试件瞬间卸载动力响应试验及突变理论研究

Study on dynamic response test and catastrophe theory of specimens under instantaneous unloading

为了研究煤岩体在瞬间卸载下的动力响应,采用相似材料制成立方体试件,利用自行设计的试验装置开展瞬间卸载试验研究,并通过试验和突变理论对试件变形和破坏机理进行分析。结果表明:试件瞬间卸载是一个复杂的非线性过程,在一定围压条件下卸载,试件会突然破坏;低应力状态下,竖向应力与横向应力有一定线性关系,竖向应力越大,试件破坏越严重,非线性特征越明显;针对不同加载级试件内部积聚的能量不同,试件会发生不同程度的破坏,且试件瞬间卸载破坏的竖向临界应力为12.6 MPa;由于试验过程具有非线性、非连续的特征,运用突变理论对试验机理进行分析,得出其破坏的竖向临界应力,约为13.27 MPa,高于该值时将出现较强破坏现象,其结果与瞬间卸载试验结果相比较为吻合。

In order to study the dynamic response of coal and rock mass under instantaneous unloading,cube specimens made of similar materials were used in this paper,and the experimental device designed and processed by ourselves was used to carry out instantaneous unloading test,and the deformation and failure mechanism of the specimens were analyzed through test and mutation theory.The results showed that the instantaneous unloading of the specimen was a complicated nonlinear process.Under certain confining pressure,the specimen would break suddenly.Under the condition of low stress,the vertical stress had a certain linear relationship with the transverse stress.According to the different accumulations of energy in the specimens of different loading stages,the specimens would be damaged to different degrees,and the vertical critical stress of instantaneous unloading failure of the specimens was 12.6 MPa.Due to the nonlinear and discontinuous characteristics of the test process,the experiment mechanism was analyzed by using the catastrophe theory,and it was concluded that the vertical critical stress of the failure was about 13.27 MPa,and stronger failure would occur when the value was higher than that.The results were in good agreement with the results of the instantaneous unloading test.