LI H Z, LI J H, YUAN R F, et al. Research on the bearing performance of grouted steel pipe piers and their application in gob-side entry retaining under fully mechanized top-coal caving mining[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(2):129-139.

doi:10.16186/j.cnki.1673-9787.2025030007

Received:2025/03/04

Revised:2025/07/28

Published:2026/01/28

Research on the bearing performance of grouted steel pipe piers and their application in gob-side entry retaining under fully mechanized top-coal caving mining

Li Huaizhen, Li Jiahao, Yuan Ruifu, Mu Bangbang, Xie Shuaishuai

School of Energy Science and Engineering， Henan Polytechnic University， Jiaozuo 454003， Henan， China

Abstract: Objectives The use of filling materials for roadside support in gob-side entry retaining under fully mechanized top-coal caving mining is often associated with large material transportation volumes， complicated construction processes， low early strength， and high costs. Therefore， there is a strong need to develop a high-strength， high-stiffness， lightweight， and modular roadside support structure. Methods The bearing performance of grouted steel pipe piers was investigated through theoretical analysis， laboratory experiments， numerical simulations， and engineering application. Steel pipe specimens with a length of 500 mm and a diameter of 159 mm， fabricated with different wall thicknesses and grouted with slurries of various water–cement ratios， were subjected to axial loading tests and numerical simulations to identify the key factors influencing bearing capacity and to determine reasonable design parameters. Based on structural optimization， steel pipe piers with a length of 1 200 mm and a diameter of 159 mm were manufactured and grouted with a slurry at a water–cement ratio of 0.4， followed by axial loading tests and numerical simulations. Furthermore， taking a gob-side entry retaining project in a fully mechanized top-coal caving working face as the engineering background， the bearing performance of field-used grouted steel pipe piers （length 3 000 mm， outer diameter 299 mm， wall thickness 8 mm， water-cement ratio 0.4） was analyzed using the limit equilibrium method and numerical simulations.<italic/>  Results The results indicate that a steel pipe wall thickness of 8 mm combined with a water–cement ratio of 0.4 provides an optimal ultimate bearing capacity for the grouted steel pipe piers. The axial ultimate bearing capacity of the piers applied on site exceeded 4 800 kN， which is in excellent agreement with theoretical predictions. Conclusions By optimizing the steel pipe wall thickness and slurry mix proportion， grouted steel pipe piers exhibit high bearing capacity while simplifying the construction process and reducing equipment requirements and material costs. Engineering practice demonstrates that when grouted steel pipe piers are applied for gob-side entry retaining under fully mechanized top-coal caving mining， the maximum convergence between the roof and floor is 78 cm， and the maximum convergence of the roadway ribs is 95 cm after stabilization， meeting the engineering requirements for roadway deformation control.

Key words: gob-side entry retaining; grouted steel pipe piers; bearing performance; fully mechanized top-coal caving mining; engineering application