1. The form of the force characteristics of a hydraulic braking device is independent of the initial energy of the body being braked, which makes it possible to vary the striker energy not fearing deterioration of the braking device performance. 2. A braking device with a constant throttle cross section area is suboptimal in terms of loads experienced by its components. 3. A braking device with a rectangular brake characteristic (a constant-resistance brake) exhibits an essentially unstable form of the braking chracteristic. There is a danger not only in the wear and tear of the shaped element of the brake but also in leaks through constant cross section openings. In both situations there is a pressure overshoot at the end of the braking process, which is equivalent to a rigid collision of brake elements. 4. A brake with a linear relationship betwen the throttle cross section and the brake path exhibits the most stable brake characteristic of all the devices studied. The level of nonuniformity of this characteristic is well acceptable for practical purposes The form of the characteristic changes slightly as the shaped element of the brake is worn out. In addition, it is not too sensitive to a constant leak. Braking devices of this kind can be recommended for high-energy impact machines.

In the study of the physical model, we investigated the interaction of blasts generated by a system of two linear bursting charges under full-scale conditions. The mechanism of the “rejection” of gaseous blast products in the stage of acceleration of ejected soil and the mechanism of mound formation at the center of the excavation, which is associated with the characteristic features of the soil's dispersion on detonating two linear charges are ascertained. It was shown that the rate of ascent of the dome of each charge increases monotonically from the velocity of an initial single charge to the velocity value of a charge of the total energy as the charges are brought together as a result of blast interaction. Correspondingly, the width of the funnel for a total-energy charge increases monotonically as the burst rate when the charges are merged into one. Relationships between the final dimensions of the excavation formed by two linear bursting charges with varying intercharge distance are established. Also determined are the optimal distances between excavations and the intercharge distances at which a wide excavation with a flat bottom is obtained without a reduction in burst volume. Conditions favorable to mound formation at the center of the excavation with increasing distance between linear excavating charges are obtained. Relationships between the dimensions of the mound and the embedment parameters of the charges are presented. It is demonstrated that the mound is an independent factor from which it is possible to judge the character of the interaction between two linear excayating charges.

The limiting width of the block between gasification channels, which exist in the limiting stress state, is determined by the dimensions of the overlapping zones of irreversible deformation from the sides of the channels. In a given case, the width of such a block must be less than or equal to a. Under these conditions, the block will be crushed, but the width of the remaining channel will be reduced. The creation of the limiting stress state gives rise to the conditions necessary for the complete gasification of the coal, without reducing the caloric value of the gas.

1. In continuous chamber mining, the structural dominant of the random function of the cumulative flow in frequency terms is described by a two-component system formed as a combination of a relatively slowly varying curve and a high-frequency component; they are generated by cyclic property of chamber working and delivery cycles, respectively. 2. The high-frequency component of the load can be eliminated by under-chamber ore closing, minimizing losses; stabilization of the flow in low-frequency component can be achieved by general mine hoppers (storage areas). The hopper capacities are determined from the control characteristic as a function of the average incoming load flow and under-hopper conveyer (feeder) reserve. The type and the parameters of stabilizing members planned for specific mining conditions should be determined by cost and engineering analysis.

1. Envelopes for yield and ultimate strengths and also strain characteristics for the materialɛP andµP are almost independent of loading path in the prelimit region. In the region of quasiplastic flow and in the post-limit region values of residual strength, fall-off modulus and dilation rate are independent of loading path. 2. The process of material volumetric disintegration with stepwise loading can be predicted on the basis of data obtained with complex loading under constant side pressure conditions. 3. The correlation dependence of ultrasound velocity on residual volumetric disinte-gration is invariant in relation to both stress-strain state parameter for the material and loading path.