饱和水煌斑岩单轴压缩力学特性变化及其微观机理

Mechanical property variation under dynamic uniaxial compression and micro-mechanism of lamprophyre in saturated state

为探究煌斑岩遇水力学特性变化及其微观机理,通过单轴压缩、吸水性试验、X射线衍射(XRD)和场发射透射电子显微镜(FETEM)试验,对不同饱水时间(0,15 d和30 d)煌斑岩试样的单轴压缩力学特性、吸水性能、矿物成分含量及微观结构进行分析。研究表明:煌斑岩经15和30 d饱水后单轴抗压强度由自然状态的121.56 MPa分别降低到80.85 MPa和70.34 MPa,不同状态试样全应力应变曲线特征变化明显;吸水饱和过程中煌斑岩吸水率随时间变化符合指数分布规律;煌斑岩矿物集合体中的矿物颗粒与水作用,发生矿物溶蚀和次生,颗粒间连结逐渐破坏,促使水分子进入层状颗粒之间并与层间矿物颗粒发生反应,进而产生大量微孔隙和局部应力集中,导致起骨架作用的矿物集合体发生层状剥落,煌斑岩内部结构体系因此发生破坏,使煌斑岩力学特性发生改变,产生软化现象。可见,矿物集合体的结构破坏是煌斑岩遇水前后力学特性改变并产生软化的根本原因,而集合体结构的破坏和矿物颗粒与水发生的反应密切相关。

In order to understand the softening characteristics and micro-mechanism of lamprophyre in water, the uniaxial compression experiments, water absorption test, X-ray diffraction and scanning electron microscope analysis were conducted ,which reveals the mechanical characteristics, water-absorption capability, mineral composition and microstructures of lamprophyre at different saturated states （0,15 and 30 d）. The results show that comparing with lampro- phyre specimen without soaking in water, the uniaxial compressive strength of that soaking in water for 15 days and 30 days decrease from 121.56 MPa to 80.85 MPa and 70.34 MPa respectively. The feature of stress-strain curve varies at different saturated states. During the water-absorptional progress of lamprophyre, the variation of water-absorption followed as the exponent distribution. Meanwhile, the micro structure of mineral aggregation and its relative content change obviously. The particles of mineral aggregates in lamprophyre involve in the reaction with water and the connection between particles will be destroyed. Thus, the water will react with the mineral particles. Due to the numerous micro-pores and the stress raisers, the mineral aggregates that play the role of skeleton will peel off. Subsequently, the inner construction of lamprophyre will microstructure mineral collection is be destroyed and its mechanical properties of it will be changed. In a word, the damaged ties. It is also the key reason of lamprophyre and hydration reaction. , which actually lead to the change ＇ s softening. There is a closed relati of lamprophyre＇ s mechanical properonship between softening phenomenon