• Geomechanics and Engineering
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• 제29권5호
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• pp.523-533
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• 2022

Several prediction model of penetration rate (PR) of tunnel boring machines (TBMs) have been focused on applying to design stage. In construction stage, however, the expected PR and its trends are changed during tunneling owing to TBM excavation skills and the gap between the investigated and actual geological conditions. Monitoring the PR during tunneling is crucial to rescheduling the excavation plan in real-time. This study proposes a sequential prediction method applicable in the construction stage. Geological and TBM operating data are collected from Gunpo cable tunnel in Korea, and preprocessed through normalization and augmentation. The results show that the sequential prediction for 1 ring unit prediction distance (UPD) is R²≥0.79; whereas, a one-step prediction is R²≤0.30. In modeling algorithm, a gradient boosted regression tree (GBRT) outperformed a least square-based linear regression in sequential prediction method. For practical use, a simple equation between the R² and UPD is proposed. When UPD increases R² decreases exponentially; In particular, UPD at R²=0.60 is calculated as 28 rings using the equation. Such a time interval will provide enough time for decision-making. Evidently, the UPD can be adjusted depending on other project and the R² value targeted by an operator. Therefore, a calculation process for the equation between the R² and UPD is addressed.

• 한국터널지하공간학회 논문집
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• 제25권5호
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• pp.387-401
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• 2023

토압식(Earth Pressure Balanced, EPB) 쉴드 TBM (Tunnel Boring Machine) 공법은 진동과 소음이 적어 도심지 지하공간 시공에 적극적으로 활용되고 있다. 이때 첨가제 주입은 막장압 유지, 전단강도 감소, 커터의 마모량 최소화, 굴착토의 투수계수 감소 등 다양한 효과를 보인다. 이러한 기술을 쏘일 컨디셔닝이라 하며, 일반적으로 첨가제로 폼, 폴리머, 벤토나이트 슬러리 등을 적용한다. 본 연구에서는 국내 터널 현장에서 빈번하게 조우하는 화강풍화토 시료에 대해 폼과 폴리머를 첨가제로 적용하여 유동학적 특성을 평가하였다. 슬럼프 시험을 통해 작업성(Workability)을 평가하고, 동일한 시험 조건에 대해 실내 가압 베인전단 시험을 수행하여 유동학적 특성을 평가하였다. 이때 슬럼프 값이 높아 작업성이 떨어지는 경우, 폴리머를 추가 적용하여 폴리머 적용이 유동학적 특성에 미치는 영향을 검토하였다. 시험 결과, 폼 주입비(Foam Injection Ratio, FIR)가 증가함에 따라 슬럼프 값은 증가한 반면 토크, 첨두강도 및 항복응력, 겉보기 점도, 틱소트로피 면적은 감소하였다. 하지만, 폴리머 주입비(Polymer Injection Ratio, PIR)는 폼 주입비와 상반되는 결과를 확인하였다. 시험결과 비교를 통해 슬럼프 값과 항복응력 간의 상관관계를 제시하였다. 그리고 폼 만을 적용한 조건과 폼과 폴리머 모두 적용한 조건을 비교한 결과, 유사한 슬럼프 값을 보이더라도 폼과 폴리머 모두 적용한 조건에서 더 낮은 항복응력이 도출되었다.

• Geomechanics and Engineering
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• 제16권6호
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• pp.643-654
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• 2018

Tunnel excavation leads to a disturbance on the initial stress balance of surrounding soils, which causes convergences around the tunnel and settlements at the ground surface. Considering the effective impact of settlements on the structures at the surface, it is necessary to estimate them, especially in urban areas. In the present study, ground settlements due to the excavation of East-West Line 7 of the Tehran Metro (EWL7) and the Abuzar tunnels are evaluated and the effect of the lateral earth pressure coefficient ($K_0$) on their extension is investigated. The excavation of the tunnels was performed by TBMs (Tunnel Boring Machines). The coefficient of lateral earth pressure ($K_0$) is one of the most important geotechnical parameters for tunnel design and is greatly influenced by the geological characteristics of the surrounding soil mass along the tunnel route. The real (in-situ) settlements of the ground surface were measured experimentally using leveling methods along the studied tunnels and the results were compared with evaluated settlements obtained from both semi-empirical and numerical methods (using the finite difference software FLAC3D). The comparisons permitted to show that the adopted numerical models can effectively be used to predict settlements induced by a tunnel excavation. Then a numerical parametric study was conducted to show the influence of the $K_0$ values on the ground settlements. Numerical investigations also showed that the shapes of settlement trough of the studied tunnels, in a transverse section, are not similar because of their different diameters and depths of the tunnels.

• 대한토목학회논문집
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• 제31권6D호
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• pp.839-848
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• 2011

TBM(Tunnel Boring Machine) 터널은 굴진 도중 장비의 교체나 개조 등은 불가능하기 때문에 굴진 종료 시까지 투입된 장비로 굴진하여야만 한다. 특히 토압식 쉴드TBM은 막장관찰이 어려우므로 굴진 중에 수집된 자료를 분석하여 지반상태의 변화를 예측하고 이를 시공에 반영하여야한다. 지금까지의 TBM에 대한 연구는 굴착 대상이 되는 지반의 특성에 따른 장비선정 및 굴진속도 예측모델 개발이 주로 이루어져왔다. 그러나 굴착의 주체가 되는 TBM 장비의 굴진자료에 의한 지반상태의 추정 및 운전방법의 개선에 초점을 맞춘 연구는 그리 많이 수행되지 않았다. 본 연구는 토압식 쉴드TBM 시공 사례에서 얻은 굴진자료를 활용하여 투입된 장비의 운전조건에 따른 굴진속도의 변화와 최적 운전조건에 대해 알아보았다. 본 연구의 결과를 요약하면 다음과 같다. 첫째, 커터헤드의 회전속도와 총추력이 굴진속도에 가장 큰 영향을 주며 둘째, 적정한 굴진속도를 위해서는 최적 회전속도를 유지하면서 총추력을 조정하는 것이 좋으며 셋째, 총추력의 증가 추세에 따라 지반조건의 변화에 대한 예측이 가능하여 이에 따라 적절한 운전조건의 변경을 결정할 수 있다.

• 터널과지하공간
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• 제34권2호
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• pp.143-153
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• 2024

TBM 공법은 발파 공법에 비해 굴착 중 소음과 진동 수준이 낮고, 안정성이 높은 터널 굴착 공법이며, 전세계적으로 터널 프로젝트에 TBM 공법을 적용하는 사례가 증가하는 추세이다. 디스크 커터는 TBM의 커터헤드에 장착되는 굴착 도구로 지속적으로 막장면 지반과 상호작용하며, 이때 필연적으로 마모가 발생한다. 본 연구에서는 지질 조건과 TBM 운영파라미터, 머신러닝 알고리즘들을 이용하여 디스크 커터 마모를 정량적으로 예측하였다. 디스크커터 마모 예측의 입력변수 중 UCS 데이터의 수가 다른 기계 데이터 및 마모 데이터에 비해 매우 부족하기 때문에, 먼저 TBM 기계 데이터를 이용하여 전체 구간에 대한 UCS 추정을 진행하고, 완성된 전체 데이터로 마모율 계수 예측을 수행하였다. 마모율 계수 예측 모델의 성능을 비교해 본 결과 XGBoost 모델의 성능이 가장 높게 나타났으며, 복잡한 예측 모델의 해석을 위해 SHapley Additive exPlanation (SHAP) 분석을 진행하였다.

• Structural Engineering and Mechanics
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• 제89권1호
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• pp.47-59
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• 2024

In this study, a new sustainable material was proposed to prepare precast tunnel lining segments (TLS), which were produced using a fiber-reinforced slag-based geopolymer composite. Slag was used as the geopolymer binder. In addition, polypropylene and carbon fibers were added to reinforce TLSs. TLSs were examined in terms of flexural performance, load-deflection response, ductility, toughness, crack characteristics, and tunnel boring machine (TBM) thrust force. Simultaneously, numerical simulation was performed using finite element analysis. The mechanical characteristics of the geopolymer composite with a fiber content of 1% were used. The results demonstrated that the flexural performance and load-deflection response of the precast TLSs were satisfactory. Furthermore, the numerical results were capable of predicting and realistically capturing the structural behavior of precast TLSs. Therefore, fiber-reinforced slag-based geopolymer composites can be applied as precast TLSs.

• 지질공학
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• 제19권4호
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• pp.483-492
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• 2009

터널 및 지하구조물 시공 중 굴착 대상 지반에 대한 정확한 정보 획득은 작업의 효율성과 안전성을 위해 매우 중요하다. 본 연구에서는 굴착 중 굴진 대상 암반의 지질 구조를 신속하고 정확하게 감지하기 위하여 천공탐사 기법을 이용하였다. 유압 착암기 천공 시 발생하는 천공속도, 회전압, 피드압 등의 기계량을 측정하여 분석하였으며, 이를 통해 암석과 지질 구조적 특성에 의해 변화되는 암반 특성을 평가 하였다. 터널 시공현장에서 굴착 중 획득된 천공데이터 분석에 의해 평가된 암반 정보는 굴착 전 수행된 선진수평시추 및 TSP 탐사 결과와 비교하여 신뢰성을 검토하였으며, 그 결과 천공 데이터의 변화가 암반 특성 및 불연속면 예측을 위해 효율적으로 활용될 수 있음을 확인하였다.

• 터널과지하공간
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• 제4권2호
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• pp.144-155
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• 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.

• 한국기계가공학회지
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• 제18권1호
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• pp.38-45
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• 2019

In this paper, the stability of the tunnel boring machine (TBM), used in tunnel excavation, according to the thrust force of the thrust jack was investigated. The existing hydraulic cylinder analysis method is fluid-structure interaction (FSI) analysis, where all of the flow setting and dynamic characteristics should be considered. Therefore, there is a need for a method to solve this problem simply and quickly. To facilitate this, the theoretical pressure in the hydraulic cylinder was calculated and compared with the analytical and experimental results. In the case of the analysis, the pressure generated inside the cylinder was analyzed statically, considering the operating characteristics of the shield TBM, and the stress and pressure were calculated. This method simplifies the analysis environment and shortens the analysis time compared to the existing analysis method. The obtained theoretical and analytical data were compared with the measured data during actual tunneling, and the analysis and experimental data showed a relative error of approximately 23.89%.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.562-570
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• 2010

This study was conducted to estimate the number of disc cutter consumption and to predict amount of disc cutters when a shield TBM(Tunnel Boring Machine) of the Han Riverbed Tunnel was applied. In fact, it is almost impossible to change the machine after starting the excavation using the shield TBM method. Therefore, it is important to design an appropriate equipment in the shield method - an efficiency choice of the operation equipment plays a key role in the shield tunnel processing. For the above reason, the disc cutter consumption prediction is quite important so that the detailed analysis is required. A number of disc cutter consumption was predicted by the three methods, viz. KOMATSU, MITSUBISHI and NTNU. In addition, the predicted results were compared with field data. The prediction of disc cutter consumption showed that 237 for KOMATSU, 501 for MITSUBISHI, and 634 for NTNU, respectively. However, a total number of 1,263 disc cutter consumption were investigated during the tunnel construction. It was found that there was a huge difference between the predicted and real values of the disc cutter consumption. The more detailed investigation showed that the disc cutter was worn out bluntly in the northbound tunnel, meanwhile it was worn out sharply in the southbound tunnel. In particular, the disc cutter consumption in the southbound tunnel was increased rapidly because of rear abrasion for remaining mucks in the chamber.