基于扰动状态概念水泥土桩-土界面强度演化规律研究

Research on the Evolution Law of Cemented Soil-Soil Interface Strength Based on the Disturbed State Concept

通过设计并制作不同养护龄期(7、14、28、35及60 d)的水泥土桩-土单元体试样,开展水泥土桩-土界面的力学性能试验,测得了各龄期下水泥土桩-土界面的剪应力-剪切位移全过程曲线,并以此建立了水泥土桩-土界面峰值抗剪强度及残余抗剪强度随龄期变化的双曲线型演化模型.同时,开展了与单元体试样同龄期的水泥土桩体材料的单轴和三轴压缩试验以及土体的三轴压缩试验,得到了水泥土桩体的单轴抗压强度和抗剪强度指标(即黏聚力c和内摩擦角φ)随养护龄期的演化规律和演化模型,且试验结果表明水泥土桩-土界面抗剪强度与水泥土桩体单轴抗压强度之间呈线性关系.最后,引入扰动状态概念理论,基于试验结果建立了水泥土桩-土界面的剪应力-剪切位移关系随试样养护龄期的演化模型,该模型计算结果与实测值吻合良好,可为水泥土类桩的荷载传递规律的理论分析和数值模拟提供可靠的计算模型.

Element-scale specimens of cemented soil piles were designed to investigate the mechanical characteristics of the cemented soil-soil interface with different curing ages(i.e.7,14,28,35 and 60 days).The complete curve of shear stress-displacement at the interface between cemented soil piles and soil was measured at different ages.Based on the element-scale test results,a hyperbolic evolution model was proposed to describe the development of interfacial peak shear strength and residual shear strength.Besides,to obtain the variation of compressive strength and shear strength indicators(i.e.cohesion,c and internal friction angle,φ)of cemented soil piles with curing age,uniaxial and triaxial compression tests of cemented soil samples under the same curing ages,as well as the triaxial compression tests of soil were carried out,respectively.The results showed that there was a linear relationship between the shear strength of the cemented soil-soil interface and the compressive strength of cemented soil.At last,the constitutive model of the cemented soil-soil interface of the specimen comprising curing age was established according to the experimental results and the disturbed state concept theory.The model fits well with the measured data,which provides a reliable calculation model for the theoretical analysis and numerical simulation in cemented soil pile engineering.