A study on the impact of ultrasonic-stimulated clean fracturing fluid on the pore structure of medium to high rank coal.

The pore structure of coal plays a key role in the effectiveness of gas extraction. Conventional hydraulic fracturing techniques have limited success in modifying the pore structure using clean fracturing fluid (CFF), and the stimulating effects of ultrasonic can enhance the effectiveness of CFF in modifying coal pore structures. To research the effects of ultrasonic stimulation on the pore structure of medium to high-rank coal when using CFF, this study employed mercury intrusion porosimetry (MIP) and low-temperature nitrogen adsorption (LT-NA) methods to analyze the changes in pore structures after cooperative modification.

Failure mechanism and control technology of high-stress red shale roadway in Kaiyang phosphate mining of China.

To solve the supporting problem of high-stress red shale roadway in Kaiyang phosphate mining area, the mechanical properties and microstructure of red shale are studied. The results show that the compressive strength of the red shale is related to the bedding angle, and the strength of the 0° samples is the highest, and the strength of the 60° and 30° samples decreases gradually. With comprehensive consideration, the composite supporting method of cantilever piles and grid arch is adopted.

Experimental study on failure mode and fracture evolution characteristics of red shale in Kaiyang Phosphorus mining area.

In order to study the failure mode and fracture evolution characteristics of red shale in Kaiyang Phosphorus mining area, conventional triaxial compression mechanical tests of red shale with different bedding dip angles were carried out by using DSTD-1000 electro-hydraulic servo rock mechanics experiment system. Based on the laboratory test results, the conventional triaxial particle flow simulation of red shale samples with different bedding dip angles was carried out using discrete element PFC2D. The results show that: (1) the failure mode of red shale is controlled by bedrock when the bedding dip angle is 0° and 60° ~ 90°.

Study on the Strength and Micro Characteristics of Grouted Specimens with Different Superfine Cement Contents.

To provide the most effective comprehensive performance grouting material ratio, in this experimental investigation, a total of eight grouted specimens with two water-cement ratios (0.45:1, 0.55:1) and four different superfine cement contents (0%, 30%, 70%, 100%) were evaluated.

Precise control of versatile microstructure and properties of graphene aerogel via freezing manipulation.

A deep understanding of the shaping technique is urgently required to precisely tailor the pore structure of a graphene aerogel (GA) in order to fit versatile application backgrounds. In the present study, the microstructure and properties of GA were regulated by freeze-casting using an ice crystal template frozen from -10 °C to -196 °C. The phase field simulation method was applied to probe the microstructural evolution of the graphene-H2O system during freezing.