土坯力学性能及受压本构模型研究

为获取传统土坯受压应力-应变特性,确定其数学表达式,针对湿制法和干打法制作的土坯开展了单轴抗压试验和三点抗折试验。分别从抗压、抗折强度、破坏机理以及应力-应变关系等方面分析了两类土坯的力学性能。结果表明,普通砌墙砖的抗压及抗折试验方法均适用于传统土坯,干打土坯的抗压强度为湿制土坯的3倍,抗折强度为湿制土坯的1.3倍,但湿制土坯的断裂能为干打土坯的2.5倍。受压初期,干打土坯的应力-应变曲线存在因土料压密而导致的下凹段,而湿制土坯未表现出该特性。基于两类土坯单轴受压状态下的应力-应变曲线特征,提出了土坯单轴受压本构模型,该本构模型与试验数据吻合较好,可用于土坯砌体结构的数值模拟研究。

Mechanical properties and compression constitutive models of adobe

To obtain the mechanical properties and stress-strain characteristics of traditional adobe and determine the mathematical expression of its variation relationship, a series of uniaxial compression tests and three-point bending tests were performed for molded adobe and compacted adobe. The mechanical properties of the two kinds of adobe were analyzed and compared by the compressive strength, flexural strength, failure mechanism, and stress-strain relationship. The results show that the test method for compression and bending of bricks can be applied to adobe. The compressive strength and flexural strength of compacted adobe are 3 times and 1.3 times of molded adobe, respectively, but the breaking energy of molded adobe is about 2.5 times higher than that of compacted adobe. In the early stage of compression, the stress-strain curve of compacted adobe has a concave section due to compaction of earth material, while this phenomenon has not been observed in molded adobe. The uniaxial compression constitutive model was proposed according to the stress-strain characteristics. This model shows a good correlation with the experimental data and may be applied to the numerical analysis of adobe structure.