Study On The Standards Of Subgrade Filler Of Hengda Highway

Sub-grade which is solid and stable is the basis for the pavement structure that can withstand traffic loads for the road and provides an important long-term guarantee. However, the strength and stability of Sub-grade has the closely related with CBR value of Sub-grade Filling, but the CBR value of some Sub-grade Filling(such as loess, low liquid limit clay with the loess properties etc.) are often unable to meet the Standard(especially the road bed of the highway), However, the premise of ensuring the quality of construction, the Sub-grade still has a good road performance and can meet the application requirements of highway. It can be seen that the Standard for CBR value requirement of Sub-grade Filling does not apply to the Sub-grade Filling, Therefore, it is necessary for these special filling to establish a reasonable standard of CBR value.Based on the strength properties and the contrast among various mechanical control indexes(shear strength, constrained modulus, unconfined compression strength,foundation modulus California Bearing Ratio etc.) of Sub-grade Filling, the paper firstly analysises CBR as the control index is reasonable and feasible; Secondly, through the the indoor and outdoor experimental and theoretical analysis, we analyzed the mechanism and conditions of CBR test. In addition, we used a lot of test to analyze value of the factors (particle size, mineral composition, degree of compaction, moisture content of Sub-grade, Soaking time etc.) of the Sub-grade Filling CBR. Furthermore, we established the relationship among CBR and degree of compaction and modulus of resilience of Sub-grade Filling. Based on the above study and analyze, it is combined with the theoretical instruction and on the statistical of CBR value of the highway Sub-grade Filling,we work out mechanical control of standard 1 of Sub-grade Filling which is shorten the soaking time of the CBR test and mechanical control of standard 2 of Sub-grade Filling which is reduced the CBR value of the Standard; Finally, we have a discussion of the methods to improve the CBR value of the Sub-grade Filling.