scientific bases for settlement calculation, settlement forecasting, design, construction, choosing right time for pavement and height reservation of embankment.
High highway embankment is increasingly adopted in rolling ground and mountainous area in order to satisfy design criterion of vertical section of highway under the complicated landform and physiognomy Conditions. At the same time, soil is often shortage While rock is abounding in those areas. So the soil and rock aggregate mixture embankment is preferred for economic and environmental factors.
Different kinds of pavement diseases or even instability of embankment can be resulted from immoderate settlement of soil and rock aggregate mixture embankment due to consolidation and deadweight compress settlement of soil and rock aggregate mixture. The design and construction criterion for soil and rock aggregate mixture embankment isn't set up yet. The quality of soil and rock aggregate mixture is difficult to control because grain size and water content vary in a large range. So it is very important to study settlement characteristics of soil and rock aggregate mixture embankment and forecast construction settlement and post construction settlement. This paper can provide scientific bases for design, construction, settlement control and height reservation for soil and rock aggregate mixture embankment.
Settlement characteristics of soil and rock aggregate mixture embankment are mainly researched in model experiments. The following conditions are strictly satisfied except for geometric similarity in planar geomechanical model experiment:
The strain of prototype and model is similar: Ct = I
The strength of prototype and model is similar: Cσ= CE
The stress-strain relationship and Mohr strength envelope of prototype and model are similar.
Planar geomechanical model is equipped with hydraulic pressure jacks to provide vertical pressure. The vertical stress is controlled by a negative feedback system which can keep a stable vertical pressure for embankment model during experiment.
In order to keep similarity between model and prototype, the strength similarity scale between model material and prototype material should meet Cσ = C1. Model material is made from field soil and rock aggregate mixture by parallel gradation method. Thus the model material's strength is larger than similarity theory need. And the model can't satisfy similarity criterion. The problem can be solved by setting a surface stress on model top surface. It is used to simulate different height embankment by changing the pressure of jacks. So the geometrical similarity scale is alterable during experiment. Thus the model can simulate different height embankment. Settlement ratio of model to prototype is irrelative to geometrical similarity scale, that is CE = 1.
The grain size of soil and rock aggregate mixture often exceeds 600 mm in highway embankment.
