Research On The Road Performance Of Natural Grit In Tibet

The resource of natural grit road material is fruitful in Tibet area , through the widespread investigation,the laboratory test and the theoretical analysis, the distribution and the characteristic of natural grit in Tibet,natural grit base asphalt pavement structure, the design method of natural grit base asphalt pavement structure and so on, which have carried on the thorough analysis and the research. Through the research of natural grit base asphalt pavement in Tibet in this project, a series of research results were obtained. The main innovation achievement includes:①Tibet district has been given, which takes climate type as the main basis Gradation composition of the representative gradation of natural grit has been studied various districts, analyzes the major project performance of the representative gradation of natural grit material.②The heavy compactionⅡ.2 standard tests have been carried on to the representative gradation of natural grit, obtain its optimum moisture content and the maximum dry density. Under the optimum moisture content and compactness 98% conditions, natural grit was molded the big test sample with D×H=308mm×290mm by static pressure, which was carried on Analysis of bearing capacity and bearing capacity-water stability, and was molded the small test sample with D×H=150mm×170 mm by static pressure, which was carried on bearing capacity-freeze-thaw stability. Research shows gritting material has the good bearing capacity,bearing capacity-water stability and freeze-thaw stability.③This project uses the LH nonlinear bearing capacity model E = ( a+bσ3 )σ1+c and The LC nonlinear bearing capacity model E = ( a+bσ30 .5)σ10.5+c to describe nonlinear bearing capacity characteristic of natural grit, proposed under different conditions nonlinear bearing capacity model through the experiments and the theoretical analysis. Through the multi-dimensional linear regression , regression equation has been established for the first time among LH and the LC nonlinear bearing capacity model parametersa,b,c of graded grit base material and the water content,fineness modulus of grit material,the 19mm aperture Pass Rate, the 4.75mm aperture Pass Rate, the 0.075mm aperture Pass Rate.④Under the nonlinear bearing capacity condition,the grit base asphalt pavement structure has been carried on structure analysis, using the structure analysis to obtain the most greatly vertical distortion and the biggest level bottom tensile stress, allowable standard axle load volume of traffic N e ( a traffic lane accumulation equivalent axis time in the design period (sequence/traffic lane)) of graded grit base asphalt pavement typical structure has been given in Tibet area. Under the nonlinear bearing capacity condition of the graded grit base,the new design method of asphalt pavement has been proposed.This project research results further promotes the natural grit in Tibet highway construction the application, the advancement road building technology, reduces the road building cost and the promotion environmental protection and so on, which have the vital significance.