Geotechnical investigations of the experimental blast-fill dam on the Burlykiya River

Abstract

To determine the design characteristics of the Kambaraty dam from the results of a model explosion it was necessary to establish the degree of similarity of blast-fill dams of different scales.It is known from similitude theory [I] that the equality of any two corresponding criteria is a sufficient and necessary condition of similarity of two phenomena or structures.Such criteria include the parameters of the system (in the case being considered these are the dimensions of the dam, blast energy, drop height of the rock, block character of the rock mass, indices of the physical and mechanical properties of the mass, etc.) and the parameters of the process (particle size of the material in the dam, deformation and strength properties, etc.).The total number of parameters of the system when modeling an explosion is greater than the main measurement parameters, and therefore it is impossible to realize the simplest case of theoretical similitude when similarity is fulfilled automatically, regardless of the absolute dimensions of the structures [2]. Hence it follows that in the case of exact mechanical similarity of blast-fill dams the scales of all main parameters should be related with the geometric scale.As a result it is necessary to model body forces (including the density and inertial forces), and they should be inversely proportional to the geometric scale.It becomes clear that in principle it is impossible to realize exact similarity of blast-fill dams under natural conditions, since in reality all body forces creating and compacting such dams are directly proportional to their dimensions.Blast-fill dams can be slmilar only with respect to their expanded mechanical similarity [3]. In this case scales of forces and deformations are introduced in addition due to some distortion of similarity of displacements of individual points.To predict the particle-size distribution it is convenient to divide the entire process of creating the dam into two stages: crushing of the rock mass and formation of the dam fill.These two stages are not interrelated, since in principle it makes no difference how the rock mass was raised into the air --its subsequent compaction does not depend on this.Therefore the explosion and drop of the rock can be examined separately.It is known that two analogous engineering-geologic masses will be similar also with respect to crushability if the consumption of explosives is proportional to the cube of the linear dimensions [4,5].In this case, in severely fractured rock masses any slight deviation from this proportionality as related to a change in the design functional relations of the charge on changing from one explosion scale to another [6] is unimportant, since crushing in this case is practically similar as a function of the parameters of the explosives [7]. This principle is confirmed by investigations of the results of blasting granites at the Medeo dam and in the Toruaigyr area. With the same engineering-geologic properties of the masses the granulometric compositions of the fills are q...

Prediction of particle-size distribution and properties of soils of a blast-filled dam

“…Thus the crushability of soil upon impact can he modeled during t = 12 sec by a static increasing load created by a press. Similar results were obtained in [12,13].…”

“…It is seen from the scheme of the explosion that when t = tma x we have y = 0 or (1 + bvoO sin ~~ t V~ = e~t u 1 (12) Equation (12) is solved by the trial and error method.…”

“…Theoretical and experimental investigations showed that fracturing of jointed rocks occurs mainly along natural joints [3,5]. This means that on the basis of the results of measuring rock joints it is possible to predict the size distribution of soil after the first stage [12,13]. The present article is limited to investigations of the second stage --the stage of formation of the dam.…”