轻质泡沫混凝土的劈裂破坏力学行为分析
Analysis of Splitting Failure Mechanical Behavior of Lightweight Foam Concrete
Received:January 16, 2013  Revised:June 17, 2013
DOI:10.7520/1001-4888-13-004
中文关键词:  泡沫混凝土  裂纹扩展过程  应力软化曲线  断裂韧度  断裂能
英文关键词:foam concrete  crack propagation process  stress softening curve  fracture toughness  fracture energy
基金项目:国家科技支持子课题(2011BAE14B05-2),国防基础科研项目(B3120110004),四川省非金属复合与功能材料重点实验室开放基金(11ZXFK08),西南科技大学博士研究基金(09ZX7128)
Author NameAffiliation
LI Dan* 1.School of Civil Engineering and Architecture, Southwest University of Science and Technology
2.State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials of Sichuan Province, Mianyang 621010, China 
SHANG Shuai-qi School of Environment and Resources, Southwest University of Science and Technology, Mianyang 621010, China 
TAO Jun-lin School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China 
WAN Ning School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China 
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中文摘要:
      利用平台巴西圆盘加载方式和钢质压条加载方式,对两种厚度为25mm和50mm、不同密度的轻质泡沫混凝土(400~1000kg/m3)进行巴西圆盘劈裂试验,研究密度和厚度对泡沫混凝土裂纹宽度、劈裂强度、断裂韧度、断裂能的影响规律。结果表明,在橡胶垫平台巴西圆盘和钢质压条加载方式下,其劈裂断裂特征大致分为四个阶段:线性弹性段、非线性弹性段、起裂阶段、失稳阶段。同样加载率下最大裂纹宽度随着泡沫混凝土密度增加逐渐减小,劈裂拉伸强度、断裂韧度、断裂能呈幂函数形式增加。借鉴Reinhardt非线性软化曲线,对不同密度泡沫混凝土的应力软化关系进行曲线拟合,建立基于拉伸强度、断裂韧度等控制参数的应力-裂纹宽度关系三段式模型。基于试验结果,对理想多孔材料细观力学预测模型进行修正,获得泡沫混凝土孔隙率与拉伸强度的半经验公式。
英文摘要:
      Using platform Brazilian disc loading and steel bars loading, Brazilian disk splitting experiment for foam concrete specimens with two different thicknesses (t=25mm and t=50mm,respectively) and with different dry bulk densities ranging from 400kg/m3 to 1000kg/m3 were carried out to study the influence of the density and thickness on the crack width, splitting strength, fracture toughness and fracture energy. Results show that the splitting fracture can be divided into four characteristic stages: linear elastic stage, nonlinear elastic stage, crack initiation stage and instability stage. Along with the increase of dry bulk density, the splitting tensile strength, fracture toughness and fracture energy of foam concrete increase in the foam of power function, whereas the maximum crack width decreases gradually. Based on Reinhardt nonlinear softening curve, stresses softening experimental data of foam concrete with different densities was used for nonlinear curve fitting. A three-stage model relating stress and crack width is established based on control parameters such as tensile strength and fracture toughness. Based on test results, micromechanical prediction model for ideal porous materials is revised, and a semi-empirical formula relating porosity and tensile strength of foam concrete is obtained.
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