Study on Nonlinear Consolidation Theory of Peat Soil
In the process of soft foundation consolidation of peaty soil,the pore ratio and permeability coefficient will gradually become smaller with the increase of consolidation time,that leads to a large error between the consolidation value of soft foundation calculated according to Terzaghi's one-dimensional consolidation theory and the measured value.Taking the lake-phase sedimentary peaty soil of Dianchi Lake as the study object,the joint consolidation-permeability test is conducted to study the rule between e-σ' and k-σ' of peaty soil,so as to obtain the models of e-lg σ' and lg k-lg σ',and these models are introduced to derive the one-dimensional nonlinear consolidation theory for peaty soil,and the analytical solutions are solved for the seepage pressure indices of Ck=1 and Ck=2 under two different conditions.According to the different Ck of the peaty soil,when Ck = 1,the analytical solution of the one-dimensional nonlinear consolidation differential equation is compared with the analytical solution of the Terzaghi one-dimensional consolidation equation and only the vertical consolidation coefficient differs,when Ck = 2,it is difficult to obtain the analytical solution of the one-dimensional nonlinear consolidation differential equation directly,and the activation function can be introduced to obtain a special solution of the nonlinear consolidation differential equation.It is found that(1)when Ck = 1,the settlement rate predicted by Terzaghi's one-dimensional consolidation theory is faster than the measured one during the consolidation of peaty soil,and the time required for the completion of consolidation is shorter than the measured one;(2)the values of the consolidation settlement predicted by the one-dimensional nonlinear consolidation theory are close to the measured ones,and the time error required for the completion of the predicted consolidation is small,and the larger the overburden load is the closer the St-t curve is to the measured one,and the results of one-dimensional nonlinear consolidation theory predicted by Terzaghi's one-dimensional nonlinear consolidation theory are closer to the measured one.The larger the overburden load,the closer the St-t curve is to the measured value,and the more accurate the prediction result of one-dimensional nonlinear consolidation theory is.The results can provide a more accurate consolidation calculation method for peaty soil soft foundation.
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