Static Modulus of Deformation of Uncemented Layers of the Railway Substructure—Comparison of Values and Determination of Correlation Dependence According to the Test Procedure of the Slovak Railways and Deutsche Bahn A.G.

Abstract

The paper focuses on the analysis of the values of the static modulus of deformation obtained by the application of the test procedure specified in the methodology for the diagnostics of the sub-ballast layers used for German railways (DIN 18 134) and the Railways of the Slovak Republic (Regulation TS4). The purpose of the study was to determine the correlation between the measured values of the static modulus of deformation according to the above-mentioned methodologies based on a series of experimental measurements on an experimental field built at a scale of 1:1. It also aimed to develop a numerical model characterising the behaviour of the loaded environment during the experimental measurements using the finite element method, which can subsequently be used for the design of the structural composition of the sub-ballast layers. For the purpose of the experimental measurements, a sub-ballast layer of 0/31.5 mm crushed aggregate of different design thicknesses was applied to the sub-ballast layers. A polynomial dependence with a high value of the reliability coefficient can be found between the results of the static modulus of deformation obtained using the mentioned measurement methodologies during the quality inspection of the implemented construction works. This dependence is valid for the specific boundary conditions of the experimental measurements performed (subsoil of clay with gravel admixture and the sub-ballast crushed aggregate layer of 0/31.5 mm dolomitic gravel). In the future, establishing correlation dependencies for other boundary conditions and structural material compositions can be considered.

Innovative Quality Assessment of Pavement Subgrades Using the Glegg Impact Soil Tester

“…This article represents the case study of the long-term research of the authors [12], enabling the use of the innovative CIST (Clegg Impact Soil Tester) device for quality control of fine-grained soils and bulk materials in Slovakia. This device can be mainly used where the static plate load test of building constructions [7,[24][25][26] or the plate bearing test of pavements and subgrades by FWD [8,24] is not possible due to spatial, temporal, or financial reasons. Homomorphic models of clay subgrades (Figure 1) and isomorphic models of pavements with clay and clay subgrades (Figures 2 and 3) have been constructed in almost 20 years of research activities.…”

“…These are mainly clay subsoils, consolidations of weak soils, geogrid-stabilized soils, the performance of unsterilized and triaxially geogrid-stabilized sandy soils [28][29][30], and Blast-Furnace Slag [31]. Generally, CIST can be used for the quality control of fine-grained soils in the context of the current upgrading of the Slovak main railway lines, which are part of the significant European corridors AGC, AGTC, and TEN-T [25,26]. The decisive criteria for in situ measurements are the area factor FA (the possibility of using larger measuring devices) and the time factor TF (the time required to carry out The decisive criteria for in situ measurements are the area factor FA (the possibility of using larger measuring devices) and the time factor TF (the time required to carry out the measurements).…”

Experimental Monitoring of Dynamic Parameters of the Sub-Ballast Layers as a Prerequisite for a High-Quality and Sustainable Railway Line

“…The deflection caused was determined by a suitable track (load plate drop) sensor. The measurement methodology using the light dynamic load test and its possible applications is described in more detail in [27].…”