• Geomechanics and Engineering
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• 제35권5호
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• pp.487-497
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• 2023

Penetration rate (PR) and penetration depth (Pe) are crucial parameters for estimating the cost and time required in tunnel construction using tunnel boring machines (TBMs). This study focuses on investigating the impact of rock strength on PR and Pe through full-scale experiments. By conducting controlled tests on rock-like specimens, the study aims to understand the contributions of various ground parameters and machine-operating conditions to TBM excavation performance. An earth pressure balanced (EPB) TBM with a sectional diameter of 3.54 m was utilized in the experiments. The TBM excavated rocklike specimens with varying uniaxial compressive strength (UCS), while the thrust and cutterhead rotational speed were controlled. The results highlight the significance of the interplay between thrust, cutterhead speed, and rock strength (UCS) in determining Pe. In high UCS conditions exceeding 70 MPa, thrust plays a vital role in enhancing Pe as hard rock requires a greater thrust force for excavation. Conversely, in medium-to-low UCS conditions less than 50 MPa, thrust has a weak relationship with Pe, and Pe becomes directly proportional to the cutterhead rotational speed. Furthermore, a strong correlation was observed between Pe and cutterhead torque with a determination coefficient of 0.84. Based on these findings, a predictive model for Pe is proposed, incorporating thrust, TBM diameter, number of disc cutters, and UCS. This model offers a practical tool for estimating Pe in different excavation scenarios. The study presents unprecedented full-scale TBM excavation results, with well-controlled experiments, shedding light on the interplay between rock strength, TBM operational variables, and excavation performance. These insights are valuable for optimizing TBM excavation in grounds with varying strengths and operational conditions.

• 터널과지하공간
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• 제8권1호
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• pp.67-73
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• 1998

This paper presents the results of deformation measurement and numerical analysis carried out to study the behaviour of the rock mass around large underground oil storage caverns. Displacements during excavation have been monitored using borehole extensometers which had been installed before the excavation of caverns proceeded. Numerical analysis has been carried out to examine the three-dimensional behaviour of rock and the face advance effect. The input parameters for this analysis were determined from the results of laboratory and field tests. The deformation modulus of the rock mass was determined from plate loading test at the site and in-situ stresses were measured from the overcoring method with USBM deformation gauge. The results from this study gave a clear picture for three-dimensional behaviour of the rock mass, hence would be used for the optimum design.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1484-1489
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• 2005

An inhomogeneous and anisotropic rock has different properties at different location. Thus, this refers to any of the properties which we may be measuring. There are two concepts of rock mass, namely, CHILE(Continuous, Homogeneous, Isotropic, Linear Elastic) material and DIANE(Discontinuous, Inhomogeneous, Anisotropic, Non-linear Elastic) rock. The former is essentially the properties of intact rock, the latter is essentially the properties governed by the structure of rock. In geotechnical aspect, the most important parameter is strength of rock or rock mass. In particular, characteristics of strength of rock mass depend upon the orientation of discontinuities And this orientation of discontinuities has different properties at different direction of excavation. Therefore, it needs for characterization of different properties of discontinuity orientation against different direction of excavation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1433-1437
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• 2010

The deep excavation work in Korean downtown is almost excuted near by existing structures and utility lines because of the diminution of available yard for construction. So, it was required more and more that the accurate control of displacement on the earth retaining system for minimizing the popular complaint and the damage from constructional accident. Automatic monitoring system is adopted in fracture zone for real time monitoring. In addition, Face mapping is carried out on the face of fracture zone according to excavation sequence. As the result of automatic monitoring system and face mapping, we was able to take the necessary reinforcement and changing excavation method within suitable time. This paper is informed about a stability case on the deep rock excavation site with fracture zone in urban area by automatic monitoring system.

• 터널과지하공간
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• 제6권4호
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• pp.326-334
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• 1996

In underground construction the multi-step excavation sequence is commonly adopted for the convenience of the underground work. A numerical simulation method which is capable of analyzing the effects of excavation sequence on the stability of the opening is greatly needed. In this study a two dimensional finite element code was developed based on the effective numerical algorithm for the multistep excavation. The practical applicability of the model was verified for the simplified excavation sequences.

• 터널과지하공간
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• 제3권1호
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• pp.54-62
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• 1993

In order to evaluate the necessity for the support during the excavation of the transport drift and use the data for design applications, laboratory testings of mechanical properties of rock samples and engineering rock mass classifications on this study site were performed. The values of RMR and Q-system are 68 and 11.8, respectively. Since these results were evaluated as good, this rock mass were determined to be unsupported. Full face excavation method was determined to be suitable for excavating this drift. In case of excavation, smooth blasting techniques must be carried out at the wall rock and the crown. However, considering the blast vibration etc. that have an effect on the surrounding rock mass, approximately less than 9kg of explosive charges per blast should be maintained.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.127-132
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• 2004

The third double-track construction part of work, called Chung Ang Railroad line(Deok-So$\∼$Won-Ju) is in progress and the personal museum located 330m from the starting point of Pal-Dang Tunnel(length=4,470m) line in the canyon is to be effected by rock blasting during the tunnel excavation work, especially museum articles and building itself. This paper is the example of application suitable tunnel rock blasting pattern for excavation after the case study about the investigation and analysis of rock blasting noise pollution during tunnel excavation work. The museum is a three-story building, RC concrete structure and is located 17m from the top of the tunnel, in the center of the double-track line. Comparing estimate vibration frequency with site vibration one, it can be verified the reasonable rock blasting noise pollution as improving the application of tunnel excavation rock blasting pattern. The above pattern has been selected economically and effectively and applied to our construction field.

• 한국철도학회논문집
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• 제12권2호
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• pp.321-328
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• 2009

기존 터널에 근접하여 절리암반 굴착시 사면의 적절한 보강방법 및 시기는 굴착사면과 터널과의 근접도, 굴착사면 경사는 물론 절리상황에 의해 영향을 받자만 현재까지는 경험적으로 결정되고 있다. 본 연구에서는 터널에 근접하여 절리암반 지반을 굴착시 굴착단계에 따른 굴착사변에서의 하중전이 특성과 터널거동과의 상관관계를 분석하기 위하여 절리각도와 굴착사면 경사를 영향인자로 한 대형 모형시험을 실시하였다. 시험결과, 터널변형은 터널 천정부 또는 바닥부에 근접한 절리면 굴착시 가장 크게 발생을 하였으며, 사면과 터널의 안정성은 굴착사면의 경사와 관련하여 굴착단계에 따라 변화하였다. 향후 본 연구결과를 활용하여 절리암반에서의 터널과 사면의 보강방안을 도출하고자 한다.

• 터널과지하공간
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• 제5권4호
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• pp.347-362
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• 1995

The purpose of this study was that manage effectively the excavation process of the transport tunnel in DONGHAE mine area by investigating the variationof the surface and groundwater flow system around the tunnel and neighbouring villages. Thus, the effect of excavation and water-prrofing process on the water system has been studied through the naked eye survey of the tunnel and the surface outcrop, joint survey, core drilling, the measurement of the surface water quantity, evapotranspiration and precipitation analysis, rock hydraulics approach, the pressure test of boreholes, the variation of the water level, and finally the numerical analysis. From above approachs, we derived the conclusion that the exhaustion of the surface water was not caused by the tunnel excavation on the groundwater system was minimized by effective water proofing process.

• 터널과지하공간
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• 제5권2호
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• pp.123-133
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• 1995

A two dimensional visco-plastic finite element model capable of handling the multistep excavaton was developed for investigating the effect of excavation-support sequences on the behaviour of underground openings in the jointed rock mass. Ubiquitous joint pattern was considered in the model and joint properties in each set were assumed to be identical. Passive, fully-grouted rockbolts were considered in the model. Visco-plastic deformations of joints and rockbolts were assumed to be governed by Mohr-Coulomb and von Mises yield criteria, respectively. With the ability of removing elements, the model can von Mises yield criteria, respectively. With the ability of removing elements, the model can simulate the multi-step excavation-support sequences. The reliability of the model to the stability analysis for the underground excavation in practice was checked by simulating the behavior of underground crude oil storage caverns under construction.