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The roadbed is the foundation of the pavement structure , sturdy and stable roadbed can withstand vehicle loads provide an important guarantee for the road long term . The strength and stability of the roadbed is closely related with the subgrade CBR value , but some roadbed filler ( such as loess , and loess nature similar to the low liquid limit clay ) CBR values ??are often unable to meet the requirements of the specification (especially high-grade highway road bed ) , but under the premise of ensuring the quality of construction , the roadbed still has good road performance, to meet the requirements of high-grade highways , can be seen , the specification requirements of the CBR value does not apply to these roadbed filler this , it is very necessary to develop a reasonable CBR value standard for these special filler . Firstly roadbed filler strength characteristics as well as the mechanical control indicators ( shear strength , compressive modulus , unconfined compressive strength , modulus of foundation reaction CBR value ) study , analysis of the CBR value as roadbed filler the reasonableness of the mechanical control indicators ; Secondly, combined with indoor and outdoor test theoretical guidance , analysis of the mechanism of CBR test and test conditions ; addition , the use of a large number of test analysis of influencing factors of Hebei Province Heng major highway roadbed filler CBR value (particle particle size , mineral components , the degree of compaction , subgrade moisture content and soaking time ) , at the same time , the establishment of a relationship between the CBR value of the subgrade filling degree of compaction and rebound modulus ; based on the above analysis , combined with theory and CBR value of high-grade highway roadbed filler statistical results , work out the roadbed filler mechanical control standards to shorten the the CBR Test soaking time and reduce the specification of the CBR value roadbed filler mechanics control standard ; Finally, explore the CBR value of subgrade filling improved methods . The research has important reference value to the design and construction of high-grade highways .
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