Dissertation > Transportation > Road transport > Road works > Roadbed, pavement engineering > Subgrade

The Experimental Study on Long-Term Road Capability of Highway Subgrade Filled Soil

Author WuQiang
Tutor CaoXinWen
School Southwest Jiaotong University
Course Road and Railway Engineering
Keywords subgrade filler static and dynamic triaxial test dynamic modulus dynamic strength cement treated soil
CLC U416.1
Type Master's thesis
Year 2011
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China is a country with a vast territory, there is great difference in the road performance of roadbed filling in each region.Moreover,the current roadbed design codes and operation technical specification put forward control demands in strength to roadbed filling by CBR value,also they control construction quality of roadbed filling by compactness and design on pavement structure by the modulus of resilience of surface layer of roadbed.However,the above requests are the fixed value standards in construction acceptance, without considering the performance degradation slowly in the roadbed course of using. And the common test methods on modulus of resilience can not accurately determined it.So this design parameters can not really reflect the long-term performance in the actual working state of roadbed.Combined with the subproject Research on Roadbed Filling Performance Test for Long Time of western transportation construction scientific projects Research on Practical Engineering Technology of Enhancing Subgrade Durability as background, this issue carried on system test room study in this aspect. Firstly, it chose four common kinds of roadbed filling (i.e. gravel soil, sand, silt and clay), then researched the basic physical mechanical properties of pure soil above including grain composition, optimum moisture content, maximum dry density and liquid-plastic limit test. Additionally, it conducted parallel test of clay with different amounts of cement to carry out comparative analysis research. Secondly, carried on static road usage performance tests for various roadbed filling and clay with cement under different test conditions including unconfined compressive strength, CBR and static modulus of resilience test, and then analyzed the change law of static strength index with its influencing factors under different test conditions, thus building the relation between modulus of resilience and moisture content as well as degree of compaction of various filling.Thirdly, based on the research results by the previous, this issue conducted system deeply dynamic elastic modulus test on various roadbed filling by dynamic triaxial test equipment, thus getting the change law of dynamic modulus with different moistness, degrees of compaction, stress grades and lime content ratio (clay) of various roadbed filling and analyzing the relative influence level of various affecting factors as well as fitting the relation between the dynamic/static modulus and CBR of various roadbed filling.Then, it carried on static triaxial compression test as well as dynamic triaxial test research. This issue analyzed and concluded the relationship between dynamic and static strength. Further, it obtained the decay law of impending plastic dynamic strength and accumulated deformation with loading cycles of various roadbeds filling under different test conditions. Finally, concluded the development and change law of various roadbeds filling’s road usage performance index, providing reference for design and construction.

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