Model test and numerical simulation of cooling effect of ventilated duct-crashed rock composite embankment

In order to study the cooling effect of ventilated duct-crashed rock composite embankment, a series of model tests are carried out under plateau environment conditions. The average annual temperature is -3.5℃, the average wind speed is 2.5 m/s, and the dominant wind direction is northwest. The air convection velocity in crashed rock, the change process of temperature at feature points and the temperature field of model are analyzed. The results indicate that an enhanced convection effect in embankment can be generated by the ventilated duct-crashed rock composite embankment. Under the effect of grooming by the ventilated duct, the air convection velocity in the composite embankment is 20% higher than that in a single crashed rock embankment, and the cooling rate at the bottom of the model of the composite embankment is 2.2 times that of the single crashed rock embankment. A numerical model for the ventilated duct-crashed rock composite embankment is established. The velocity distribution in the ventilated duct-embankment temperature field is analyzed. Numerical calculations show that the air flow rate which reaches a maximum at the center vent pipe is 4.06 m/s. A rapid decline in velocity occurs at the wall of the ventilated duct. The magnitude of the air flow in the crashed rock is 10^-1. The calculated results are consistent with those of laboratory tests. The model test and numerical simulaton show that the composite embankments can deposit cold quantity and cool down the permafrost.