加重微粒混凝土力学性能及应力-应变本构关系研究

Mechanical property and strain-stress constitutive relationship of weighted micro-concrete

针对模型试验用微粒混凝土未充分考虑质量密度相似条件的问题,提出了在基础配合比(大理石粉∶水泥∶重晶石砂∶水=1∶1∶16∶1.6)的基础上,用铁砂和铅丸等质量替代骨料(10%、20%、30%)的加重微粒混凝土配合比设计试验方案,研究其力学性能以及应力-应变本构关系。结果表明:各替代组表观密度均在3000 kg/m3以上,表观密度提升效果明显。两替代组的28 d抗压强度均低于11 MPa,弹性模量在1.11×10^(4)~1.72×10^(4)MPa之间,符合低抗压强度、低弹性模量的相似要求。两替代组的破坏形态以及应力应变全曲线形状与普通混凝土相似,并对比分析两替代组的峰值应力与峰值应变随替代组的变化规律。建立了适用加重微粒混凝土的分段式本构方程以及损伤本构方程,两种方程的预测结果与试验数据具有较好的一致性。试验结果满足模型试验的相似要求,并通过本构关系的研究有利于了解原型混凝土的力学性能与破坏机理,为相关试验人员提供参考和借鉴。

Considering their similar mass densities,an attempt was made to optimize the mix design of weighted micro-concrete that used basic mix ratio(marble powder∶cement∶barite sand∶water=0.5∶0.5∶8∶0.8)by substituting iron sands(10%,20%,30%),lead pellets(10%,20%,30%)for the aggregates(by mass)to form specimens for model tests.Then studied their mechanical properties and stress-strain constitutive relationship.The test results showed that the apparent density of each substitution group was above 3000 kg/m3,and the apparent density enhancement effect was obvious.The 28 d compressive strength of the two groups was both lower than 11 MPa,and the elastic modulus was between 1.11×10^(4)~1.72×10^(4) MPa,which met the similar requirements of low strength and low elastic modulus.The failure patterns and the shape of the full stress-strain curve of the two substitution groups were similar to those of ordinary concrete,and the various patterns of peak stress and peak strain with the alternative groups were compared and analyzed.The dimensionless stress-strain curves of the two groups were fitted with good results.The test results met the similar requirements of high density,low strength,and low elastic modulus of micro-concrete for model testing.And through the study of constitutive equations,it was helpful to understand the mechanical properties and failure mechanism of prototype concrete,providing reference and help for relevant experimenters.