早龄期水泥基灌浆料受压统计损伤本构模型

Statistical damage constitutive model of early-age cementitious grout under compression

摘要:

为研究早龄期水泥基灌浆料受压本构行为,对不同龄期（1 d≤t≤28 d）的水泥基灌浆料和同强度的普通混凝土开展单轴受压全过程试验,分析龄期对水泥基灌浆料、同强度混凝土单轴受压应力-应变曲线特征参数的影响,并将水泥基灌浆料的单轴受压应力-应变曲线特征参数与同强度混凝土进行对比。结果表明:随着龄期的增长,试件峰值应力、峰值应变、极限应变、弹性模量、峰值割线模量、应变延性系数和能量耗散系数均有不同程度的增大；水泥基灌浆料试件峰值应力、峰值应变、极限应变、应变延性系数和能量耗散系数均大于同强度混凝土,但试件弹性模量、峰值割线模量均小于同强度混凝土。结合水泥基灌浆料自身特征,基于现有模型建立了修正的分段式水泥基灌浆料受压本构模型,并基于统计损伤理论推导给出了水泥基灌浆料受压统计损伤本构模型。建议的受压本构模型计算结果与试验结果吻合较好,可以较为准确地描述早龄期水泥基灌浆料在单轴受压作用下的受力变形特点。

Abstract:

Uniaxial compression tests on cementitious grout specimens and ordinary concrete specimens with same strength at different ages (1 d≤t≤28 d) were carried out to investigate the compressive constitutive behavior of early-age cementitious grout. The effects of age on the characteristic parameters of stress-strain curves of cementitious grout specimens and concrete specimens under uniaxial compression were analyzed. The characteristic parameters of cementitious grout specimens were compared with those of concrete specimens. Results show that with the increase in specimen age, the peak stress, peak strain, ultimate strain, elastic modulus, peak secant modulus, strain ductility coefficient, and energy dissipation coefficient of the specimens gradually increased. The peak stress, peak strain, ultimate strain, strain ductility coefficient, and energy dissipation coefficient of cementitious grout specimens were greater than those of concrete specimens, while the elastic modulus and peak secant modulus were smaller. Considering the characteristics of cementitious grout, a modified segment-based compressive stress-strain model was proposed based on the existing compressive stress-strain models, and a statistical damage constitutive model was derived according to the statistical damage theory. The calculated results of the proposed models were in good agreement with the experimental results, which indicates that the proposed models can accurately describe the deformation characteristics of early-age cementitious grout under compression.