高温焙烧后黏土孔隙与力学特征研究

 为研究温度作用后黏土孔隙与力学参数变化规律，以不同温度作用后黏土为研究对象，主要采用压汞法、单轴压缩试验，着重分析其孔隙度、渗透率、体积分维数、单轴抗压强度、普氏系数变化规律。得到以下结论：试样中孔隙开放孔较多，孔隙连通性较好，孔隙主要以500 nm～1 000 nm为主；试验温度范围内，大孔总体积随温度的升高而增大，100 ℃～650 ℃之间，微孔总体积随温度的升高而增大，650 ℃以后，随温度的升高而减小；100 ℃～700 ℃之间孔隙度随温度的升高而增大，700 ℃以后有所减小；采用Menger海绵体模型和热力学模型得到的体积分维数随温度的升高整体减小，而采用热力学方法得到的孔隙分维值更能表征试样孔隙特征；100 ℃～700 ℃之间渗透率随着温度升高而增大，700 ℃以后有所减小；100 ℃～400 ℃之间，单轴抗压强度和普氏系数基本维持不变，400 ℃～700 ℃之间，两者随温度的升高快速增大，700 ℃以后，两者随温度的升高而减小，这与试样内部矿物的转变密切相关。

STUDY ON THE PORE AND MECHANICAL CHARACTERISTICS OF HIGH-TEMPERATURE ROASTED CLAY

To study the change laws of clay pore and mechanical parameters under different temperature effect，this paper，taking the different-temperature roasted clay as the research object，mainly analyzed the law of porosity，permeability，fractal dimension of pore volume，uniaxial compressive strength and Protodyakonov scale of hardness by using the mercury injection method and uniaxial compression test. The findings were as follows：The pore in samples was dominated by the open pore，and the connection among pores was well. The main pore size ranged from 500 nm to 1 000 nm. Within the temperature range tested，the total volume of macropores increased with the temperature rising，the total volume of micropores increased between 100 ℃～650 ℃ but decreased over 650 ℃ as the temperature rose；Porosity increased between 100 ℃～700 ℃ but had a slightly decline over 700 ℃ with the increase of temperature；the fractal dimension of pore volume，by means of Menger fractal sponge and thermodynamic model，in general increased with the temperature rising，and the pore characteristics of samples could be represented better by the fractal dimension of pore volume through thermodynamics；with increasing temperature，the permeability increased when the temperature ranged from 100 ℃ to 700 ℃ and slightly decreased when the temperature exceeded 700 ℃；as the temperature rose，uniaxial compressive strength and Protodyakonov scale of hardness remained constant basically between 100 ℃～400 ℃，increased rapidly between 400 ℃～700 ℃ and decreased over 700℃，which was closely related to the transformation of minerals inside samples.