Stressing State Analysis of CFST Arch Supports in Deep Roadway Based on NSF Method

This paper experimentally analyzes the working behavior characteristics of five concrete-filled steel tube (CFST) arch supports in deep roadway based on the numerical shape function (NSF) method and structural stressing state theory. First, the measured strain data are expanded by the NSF method and modeled as generalized strain energy density (GSED) to characterize the stressing state of the supports. Then, one of the supports is taken as an example and the Mann-Kendall (M-K) criterion is adopted to detect the mutation characteristics of the support, which derives the new definition of structural failure load. Correspondingly, the stressing state modes as well as strain and stress fields for the support are proposed to verify their mutation characteristics. Finally, the common and different characteristics of stressing state, damage development and internal forces for different supports are also summarized. The analytical results of the supports explore a new analysis method for underground structures and the unseen knowledge provides a reference to more rational future design.

Simulation of Laboratory Tests of Steel Arch Support

The total load-bearing capacity of steel arch yielding roadways supports is among their most important characteristics. These values can be obtained in two ways: experimental measurements in a specialized laboratory or computer modelling by FEM. Experimental measurements are significantly more expensive and more time-consuming. However, for proper tuning, a computer model is very valuable and can provide the necessary verification by experiment. In the cooperating workplaces of GIG Katowice, VSB-Technical University of Ostrava and the Institute of Geonics ASCR this verification was successful. The present article discusses the conditions and results of this verification for static problems. The output is a tuned computer model, which may be used for other calculations to obtain the load-bearing capacity of other types of steel arch supports. Changes in other parameters such as the material properties of steel, size torques, friction coefficient values etc. can be determined relatively quickly by changing the properties of the investigated steel arch supports.

Nonlinear Solution of Steel Arch Supports

Steel arch supports are used widely in long workings in coal and ore mines. Their displacements are in difficult conditions often comparable with the size of the structure. Changes in the geometry of whole arch support including changes in the shape of a rod cross-section require geometric and physical nonlinear solutions. The paper is focused on methods for the geometric and physical nonlinear analyses of unyielding steel arch supports which are consisting of rolled open cross-sections. These methods are based on the knowledge of effective flexural rigidity which is defined as the function of acting internal forces. The direct stiffness method was used to solution first, but this method has some computational limitations. The modified force method was used for calculation as the second computational variant. This method can be successfully applied when the displacements are large. The results of the numerical analyses are compared with the values which have been experimentally obtained using strain-stress test of unyielding steel arch supports.

Effect of unilateral and bilateral use of laterally wedged insoles with arch supports on impact loading in medial knee osteoarthritis

Background: Increased impact loading is implicated in knee osteoarthritis development and progression. Objectives: This study examined the impact ground reaction force (GRF) peak, its loading rate, its relative timing to stance phase timing, and walking speed during unilateral and bilateral use of laterally wedged insoles with arch supports. Study design: Within-subject design. Methods: Thirty-three female patients with medial knee osteoarthritis were examined with (unilateral 6° and 11°, and bilateral 0°, 6°, and 11°) and without insole use. Results: Repeated measures MANOVA revealed that the impact force increased significantly in bilateral 11° versus unilateral 6° and without-insole conditions. The loading rate decreased significantly in unilateral 11° versus bilateral 6° insoles. The relative timing increased significantly in each of bilateral 6°, bilateral 11°, and unilateral 11° versus bilateral 0° insoles and in each of bilateral 11° and unilateral 11° versus without-insole condition. There were significant positive correlations between the walking speed and each of the force and loading rate. The Chi-square test revealed insignificant association between the insole condition and the presence of impact forces. Conclusion: Unilateral 11° insoles are capable of reducing impact loading possibly through increasing foot pronation. Walking slowly is another possible strategy to reduce loading. Clinical relevance Unilaterally applied 11° laterally wedged insoles are capable of reducing and delaying the initial impact ground reaction forces and reducing their loading rates during walking in patients with medial knee osteoarthritis, thus reducing osteoarthritis progression. Walking slowly could also be used as a strategy to reduce impact loading.