Experimental Study On Saturated Over Consolidated Soft Clay Under Traffic Load

As the biggest developing country in the world, China has the most population, the GDP of China ranks only second to American in 2015, under such a large economic aggregate, the growth rate of GDP still stands first in the world, and there is a large development space in the future. Transportation infrastructure is necessary to economy and successive goverments pay attention to it, expecially in southeast coastal area of china, which is the example to the development of Chinese economy, it has a strong damand for the transportation infrastructure. There is much soft clay stratum in southeast coastal area, the soft clay stratum has the characterisitc of high water content, large compressibility and low strength, and The soft clay roadbed is easy to damage because of excessive settlement under traffic load, which affect the efficiency of traffic, reduce the driving comfort and increase the difficulty of operation and maintenance of transportation infrastructure. In recent yeas, surcharge preloading is widely used to reinforce the soft clay roadbed to reduce the settlement under traffic load, the roadbed processed is over consolidated. In this paper,traffic load is simulated by the dynamic hollow cylinder system, which apply axial stress and shear stress at the same time, study the property of accumulated strain, pore pressure, stress-strain hysteresis curve and modulus of resilience of saturated over consolidated soft clay, supplement the theory research of saturated soft clay under traffic load, provide the basis for design of over consolidated roadbed.Comparing with the load traffic which only exit axial stress, research shows that the existence of the shear stress can make saturated over consolidated soft clay stress path changed, pore pressure and strain increased,modulus of resilience decreased under traffic load.This text study the effect of over consolidation ratio to the soft clay properity under traffic load, the results show that under the same load, the pore pressure and axial accumulated strain decrease with the increase of the over consolidation ratio, when the traffic is higher, the influence degree is weaker. Under the same load, if the over consolidation ratio is larger, the characteristic of elasticity is more obvious, the modulus of resilience is more large, and the smaller the over consolidation is, the increase of over consolidation influence more.Considering the influence of over-consolidated ratio, cyclic stress ratio CSL is put forward. The influence of CSL to the properity of saturated soft clay is studyed, it shows that the soft clay of different over consolidation ratio shows a same law when the CSL changes, pore pressure shows a trend of linear growth with the increase of CSL, axial accumulated strain shows a trend of exponential growth with the increase of CSL, modulus of resilience shows a trend of linear decrease with the increase of CSL, The prediction equations of axial accumulated strain and stable modulus of resilience of saturated over consolidated soft clay under traffic load is also put forwerd.Combined with the track of Wenzhou airport, the settlement of over consolidated roadbed under traffic load is calculated and compared with the settlement of normal consolidated roadbed,it shows that the settlement of over consolidated roadbed under traffic load decrease 50%. The papre analyse the reason of lower settlement of over consolidated roadbed, study the influence degree of over consolidated ratio to the settlement of roadbed, provide the reference for the design of over consolidated roadbed.