京沈高铁风积土路基弱化特性的试验研究

Experimental study on the characteristics of weakened subgrade of aeolian soil along the Beijing-Shenyang super rail

基于循环三轴试验,研究了辽西风积土在不同固结条件和施加初始静偏应力作用下刚度的循环弱化特性,提出了考虑有效固结应力、初始静偏应力、动应力水平和循环荷载作用次数的风积土刚度弱化模型。结果表明:在相同固结条件下,风积土的刚度随固结围压增大而增大;随循环次数的增加、初始静偏应力的施加和动应力比的提高,风积土的刚度衰减显著;在试验基础上提出的风积土刚度弱化模型,能够较好地反映在循环荷载作用下刚度的衰减规律。

The present paper intends to offer an experimental study on the characteristics of weakened subgrade of aeolian soil along the Beijing-Shenyang super rail. For our research purpose, we have done a series of triaxial tests on the behaviors of the aeolian soil. On the basis of our tests, we have explored the effects of consolidating the confining pressure, the consolidating ratio, the number of cycles, the stiffness of the initial static deviator and the dynamic stress ratio on the degradation of the aeolian sand soil. The results of our analysis show that under different consolidation tests, the dynamic shear mod- ulus tends to decrease apparently with the decrease of the cycle num- bers. However, it tends to decrease scarcely with the increase of such numbers. At the same time, the relationship between dynamic shear modulus and cyclic strain tends to have exponential function. Under different confining pressures, the dynamic shear modulus tends to be in good consistency with the cyclic strain after the regulation. Howev- er, under the same consolidation confining pressure and the same consolidation ratio, the maximum dynamic shear modulus of the aeo- lian soil＇s initial deviator stress is slightly higher than the considering initial deviator stress. Thus, it can be seen that the maximum dynam- ic shear modulus of the aeolian soil tends to be affected by the initial deviator stress in a slight degree. In addition, the increase of the dy- namic stress may speed up the degradation of stiffness. Therefore, based on the above research results, we have analyzed the degrada- tion characteristics under different consolidation conditions and the initial static deviator stiffness and put forward a stiffness degradation model for effective consolidation of the initial static deviator stress, the dynamic stress and the number of cycles. The stiffness degrada- tion model proposed here can be taken as the basis for better reflec- tion of the law of stiffness degradation.