Effects of Heating Rate on the Dynamic Tensile Mechanical Properties of Coal Sandstone during Thermal Treatment

Li, Ming; Mao, Xianbiao; Pu, Hai; Chen, Yanlong; Yu, Wu; Zhang, Lianying

doi:10.1155/2017/4137805

Cited by 7 publications

(7 citation statements)

References 37 publications

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“…Additionally, new pores and cracks between the mineral particles begin to be concentrated and interlinked (Figure 9(i)-(l)). In contrast, by observation and comparison of EDS results under room temperature of L-T group, M-T group, and H-T group, a large number of cracks and pores appear inside rock after 12 H-C cycles in H-T group (Figure 9(c) and (d)); study results show that the presence of clay minerals, such as kaolinite, may lose water with hydroxyl groups and change the structure of rock after 400°C treatment [35][36][37][38].…”

Section: Microstructure Characteristic Of Rock After H-c Cyclementioning

confidence: 89%

Effect of hydrothermal coupling on energy evolution, damage, and microscopic characteristics of sandstone

Zhang

et al. 2020

High Temperature Materials and Processes

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Heat–cool (H–C) cycle is a serious natural weathering mechanism for rock engineering in temperate desert climate; meanwhile, engineering rocks usually involve responses to impact loads arising from blasting operation, mechanized construction, and seismic oscillation. Considering the universality and destructiveness of rock failure caused by H–C cycle weathering coupled with dynamic loading, split Hopkinson pressure bar tests were conducted for sandstone with various H–C cycles. Additionally, hydrothermal coupled damage (D) was defined based on variation of total import strain energy. Energy evolution, damage, and microscopic characteristics of sandstone after diffierent H–C cycles were studied. Finally, the microcosmic structure changes of sandstone after various H–C cycles are compared by means of scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) technology. Results show that decreasing rate of total import strain energy in high temperature group is significantly larger compared with that in low temperature group and moderate temperature groups. Repeated H–C cycles produce the thermal stress at the mineral boundary constantly and fracture along the boundary of the mineral particle according to the SEM and EDS results.

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Section: Microstructure Characteristic Of Rock After H-c Cyclementioning

confidence: 89%

Effect of hydrothermal coupling on energy evolution, damage, and microscopic characteristics of sandstone

Zhang

et al. 2020

High Temperature Materials and Processes

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“…Then the area of the fracture surface can be calculated by Equation (10). VOLUME XX, 2017 d S SS   (10) Based on the 'replace curve by straight line' concept in calculus, a tangent plane at the fracture surface is assumed to have the same area (dA) as dS as shown in Figure 15. Assuming the existence of the two vectors, du and dv , Equation 11is derived and Equation 12can be deduced to calculate the actual area of the fracture surface.…”

Section: ) Roughness Coefficient Methodsmentioning

confidence: 99%

“…Based on the static test method, the split Hopkinson pressure bar (SHPB) has been developed to perform dynamic indirect tensile tests on disc shaped specimens. It is found by many authors that the mechanical characteristics of rocks under dynamic tension highly depend on the strain rates of the external loading [9], [10], [11]. Besides, the mechanical characteristics of rocks under dynamic tension were indirectly measured by some authors with three-point bending tests [12], [13], [14].…”

Section: Introductionmentioning

confidence: 99%

Strain Rate Effect on the Mechanical Properties and Fracture Surface Roughness of Sandstone Subjected to Dynamic Direct Tension

et al. 2020

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Dynamic properties of rocks are extremely important in a variety of rock mechanics and rock engineering problems. The split Hopkinson tensile bar (SHTB) system is used in this paper to measure the mechanical properties of sandstone specimens under dynamic direct tension, and the full stress-strain curves of the specimens at different strain rates is obtained. The experimental results indicate that the tensile strength, the tensile modulus and the peak strain of the specimen increase almost linearly with the strain rate. The increases in the tensile strength, the tensile modulus and the peak strain reach 125 %, 37 % and 98 % respectively as the strain rate increases by 252 %. The microscopic structure characteristics of the fracture surfaces after the tensile failure of the specimens are investigated by three-dimensional scanning. The results suggest that the fracture surface roughness of the sandstone under direct tension is significantly sensitive to the strain rate. Both the roughness coefficient and the fractal dimension of the specimen increase with the strain rate. The fracture surface of the specimen changes from a relatively flat two-dimensional state to a three-dimensional state, and its relative area gradually increases. Finally, it is manifested from the aspect of energy consumption that both the energy consumed in the fracture process and the dynamic direct tensile strength enhance with the fracture surface roughness. It is believed that the investigation results can provide an important reference for the research on dynamic properties of rocks involved in experimental research and engineering practice.

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“…e stress schematic of active confining pressure state and onedimensional coupled static and dynamic loads is shown in Figure 2. SHPB equipment has been successfully used to investigate the dynamic behaviors of materials, such as rock [21], frozen soil, and concrete. In this test, a modified dynamic testing equipment is adopted [18,19], as shown in Figure 3.…”

Section: Artificial Frozen Soil Specimen Preparationmentioning

confidence: 99%

Dynamic Mechanical Properties and Failure Mode of Artificial Frozen Silty Clay Subject to One‐Dimensional Coupled Static and Dynamic Loads

Yao

et al. 2019

Advances in Civil Engineering

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The dynamic stress-strain relationship of artificial frozen silty clay under one-dimensional coupled static and dynamic loads is obtained using modified split Hopkinson pressure bar (SHPB) equipment. The variation in dynamic compressive strength, dynamic deformation modulus, energy dissipation, and failure mode of artificial frozen silty clay with axial precompressive stress ratio are studied in this research. Experimental results indicate that the dynamic stress-strain curves under uniaxial state and one-dimensional coupled static and dynamic loads can be divided into four stages, i.e., compaction stage, elastic stage, plastic stage, and failure stage. The dynamic compressive strength, first-stage deformation modulus, second-stage deformation modulus, and absorbed energy density of artificial frozen silty clay present a trend of first increase and then decrease with the increase of axial compressive stress ratio, and the axial compressive stress ratio corresponding to the peak value is 0.7 in this test. In addition, there is a very similar effect of axial precompressive stress ratio on dynamic compressive strength and second-stage deformation modulus of artificial frozen silty clay. At 0.4 axial compressive stress ratio, spall phenomenon appears at circumferential direction and center position of the frozen soil specimen has no obvious failure. Shear failure appears at 0.7 to 0.9 axial compressive stress ratio, and the larger the axial compressive stress ratio applies, the more obvious the shearing surface appears; moreover, comminution failure mode appears at 1.0 axial compressive stress ratio.

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Effects of Heating Rate on the Dynamic Tensile Mechanical Properties of Coal Sandstone during Thermal Treatment

Cited by 7 publications

References 37 publications

Effect of hydrothermal coupling on energy evolution, damage, and microscopic characteristics of sandstone

Effect of hydrothermal coupling on energy evolution, damage, and microscopic characteristics of sandstone

Strain Rate Effect on the Mechanical Properties and Fracture Surface Roughness of Sandstone Subjected to Dynamic Direct Tension

Dynamic Mechanical Properties and Failure Mode of Artificial Frozen Silty Clay Subject to One‐Dimensional Coupled Static and Dynamic Loads

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