Experimental and Numerical Simulation Research on Controllable Shock Wave-Induced Shale Fracturing under Repeated Action.

Low permeability is a key geological factor constraining the development of shale gas, and reservoir modification to improve its permeability is a prerequisite. Controlled shock wave fracturing can induce the formation of complex fractures in reservoirs and is expected to become an important means of reservoir modification. However, the mechanism of controlled shock wave fracturing in shale and the geological engineering control factors are unclear.

The chemical damage of sandstone after sulfuric acid-rock reactions with different duration times and its influence on the impact mechanical behaviour.

The low-permeability characteristic of sandstone-type uranium deposits has become the key geological bottleneck during the in-situ leaching mining, seriously restricting the development and utilization of uranium resources in China. At present, the blasting-enhanced permeability (BEP) and acidizing-enhanced permeability (AEP) are confirmed to be mainstream approaches to enhance the reservoir permeability of low-permeability sandstone-type uranium deposit (LPSUD). To clarify the synergistic effect of BEP and AEP, the acid-rock reaction and dynamic impact experiments were conducted, aiming to study the effect of chemical reactions on pore structure, dynamic mechanical properties and failure pattern of sandstone.

Risk factors for non-fusion segment disease after anterior cervical spondylosis surgery: a retrospective study with long-term follow-up of 171 patients.

Background: The purpose of this study was to investigate the incidence and causes of non-fusion segment disease (NFSD), both adjacent and non-adjacent to a fused segment, after anterior cervical arthrodesis.

Methods: This is a single-center study. Between January 1998 and January 2011, two surgeons' 171 patients who had an anterior cervical decompression and fusion were followed clinically for more than 5 years.

Abrasion of yardangs.

A model for the collision between a sand grain and a body of yardang material is established by using the principles of classical mechanics. A new nondimensional parameter, the "abrasion number" A(n), is derived from the model. The volume removed per impact for different targets is proportional to A(n) approximately.