The article is focused on the medium-term negative effect of groundwater on the underground grout elements. This is the physical–mechanical effect of groundwater, which is known as erosion. We conduct a laboratory verification of the erosional resistance of grout mixtures. A new test apparatus was designed and developed, since there is no standardized method for testing at present. An erosion stability test of grout mixtures and the technical solutions of the apparatus for the test´s implementation are described. This apparatus was subsequently used for the experimental evaluation of the erosional stability of silicate grout mixtures. Grout mixtures with activated and non-activated bentonite are tested. The stabilizing effect of cellulose relative to erosion stability has been also investigated. The specimens of grout mixtures are exposed to flowing water stress for a certain period of time. The erosional stabilities of the grout mixtures are assessed on the basis of weight loss (WL) as a percentage of initial specimen weight. The lower the grout mixture weight loss, the higher its erosional stability and vice versa.

No abstract

No abstract

No abstract

Deformation process and strength of rock environment is significantly influenced by a presence of discontinuity planes. The paper deals with experimental modeling of underground structures in such a rock environment. Parametric analysis presents results from twin circular tunnels simulated in a scale model. The cases with and without zone of dislocations in between the tunnels were observed. Another variable factor studied was the distance between tunnels. The relation between model surface displacement and excavated length of the tunnel, which was monitored during the simulations, was used for mutual comparison of individual cases.