Influence of temperature on physical and mechanical properties of a sedimentary rock: Coal measure mudstone

Abstract

Determining the physical and mechanical behavior of sedimentary rocks is one of the most common challenges in deep rock mass engineering. Experiments were conducted to study the physical and mechanical properties of coal measure mudstone with scanning electron microscope, xrays diffraction and uniaxial compression testing. The results show that temperature has a significant effect on the physical and mechanical properties of coal measure mudstone. The presence of clay minerals in the evaluated mudstone contributes to the unique characteristics seen at high temperature. The mudstone experiences obvious color changes on the surface as temperature rises. This is mostly attributed to the iron-bearing clay minerals. Internal color change is caused by thermal decomposition of kerogen associated with the clay minerals. As the major clay mineral in mudstone, kaolinite undergoes significant phase changes at high temperatures, which leads to changes in mechanical properties. From 25℃ to 200℃, due to the evaporation of absorbed water from the clay minerals, the strength of the mudstone increases significantly. As the temperature continues to rise beyond this, water evaporation continues and the rock strength increases gradually from 200℃ to 400℃. When the temperature reaches 400℃, this mudstone was strengthened as a result of decomposition of the kaolinite and thermal expansion of crystalline minerals. Above 600℃, dehydration of the clay minerals ends while thermal cracking initiates gradually, which results in decreasing strength.

Analysis of Rock Mechanical Characteristics and Establishment of an Evaluation System for Coal Measures in the Longtan Formation, Guizhou Province

“…Additionally, the seepage pressure substantially impacts the failure pattern and extent of damage within coal measure rocks under the action of water seepage. − Moreover, the increase in temperature exerts a discernible effect on the coal measure rock strength, presenting an initial increase followed by a subsequent decrease. Observations pertaining to the composition of the rock material and changes in the fine structure illustrate that augmented strength emanates from the thermal expansion of crystalline minerals, while the ongoing temperature rise leads to the decomposition of kaolinite and the thermal cracking of mineral grains, ultimately diminishing the rock strength. − Guizhou’s coal measure gas resources are primarily located in western Guizhou. The main coal measure is the Permian Upper Longtan Formation, characterized by thin to medium-thick coal seams.…”

Research on physical-mechanical properties and energy evolution characteristics of granite after high temperature treatment

“…Rossi et al [15] studied the weakening phenomenon of sandstone and granite after flame-jet heating, and clarified the influence of the heating rate on the formation of microcracks. Zhang et al [16] conducted SEM, XRD and uniaxial compression tests on coal measure mudstone after different high temperaturetreatments, and found that temperature has a significant effect on the physical-mechanical properties of mudstone. Luo et al [17] studied the change of Young's modulus of red sandstone after heating-cooling cycle, and analyzedthe main causes of thermal-induced damages.…”

مطالعه ی آزمایشگاهی اثر حرارت و اثر اندازه در مقاومت فشاری سنگ گرانیت

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