Study On The Aging Characteristics Of Freeze-thaw In Alpine Clod Rock Slope

Sichuan-tibet highway(G317,G318)is located in the east edge of qinghai-tibet plateau,the area not only strong tectonic activities,most of the road is located in high altitude area.Slope of the rock body structure developed,circulation freez-thawing effect makes the rock structure surface open to penetrate,which leading to the overall instability of the rock in a period of time,affecting the safety of human activities and road operations.In this paper,subjected to cyclic freezing and thawing affect the alpine region of rock slope collapse development as the breakthrough point,by monitoring atmospheric temperature on the influence of the temperature of slope rock mass,and analyzed the relations between the cold environment and geological disasters.Rocks carried out the freeze-thaw cycle monitoring test and triaxial strength test,and combined with the theory of damage mechanics,rock freeze-thaw damage timeliness model is set up,freeze-thaw rock timeliness damage evolution rule is deduced.Next,in 3DEC simulation G317 GAN YANGGOU tunnel slope worksite after freezing and thawing cycle of rock mass slope stability,freeze-thaw cycle timeliness damage characteristics of slope is analyzed,and the characteristics of disaster chain effect.And proposed the alpine region of rock slope freeze-thaw damage prevention measures,to suppress the geological disaster alpine region,studies results of the paper are as follows:(1)Alpine region development features the collapse of the slope rock mass affected by freeze-thaw actionThrough the collection of regional geological environment data,the landslide in the alpine mountain area is analyzed statistically.Most of the disaster is related to the freeze-thaw cycle.By the monitoring of atmospheric temperature and rock mass temperature,the freeze-thaw cycle is analyzed to promote the formation of geological disasters.(2)Fracture of rock freeze-thaw strength strain characteristics and freeze-thaw cycles on damage characteristicsThrough the study of the freeze-thaw cycle of rock fracture micro strain monitoring test,found inside a freezing and thawing cycles,a crack of rock in the cold experienced the cold shrink stage,frost heave stage,the frost heave stability stage,shrink stage,spring back stage and stabilization stage.Crack produced at the end of a cycle of unrecoverable plastic deformation,and the deformation of the next cycle is on the basis of the residual deformation in a cycle,in a certain time,cracks will continue to open to the end,it makes the rock damage.Through the study of the triaxial strength test of rock,found that with the increase of number of freezing and thawing,the compressive strength and shear strength of the rock are reduced,the freezing and thawing of the rock damage.(3)Aging damage model of rock freeze-thaw cycleBased on the theory of damage mechanics,in combination with rock intensity of freezing and thawing cycle triaxial test,freeze-thaw strength of rock mass is derived for the aging damage model,through the model can analyze the rock mass in a certain time on freeze-thaw damage evolution rule,for the study of freezing and thawing the mechanical strength of the rock damage mechanism provides a feasible method.(4)Numerical simulation analysis of rock mass slope freeze-thaw cycleBased on GAN YANGGOU tunnel slope,rock slope of alpine region 3DEC numerical simulation.In this paper,the instability failure tendency and the process prediction of the rock mass of the slope affected by freeze-thaw weathering of in are studied,and the evolution trend of unstable development of rock mass affected by frozen-thaw weathering is explored,and the aging characteristics of the slope rock mass instability.(5)Suggestions on prevention and cure measures of freezing and thawing damageComparing the freezing-thawing cycle tests of rocks in the water environment and chloride solution environment,it is found that the maximum variable value of the freezing-thawing rock-like fissures under the chlorine salt solution environment is much smaller than the rock-like fissure in pure water environment.And when the temperature rebound,the shrinkage cracks will be gradually restored to the initial state,only a small residual deformation;chloride solution environment can also inhibit the strength deterioration effect of the frozen-thaw cycle,and the attenuation amplitude is less than 1/2 of the pure water environment.