scholarly journals Acoustic Emission Characteristics During Rock Fragmentation Processes Induced by Disc Cutter under Different Water Content Conditions

2019 ◽  
Vol 9 (1) ◽  
pp. 194 ◽  
Author(s):  
Qibin Lin ◽  
Ping Cao ◽  
Rihong Cao ◽  
Xiang Fan
Keyword(s):  
Acoustic Emission ◽  
Water Content ◽  
Specific Energy ◽  
Tunnel Boring Machine ◽  
Rock Breaking ◽  
Rock Fragmentation ◽  
Disc Cutter ◽  
Physical Acoustics ◽  
Indentation Force ◽  
Penetration Force

Based on a properly modified testing platform and Physical Acoustics Corporation (PAC) Micro-II acoustic emission (AE) system, a series of sequential indentation tests on granite samples with five different water contents was conducted to investigate the effect of the water content on the rock fragmentation process induced by a tunnel boring machine (TBM) disc cutter. During these tests, the effects of the water content on the characteristics of the peak penetration force, AE events, consumed energy, rock chip volume, and specific energy were analyzed. The results showed that the AE events were associated with the whole second indentation process of the granite. Under conditions with the same water content, the peak penetration forces and the consumed energy were smaller than those in the first indentation force. Additionally, subsequent chips were formed more frequently than the first indentation chips. The specific energy was lower, which meant that the rock breaking efficiency was higher. With the increase in the water content, the acoustic emission events reduced. The peak penetration force and consumed energy decreased with the increase in the water content. The volume of the chips increased significantly as the water content increased. The specific energy was promoted by the increase of the water content and then by the increase in the rock-breaking efficiency of the TBM disc cutter.

Distribution Law of Excavating Load of TBM Disc Cutter and Cutterhead

2014 ◽  
Vol 615 ◽  
pp. 22-26
Author(s):  
Xiang Heng Zhu ◽  
Yi Min Xia ◽  
Tao Ouyang ◽  
Kai Yang
Keyword(s):  
Yield Criterion ◽  
Tunnel Boring Machine ◽  
Element Model ◽  
Rock Breaking ◽  
Disc Cutter ◽  
Distribution Law ◽  
Disc Cutters ◽  
Lateral Forces ◽  
Simulation Results ◽  
Thrust And Torque

Cutterheads and disc cutters are the key components of Tunnel Boring Machine (TBM) used to fulfill the rock-breaking task. In order to study the variation and distribution law of cutting forces induced by disc cutters on TBM cutterhead, a finite element model of rock-breaking process is established based on the extended Drucker-Prager yield criterion for rock and then the excavating process of cutterhead is simulated. The simulation results show that: in the rock fragmentation process, the rock-breaking forces are step changing; with the increase of installation radius, the vertical forces of inner and face cutters increase, while the lateral forces decrease; with the increase of installation angle, the vertical forces of edge disc cutters decrease, while the lateral forces increase; the mean total thrust and torque of cutterhead are 5418.2 kN and 1624.4 kN·m respectively, the simulation results are verified by engineering data.

Research on the Rock Breaking by Double Disc Cutter Test-Bed

2013 ◽  
Vol 690-693 ◽  
pp. 2484-2489 ◽  
Author(s):  
Peng Zhou ◽  
Chao Wang ◽  
Wei Xian Gao ◽  
Yu Hou Wu
Keyword(s):  
Maximum Stress ◽  
Tunnel Boring Machine ◽  
Rock Breaking ◽  
Disc Cutter ◽  
Test Bed ◽  
Underground Engineering ◽  
Tunnel Boring ◽  
Disc Cutters ◽  
Optimal Spacing ◽  
Rock Tunnel

Rock tunnel boring machine is one of the main machineries and equipments for underground engineering, and the failure of tool systems is its main failure form. Rock hob test-bed is the only testing equipment for tool failure and wear. In this paper, the breaking rock by the double disc cutter is simulated and four kinds of rocks are selected to test the influece of rock characteristics and spacing between two disc cutters on the rock breaking by the double disc cutter test-bed. The results show that there is different optimal spacing between two disc cutters for different rock; the optimal spacing is inversely proportional to the hardness of the rocks; the maximum stress appears the boundary between the disc cutter and rock.

scholarly journals Experimental Evaluation of Fragments from TBM Disc Cutting under Different Load Cases

2018 ◽  
Author(s):  
Yimin Xia ◽  
Yupeng Shi ◽  
Laikuang Lin ◽  
Yichao Zhang ◽  
Qing Tan ◽  
...  
Keyword(s):  
Production Rate ◽  
Specific Energy ◽  
High Efficiency ◽  
Impact Load ◽  
Tunnel Boring Machine ◽  
Cutting Parameters ◽  
Disc Cutter ◽  
Absolute Size ◽  
Coarseness Index ◽  
Construction Efficiency

The Tunnel Boring Machine (TBM) tunneling process always contains a certain degree of vibrations due to the step broken phenomenon of the cutting tools. Undoubtedly, there is a quite difference in the fragment characteristics which are related to the construction efficiency of TBM under the static load and the combination of static and impact load. In this study, a series of rock breaking tests with a 216 mm diameter disc cutter and marble samples were conducted under different load cases. Based on the Rosin–Rammler distribution curve, the fragments from the cutting tests were also sieved to calculate the absolute size constant (x’) and coarseness index (CI). The relationship between coarseness index, absolute size parameter and the cutting parameters, specific energy, production rate was evaluated. The results show that there is an increasing trend of x’ and CI with the increase of cut spacing and penetration as well as adding impact load component. An overall downtrend in specific energy and upward trend in production rate which are associated with the high efficiency can be observed with the increasing CI and x’. It is believed that the conclusions are of great significance for improving TBM construction efficiency and cutterhead design.

scholarly journals Mechanical and Acoustic Emission Responses of Rock Fragmentation under Disc Cutter Penetration

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Qi Liu ◽  
Yucong Pan ◽  
Penghai Deng
Keyword(s):  
Acoustic Emission ◽  
Damage Zone ◽  
Three Dimensional ◽  
Rock Fragmentation ◽  
Disc Cutter ◽  
Rock Damage ◽  
Rock Types ◽  
Penetration Ability ◽  
Indentation Tests ◽  
Spatio Temporal

To better understand the rock fragmentation mechanism and optimize cutter design and selection for rock excavation by TBM, a set of three-dimensional indentation tests was conducted with different rock and cutter types. Acoustic emission (AE) monitoring technique was employed to capture the information of the rock damage evolution real-timely. It is found that the penetration by using the constant cross section (CCS) cutter tends to induce inconspicuous rock chips formation before the sudden occurrence of the macrocrack, but that by using the V-type cutter tends to induce gradual rock fragmentation accompanied by the multiple local rock chips formation and the sawtooth force-penetration curve. Meanwhile, rock fragmentation models for CCS and V-type cutters were compared, and the spatio-temporal evolution of AE events was quantitatively analyzed to reflect the rock damage zone development process. Results indicate that the V-type cutter has greater penetration ability and the CCS cutter can cause larger unit damage zone radius. Microscopic observation by using the scanning electron microscope (SEM) reveals that the fracture mechanism for the crushed zone of rock is mainly shear type and that for the major crack is tensile type. It does not matter with rock types or cutter types.

Numerical Simulation of Rock-Breaking Process by Disc Cutter in Tunnel Boring Machine

2014 ◽  
Vol 487 ◽  
pp. 513-516 ◽  
Author(s):  
Yu Zhang ◽  
Xing Wen Wang ◽  
Hui Fang Liu
Keyword(s):  
Working Life ◽  
Tunnel Boring Machine ◽  
Dynamic Contact ◽  
Negative Influence ◽  
Rock Breaking ◽  
Disc Cutter ◽  
Element Analysis ◽  
Tunnel Boring ◽  
Stress Load ◽  
Rule Dynamics

The force load research of disc cutter can be used in the design of disc cutter, in order to improve the working life, determine when to change another cutter. Based on the working platform of ABAQUS finite element analysis module, single disc cutter rock-breaking of the simulation model is established, and according to the theory of rocks plastic rule, dynamics analysis and dynamic simulation are done when the cutter is in rock-breaking process by which, the added force can be got when the disc cutter and rocks contact each other in different wear conditions of contact force in the process of the dynamic contact each other. The results show that with the cutter damage increasing, the added force is increased and cutters maximum instantaneous stress load is 1.5 ~ 2.5 times than the average stress load, which has a negative influence on working efficiency. To have a clear understand of cutters design and working life and when to change another cutter in working time, the results also offer an engineering parameters for researching the load state of TBM tunneling.

Studies on Rock-Breaking of Positive Disc Cutter and Edge Disc Cutter

2014 ◽  
Vol 508 ◽  
pp. 159-164 ◽  
Author(s):  
Kai Yang ◽  
Yi Min Xia ◽  
Yuan Wu
Keyword(s):  
Energy Consumption ◽  
Simulation Model ◽  
Specific Energy ◽  
Inflection Point ◽  
Rock Strength ◽  
Specific Energy Consumption ◽  
Rock Breaking ◽  
Disc Cutter ◽  
Installation Angle ◽  
Optimal Values

Based on TBM disc cutter layout, a rock-breaking model of positive disc cutter and edge disc cutter is built. Sequential rock-breaking of the two cutters under different parameters is simulated; rock fragmentation, three-axis force and energy consumption are studied; optimal rock-breaking condition with different parameters is determined; feasibility of the simulation model is finally verified by experiment. The results show that three-axis force of positive disc cutter and edge disc cutter both increase with the increase of rock strength. Also, the increase of installation angle leads to larger three-axis force of edge disc cutter. Compared with positive disc cutter, edge disc cutter suffers larger squeezing strength from rocks, which results in larger three-axis force in edge disc cutter. Specific energy consumption variation has an inflection point. To meet optimal rock-breaking condition, the optimal values of installation angle in breaking siltstone, granite and marble are respectively 6°, 7° and 7°.

A Method to Predict Disc Cutter Specific Energy for TBM Based on CSM Model

2012 ◽  
Vol 236-237 ◽  
pp. 414-417
Author(s):  
Gang Li ◽  
Li Da Zhu ◽  
Jian Yu Yang ◽  
Wan Shan Wang
Keyword(s):  
Specific Energy ◽  
Performance Prediction ◽  
Dynamic Models ◽  
Tunnel Boring Machine ◽  
Disc Cutter ◽  
Energy Prediction ◽  
Tunnel Boring ◽  
Csm Model ◽  
Tbm Cutter ◽  
Cutter Head

By using fracture mechanics theory of rock, the rock fragmentation mechanism of tunnel boring machine (TBM) cutters is analyzed and the analysis of forces of cutter is carried out. A new method to predict disc cutter specific energy for TBM is developed in this study. By using the dynamic models of TBM cutters interaction with the rock, specific energy prediction model for TBM cutter head is developed. The data from the actual tunnel construction is analyzed by using an example of Qinling tunnel and the comparison is made with the field data. The results indicate that the model developed in this study could not only replace the experiment to disc cutter specific energy for TBM, but also provide a theoretical basis for the performance prediction and optimal design of cutter head for TBM.

scholarly journals Using a high-pressure water jet-assisted tunnel boring machine to break rock

2020 ◽  
Vol 12 (10) ◽  
pp. 168781402096229
Author(s):  
Jinliang Zhang ◽  
Yongchang Li ◽  
Yuansheng Zhang ◽  
Fengwei Yang ◽  
Chao Liang ◽  
...  
Keyword(s):  
High Pressure ◽  
Tunnel Boring Machine ◽  
Rock Breaking ◽  
Water Jet ◽  
Water Diversion ◽  
Disc Cutter ◽  
Tunnel Boring ◽  
Water Jets ◽  
Pressure Water ◽  
High Pressure Water Jet

The concept of tunnel boring machine (TBM) disc cutter rock breaking coupled with high-pressure water jets has been proposed to overcome the difficulties that occur when TBMs encounter extremely hard rocks. Thus, to meet actual engineering requirements for the TBM construction of tunnels as part of the Wan’anxi water diversion project in Longyan City (Fujian Province, China), experiments were conducted on high-pressure water jet-assisted TBM disc cutter rock breaking. By varying kerf depth and width under different water jet parameters and performing disc cutter rock breaking tests on rock surfaces with no kerf, single kerf, and double kerfs, the effects of different kerf depths on the disc cutter rock breaking process, load, and efficiency were examined. The test results showed that high-pressure water jets can generate the regular kerfs required for the coupled disc cutter rock breaking of granite. Employing the coupled rock breaking method also resulted in a decrease in specific energy and an approximately 40% decrease in the normal force of the disc cutter, thereby significantly improving rock breaking efficiency. These results provide key technical parameters for the design and manufacture of high-pressure water jet-assisted rock-breaking TBMs and serves as a reference for similar processes.

Numerical Simulation of the Rock Fragmentation Process Induced by TBM Cutters

2012 ◽  
Vol 249-250 ◽  
pp. 1069-1072 ◽  
Author(s):  
Gang Li ◽  
Bo Wang ◽  
Ya Dong Chen ◽  
Wan Shan Wang
Keyword(s):  
Rock Mass ◽  
Rock Breaking ◽  
Rock Fragmentation ◽  
Fragmentation Process ◽  
Disc Cutter ◽  
Material Strength ◽  
Joint Spacing ◽  
Geological Conditions ◽  
Breaking Mechanism ◽  
Cutter Spacing

The rock fragmentation process is the interaction process between TBM and rock mass, which is affected by TBM specifications, such as thrust force, cutter tip width and profile, cutter spacing, RPM, and torque, and rock mass properties mainly including rock material strength, rock brittleness, joint spacing and orientation. In this study, based on the systematic study of the existed rock constitutive model achievements and introduction of rock breaking mechanism, main failure mode of rock in the breaking process of disc cutter is added and revised in order to meet the actual situation. The method of establishing numerical model of disc cutter breaking process is introduced. After the dynamic simulation, we can obtain that geotechnical interface disturbance insulted by disc cutter. Based on plenty of experiments, it confirms reliability of numerical methods and provides a method to study cutting performance for different geological conditions.

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