Mid-high Liquid Limit Clay Compaction Characteristics Of Lake Deposition And Rolling Control Standard Research

Region on the lower reaches of the Yellow River,the Yellow River floods in the low-lying static water deposition phase formation of the mid-high liquid limit clay,mainly concentrated in the southwest and northwestern plains of Shandong province.As subgrade filling has its rolling properties:hard to dry,drying is easy to appear "wet inside and dry outside" phenomenon; uneven distribution in the vertical direction after rolling, form " hard shell layer";after rolling soil surface is easy to crack by water loss; the compaction of soil in a certain water content,the strength significantly lower when mixing with water and so on.To explore the road with the performance of the soil after rolling and rolling control standards, this study through the field grain size composition and plasticity of soil test, compaction test, triaxial shear test, consolidation compression test and permeability test and a series of indoor experiment, analyzes the particle composition and mechanical properties of the soil.By the field test road in different water content and rolling equipment and process rolling scheme of test, determined the suitable for this kind of soil compaction machine and the rolling process.By simulating after field rolling subgrade work character of indoor test tank model test, reveals the "hard-soft double" working mechanisms of the subgrade,verified the applicable compaction control indicators To this kind of soil.By indoor, outside and model tank tests trough the analysis of the test results, the conclusion is as follows:(1)Yellow River flood area mid-high liquid limit clay,clay and silt content is high, small permeability coefficient, good water retention and named point fall on the plasticity chart at low liquid limit clay with mid-high liquid limit clay in the transition area, the characteristics of its physical and mechanical properties are different from other soil, is a special kind of middle liquid limit clay.(2)The soil mechanical properties affected by the moisture content is obvious. According to different moisture content, can be divided into three typical area:high strength and low moisture content area, near 17% moisture content is between the optimal moisture content; The stable moisture content areas have a certain strength, moisture content is increased to 20～23%; Low intensity and high moisture content, moisture content is further improve to 26-29%.(3)The soil moisture content uneven distribution during the construction, overpressure is easy to frost boiling. Through field test, the soil compaction technology is:smooth-wheel roller static pressure 1 time,Cam roller strong vibration of 3～4 times and tyre roller surface finishing 1 time.(4) The mid-high liquid limit clay, when there is a certain thickness of the upper hard shell layer, "hard-soft" double-layer subgrade has special work mechanism and performance.The upper strength higher hard shell layer undertake and diffusion for the most part external load;and high clay content,when the higher moisture contenthas the effect of "solid water and gas protection".Therefore,with appropriate saturation the subgrade has a stable performance characteristic.