Study On Temperature Effect Of Shallow Rock Mass In Alpine Area

Wen-ma highway,Ya-kanghighway and G318(from Kangding to Zhubalong section),G317(from Maerkang to Dege section)is the vital traffic road to Tibet and Qinghai area.There arecomplex geological environment and intense tectonic activity in this region.These roads go through high mountains,canyons,plateaus,basins and other geomorphic patterns.Strong frost weathering caused a lot of geological disasters along the roads.the main diseases in the study area,surface cracking and spalling weakens the physical and mechanical properties of rock mass,if the surface rock spalling eventually lead to slope instability.Alpine mountain shallow temperature effect of rock mass is an important content of "high altitude and high intensity deep canyon area of high steep slope geological hazards research" project,the main research results are as follows:(1)Through the collection and analysis of the study area along highway 17 meteorological station temperature data,the temperature and altitude,longitude and latitude factors such as regression analysis,mean temperature,minimum temperature,average temperature of less than 0 DEG C altitude days and correlation coefficient were above 0.85,there is a certain relationship with latitude longitude.The effect can be neglected.It is concluded that the elevation of the study area is 100 m,and the annual average temperature is about 0.579~0.613.The lower bound of height,the study area of slope freeze-thaw effect by empirical formula 1840-1906 m,and in this altitude range Lixian County temperature were analyzed with the formula.The northern Sichuan Tibet highway reconstruction engineering exploration data recorded on the frozen depth data,analysis of factors affecting the effect of deep frozen zone,respectively,altitude,latitude and longitude,topography,vegetation,soil characteristics,snow thickness and water content,the altitude for the decisive influence of terrain slope on the slope of the frozen depth has great influence.(2)Through the analysis of the shallow rock mass measured temperature data of the study area,found in shallow rock temperature field is in the scope of the cross state heat conduction,respectively 10-30 cm,determine the shallow rock temperature stress concentration zone,Luding bridge as the 0-5cm area,Zhegushan tunnel exit to the 0-10 cm area.The diurnal variation of temperate zone of the two monitoring points is divided,and the diurnal variation of the temperate zone thickness of the Luding bridge is 30 cm,and the diurnal variation of the temperature at the outlet of the partridge mountain tunnel is 50 cm.Based on the solution of the differential equation of heat conduction in shallow rock mass,the analytical solution equation and the numerical solution equation.By using Matlab software,the numerical solution program is compiled to solve the shallow temperature field of the partridge mountain.The results are in good agreement with the measured data.(3)In the dry and saturated rock samples by freeze-thaw cycle test of different cycles,analysis of phyllite,sandstone and granite in different cycles after the shape,velocity and quality variation of specimens before and after freeze-thaw and no rupture phenomenon obviously,only shows that the rust phyllite samples.The rust appeared along the original cracks,and the particles on both sides of the cracks appeared slight spalling.Local granite block.The quality of the changes caused by freezing and thawing phyllite,sandstone are very small,and partially saturated granite block falling,quality changes.The uniaxial compressive strength of rock samples with different water content increases with the increase of freeze-thaw cycles.The strength of linear attenuation of phyllite.According to the initial specimen strength and strength analysis of freezing thawing cycles to calculate the strength loss rate,the result shows: with the increase of the number of freeze-thaw cycles,the specimen uniaxial compressive strength loss rate showed an increasing trend,and experience the same number of freeze-thaw cycles,the attenuation of the attenuation of saturated rock specimens was greater than that of dry sample.(4)Get through the temperature characteristics of rock mass of rock mass under high and low temperature thermal coupling is considered: the effect of temperature field on the rock to low temperature and high temperature are analyzed,the main consideration of the rock itself thermal stress,temperature should be mainly considered the phase transition of frost heave force.The numerical simulation of temperature field distribution using Flac3 D is more suitable for the field test results.With the increase of freezing temperature,the stress,strain and displacement of rock mass increase with the increase of freezing temperature.When the slope is subjected to a freeze-thaw cycle of 12 h 12h,the stress,strain and displacement of the rock mass are greater than that of the 72 h,which reflects the influence of freeze-thaw cycles on the shallow rock mass.The innovation of this paper is mainly reflected in:(1)In the research area of two typical regions(different lithology and elevation)monitoring of shallow rock temperature field,the complete data for these areas of rock shallow temperature of a weather,the data base for the research work in the area of shallow rock temperature field in the future.For the first time on the monitoring of regional atmospheric and shallow rock temperature variation analysis,the thermal physical parameters of the test,is established in Sichuan shallow rock temperature distribution formula,and to solve the equation by using Matlab software.(2)Study on slope by first freezing thawing and thermal stress coupling,using Flac3 D software,the coupling at low temperature is divided into 12 h,36h,72 h three time steps,reveals the essence of the freezing and freeze thaw weathering shallow rock thermodynamics.