Research On The Rockfall Treatment Technology Of Strongly Weathered And Super High Slope Along The River

The trend of high-class highway construction in mountainous area is more and more prominent with the further development of China.But the route selection in western mountainous areas is limited by many factors because of the unique geological conditions.So route going along the river has become a common form.The traditional concept of highway construction is mainly based on the excavation of cutting,but in the mountainous area or riverside,the emergence of high cutting slope is inevitable so that geological disasters such as perilous rocks and rockfall often happen on the slope.Therefore,it is of great socially economic benefit to improve the design level and reduce the investment cost of the slope disaster control engineering in our country by systematic study on the treatment technology of rock slope with strong weathering and high slope along the river.This paper is based on the secondary road engineering from Deqin to Shangri-La.First of all,this paper analyzes the formation of the river bank slope through the summary of the geological characteristics of the western mountainous area along the river bank slope and combining with the problems in the engineering applications.In conclusion,the formation of high slope often is one slope along the slope excavation and the rock mass is very unstable due to the remarkable weathering effect and collapses easily before and after excavating.Another conclusion is that setting up the shed-tunnel is the best choice to prevent the slope rockfall along the river in the western mountainous areas,which,is based on the summary of rockfall prevention measures,and the high frequency and big scale of rockfall hazards.Secondly,this paper introduces the existing rockfall calculation theory,combined with the existing theory.And based on the actual rockfall shed-tunnel structure,numerical simulation is carried out by ABAQUS finite element calculation software of rockfall impact shed-tunnel process.Then the study of rockfall impact mechanical power shed tunnel structure at different impact angle,impact velocity and different cushion the thickness of case provides the reference for rockfall treatment technology and practical engineering design.According to the analysis of the numerical simulation results,the following conclusions are drawn:1.The impact force at the angle of 0 degrees(normal impact)is the largest when the rockfall impacts the shed from different angles.And the maximum impact depth and impact force are much larger than the oblique impact.In the design of the actual rock drop treatment project,the normal impact should be taken as the main consideration.2.In a certain speed,with the increase of the thickness of cushion,rockfall impact depth increases,and the maximum impact force decreases.But beyond a certain thickness,the maximum impact depth and the maximum impact force will tend to be stable.3.Under the condition of low impact velocity,the change of the thickness of sand cushion has little influence on the impact force of the rock,and the sand cushion with small thickness also has a certain energy absorption effect.However,under the action of high impact velocity,the energy absorption effect of sand cushion with different thickness shows obvious difference.4.If the pure sand cushion layer is chosen,then the reasonable thickness should be between 0.9m and 1.2m.But in the actual project,if further consideration of self-respect and economy structure is needed,0.6m thick sand with a certain thickness of other buffer materials(such as foam pad,EPE,etc.)is a good choice to be optimized,which will make a shed hole structure design more reasonable.In the end,this paper introduces the design,construction and monitor of Yuren shed-tunnel in K226+330~K226+416 section of the secondary road engineering from Deqin to Shangri-La.