高温三轴应力下无烟煤、气煤煤体渗透特性的试验研究

EXPERIMENTAL STUDY OF PERMEABILITY OF ANTHRACITE AND GAS COAL MASSES UNDER HIGH TEMPERATURE AND TRIAXIAL STRESS

利用自主研制的600℃20MN伺服控制高温高压岩体三轴试验机系统,分别研究大尺寸(φ200mm×400mm)晋城无烟煤和兴隆庄气煤试样在恒定500m原岩应力(侧压系数1.2)条件下不同温度时渗透特性的演化规律。结果表明:(1)在室温～300℃中低温段,煤体渗透率随温度的变化存在一个阈值温度。当温度达到阈值温度时,渗透率降至最低值。(2)在300℃～600℃高温段,煤体渗透率随温度的变化存在一个峰值温度,峰值温度处渗透率为该温度段内的最大值。(3)煤体渗透率随温度的变化呈现阶段性:室温至阈值温度为第一阶段,渗透率随温度的增加而降低;阈值温度至峰值温度为第二阶段,渗透率随温度的升高而增加;高于峰值温度后,渗透率随温度的增加而降低。(4)渗透率随温度变化的阈值温度和峰值温度与煤阶有关。无烟煤渗透率的阈值温度是150℃～200℃,峰值温度为450℃～500℃,而气煤渗透率的阈值温度为200℃～250℃。

Utilizing the 600 ℃ 20 MN servo-controlled rock triaxial testing machine with high temperature and high pressure developed by the authors,the research of permeability of anthracite from Jincheng and gas coal from Xinglongzhuang coal mine with 400 mm long and 200 mm in diameter is carried out under in-situ stress with depth of 500 m and different temperatures,considering coefficient of horizontal pressure 1.2.The research results indicate that：（1） A critical temperature is found when the permeability of samples experienced changes with temperature from room temperature（RT） to 300 ℃,evidencing that the permeability of coal samples reaches the minimum value at this temperature stage.（2） A peak temperature is also found from 300 ℃ to 600 ℃,and the permeability at this temperature point reaches the maximum value at temperature over 300 ℃.（3） The process of coal samples＇ permeability changing can be divided into three stages by the critical temperature and peak temperature from RT to 600 ℃.The permeability decreased from RT to the critical temperature;it increases between the critical temperature and the peak temperature;above the peak temperature,it decreases as well.（4） The critical temperature and the peak temperature of permeability are related with coal rank.The critical temperature of anthracite is from 150 ℃ to 200 ℃ and the peak temperature is between 450 ℃ and 500 ℃;the range from 200 ℃ to 250 ℃ is the critical temperature of gas coal and the peak temperature does not emerge with the experimental temperature changing from RT to 400 ℃.