Research On The Embankment Filling Technology And Quality Control Of Completely Decomposed Granite

Completely decomposed granite is widely distributed in southern China, crossing the completely decomposed granite area is inevitable in highway construction process. However, completely decomposed granite can not be directly used for highway embankment for the engineering characteristics of high mica content, loose structure, poor water stability, small cohesion, while the completely decomposed granite road can be taken measure with abandoning square and borrowing soil, there is a greater consideration in economic and environmental protection. Therefore, study on the basic characteristics of completely decomposed granite and treatment methods of embankment filling have important significance. In this paper, based on Liu li highway project, there is conducted on the embankment filling and quality control technology of completely decomposed granite. The main contents are as follows:(1) By investigating completely decomposed granite along the Liu li highway in detail, the distribution of completely decomposed granite is identified. There are a large number of physical and mechanical properties test to the soil samples of completely decomposed granite road, engineering properties of the road are summed up, which mainly has for poor grading, loose, low intensity, they are only suitable for the filling construction of embankment 93. Cement and lime are respectively used in the improved test of completely decomposed granite filler, basic physical improvements and changes in mechanical properties were analyzed by fully considering the economic and other aspects of mixing uniformity, selecting 4% of cement improved soil and 7% of lime improved soil is applied to the actual construction.(2) Combined with on-site compaction test, the main factors affecting compaction are analyzed. Meanwhile, based on comparative analysis of the compaction effect under different water content, thickness of uncompacted layer and strong vibration times, it shows that achieving the best compaction effect should use thickness of uncompacted layer about 30cm and reasonable rolling case combination, which is one times of light wheel hydrostatic+ two times of weak vibration+ three to five times of light wheel intensity vibration+ one times hydrostatic. The use principle of completely decomposed granite under high water content is proposed. Non-linear regression equation of the strong vibration times, filler water content and thickness of uncompacted layer is acquired by formula fitting for rolling data, which is N= 3.723w2.184h-1.363K24.538,it can be used in construction control, reducing project cost and construction period.(3) According to the actual situation of completely decomposed granite along the Liu li highway, three treatment programs about improvement and replacement of cement, lime in 94, 96 area are proposed, Feasible solutions are acquired by feasibility analysis on the degree of compaction and deflection measured from on-site compaction tests. Meanwhile, factors effecting feasible solutions are pros-cons analyzed, there is an optimal selection on treatment programs based on grey incidence decision and applying treatment program which maximum contract segment correlation to practical engineering.