A New Approach for Mitigating Subsidence Influences on High Tower Structures Induced by Longwall Mining Based on Foundation Grouting Reinforcement Mechanism

Abstract

ABSTRACT: This paper presents a new approach for mitigating high tower structures slope based on the foundation grouting reinforcement (FGR) mechanism. Three effects of the FGR approach were analyzed: the reinforcement provided by grouting to improve the strength of the foundation, filling gaps around foundation provided by grouting materials to compensate for the subsidence, and adjusting foundation elevation provided by controlling grouting pressure to reduce the slope of the high tower structure body. The FGR mechanism was further developed by the theoretical analysis of foundation vertical deformation under the effect of grouting, and the theoretical equation for calculating the grouting pressure based on the subsidence induced by longwall mining was derived. Finally, the systematic procedure of the FGR approach was presented, and applied to mitigate the slope of a radio signal tower located above the active panel of a Chinese coal mine. The results of this application show that: after implementing the FGR approach, the tower foundation slope decreases as face advances, and is less than its limited deformation. 1. INTRODUCTION High tower structures refer to structures with large height and relatively small cross section. Taking horizontal load (especially wind load) as the main basis for structural design (Shu et al. 2018), they can be divided into self-supporting tower structure, guyed mast structure, and lattice steel tower structure (Lee and McClure 2007), mainly including high-voltage transmission tower, radio signal tower, and communication tower, as shown in Fig.1. Particularly, in China, there are abundant recoverable coal reserves buried under high-voltage transmission lines in coal mines(Guo and Yong 2011). For examples, in Yanzhou Coal Mine, 21.89 million tons of recoverable coal reserves is under high-voltage transmission lines; the first 1000 kV high-voltage transmission line passes through Sihe Coal Mine, affecting a total coal reserves of 30.78 million tons. It is a technical and engineering problem to mining these coal reserves without affecting the high-voltage transmission lines safety.