带有橡胶垫层的混凝土接触特性试验及其内聚力模型

CHARACTERISTICS OF DIRECT SHEAR TEST FOR PLAIN CONCRETE JOINT WITH RUBBER AND ITS COHESIVE ZONE MODEL

  • 摘要: 针对带有橡胶垫层的混凝土试件,通过直剪试验研究了带有橡胶垫层的混凝土接触摩擦特性。采用PPR内聚力模型表征接触面的接触摩擦特性,对试验结果进行了模拟分析。试验结果表明:在带有橡胶垫层的混凝土接触面剪切过程中,剪切应力与剪切位移的变化过程可分为弹性、弹塑性硬化和应变软化变形阶段。当轴向应力在1.5 MPa~13 MPa范围内时,残余强度与剪切强度比在55%~65%,当轴向应力为17 MPa和21 MPa时,残余强度与剪切强度比大约分别为70%、80%。橡胶垫层在混凝土之间起到良好的缓冲作用。在轴向应力较大时,接触面的应力变形会伴有明显的软化变形阶段。利用Archard非线性幂次准则描绘了剪切峰值应力与轴向应力的关系,准则中常数km分别为0.97和0.33。PPR内聚力模型计算表明剪切应力随剪切位移变化关系曲线与试验结果基本吻合,为研究盾构管片块体间的接触摩擦作用研究提供借鉴。

     

    Abstract: The contact and friction characteristics of concrete specimens with rubber is studied by direct shear tests in conjunction with theoretical model, i.e., PPR's cohesive zone model, which was employed to describe the mechanical behaviors of the specimens under shear loading conditions. The experiment results show that the constitutive response of the shear stress-displacement in the interface can be approximately characterized by initial elasticity, elastoplastic hardening, and strain softening. When the normal pressures acted upon the concrete specimens are in the range of 1.5 MPa~13 MPa, the ratio of residual strength with respect to shear strength is about 55%~65%. When the normal pressures acted upon the concrete specimens are 17 MPa and 21 MPa, the ratio of residual strength with respect to shear strength are then about 70% and 80%, respectively. Furthermore, the rubber plays a good buffer role in the interfaces. Especially in the large normal pressure, the phenomena of significant softening and sliding are observed at the contact surface, in which the Archard nonlinear power law is used to describe the relation between peak shear stress and the normal stress in the friction contact, and the constants parameters k and m in the law are 0.97 and 0.33 respectively. Finally, the prediction by the PPR model employed in the numerical modelling is found in fair agreement with the experimental results, which is helpful to study the joint behavior of shield tunnel.

     

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