I. V. Tishchenko

Effect of blow frequency and additional static force on the vibro-percussion pipe penetration rate in soil

The authors describe and discuss experimental investigation of the effect exerted by blow frequency and additional static force on penetration rate of a pipe under vibration-percussion by a pneumatic hammer with using a measuring and recording instrumentation developed at the Institute of Mining, Siberian Branch, Russian Academy of Sciences. The penetration velocity ranges are found for the real blow frequencies of the test pneumatic hammer equipped with additional static load. Determination of static force sufficient to press the pipe in soil in hammer-free regime is reported.

Effect of additional vibration exciter and coupled vibro-percussion units on penetration rate of pipe in soil

Aimed to improve capacity of vibro-percussion driving of steel pipes in soil, the authors describe experimental modeling of the process with additional vibration exciters of axial and transverse vibrations series-linked to impulsive load source. Workability of the combination of two extended action spectrum percussion units as the vibration exciter is illustrated.

Influence of energy parameters of shock pulse generator on the pipe penetration velocity in soil

In the context of the problem of increase in efficiency of vibro-percussion driving of steel pipes in soil, a pilot model of shock generator with step speed adjustment for the bit and anvil impact is described. The authors report experimental modeling of pipe penetration depending on load of stalk. The influence of the stalk load parameters on the amplitude of generated shock pulses and the pipe penetration rate in elastoplastic soil is defined.

Evaluation of Layout of Air Drill Hammer with Smooth Adjustment of Impact Impulse Frequency

Design of an air drill hammer with the smooth adjustment of the percussion frequency at the constant blow energy is considered. The proposed and analyzed modifications of air distribution system are based on using a mechanically closing elastic valve. The test data on experimental prototypes of the air drill hammer with the external distributing elements that set blow frequency are presented. The frequency adjustment ranges are determined.

Estimate of blow frequency range for an air drill hammer with a ring-shaped elastic valve in the backstroke exhaust line

The authors report and discuss the experimental results on an air drill hammer with an elastic valve installed in the backstroke exhaust line for mechanical closing. It is approved that such air hammer is capable to ensure the wanted blow capacity at the fixed blow energy by varying blow frequency through adjustment of cross section choke coupling the backstroke and front stoke chambers of the hammer. With the larger cross section of the choke coupling, the maximum blow frequency is achieved and remains the same later on.

INCREASE IN EFFICIENCY OF THE CYCLIC DRIVING OF WELLS IN SOIL

Processing methods of a cyclic driving of wells with a diameter over 300 mm by methods of vibro-impact pushing and combined with partial consolidation and excavation of soil on the basis of use of pneumo-percussive mashines (pneumatic bore-hole driver) are given in work. The results of researches received with use of the ground intake devices physical models have allowed to establish characteristics of change of force of resistance to the return transportation of the equipment with the taken soil core in process of his removal from a face. Analytical expressions for engineering calculation of the winch tractive force are received. Technical characteristics of the created number of the winches of scraper type working at the uniform energy carrier with shock cars – compressed air are given.The schematic diagram winch with hybrid pneumatic drive, the having variable traction and high-speed characteristic is offered at a limited expense of the energy carrier which realization of a design at vibroshock breakdown and a combined method allows to reduce time of a production cycle of formation of wells and to increase productivity of driving works. A schematic diagram of a winch with a hybrid pneumatic drive is proposed, which has variable traction and speed characteristics with a limited energy carrier consumption, the implementation of the design which in vibro-impact pushing and combined method allows to reduce time of process of formation of wells and improve the performance of the tunneling works.

Estimation of Influence Exerted by Powered Closure Stability of Elastic Valve on Efficiency of Air Hammers

In focus of the studies is the influence exerted by the radial displacement of the hammering unit on the air distribution in the air hammer with the ring-shaped elastic valve. The minimal allowable volume of the backstroke chamber at the frontmost position of the hammering unit when it contacts the anvil is calculated with regard to the limited maximum pressure in the impact stroke chamber at the moment of the blow. In the capacity of the air hammer efficiency criterion, it is suggested to use the length of the powered closure of the elastic valve, that compensates rotation of the hammering unit in the body when the radial clearance between these parts grows. The parameters of the air distribution system are estimated for all standard sizes of air hammers with the ring-shape elastic valves.