Rock Breaker Research Articles

Deflection of Prototype Geosynthetic-Reinforced Working Platforms over Soft Subgrade

Large-scale experiments were conducted on working platforms of crushed rock (breaker run stone or Grade 2 gravel) overlying a simulated soft subgrade to mimic conditions during highway construction where a working platform is used to limit total deflections because of construction traffic. Tests were conducted with and without geosynthetic reinforcement to evaluate how deflection of the working platform is affected by the presence of reinforcement, type of reinforcement, and thickness of the working platform. Four different geosynthetics were used: geogrid, woven geotextile, nonwoven geotextile, and drainage composite. Reinforced working platforms deformed at a slower rate, and, in most cases, deformation of geosynthetic-reinforced working platforms nearly ceased after approximately 200 loading cycles. Total deflections at 1,000 cycles were smaller by a factor of approximately two for reinforced working platforms relative to unreinforced working platforms, and smaller deflections were associated when less...

Automatic recognition of working states of a rock breaker machine from acoustic signal processing

In underground mining, there are risks involved in operating heavy machinery such as Load–Haul–Dump and rock breakers. In order to minimize those risks, that can be fatal, it was proposed to study the feasibility of employing both vision and sound to improve either human-based teleoperation or robotized machinery. Earlier attempts have considered only visual input data. In this work, recognition results carried out on acoustic emissions generated by a rock breaker during normal operating activities, are presented. These acoustic data were recorded in-situ and then analyzed using four different techniques: FFT, FFT-Wavelet, Cepstrum, and Time–Frequency. The results indicate that Power Cepstrum analysis provides the best performance both in terms of finding noticeable differences between the signals representing the operating states of the rock breaker as well as in terms of data compression capabilities. A back-propagation neural network was then trained to classify the signals into the different operating states of the machine. [Work partially supported by Project Dicyt 009913SS, University of Santiago, Chile.]

Non-explosive applications of the PCF concept for underground excavation

The ever-expanding need to excavate more rock per unit energy and environment constraints have created new demands on rock excavation technology. Research efforts have been directed towards those techniques which break rock less violently by tensile stresses instead of compressive. The Penetrating Cone Fracture' (PCF) is one of the novel techniques which fall in this category. The paper encompasses the rock breaking technology based upon PCF and related concepts. The non-explosive methods like Drill-splitting, Static rock breaker, Water injection, Plasma blasting, Cardox tube and controlled foam injection have been described.

Development and practice of Tele-earthwork system

The Tele-Earthwork System is able to remotely control unmanned heavy construction equipment, buldozers, power shovel, crawler dumptruck, rock breaker, mobile TV camera and mobile transmitter.All the equipments operated from a control room located 2 kilometers away from dangerous construction sites, that was near by Mt. Fugen.

海底岩盤への砕岩棒の貫入特性

Rock breaker is widely used to break seabed rock. A force-penetration relationship appears to be closely related to deformation and fracture mechanism of rock.Penetration test of rock breaker was conducted on seabed weathered granite at the base of Kurushima Bridge. The rock breaker weighs 46 tons and is 5m long. The angle of its cutting edge is 45 degrees. It is found that a linear relationship exists between force F and penetration u;F=ku, where k is a constant. This equation has been pointed out by many authors based on the experiments where typical penetration is 1mm or less. In this study, the penetration reaches as much as 500mm and it is found that this equation is still valid in case of such deep penetration.The following equation is also obtained considering energy balance;k (u-0.05) 2/2=m· a · h, where m, a and h are respectively mass of the rock breaker, falling acceleration and falling height. This equation is consistent with the experimental results.

ＴｉＮｉ形状記憶合金を圧力源とした静的岩石破砕器の開発

ＴｉＮｉ形状記憶合金を圧力源とした静的岩石破砕器の開発

Practical Application of Static Rock Breaker Using TiNi Shape Memory Alloy

AbstractA newly invented static rock breaker using TiNi shape memory alloy has been proposed. The breaker consisted of compressively pre-strained TiNi rods of 15mm in diameter and 29mm in height and a pair of two-layered wedge type platens of steel, and required no accessory equipments other than heating apparatus. The maximum breaking force per unit length of the breaker was 3 to 5MN/m. The total breaking force was about 300 to 900kN, depending on the number of TiNi rods used. To examine the practicality, the breaker has been applied to concrete wall of building, natural boulder, etc. It was confirmed that the breaker was not lack in terms of performance and was possible to control the direction of crack initiation and propagation. It can be concluded that TiNi shape memory alloy has a bright prospect as a solid pressure source.

Development of an impact rock breaker shaft sinking system : Phillips, S H E US Bureau of Mines report OFR 20–82, June 1981, 87P

Development of an impact rock breaker shaft sinking system : Phillips, S H E US Bureau of Mines report OFR 20–82, June 1981, 87P

Practical calculations and recommendations on the use of gunpowder rock breakers in hydrotechnical construction

The effectiveness of using rock breakers largely depends on the parameters of the hydraulic pulse, which are determined by the design of the elements of the implement, geometry of the shothole, and physical constants of the medium being fractured.

A novel concept for a rock-breaking machine. II. Excavation techniques and experiments at larger scale

This is the second paper describing the ‘Max’ rock breaker. In the preceding part I, early experiments and the theory of the rock-breaking process were described. This report continues with a description of experiments made with a model unit (hole diameter 6.7 mm) to investigate the behaviour of the device in various geometries (tunnelling, stoping, and quarrying). It then describes the design and testing of two larger machines, to fit holes of 35 and 57 mm diameter, respectively. The former of these machines was intended as a hand-held unit, while the latter was boom-mounted and provided with the means of drilling its own hole. Experiments with the model showed that even if very much confined, the rock could be extracted satisfactorily, and in geometries of low confinement, this could be accomplished with high efficiency. In concrete-breaking, no problems were encountered in breaking the concrete itself but, if present in a three-dimensional array, the reinforcing bars could cause trouble. Tests with the largest machine confirmed its ability to deal with rock at full scale, whether hard, soft, or badly fissured, and suggest the possibility of making a variety of very flexible and environmentally attractive mining machines.

The first geologists—the archaeology of the original rock breakers

What good is a broken stone—then or now? How and when did this venerable practice begin? Did the Stone Age start with a big bang or a series of little taps? Aspects of East Africa’s long record of stone tools are considered from a geological and an evolutionary perspective.

Use of rock breakers for shattering concrete masses at the Dneprogés-II hydroelectric plant

1. Experience with more than four years of operation of rock breakers has demonstrated that they can be successfully used for construction and repair work under any conditions, near transmission lines, existing equipment, residential buildings, and bridges, without removing people and equipment from the work zone and without interrupting the parallel technical processes. 2. The use of rock breakers is especially effective for the reconstruction of different types of industrial structures where it is necessary to destroy old foundations, masonry, and concrete masses.