Lumír Miča

Design parameters assessment for ground anchors in tertiery fluvial clays

AbstractThe design of the bond length of an postgrouted presstressed anchor is based on presumption of bond shear stress on contact of the bond skin and surrounding soil. Statistical analysis of measured test data was performed, including Latin Hypercube Sampling technique, to specify shear stress parameter for geotechnical conditions of Neogene fluvial clays stiff to very stiff consistency. Information about anchors installed into clays was abstracted from acceptance tests records provided by TOPGEO – Czech special foundations contractor. All tested anchors were used as supports of temporary retaining structures on construction site in Olomouc, Czech Republic. Results of conducted analysis are expressed as confidence interval estimation of mean of bond shear stress parameter. This parameter is usable for future design of anchors installed into analogical geotechnical conditions. Influencing of results by technological aspects of the construction process is partially discussed too.

Calibration of an advanced material model for a shotcrete lining

Proper choice of a constitutive model is an essential part of any successful application of numerical methods in geotechnical engineering. In most cases, attention is paid to the soil constitutive model. For structural elements, such as tunnel linings, retaining structures etc. elastic constitutive models are often used. These material models however do not involve many aspects of a real structural behavior such as limited tensile and compressive strength, strain softening and time dependent behavior during service life of a construction. In the proposed paper, an application of the novel constitutive model for shotcrete (Schadlich, Schweiger, 2014) is presented. The paper is focused at the process of determination of input parameters values of this model based on performed laboratory test. Section of the primary collector network in Brno was chosen for the purpose of obtaining shotcrete lining samples.

Experimental investigation of clay-straw building finishing layer under different drying conditions

AbstractThis manuscript represents investigation of six different clay mixtures under variable drying conditions, namely: bright yellow clay (typical for Lithuania), brown clay (Lithuania Sergėnai district), mixture of different clays, white Spanish clay, clay mass which is resistant for thermal coldness (with synthetic cardigan) and Lithuanian coarse clay with granite additives. Drying process was provided imitating natural drying process and fast drying in drying oven at 110 C°. The main idea of this study – imitate clay and clay-straw buildings drying process and to determine which of used clay types had smallest volumetric and linear deformations. Volumetric and linear deformations for clay-straw buildings is one of the most important factors evaluating cracking in this type of buildings. To reach this purpose six tiles of different clay types were used. Before drying stage water content, plasticity, and liquid limits index, respectively was determined for all types of clay. All clay tiles volumetric ...