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Double-shield TBM performance analysis in clay formation: A case study in Iran
Published in Daniele Peila, Giulia Viggiani, Tarcisio Celestino, Tunnels and Underground Cities: Engineering and Innovation meet Archaeology, Architecture and Art, 2020
M. Fallahpour, M. Karami, T. Sherizadeh
Accurate Estimation and evaluation of TBM operational parameters, such as rate of penetration, advance rate, utilization factor and wear of disc-cutters is necessary to achieve high efficiency in mechanized tunneling. This study aimed to analyze the TBM performance parameters in the Konjancham water conveyance tunnel in Iran as a case study. Based on the data obtained from an approximate 5 Km of bored tunnel in clay and silt rocks types within the Aghajari and Lahbari formations, an evaluation of actual field parameters was conducted based on daily and weekly operations results. Also, a comparison was made between results of the three commonly used TBM performance prediction models and actual performance of the TBM for this project. The results indicate that the actual performance parameters in KT-2 correlates very well with the RME prediction model. The wear of disc-cutters was also analyzed as it was noted to be an important index in determining the success of the project. Normal wear, oil leakage, and cutter jamming were the main reasons of disc-cutters substitution. The results indicated, 62 disc-cutters including 4 center, 29 face, and 29 gauge were consumed in the excavated section of the KT-2 project.
Analysis of stress distribution of disc cutter under different tunnelling parameters
Published in Australian Journal of Mechanical Engineering, 2018
At present, the rapid development and utilisation of urban underground space has promoted expansion of application market for tunnelling boring machine. Putting TBM into production and using can not only make the idea of developing underground space possible, but also minimise the pollution of garbage to the city within a reasonable range, which also meets the requirements of the development of modern society. Disk cutter is the core rock-breaking tool of TBM. Because of the complexity of its working conditions, disc cutter is often subjected to strong impact and overloading, which results in abnormal damage such as cutter rim fracture, edge grinding and so on. According to statistics, in the process of Qinling tunnel tunnelling, the cost of cutting tool consumption accounts for one third of the total project cost (Song, An, and Yuan et al. 2009; Rostami and Ozdemir 1993). In the construction of hard rock or composite stratum, tool damage is the most important factor that affects the efficiency of TBM driving, and the overloading of disc cutter is the main reason of tool damage (Rostami 1992). Therefore, studying the stress distribution law of blade in the process of rock breaking is helpful to master the deformation characteristics of disc cutter, evaluate its strength and guide the design and selection of cutter structure better at the same time. Based on the theoretical and practical experience, it is assumed that the contact force at the bottom of the cutting blade is linear distribution and uniform distribution, and the calculation formula of triaxial force is derived in order to improve the rock-breaking efficiency of the hob and prolong the service life of the hob (Rostami 1997; Rostami, Ozdemir, and Nilson 1996). Tan Qing et al established the model of tool invading rock by PFC2D, and obtained the stress distribution law of rock when combined with double hobs. Wang et al. (2011) obtained the distributed load law of the arc length between disc cutter and the rock contact surface by theoretical derivation, and verified it with the finite element software. Through theoretical analysis and derivation, it is considered that the contact pressure of the hobbing cutter in the continuous cutting process is equal everywhere and the contact pressure is uniformly distributed by Zhang, Wang, and Zhang (2009). The above study is of guiding significance for understanding the characteristics of contact force distribution of the knife rock.