中文摘要：

为深入研究褐煤原位注热开采过程物性特征的衍变,应用高温高压实验平台,研究7 MPa三轴等压条件下,Φ50 mm×100 mm褐煤以3℃/min升温速率由室温升高到400℃过程中及恒温恒载5 h的变形特征规律。并应用显微CT、压汞、液氮吸附解吸方法综合分析褐煤不同孔径范围的孔裂隙衍化规律。研究发现：热力耦合作用下,褐煤变形过程可以划分为缓慢膨胀阶段（室温-170℃）、剧烈压缩阶段（170℃-289℃）及缓慢压缩阶段（289℃-400℃）,褐煤脆性–韧性转变临界温度为180℃。恒温恒载5 h过程中,褐煤轴向线应变终值随温度的升高先增大后减小,最大值为2.5%（200℃）,最小值为1.3%（100℃）。褐煤最大径向累积压缩应变约为19%（400℃）,最大体积累积压缩应变约为41%（400℃）。热力耦合作用下,褐煤变形对其结构衍化有重要影响。随着温度的升高,褐煤总孔隙率表现为先增大后减小,孔裂隙率极大值为21.46%（200℃）,最小孔裂隙率为7.61%（23℃）;主要孔裂隙的孔径逐渐增大。褐煤孔裂隙率衍化具有较好的分形特征,随着温度的升高,孔裂隙率的分形维数表现为先减小后增大、分形初值则先增大后减小。

英文摘要：

To investigate the deformation and structure variation of lignite under the thermal-mechanical action,experiments were performed to the lignite samples of 50 mm in diameter and 100 mm in length with the high temperature and trixial stress testing platform. The structure variation was studied with Micro-CT,mercury intrusion and liquid nitrogen adsorption methods. Several fundamental characteristics of lignite deformation were obtained when the temperature rose from 23 ℃ to 400 ℃ at a rate of 3 ℃/min under the triaxial constant stress of 7 MPa. The deformation process of lignite can be divided into three stages：a slowly swelling stage with the temperature rising from 23 ℃ to 170 ℃,a rapidly compressing stage with the temperature rising from 170 ℃to 289 ℃ and a relatively slowly compressing stage with the temperature rising from 289 ℃ to 400 ℃. The critical temperature of the brittle-ductile transition for lignite is about 180 ℃. During the constant load and temperature process,the final value of the axial strain increased firstly then decreased with the largest value of 2.5% at 200 ℃ and the smallest value of about 1.3% at 100 ℃. The largest total radial strain is about 19% and the largest total volume strain is about 41% at 400 ℃. The lignite deformation has great effect on its structure evolution. The total porosity of lignite increased firstly then decreased with the temperature rising. The largest total porosity is 21.46% at 200 ℃ while the smallest total porosity is only 7.61% at 23 ℃. The diameter of the main fissures increased with the temperature rising. The lignite porosity in the heating process has good fractal characteristics. The fractal dimension value decreased firstly then increased while the value of ln A0 increased firstly then decreased with the temperature rising.