excavation of high stressed hard rock with roadheader

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Effect of excavation stress condition on hydraulic fracture

Therefore when using high-pressure HF for preconditioning the rock mass to assist mechanical excavation in hard rock mining performance can be enhanced by understanding the impact of stress changes and careful selection of appropriate HF methods depending on the in situ stress.

PDF How highly stressed brittle rock failure impacts tunnel

Rock mass strength in brittle failing rockBased on the experiences summarized above from tunnelling in massive to moderately jointed brittle rock masses it was found that damage initiation occurs at a stress level σ θmax /UCS I well below unity i.e. at about 0.3 to 0.5 UCS I Kaiser et al. 1996;Castro 1996;Martin et al. 1999 .The

Excavation of High-Stressed Hard Rock with Roadheader

Mechanical excavation with roadheader EBZ160TY was trialed at work face with hard rock and high ground stress. Work procedure and performance of the roadheader were recorded and analyzed.

INNOVATIVE ROADHEADER MINING HEAD WITH ASSYMETRICAL DISC

References: 16th International Multidisciplinary Scientific GeoConference SGEM 2016 www.sgem.org SGEM2016 Conference Proceedings ISBN 978-619-7105-56-8 / ISSN 1314-2704 June 28 - July 6 2016 Book1 Vol. 2 489-496 pp

Roadheader solutions in focus - TunnelTalk

The Herrenknecht shaft boring roadheader SBR was developed specifically for mechanized sinking of blind shafts in soft to medium-hard rock. The SBR has been equipped with a roadheader boom and a rotating cutting drum that enables the cutting of variable shaft diameters from 8m to 12m.

Suitability of Brisbane Rock Conditions to Roadheader Excavation

Rock 2 may be attributed to the fact that Thuro and Plinninger’s 2004 model takes into account the high abrasivity of Rock 2 whereas Copur Ozdemir and Rostami’s 1998 model does not consider the abrasiveness at all. Validation to roadheader excavation.

Rock Mechanical Aspects of Roadheader Excavation ISRM

Hard rock excavation by roadheaders presents an interesting alternative to mechanical excavation methods or conventional drill and blast excavation. The very low vibration emissions and precise profile of a roadheader excavation may effectively contribute especially to projects with sensible infrastructure in the vicinity.

Experimental and numerical investigation of roadheader for

Roadheaders are one of the most widely used machines for fast roadway constructions in soft to medium‐hard rocks owing to their advantages such as high advance rates good mobility and versatility. 1 2 However when breaking hard and abrasive rocks the cutters of a roadheader are subjected to serious shock high forces excessive wear

Challenges and Strategies for Tunnelling in the Himalayan Region

rock sequence in-situ stresses rock cover ingress of water geothermal gradient ingress of gases high level of seismicity etc. All these challenges may result in increased cost and extended completion period. Compared with the great advances made in methodology for tunnelling all around the globe it is obvious that we in India have

A model to predict the performance of roadheaders based on

for excavation during the project. The roadheader production rate and pick consumption are controlled by several parameters including2: Rock parameters such as rock compressive and tensile strength per cent of hard and abrasive mineral content i.e. quartz rock fabric and matrix type and hardness

Ug mechanical excavation - SlideShare

Mechanical Excavation Systems Different mechanical excavation systems like machines with; Teeth Dozer Shovel Scraper Bucket wheel excavator Bucket chain excavator Ripping tool Coal Plough ripper rock breaker Pick mounted rotary cutting head/drum Roadheader Shearer Continuous miner Surface miner Disc cutters and button bits

Experimental and numerical investigation of energy

The surrounding rock vertical stress distribution of the roadway rib before and after the pressure relief borehole implementation is shown in Figure 15. After the pressure relief drilling the distance from the vertical stress peak to the surface of the roadway increased from 1.6 to 4.2 m and the whole roadway was in the stress reduction zone.

Experimental Investigation of the Influence of Confining

High geostress is a prominent condition in deep excavations and affects the cuttability of deep hard rock. This study aims to determine the influence of confining stress on hard rock fragmentation as applied by a conical pick. Using a true triaxial test apparatus static and coupled static and dynamic loadings from pick forces were applied to end faces of cubic rock specimens to break them

Effect of initial minimum principal stress and unloading rate

Hard rock often performs as brittle failures such as cracking spalling and rockburst induced by excavation in deep underground engineering. To understand the effect of the minimum principal stress and unloading rate on the spalling and rockburst of marble unloading experiments were carried out by using true triaxial equipment combined with a high-speed camera acoustic emission

Road Headers - Products MITSUI MIIKE MACHINERY CO. LTD.

SLB-350S is designed for highly efficient tunneling apt for high-speed soft rock excavation with large volume and for powerful medium-hard rock excavation. SLB-350S is equipped with a 350/350kW rated output 2-speed motor which is the most powerful motor manufactured in Japan in this field.

Rock Mechanical Aspects of Roadheader Excavation

ABSTRACT: Hard rock excavation by roadheaders presents an interesting alternative to mechanical excavation methods or conventional drill and blast excavation. The very low vibration emissions and precise profile of a roadheader excavation may effectively contribute especially to projects with sensible infrastructure in the vicinity.

Slope Stability in High Stress and Hard Rock Conditions

The stresses in the rock are unknown but taking into account the near surface lo ion and the shallowness of the quarry are unlikely to exceed say 10 MPa. Even if higher than these magnitudes the stress would be unlikely to be anywhere near the strength of the rock. Slope Stability in High Stress and Hard Rock Conditions T.R. Stacey

Theories of interaction of rock cutting tools

Mechanical Excavation Systems Different mechanical excavation systems like machines with; Teeth Dozer Shovel Scraper Bucket wheel excavator Bucket chain excavator Ripping tool Coal Plough ripper rock breaker Pick mounted rotary cutting head/drum Roadheader Shearer Continuous miner Surface miner Disc cutters and button bits

Overcoming squeezing in the Yacambú-Quibor tunnel Venezuela

Figure 7. Modified horseshoe section used at Chainage 2 100 in type D2 rock with a GSI rating of 26 to 37 at a depth below surface of 570 . This section of the tunnel was constructed with excavation by means of a roadheader of a

In Situ Instrumentation And Monitoring of the Deformation of

The investigation of tunnel stability in a highly stressed rock mass has been an area of interest for a number of years. Work has been conducted on understanding the development of the fracture zone with associated dilation of the sidewall of the excavation under the influence of different support systems Haile 1995 .

Herrenknecht Mining Pioneering Underground Technologies

SBR - Shaft Boring Roadheader Geology soft/medium hard rock 120 MPa Shaft diameters / depth 7 - 12m / 1000 m Machine height / weight 50m / 350t Suspension Headframe / ropes Mucking method slurry pneumatic Rock Support/Lining per requirement Net excavation 3 m/d Herrenknecht. Pioneering Underground Technologies

Research on Excavation and Stability of Deep High Stress

Because the excavation of chamber group is a dynamic and multi factor coupling process of it is necessary to adopt dynamic construction mechanics to optimize the excavation scheme. Therefore based on the engineering background of − 1155 m level at Anju coal mine in Shandong the numerical model of deep high stress chamber group is established.

Seismic characterization of a highly stressed rock mass using

Yong Fan Xianze Cui Zhendong Leng Yurong Zhou Junwei Zheng Feng Wang Development of a Model to Predict Vibrations Induced by Blasting Excavation of Deep Rock Masses under High In Situ Stress Shock and Vibration 10.1155/2020/8817631 2020 1-14 2020 .

Roadheader Excavation Performance - Geological And

During the last few years in mechanical excavation problems have occured also connected with the accurate prediction of excavation performance and tool wear in soft and hard rock. Every now and again problems have been encountered leading to high bit consumption and low cutting performance of roadheaders.

PDF Use of GSI for Rock Engineering Design Trevor Carter

Lo ion D-Factor Disturbance Characteristics The chart in Figure 4 was also introduced because Underground High Quality Perimeter Blasting 100% half barrel traces 0 or Mechanical Excavation with TBM or Roadheader the lack of quantified scales on the original GSI Excavations NATM excavation in weak rock with mechanical excavation confined

Research on fracture mechanism of high ground stress fracture

When the tunnel excavation form a free face the crustal stress is released the rock mass slides extrudes and shears along the joint fracture; and the adjacent rock mass is dragged and lost its self-maintaining ability resulting in "rock burst" or "large deformation" which has a great impact on personnel and equipment safety.

Wear mechanisms associated with rock excavation using attack

Conclusions The wear associated with the excavation of rock using attack picks on roadheader tun- nelling machines is complex and almost cer- tainly a composite mechanism. The previous extension of abrasive wear theory into an environment that is not entirely suitable had led to a rather narrow view of the processes behind pick consumption.

TUNNELING ROADHEADER MT720 HARD ROCK

The Tunneling Roadheader MT720 is an extremely powerful boom-type roadheader of the 100 tons class and has proven its unique transverse cutting technology in hard rock appli ions worldwide. This machine has an extended field of operation for mechanized tunneling in hard and abrasive rock formations.

Rock Mechanics

Deformation - Response to Stress Failure of a brittle rock - point when the rock loses all resistance to stress and crumbles. In plastic material specific point of failure difficult to identify - because deformation continues indefinitely at a constant level of stress. Strength in plastic materials – is defined as the

Rock Mechanical Aspects of Roadheader Excavation

Rock Mechanical Aspects of Roadheader Excavation Minimizing Risks in RH Appli ion In order to minimize operational ri sks for r oadheader appli ion it is mandatory to perform high quality site investigation which takes into account not only the stability of the rock mass but also puts a focus on the specific rock excavatability.

Geotechnical Risk Assessment and Selection of Suitable

the 1960s use of roadheader for mechanized tunneling began and by the end the 1970s it gained considerable acceptance worldwide. In the past decade the development of roadheader in tunneling has reached a cutting level not only in soft rock but also in medium to hard rock.

Evolution Mechanism of Deformation and Failure of Surrounding

To deeply analyze the failure evolution of surrounding rock during excavation-induced unloading of the high-stress rock mass a multistage failure model was established based on revealed failure patterns. The critical conditions for wing cracks were determined. The slab crack buckling analysis was carried out. The true-triaxial rockburst testing system was used for the miniature model test to

Microseismic Signals in Heading Face of Tengdong Coal Mine

Microseismic MS monitoring is an important and commonly used geophysical method in coal mines to predict rock burst which has great influence on safety production. MS monitoring technology and analysis method of the whole mine or working face have been matured but its use in heading faces of coal mine is not mature due to small disturbances and narrow layout spaces. To carry out MS

UNDERGROUND EXCAVATION Alternative excavation

30 m of the advancing drift excavation heading. This would ensure no delays to subsequent work activities once the drifts were complete. The final drift construction methodology proceeded with the major excavation equipment comprising of a Mitsui S200MA roadheader combined with an integrated ground support system. It was further concluded that

ROADHEADER IN TUNNELING

SELECTION CRITERIA FOR EXCAVATION METHOD . EXAMPLES – ROADHEADER SELECTION . 7 Complex geology Free access to the face Ability for partial face excavation Gentle excavation Not sensitive against squeezing rock High cutting performance in soft and medium hard rock up to 130 m³/NCH

Excavation of High-Stressed Hard Rock with Roadheader

Mechanical excavation with roadheader EBZ160TY was trialed at work face with hard rock and high ground stress. Work procedure and performance of the roadheader were recorded and analyzed. The results showed that roadheader EBZ160TY with designed excavating strength of 80 MPa presented amazingly good performance in hard rock with strength of

Lec8-Roadheader Machine Excavation.pdf - Roadheader Machine

Roadheader Machine Excavation Dr. M. Zubair Abu Bakar Introduction Machine excavation is achieved mainly by two methods: – By selective cutting partial face machines using roadheader whose boom mounted cutting head concentrates the rock excavation forces and is usually equipped with drag picks cutters .

PDF Rock Mechanical Aspects of Roadheader Excavation

The lifetime of the present pick tools in higher rock strength and abrasivity is the major limiting factor for roadheader use in hard rock 2 – see Fig. 2. But also the geometric configuration

roadheader excavation

PDF Geological limits in roadheader excavation - Four. Two case studies are supposed to show how layers of hard calcrete so called "quacken" layers as well as soft clay-sillstone-layers reduced the efficiency of the roadheader excavation system.

Numerical simulation of optimum mining design for high stress

Thus the rock ore becomes easier to be fragmented which provides advantageous conditions for roadheader to cut high stress hard-rock. It is worthy noting that there is a large difference in effective utilization of deep ground pressure between horizontal and vertical excavation directions.

Rock Tunneling WSP

The Chinatown station of San Francisco& 39;s Central Subway is being constructed in poor rock conditions using the NATM method. Roadheaders. A roadheader is used as a mechanized method of cutting that has more precise cutting less vibration and no overbreak. Recent developments have allowed the excavation of rock tunnels in very hard rock.

The Importance of Research on Alternative and Hybrid Rock

Current methods of mechanical excavation of rock are limited in regard to the material which can be extracted economically. The use of roadheaders with pick tools has the advantage of high flexibility in form of turn off radii down to 1 m but is limited by rock strength to figures below 150 MPa UCS.While mechanical rock excavation machines with disc cutters can handle rock strengths above 150

Advanced Rock Tunnelling Engineering Solutions WSP

A roadheader is used as a mechanized method of cutting that has more precise cutting less vibration and no overbreak. Recent developments allowed the excavation of rock tunnels in very hard rock. The basic cutting tool is a very large milling head mounted on a boom which is in turn mounted on tracks or within a shield.

Excavation Hazards- Effects and Prevention Measures

Excavation Hazards- Affects and Prevention Measures 1. Pit Excavation up to 3m. Pits up to three meters may be excavated for testing subsurface soil monitoring water table foundation construction etc. There are number of hazards which may be encountered in excavations of pits up to 3m depths.

Effects of Unloading Rate on Energy Evolution Mechanism in

Highly stressed rock masses continuously exchange substances and energy with the outer environment during single-side unloading which is a damage evolution process with energy dissipation. The true triaxial unloading disturbance rock test system was utilized to perform single-side unloading tests of marble specimens at different unloading rates and axial pressures. The unloading failure

Excavation of High-Stressed Hard Rock with Roadheader

also tryhard rock roadheader process - divinemeadows.in. Excavation of High-Stressed Hard Rock with Roadheader; to the improvement of infrastructure not only of China but also all over the world. roadheader for sale Get a Price Hard Rock Lo ions Quiz - … Learn More

roadheader excavation rates

PDF Roadheader appli ions in mining and tunneling. Roadheaders offer a unique capability and flexibility for the excavation of soft to medium strength rock formations therefore are widely used in underground mining and tunneling operations.

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