Stability Analysis Of The Ventilated Embankment Of The Warm And Ice-rich Frozen Soil

The permafrost of Qinghai-Tibet Plateau will gradually degenerate into the warmer permafrost with the global warming.The stability of road engineering which is built on the frozen ground will be affected by the change of the temperature of the frozen soil.The warm and Ice-rich soil which has temperature sensitivity and deformation ability is a special type of warmer permafrost to cause the embankment disease.A variety of measures have been adopted in the construction of the road engineering in permafrost regions to prevent the permafrost degradation.such as the broken stone embankment,the ventilation embankment,the insulation board(XPS)and the sun shield etc.Taking the ventilation embankment for example in this paper to study effects of the warm and rich-Ice soil on the ventilated embankment stability.In the present work,a highway in Qinghai Province was taken into account to simulated and analyzed the temperature field of the embankment by setting the temperature of boundary of the ventilation pipe into a step change.On the basis of the temperature field,the stability of the ventilated embankment is analyzed.(1)It is set to that the minimum temperature is in order to increase and the maximum temperature is maintain the same form of the ventilated pipe of boundary temperature.the ventilation under the condition of this paper and the ventilation under the traditional setting condition have a good cooling effect based on the numerical calculation of the temperature field.(2)Through the analysis of the different forms of the slope of the embankment and the ventilation pipe,it is concluded that the effect of the Yin and Yang of the embankment on the different levels of the effect of the cooling efficiency of the ventilation pipe.The effect of yin and Yang slope effect on embankment temperature field is great that on the sunny slope can obviously heat the temperature of embankment soil and on the shady slope can significantly reduce the temperature of embankment soil,It also increases lateral inhomogeneity of permafrost temperature of the embankment.(3)In the case of seepage,the infiltration of water with heat will deepen the depth of the frozen soil,and the upper limit of frozen soil is decreased in different levels.Under the condition that the boundary of temperature is set step in the ventilated pipe,the infiltration of water increases lateral inhomogeneity of the temperature of the frozen soil.(4)For embankment slope stability numerical calculation analysis: during the melt period,the slope stability coefficient decreased no matter what kind of material for embankment filling with increase of melt depth,At the same time,the stability coefficient of embankment slope decreases along with the increase of slope gradient.In the warm and Ice-rich soil,the stability of the embankment is most by 1.75 slope,when using 1: 1.25,the slope stability is the worst.(5)For ventilated embankment,two section of slope stability with similar rules is that the slope stability coefficient decreases with the increase of the melting time,and the slope stability coefficient decreases with increase of slope gradient.(6)Through analyzing the slope stability of two kinds of different section of ventilated embankment,two kinds of different failure modes that Slope angle damage and failure of the slope shoulder are found.the Slope angle of failure mechanism is: the warm and Ice-rich soil strength is not enough to bear the upper transfer load,and the warm and Ice-rich soil has strong ability of deformation and low shear strength,therefore the slope angle is failure until the sliding surface runs through the whole embankment by pushing the formation of soil slope uplift in the corner.The failure of the slope shoulder is due to the decrease of the soil strength,the mirror effect of the freezing thawing interface and effect of moisture of the melting zones.and the failure of the slope under the action of the load.