孔压滞后现象及其对固结系数的影响

DELAY OF PORE PRESSURE IN OEDOMETER AND ITS EFFECT ON DETERMINATION OF COEFFICIENT OF CONSOLIDATION

从常规固结试验入手,对固结系数进行了相关的研究。利用底部可测孔压的固结仪做了常规固结试验,发现试样底部孔压出现滞后现象。孔压峰值出现的前后,沉降曲线出现第 1 次转折,孔压完全消散后,沉降曲线出现第 2 次转折。因为孔压与位移有着紧密的联系,所以孔压的滞后会影响固结曲线,进而影响固结系数的确定。因此,进行了进一步的分析,指出常规试验中侧壁摩阻力和试样的饱和度会对试样内孔压的分布产生滞后的影响。通过对底部孔压滞后现象的分析,在确定固结系数时考虑了孔压滞后效应的影响。最后对室内测定固结系数的方法进行了讨论。

From common consolidation tests, a new oedometer which can measure the pore pressure from the bottom of specimen is employed. A phenomenon is found that the pore pressure in the specimen inclines to delay. Compared curves of the pore pressure and the displacement, it can be concluded that around the appearance of the of peak value pore pressure, the displacement curve finds its first turn. When the pore pressure reaches its total dissipation, the displacement curve finds its second turn. Because the pore pressure has strong relationship with the displacement, research work is carried out to reveal the cause of the delay. With further experiments under various conditions, it can be found that the side friction and the degree of saturation have strong influences on the delay of pore pressure in the specimen. So the delay rance of pore pressure should be considered in determining the consolidation coefficient, and at last, the measuring relative methods are discussed.