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1. In studying the mechanism of emergence of pendulum-type waves (/z-waves), the authors [1] revealed the effect of friction "disappearance" between the interacting blocks from geomaterials at definite energy levels of the pulse effect on the models of block media. The disappearance of friction is observed in the directions orthogonal to the line of action of the external pulse. In this connection, several problems concerning the mechanical conditions and manifestation of the effect of anomalously low friction in block media arise.Here we confine our analysis to the following problems:(1) Finding the link between the transverse displacements of blocks from geomaterials in two-sided hindered conditions when the vertical pulse acts on the block system and the horizontal pulse (or the force) acts on the working block;(2) the effect of the time interval of delay between the horizontal and vertical pulse effects on the character of transverse displacements of the working blocks.2. To solve the above problems, a number of experiments were performed by the method of physical modeling. The experiments were carried out on two models. (Fig. 1). In this scheme, a node 12 is the node of specification of the static horizontal action. A platform 8 with a dynamometer 9 is fastened rigidly to block IV by means of screws 11. In block III, there is a screw which is connected to the dynamometer by a regulator of action 10. This regulator creates the necessary horizontal action for block III relative to blocks II and IV. Together with block III, a stop 7 on the platform serves to prevent motion of block II. At the point A of block I, at the center a hardened screw, which is the "point" of vertical pulse excitation, is placed. The role of the vertical pulse action is played by a hardened hammer head 2 of weight 82.71 g. To specify different levels of energy action on the block system, the hammer head was dropped from different heights relative to the point A of block I. The fraction of the kinetic energy transmitted from the Mining Institute, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090.

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