Numerical calculations of shield support stress based on laboratory test results

This article presents the results and analyses of numerical calculations and laboratory tests performed on a two-legged shield support. The shield was placed on a special device (hydraulic cushion) that can simulate the ground with different load-bearing capacities. Applying the hydraulic cushion allows for laboratory testing of the shield for various base support configurations. Over 60 laboratory tests of the shield were conducted for different patterns of loading in accordance with the PN-EN standard 1804-1+A1. To reproduce the results of the laboratory tests, a 3D numerical model of the shield placed on the hydraulic cushion was developed. Numerical calculations were performed using the finite element method (FEM). To simulate the performance of the hydraulic cushion, SPRING-type elements of adjustable yield capacity were applied, which enabled a highly accurate reproduction of the results of the laboratory tests. The laboratory tests and numerical calculations showed that the type of base support influences the stress distribution in the shield. When the entire base was supported with all the active hydraulic cylinders, the stress values in the base decreased by 32% compared with the stress when the base was supported according to the PN-EN standard 1804-1:2004 (with only the outermost cylinders active). Moreover, a comparison of the results obtained for the different types of base supports indicated that when the base was supported over its entire length, the load on the ground at the front part of the base was reduced by approximately 45%. The numerical calculation method presented here can be useful for designing a shield support for specific geo-mining conditions. (C) 2015 Elsevier Ltd. All rights reserved.