Experimental research on temperature variation and crack development in coalfield fire

Abstract

With the destruction of numerous coal seams around the world, coalfield fire is becoming a matter of global concern. This paper probes into the crack features of rock strata in a coalfield fire-stricken area, to answer to call for energy conservation and environmental protection. Specifically, the temperature variation was investigated through simulation experiments based on the coal seam model and rock strata model, and the crack development was qualitatively researched on the surface of coal seam and the overlying strata. The main conclusions are as follows. Comparing the temperature of measuring points on the same horizontal plane, it is concluded that the temperature of the coal seam above the heat source increased with the distance from the heat source within a certain range. The temperature diffusion was rather slow in coal and rock and the fire source movement was very time-consuming. The surface temperature variation of the overlying strata was similar to that of the fire source, indicating that the fire source could be roughly located by the surface temperature variation of the overlying strata. Meanwhile, the thermal destruction resulted from high temperature boosted the crack development in both coal seam and rock strata, and collapse occurred when the coal burned out. During the coalfield fire, the crack development was bolstered by the high temperature produced in the interaction between the crack field and the temperature field; besides, the cracks created a passage for oxygen supply, which favours the coal combustion. All in all, the coalfield fire development was enhanced by the interaction between the crack field and the temperature field.

Experimental Study on the Performance of a Novel Unidirectional Explosive Element and an Explosive Logic Network

“…As shown in Figure 2, the unidirectional explosive element (named explosive diode) is composed of a metal shell (2), sealing elements (1 and 8) at both ends of the element, the input end of the detonation signal (14, End A), a hollow rubber structure (13), sealing wax paper (4), an excitation setting (5), an explosion-proof structure (6), and the output end of the detonation signal (7,End B). The relevant parameters of the initiating equipment (End A and End B) used in the experiment mentioned in this paper are listed in Table 1.…”

“…In many countries, such as China [2,3], South Africa [4], India [5], USA [6] and Australia [7], coal fires cause major disaster during opencast working. Domestic and international research on coal fires primarily include the following aspects: the distribution and development of coal fires, the detection and monitoring of coal fires [8][9][10], the modelling of underground coal fires [11][12][13], assessments of the impact on the environment and human health [14] and fire-fighting engineering [15,16]. Due to different geological conditions in China compared to other countries, there are fewer studies regarding blasting mining in coalfield fires outside of China.…”

An Improved Composite Fly Ash Gel to Extinguish Underground Coal Fire in Close Distance Coal Seams: A Case Study

“…In India, more than 80% of coal mine fires are caused by spontaneous combustion [5]. Also, the spontaneous combustion attacks Chinese coal mines seriously [6]. Along with the continuous development of science and technology, coal spontaneous combustion prevention technology has been greatly developed.…”