漳州软土直接剪切蠕变特性及蠕变参数的研究

Study on Direct Shearing Creep Characteristics of Zhangzhou Soft Clay and Creep Parameters

为了研究软土蠕变特性与蠕变参数的变化规律,对漳州软土进行不同固结压力下的直接剪切蠕变试验,并通过陈氏法处理蠕变试验数据。结果表明,漳州软土具有非线性蠕变特性,应力水平越高,非线性特征越显著。相同剪应力下,剪切模量G的最大值与稳定值随固结压力的增大而增大;相同固结压力下,剪切模量G的最大值与稳定值随剪应力的增大而减小。瞬时剪切模量G0与长期剪切模量G∞关系可通过G0=a t-b+G∞来确定。粘滞系数随剪应力的增大达到峰值,固结压力越大峰值体现越明显,峰值对应的剪应力也越大,这主要是微观结构随剪应力增大逐渐破损所引起的。得到漳州软土的C∞=6.71 kPa,φ∞=9.66°。剪切模量系数K=(0.424～0.56),长期强度与瞬时强度比值C∞/C=86.3%,φ∞/φ=72.4%,说明工程中需要考虑蠕变影响时,变形与强度参数应采用长期剪切模量与长期强度。研究结果对掌握软土蠕变参数变化规律,快速预测模型参数具有一定理论意义。

In order to study the creep characteristics and the creep parameter change law of Zhangzhou soft clay,a direct shear creep test with different consolidation pressure was carried out,and Chen method was used to process the creep test data.The test results showed that the creep deformation of Zhangzhou soft clay was nonlinear that the stress level was higher,the nonlinear characteristic was more remarkable.The modulus of shearing G maximum value and stable value increased along with the increase of consolidation pressure under the same shearing stress,while it increased along with the decrease of shearing stress under the same consolidation pressure.The relation between instantaneous shear modulus G0 and the long-term shear modulus G∞ could be determined with G0=at-b＋G∞.Because the microscopic structure was damaged gradually along with the increase of shearing stress,the viscosity coefficient increased along with the shearing stress and achieved a peak value,and a bigger consolidation pressure made the peak value more obvious.Zhangzhou soft clay＇s C∞=6.71 kPa,φ∞=9.66°,Shear modulus coefficient K=（0.424~0.56）,long-term strength and instantaneous strength ratio C∞/ C =86.3%,φ∞/φ=72.4%.