热处理后花岗岩纳米压痕试验研究

Nanoindentation tests on granite after heat treatment

随着温度的升高,花岗岩宏观力学参数往往经历略升高、小幅降低、大幅降低几个阶段。利用纳米压痕测试仪器,对热处理后的花岗岩中主要矿物成分进行纳米压痕试验,揭示花岗岩宏观力学参数随温度演化的微观机理,(1)温度在300℃以内微观结构没有显著变化,基本上没有微裂纹产生,在300~500℃之间时岩体内部开始产生微裂隙,温度超过500℃时岩体内部产生大量微裂隙,并逐渐扩展增大;(2)石英在300℃以内弹性模量和硬度略有增加,超过300℃弹性模量和硬度开始下降。超过500℃晶体结构发生?相到?相转变,弹性模量和硬度急剧下降,长石在400~500℃之间时,弹性模量和硬度开始下降,超过800℃弹性模量和硬度急剧下降,云母在800℃以内弹性模量和硬度有所增加;超过800℃时弹性模量和硬度开始下降;(3)花岗岩宏观力学性能与主要矿物成分的力学性能和微观结构均相关,室温~300℃范围内主要受到前者控制,300~500℃范围内时受到两者联合控制,超过500℃后主要受到后者控制。研究结果可为研究花岗岩和其他岩石的温度效应提供实验数据和理论支持。

With the increase of temperature, macroscopic mechanical parameters of granite often experience a slight increase, a slight decrease, a substantial reduction in several stages. The nanoindentation test is carried out on the main mineral components of the heat treated granite to reveal the microscopic mechanism of the evolution of the macroscopic mechanical parameters of the granite with temperature.(1) The microstructure does not change significantly under the temperature of 300 ℃; and no microcracks are found. At the temperature between 300 ℃ and 500 ℃, microcracks begin to occur in the interior of the rock mass; when the temperature exceed 500 ℃, a large number of microcracks are generated in the rock mass and gradually expand and increase.(2) The elastic modulus and hardness of quartz increased slightly at 300 ℃. When the temperature exceeds 300 ℃, the elastic modulus and hardness begin to decrease. When the temperature exceeds 500 ℃, the crystal structure changes from ? phase to ? phase; 400-500 ℃, the elastic modulus and hardness begin to decline. When the temperature exceeds 800 ℃, the elastic modulus and hardness drop sharply, for mica, the elastic modulus and hardness increase within 800 ℃, above 800 ℃, the modulus of elasticity and hardness decrease sharply.(3) The macroscopic mechanical properties of granite are related to the mechanical properties and microstructure of the main mineral components; it is mainly controlled by the former in the range of room temperature to 300 ℃ and controlled by the combination in the range of 300-500 ℃. When it exceeds 500 ℃, it is mainly controlled by the latter. The related research results can provide experimental data and theoretical support for studying the temperature effect of granite and other rocks.