• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.403-413
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• 2015

This paper presents the cutter bit damage due to the rotation speed of shield TBM cutter head in the mixed ground. The efficient of cutter bits and disk cutter are very important for tunnelling in mixed ground. In particular, this research is focused on the performance of cutter bits during excavation in mixed ground which is consist of the weathered soil and rock formation. In order to carry out this research, the experimental works are prepared performed by using the scaled shield TBM cutter bits evaluation machine developed. The mixed ground is prepared considering with a scale effect of tunnel size. Three different rotation speeds of shield TBM cutter head (i.e. 2, 3, 4 rpm) are applied in the experimental work. The drag forces acting on the cutter bits are measured at each cutter bit during rotation of cutter head. It is also analysed the variation of drag forces due to the rotation speed of shield TBM cutter head. The results of this research are clearly shown that the drag forces acting on the cutter bits are jumped up at the boundary between weathered soil and rock. It is also indicated that the jamping drag forces are increased with increasing the rotation speed of the cutter head. It is found from the research that the higher rotation speed of shield TBM cutter head will be high risk in the mixed ground. It is, therefore, suggested that the use of lower rotation speed of shield TBM cutter head is recommended for reducing the cutter bit damage in practice.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.51-58
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• 2013

In this study, the hydraulic experiments were conducted for the dredging efficiency of the cutter head type, which includes the open type and the close type cutter head. The dredging experimental instrument was installed in the large water tank which has the dimension of $4.9m(L){\times}2.2m(W){\times}1.5m(H)$. The dredging experiments were performed for the various conditions of dredging depth, rotating speed, and suction speed of the cutter head. As the results, the dredging efficiency of the close-type cutter head is much higher than that of the open-type cutter head. The dredging efficiency of the same cutter head type was mainly influenced by the rotating speed of cutter head. Also the adequate suction speed of the cutter head is needed for more effective dredging.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6B
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• pp.491-497
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• 2011

In this study, the flow characteristics around the cutter head, which makes the dredging soil suspended, were measured to evaluate the environmental affect of the dredging works. The PIV was used for measuring the flow characteristics around the cutter head for suction and non-suction cases. As the results, the mean velocity was decreased from the cutter head to outward. The mean velocity decreasing rate of the non-suction case was larger than that of the suction case, but the turbulence intensity decreasing rate of the non-suction case was smaller than that of the suction case because of the suction energy which makes the z-direction flow.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.588-592
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• 2008

In this study the flow characteristics around the cutter head which makes the dredging soil suspended were measured to evaluate the environmental affect of the dredging action. The PIV was used for measuring the flow characteristics around the cutter head for suction and non-suction cases. As the results, the mean velocity was decreased from the cutter head to outward. The mean velocity decreasing rate of the non-suction case was larger than that of the suction case, but the turbulence intensity decreasing rate of the non-suction case was smaller than that of the suction case because of the suction energy which makes the z-direction flow.

• Journal of the Korean Geotechnical Society
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• v.28 no.5
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• pp.67-76
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• 2012

This study is a research about cutter bits arrangement of shield-TBM and carried out a scale model test and numerical analysis according to a space of cutter bits. A cutter head pressures and an advance time are measured to be followed by the space of cutter bits with an advance speed through the scale model test. We conducted the numerical analysis to verify the result of the scale model test, and to compare with the scale model test. There are three cases of space : unification 1.0D and 1.5D. In case TBM is excavated and space is 1.0D, the advance speed is much faster than the other cases, and pressure of face of ground deformation and cutter head is maintained stably. If additional researches about bits arrangement of cutter head of sand ground based on the result of this research are performed, substantial results may be obtained.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.501-513
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• 2020

Cutter cutting tests for the cutter placement in the cutter head are being conducted through various studies. Although the cutter spacing at the minimum specific energy is mainly reflected in the cutter head design, since the optimum cutter spacing at the same cutter penetration depth varies depending on the rock conditions, studies on deciding the optimum cutter spacing should be actively conducted. The machine learning techniques such as the decision tree-based regression model and the SVM regression model were applied to predict the optimum cutter spacing ratio for the nonlinear relationship between cutter penetration depth and cutter spacing. Since the decision tree-based methods are greatly influenced by the number of data, SVM regression predicted optimum cutter spacing ratio according to the penetration depth more accurately and it is judged that the SVM regression will be effectively used to decide the cutter spacing when designing the cutter head if a large amount of data of the optimum cutter spacing ratio according to the penetration depth is accumulated.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.5-9
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• 2009

In this experiment, the cutter head was designed as the down-scaled shape from the cutter head of the Asan-3 of Hyundai Construction Company. The dredging simulation instrument was installed in the experiment water tank which has the dimension of $4.2m(L){\times}2.2m(W){\times}1.5m(H)$. The speed of all components were controlled manually through the hydraulic tool and motors to find the effective desilting condition. As the results, the experiment was conducted to find the optimate dredging cutter head operation rate. To compare the factors which effect on the dredging effectiveness, the dimensionless dredging volume ratio was introduced and it can be found the best effectiveness at 2.0 m/s suction speed, 8 cm dredging depth and 4~4.5 dimensionless dredging volume ratio. Therefore, in order to take the best effectiveness these 3 components factors should be adequately considered.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.666-675
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• 1993

In order to prevent bodily injuries frequently suffered in using bush cutters, especially from spattered stones, we developed a unique new cutting system equipped with a fixed blade on top of the rotary blade, and checked into the mowing performance of the cutter. From experimental test of mowing efficiency and measuring test of physical stress (O$_2$ consumption and heartbeat rates) , the new cutting system with a fixed blade proved that it keeps good cutting performance with lower peripheral speed of the rotary blade(22m/sec), compared to that of ordinary cutting blade, yielding more safety in operation. Weight of the cutter head is, however, heavier than that of ordinary machine by about 70% which increased a physical stress on the operator with slightly faster heartbeat rates. In mowing along edge of concrete wall, the operator enjoyed using the cutter with no anxiety , owing to function of the fixed blade.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.6
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• pp.573-584
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• 2014

In this study, the variations of cutter acting forces depending on cutting conditions were examined to obtain basic data for roadheader cutting head design. The linear cutting tests were performed in the condition of different attack angles, penetration depths, cutter spacings by using a slim conical pick for the light cutting condition. Cutter acting forces were measured by 3-directional load cell under different test conditions, and the analysis for cutting performance were carried out after calculating average values of the measured results. It is confirmed that the optimal cutting condition for the mortar specimen is the 50 degree attack angle, the cutter spacing of 12 mm, the cutting depth of 9 mm which are obtained from the analysis results. In addition, 50 degree attack angle is more effective than 45 degree attack angle to design optimal specifications of cutting head.

• Tunnel and Underground Space
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• v.25 no.6
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• pp.496-504
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• 2015

Roadheader that excavates ground using pick cutters installed on the cutting head is one of the partial-face machines. A conical cutter among pick cutters is excavation tool decreasing the loss of cutter using tungsten carbide insert at the tip of the cutter and it has been widely used in the roadheaders. In this study, durability performance for three kinds of conical cutters was evaluated in copper mines composed of Manto and conglomerate. After field test, the visual inspection as well as the weight loss measurement of pick cutters was carried out to investigate the damage of pick cutters. In addition, CT scan and SEM were performed to check whether or not crack and apertures in pick cutters. As results, the conical cutter with hardfacing was evaluated as having the best durability performance and it was unable to find cracks in all cutters investigated.