ABSTRACT:

This paper presents an innovative bolt which has the Negative Poisson's Ratio effect (NPR bolt). The NPR bolt can absorb energy and sustain high constant resistance and large deformation. The working principle of this new type of bolt is introduced and a series of dynamic laboratory tests have been conducted to verify its large deformation resistance and high dynamic bearing capacity. The results of the dynamic tests show that the NPR bolt can withstand repeated impact, and maintain the stability of the constant value under impact load. Finally, the NPR bolt is applied for rock burst control.

1 INTRODUCTION

Bolt/Cable-supporting technology is one of effective quasi-supporting means in tunnel, which can reinforce the surrounding rock structure effectively, strengthen the roadway structural strength and improve the stability of surrounding rock significantly, and has gradually become the main measure for tunnel support all over the world (Corbett 1996). As an effective quasi-supporting way in tunnel, bolt-supporting technology, which will change the structure and strength of the surrounding rock, can significantly improve the stability of the rock mass surrounding a tunnel. In addition, with the characteristics of low cost, fast installation, low labour intensity, more utilization of tunnel section, better and safer working conditions, bolt-supporting technology will gradually become a major support way for tunnel support worldwide. It has also represented the main direction of tunnel support technology (Jiang et al. 2014). Because of the superiority of bolting technology, it has more than 50 years development history since the first use in ore, coal system in China in the 1950s. This advanced supporting technology has been widely used in mining, construction, hydropower and other engineering fields, which has become the main supporting method on geotechnical engineering.

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