• Tunnel and Underground Space
• /
• v.30 no.5
• /
• pp.484-495
• /
• 2020

To numerically simulate the advance of EPB TBM, various type of numerical analysis methods have been adopted including discrete element method (DEM), finite element method (FEM), and finite difference method (FDM). In this paper, an EPB TBM driving model was proposed by using coupled DEM-FDM. In the numerical model, DEM was applied in the TBM excavation area, and contact properties of particles were calibrated by a series of triaxial tests. Since the ground around the excavation area was coupled with FDM, the horizontal stress considering the coefficient of earth pressure at rest could be applied. Also, the number of required particles was reduced and the efficiency of the analysis was increased. The proposed model can control the advance rate and rotational speed of the cutter head and screw conveyor, and derive the torque, thrust force, chamber pressure, and discharging during TBM tunnelling.

• Tunnel and Underground Space
• /
• v.28 no.6
• /
• pp.528-546
• /
• 2018

Cases of TBM tunnelling have been consistently increasing worldwide. In many recent subsea and urban tunnelling projects, TBM excavation has been preferably considered due to its advantages over drill and blast tunnelling. Difficult ground conditions are highly probable to appear in subsea and urban tunnels because of the shallow working depth and alluvial characteristics. Under the difficult ground conditions, ground reinforcement measures should be considered including grouting, while it is of great importance to select the optimal grout material and injection method to cope with the ground condition. The benefits from TBM excavation, such as fast excavation, increased safety, and reduced environmental impact, can be achieved by applying appropriate ground reinforcement with the minimum overrun of cost and time. In this report, various grouting methods were reviewed so that they can be applied in difficult ground conditions. In addition, domestic and international cases of successful ground reinforcement for difficult grounds were introduced for future reference.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.1
• /
• pp.13-24
• /
• 2021

Tunnel boring machine (TBM) is widely used for tunnel excavation in hard rock and soft ground. In the perspective of TBM-based tunneling, one of the main challenges is to drive the machine optimally according to varying geological conditions, which could significantly lead to saving highly expensive costs by reducing the total operation time. Generally, drilling investigations are conducted to survey the geological ground before the TBM tunneling. However, it is difficult to provide the precise ground information over the whole tunnel path to operators because it acquires insufficient samples around the path sparsely and irregularly. To overcome this issue, in this study, we proposed a geological type classification system using the TBM operating data recorded in a 5 s sampling rate. We first categorized the various geological conditions (here, we limit to granite) as three geological types (i.e., rock, soil, and mixed type). Then, we applied the preprocessing methods including outlier rejection, normalization, and extracting input features, etc. We adopted a deep neural network (DNN), which has 6 hidden layers, to classify the geological types based on TBM operating data. We evaluated the classification system using the 10-fold cross-validation. Average classification accuracy presents the 75.4% (here, the total number of data were 388,639 samples). Our experimental results still need to improve accuracy but show that geology information classification technique based on TBM operating data could be utilized in the real environment to complement the sparse ground information.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.24 no.1
• /
• pp.57-78
• /
• 2022

The disc cutter and cutterbit, which are the most important factors to increase the excavation efficiency of TBM, are key factors in the design and construction of the cutter head. The arrangement, spacing, number, size, and material of disc cutters suitable for the ground conditions determine the success or failure of TBM construction. The disc cutter, which is a representative consumable part in TBM construction, can cause enormous disruption to the construction cost as well as the construction cost unless accurate prediction of wear and replacement cycle is accompanied. Therefore, in this study, the method of calculating the replacement cycle of the disc cutter calculated at the time of design for the slurry shield TBM field, and the depth of wear and replacement location of the disc cutter that occurred during actual construction were compared by analyzing the field data. For a quantitative comparison, weathered soil/weathered rock, soft rock, and hard rock were classified according to the ground in the section showing constant excavation data, and the trajectory of circle was different depending on the location of the disc cutter, so it was compared and analyzed.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.26 no.3
• /
• pp.209-222
• /
• 2024

The Earth Pressure Balance (EPB) shield Tunnel Boring Machine (TBM) is widely used for underground tunnel construction for its advantages, such as eliminating the need for additional facilities compared to the slurry shield TBM, which requires Slurry Treatment Plant (STP). During EPB shield TBM excavation, a soil conditioning technique is employed to enhance the physical properties of the excavated soil by injecting additives, thus broadening the range of applicable ground conditions to EPB shield TBMs. This study explored the use of xanthan gum, a type of biopolymer, as an alternative to the commonly used polymer additive. Biopolymers, derived from biological sources, are fully biodegradable. In contrast to traditional polymers such as polyacrylic acid, which contain environmentally harmful components, xanthan gum is gaining attention as an eco-friendly material due to its minimal toxicity and environmental impact. Test conditions with similar workability were established through slump tests, and the rheological characteristics were assessed using a laboratory pressurized vane shear test apparatus. The experiments demonstrated that, despite exhibiting similar workability, the peak strength in the flow curve decreased with increasing the content of xanthan gum. Consequently, a correlation between the xanthan gum content and peak strength was established. Replacing the traditional polymers with xanthan gum could enable stable EPB shield TBM operation by reducing equipment load, in addition to offering environmental benefits.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.353-364
• /
• 2011

This paper presents the ground behaviour of shield TBM lunching area during excavation. In order to perform this study, a scaled model test was carried out in the 1/45 scale for a field tunnel in practice where the tunnel had about 7.8 m diameter at Seoul Metro Line 9 construction site. The test to simulate earth pressure balance (EPB) shield TBM tunnelling at the lunching area was conducted with the developed small scaled shield TBM machine. Measurements were performed during simulation of excavation for total jacking thrust force, ground displacements and pressures. Based on the analysis of simulation results, the stability of ground was verified and evaluated. In particular, the suitable reinforcement range and methods are also suggested. In addition, these results are useful for engineers and technicians to select suitable and serviceable machine operation parameters and reduce environmental influence at all stages of tunnel construction.

• Proceedings of the KSEG Conference
• /
• 2002.04a
• /
• pp.211-218
• /
• 2002

TBM 터널굴진시 공법적합성을 평가하기 위한 현장조사 및 물리탐사와 세부지질조사를 수행하였다. 해당지역은 부산시 진구 가야동과 동구 수정동이며 인근 수원지인 덕정정수장에서 생산하는 수돗물을 수정산 배수지까지 확대 공급함으로서 송수공급 계통의 이원화로 안정적인 수돗물공급을 수행하기 위한 배수지터널이다. 이론적으로 굴착속도는 암반의 반발경도, 일축압축강도, 석영함량 및 각종 지질특성에 의하여 좌우되는데, 실지 시공에 있어서는 현장여건상 지질조건이나 일축압축강도등 한정된 자료들을 토대로 시공에 임할 수밖에 없다. 이러한 한계를 극복하기 위한 모형개발을 목표로 본 연구에서는 다양한 현장시험을 토대로 한 TBM 굴진 적합성을 검토하고자 하였다. 국내 시공경험상 및 지질특성만을 고려 할 때 본 과업구간의 TBM 적용성은 양호할 것으로 판단하였으나, 뚜렷한 근거에 의거하지 않은 설계는 시공단계에서 엄청난 손실을 야기하게 되므로 보다 상세한 검토를 수행하게 되었다. 본 연구에서는 TBM 공법선정의 적합성을 검토하기 각종 조사 자료들을 정리하였고, 국내시험의 한계점들을 극복하기 위한 적합한 모형개발의 필요성을 제시하고자 하였다.

• Magazine of korean Tunnelling and Underground Space Association
• /
• v.1 no.2
• /
• pp.161-170
• /
• 1999

본고에서는 $1986.8\~1988.7$월중에 시공된 부산지하철 1호선 3단계 건설구간 중 서대신동 로타리에서 괴정국민학교 앞까지 연${\cdot}$경암지역에서의 TBM(Tunnel Boring Machine)으로 시행된 단선터널(7.0m)과 NATM으로 시행한 복선터널의 근접시공에 따른 간벽부 보강설계 내용과 근접부 시공시 계측결과 분석, 지보 Pattern조정 및 시공 실적 등을 제시하였다. 원설계 내용 분석 결과 지보 Pattern이 현장 지반조건에 비해 과다하였고 TBM 굴진시 Thrust 2500kN(본 기계 기준) 이상인 연암이상의 지반에서는 TBM 굴착으로의 효율성이 있었고, 경암구간에서 병행터널의 간섭영향을 배제하려면 터널간의 중심거리가 터널직경의 2배 이상이 되어야 하며, TBM 단선터널(7.0m)의 일 평균 굴진 길이는 4.6m로 분석되었다. 앞으로 이와 유사한 암층에서의 터널근접 시공 및 TBM 굴착시 본 분석내용이 참고가 되기를 기대하여 본고를 작성하였다.

• Tunnel and Underground Space
• /
• v.4 no.2
• /
• pp.144-155
• /
• 1994

This research is designed to assess current achievement levels for mechanized excavation systems in Korea adn suggest the model predictive of TBM performance using statistical approaches. A test section in the TBM construction sites is selected to measure and analyze TBM performance. The field records including operating data, time allocation into downtime catagories, and machine design are analyzed on a shift basis. There are a total of 240 shifts, with most days operating two shifts per day. Examples of the probability density functions produced from the test section are presented and discussed. Relationships between TBM penetration rate and rock physical properties are investigated and the empirical equations for TBM performance prediction are also assessed with the field data.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.1
• /
• pp.57-70
• /
• 2017

In this study, we investigated the wear measurement methods for slurry pipe applied in the field of mining and oil sand industry and theoretical equations related to the prediction of wear in slurry pipe through literature review. Average daily wear rate and wear rate per excavated distance were determined from slurry discharge pipe thickness measurement data periodically measured at the actual slurry shield TBM site in Singapore. The wear rate of slurry pipe for Bukit Timah Granite was obtained. The wear rates for G (V) grade and mixed zone were 1.5 times higher than that of G (I) to G (IV) grade. Slurry pipe wear rate tends to increase in proportion to the slurry discharge velocity. The optimal slurry pipe replacement or rotation frequency can be estimated through the selection of the pipe wear rate considering geological condition and the reasonable pipe management thickness.