高温后花岗岩力学性质变化及结构效应研究

Effect of High Temperatures on the Mechanical Characteristics and Crystal Structure of Granite

为了研究高温作用下岩石力学性质的变化与结构晶体学性质变化的相关性,利用MTS815电液伺服材料试验系统,研究了花岗岩在常温至1300℃高温作用下的应力-应变全过程特性,基于日本理学D/Max-3B型X射线衍射仪和晶体学理论,分析了花岗岩经不同温度加热处理产物的物相特征,并将力学实验结果和衍射实验结果进行了对比分析.结果表明:在800℃之前,花岗岩力学性质变化规律不明显,衍射信息没有明显变化;超过800℃,岩样强度迅速劣化,样品衍射强度降低、衍射角度变宽,结构发生脆塑性转变的相变行为;在1200℃,花岗岩基本失去了承载能力,结晶状态变差,结构发生了化学反应.表明岩石组份改变以及结晶态相变是导致高温下岩石力学性质突变的重要原因.

This study addresses the relationship between the mechanical characteristics and the crystallographic structpre of the rock as a function of temperature. The stress-strain behavior of granite was measured at temperatures from room temperature to 1 300 ℃, using an MTS815 hydraulic-pressure servo testing system. X-ray powder diffraction patterns of heated granite samples were obtained using a D/Max-3B diffractometer and crystallographry theory. The results of the mechanical and crystallographic experiments are compared. Mechanical and crystalline properties appear unchanged below 800 ℃. Above this temperature the strength decreases and the diffraction pattern becomes broader. This indicates a phase transformation leading to a change from brittle to ductile mechanical properties. At 1 200 ℃ the granite has lost most its load bearing capacity and the crystal structure has become disordered： This indicates a chemical reaction has occurred. These results show that the sudden change in rock mechanical properties at high temperatures are caused, in part, by a change in the composition and crystalline state of the rock.