Cable Tunnel Research Articles

국산 커터헤드를 장착한 직경 3.6 m 토압식 쉴드TBM의 제작과 현장적용성 분석

ABSTRACT: A domestic cutterhead with the diameter of 3.6 m was designed and manufactured in this study. Then, it was attached to an existing earth-pressure balanced shield TBM to excavate a cable tunnel with the length of 1,275 m. Especially, the procedures for TBM cutterhead design and its corresponding performance prediction were also summarized. From field data analyses of the refurbished shield TBM, its maximum advance rate was recorded as 14.4 m/day. Penetration depths of disc cutters were found to be approximately 4 mm/rev, which is equal to the maximum penetration depth designed for the strongest rock strength condition in th e target tunnel. Every TBM operating thrust and cutter normal force during TBM driving was much smaller than their corresponding maximum capacities. When cutter acting forces recorded in the field were analyzed, their prediction errors by the CSM model were very high for weak rock conditions. In addition, rock strength showed very close relationships with cutter normal force and penetration depth.Keywords: TBM, Cutterhead, Refurbishment, Disc cutter, Advance rate, Excavation performance

Migrants, Drugs and Xenophobia: The Case of Whoonga Park in Durban

Whoonga, also known as “nyaope” in Cauteng and sugars in Chatsworth, is a street drug that has been widely used in South Africa from around 2010. It is most prevalent in the townships around Durban where rates of poverty and unemployment are very high. Whoonga is a highly lethal and addictive concoction that leads to anxiousness, aggression, and stomach cramps. Whoonga Park was an area in the Durban inner city which included a network of storm water and cable tunnels which, according to police, were used by criminals, allegedly foreign migrants addicted to whoonga, to carry out crime in surrounding suburbs such as Glenwood, Umbilo, and Glenmore. This article, based on qualitative research, examines the prevalence of the drug, its effects on users, and the reaction of residents, civic organisations and the Ethekweni Municipality to Whoonga Park and its residents, and how this reflects xenophobic attitudes among locals who associate foreign migrants and refugees with being drug lords and with being responsible for destroying local communities.

Optimum operating conditions of a multi-hammer drilling machine assessed using a linear percussion test

To minimize social cost and to avoid existing obstacles (e.g., buildings, buried pipes, rivers, and ocean), cable and electricity tunnels are constructed mainly using trenchless technology. We have developed a new method for micro-tunnel excavation using a multihammer drilling machine and identified the optimum operating conditions of the system. A linear percussion testing system was constructed to acquire rock drilling data. The tests were conducted under various air pressures and RPMs consistent with field conditions. Three classes of rock specimens in terms of strength (i.e., hard, medium, and moderate rock) were tested. The test results yielded the optimum operating conditions of the multi-hammer drilling machine according to rock strength.

이상대 판정기법을 활용한 지하매설물 탐사

급격한 도시화 및 산업화는 전력구를 비롯한 공동구의 수요를 증가시키고 있다. 하지만 기존 지하매설물, 특히 전력구에 대한 불충분한 정보와 지하매설물의 무분별한 건설로 인해 최근 도심지 내 새로운 지하매설물을 건설하는 것이 매우 어렵다. 뿐만 아니라, 전력구를 비롯한 지하매설물이 건설된 위치와 방향에 대한 부족한 정보는 신규 지하매설물의 계획노선을 설정하는데 많은 문제를 야기시키고 있다. 이러한 문제를 해결하기 위해서 본 연구에서는 기존의 전기비저항 탐사방법과는 다른 이론적 방법으로 해결하고자 하였다. 전력구를 비롯한 지하매설물이 건설된 지반에서 가우스 법칙과 라플라스식을 이용하여 전기장 해석이 수행하였다. 전력구의 방향, 전력구의 위치, 전력구의 전기전도도 등의 함수로 표현된 전기비저항 이론식은 전기장해석을 통해서 획득하였다. 이론식을 검증하기 위해서 현장실험이 수행되었으며 현장실험 결과, 지반 내 지하매설물의 위치와 방향을 오차범위 내에서 예측하였다. Rapid urbanization and industrialization have caused increased demand for underground structures such as cable, and other utility tunnels. Recently, it has become very difficult to construct new underground structures in downtown areas because of civil complaints, and engineering problems related to insufficient information about existing underground structures, cable tunnels in particular. This lack of information about the location and direction-of-travel of cable tunnels is causing many problems. To solve these problems, this study was focused on the use of geophysical exploration of the ground in a way that is theoretically, different from previous electrical resistivity surveys. An electric field analysis was performed on the ground with cable tunnels using Gauss' law and the Laplace equation. The electrical resistivity equation, which is a function of the cable tunnel direction, the cable tunnel location, and the electrical conductivity of the cable tunnel, can be obtained through electrical field analysis. A field test was performed for the verification of this theoretical approach. A field test results provided meaningful data.

Structural Behavior of Thin-Walled Concrete-Filled Steel Tube Used in Cable Tunnel: An Experimental and Numerical Investigation

One steel grid and five thin-walled concrete-filled steel tubes (CTST) used as the supports of tunnel were tested in site for investigating the mechanical behavior. The mechanical influences of thickness, node form, and concrete on CTST were gained and compared with the impacts on steel grid. It is indicated that high antideformation capacity of CTST improved the stability of surrounding rock in short time. The cementitious grouted sleeve connection exhibited superior flexibility when CTST was erected and built. Although the deformation of rock and soil in the tunnel was increasing, good compression resistance was observed by CTST with the new connection type. It was also seen that vault, tube foot, and connections were with larger absolute strain values. The finite element analysis (FEA) was carried out using ABAQUS program. The results were validated by comparison with experimental results. The FE model could be referred by similar projects.

Laboratory Model Test Study of Tunnel Anchor

A laboratory model test of tunnel anchor was conducted to investigate its pullout mechanism and bearing capacity. Surface and rock deformation, strain and stress were measured during the entire model test process. The results show that: under pull out load, tensile failure first occurs in top surface rock near the anchor, then shear failure occurs in anchor-rock interface and rock around the anchor. The failure surface is inverted cone from the anchor bottom. Under 50 times design cable force tunnel rock is in elastic stage, suggesting that current tunnel anchor design is quite conservative and can be further optimized.

Research on Application of the Television Image Logging Technique in the Englineering Test Borehole

A whole image of a reconnaissance well with acoustic time, acoustic amplitude and video can be obtained by an image logging apparatus. The results (feature dip/strike and azimuth, joint density analysis, synthetic cores, feature stereograms, rose diagrams, deviation plots of borehole) of image logging are displayed in the form of well explained figures, intuitionistic, vivid and easy to be analyzed. Image well logging technique has played an important role in oil and gas exploration, but its application in construction engineering is still in its initial testing phase. The hardware constitution and the basic principle of RG image logging apparatus system are simply introduced, and its application effects in transmission cable tunnel project are also displayed in this paper

Field test of optical and electrical fire detectors in simulated fire scenes in a cable tunnel

This paper presents the testing results of three types of fire detectors: electrical heat sensing cable, optical fiber Raman temperature sensing detector, and optical fiber Bragg grating (FBG) temperature sensing detector, in two simulated fire scenes in a cable tunnel. In the small-scale fire with limited thermal radiation and no flame, the fire alarm only comes from the heat sensors which directly contact with the heat source. In the large-scale fire with about 5 °C/min temperature rising speed within a 3-m span, the fire alarm response time of the fiber Raman sensor and FBG sensors was about 30 seconds. The test results can be further used for formulating regulation for early fire detection in cable tunnels.

Engineering design of the IFMIF EVEDA reference test cell and key components

The latest design updates of the IFMIF-EVEDA reference test cell (TC) are described with emphasis on the following key components: active cooling pipes for concrete biological shielding walls and stainless steel liner, TC gas leak tight boundary, and piping and cabling inside TC and between TC and the access cell (AC). Water cooling is adopted for concrete shielding walls and the liner. Buried pipes are selected for active cooling of the TC surrounding shielding walls; directly welded pipes on the liner are used to remove nuclear heat of the liner. Technical features and layout of the cooling pipes are preliminary defined. The TC vacuum boundary, which includes the TC liner, an independent TC cover plate, a rubber based sealing gasket, and welding seams between interface shielding plugs and TC liner, is described. Engineering design of the piping and cabling plugs as well as the arrangement of pipes and cables under the TC covering plate and the AC floor are updated. Pipes and cable tunnels inside the shielding plugs are arranged with several bends for minimizing neutron streaming from inside to outside of the TC. Pipes, cables, and the corresponding penetrations between the TC and the AC are carefully arranged for convenient access and maintenances.

The study on the effect of fracture zone and its orientation on the behavior of shield TBM cable tunnel

최근, 기후변화에 따른 하절기 기온 상승으로 인하여 전력사용량이 급증하고 있다. 이에 따라 발전시설이 새로 준공되고 있으며, 생산된 전기를 도심지로 송전할 초고압 송전선로 시설의 필요성이 증가하고 있다. 쉴드 TBM을 이용한 기계화 터널 굴착공법은 기존의 재래식 공법에 비해 지반 침하와 지반에 전달되는 진동을 최소화 할 수 있는 장점이 있다. 도심지에서의 전력구터널 굴착을 위한 쉴드 TBM 공법이 증가함에도 불구하고, 전력구 쉴드 TBM 터널의 거동 분석에 관한 연구는 미비한 실정이다. 본 연구에서는 파쇄대를 포함하는 복합지반에서 파쇄대 너비, 각도에 따른 전력구 쉴드 TBM 터널의 거동 특성을 분석하고, 인터페이스 요소를 적용한 파쇄대와 연속체로 모델링한 파쇄대의 거동 특성을 비교하고자 한다. 쉴드 TBM을 이용한 터널 굴착은 3D FEM을 이용하여 시뮬레이션 하였다. 파쇄대의 방향과 크기의 변화에 따라 세그먼트 라이닝에 작용되는 축력, 전단력, 휨 모멘트를 검토하고 지표면에서의 연직변위를 분석하였다. FEM 해석으로 얻어진 결과와 안정성 분석에 기초하여, 전방의 파쇄대를 예측하여 터널 구조물의 안정성을 확보할 수 있다. Recently, the temperature rise in the summer due to climate change, power usage is increasing rapidly. As a result, power generation facilities have been newly completed and the need for ultra-high-voltage transmission line for power transmission of electricity to the urban area has increased. The mechanized tunnelling method using a shield TBM have an advantage that it can minimize vibrations transmitted to the ground and ground subsidence as compared with the conventional tunnelling method. Despite the popularity of shield TBM for cable tunnel construction, study on the mechanical behavior of cable tunnel driven by shield TBM is insufficient. Thus, in this study, the effect of fractured zone ahead of tunnel face on the mechanical behavior of the shield TBM cable tunnel is investigated. In addition, it is intended to compare the behavior characteristics of the fractured zone with continuous model and applying the interface elements. Tunnelling with shield TBM is simulated using 3D FEM. According to the change of the direction and magnitude of the fractured zone, Sectional forces such as axial force, shear force and bending moment are monitored and vertical displacement at the ground surface is measured. Based on the stability analysis with the results obtained from the numerical analysis, it is possible to predict fractured zone ahead of the shield TBM and ensure the stability of the tunnel structure.

Analysis on the behavior of shield TBM cable tunnel: The effect of the distance of backfill grout injection from the end of skin plate

최근, tunnel boring machine (TBM)을 이용한 도심지 지중 전력구 터널 건설이 증가하고 있다. 쉴드 TBM을 이용한 기계화 터널 굴착 공법은 재래식 공법에 비해 지반침하를 최소화 하고 발파에 의한 진동을 줄일 수 있는 장점이 있다. 국내에서는 earth pressure balance(EPB) 쉴드 TBM이 주로 사용되고 있다. 그러나 전력구 터널 굴착을 위한 쉴드 TBM 공법이 증가함에도 불구하고, 전력구 쉴드 TBM 터널의 거동 분석에 관한 연구는 미비한 실정이다. 본 연구에서는 후방주입 거리에 따른 전력구 쉴드 TBM 터널의 거동 특성을 분석하고, 굴착면 지반 손실과 후방주입 거리와의 상관관계를 도출하고자 한다. 쉴드 TBM을 이용한 터널 굴착은 3D FEM을 이용하여 시뮬레이션 하였다. 뒷채움 그라우트가 설치되는 거리의 변화에 따른 축력, 전단력, 휨 모멘트와 같은 단면력을 검토하고 지표면에서의 연직 변위를 분석하였다. 또한, 유한요소해석으로 얻어진 결과와 안정성 분석에 기초하여, 지반과 터널 구조물의 안정성을 확보할 수 있는 뒷채움재 주입시기를 결정할 수 있다. Recently, tunnelling with TBM is getting popular for the construction of cable tunnel in urban area. Mechanized tunnelling method using shield TBM has various advantages such as minimization of ground settlement and prevention of vibration induced by blasting that should be accompanied by conventional tunnelling. In Korea, earth pressure balance (EPB) type shield TBM has been mainly used. Despite the popularity of EPB shield TBM for cable tunnel construction, study on the mechanical behavior of cable tunnel driven by shield TBM is insufficient. Especially, the effect of backfill grout injection on the behavior of cable tunnel driven by shield TBM is investigated in this study. Tunnelling with shield TBM is simulated using 3D FEM. The distance of backfill grout injection from the end of shield skin varies. Sectional forces such as axial force, shear force and bending moment are monitored. Vertical displacement at the ground surface is measured. Futhermore, the relation between volume loss and the distance of backfill grout injection from the end of skin plate is derived. Based on the stability analysis with the results obtained from the numerical analysis, the most appropriate injection distance can be obtained.

Analysis on the behavior of shield TBM cable tunnel: The effect of the distance of backfill grout injection from the end of skin plate

Analysis on the behavior of shield TBM cable tunnel: The effect of the distance of backfill grout injection from the end of skin plate

Research of the Self-Balanced Cable Support System for Large Cross-Section Cable Tunnel

The cable support system in large cross-section cable tunnel, which can solve the cable laying problem of big cross section cable and multi-loop cable effectively, gradually become the development trend of urban electricity transmission. Combined with the structure feature of large cross section shield tunnel, a new type of self-balanced shield tunnel cable support system is proposed. The safety and rationality of this system has been validated by the structure calculation, the finite element analysis of ADINA and the full scale model test. The analysis shows that the system has some advantages, such as excellent whole mechanical characteristics, strong adaptability, convenient construction and low cost. The system can fully satisfy all requirements of the cable tunnel construction and all functions of operation. The stress distribution of the structure is relatively homogeneous, the bearing capacity of components and the global stability of it also meet the requirements. With the test load which is about 1.5 ~ 4.0 times as large as design load, the support system displacement is 0.65 ~ 2.5 mm, which shows that the structure is safe and reliable. The research achievements can provide theoretical basis and experimental basis for the design of large cross-section cable tunnel.

Model Test Study on a Large-Section Cable Tunnel

The profile layout rationality and internal stress structure of a large-section cable tunnel and a cable-laying scheme at splicing locations were studied through full-scale model test. The full scale shield tunnel which the diameter was 6m was built on the ground. The model tests test the displacement of cable bearers, the coupling area between horizontal beam and steel ring, the coupling area between horizontal beam and steel pillar, edge beam and center beam under design loads, and the safety and reliability of an arc steel framing system that supports the cable load inside the cable tunnel during the operation stage were demonstrated. The cable-laying schemes for the cross section and straight-through-type and T-type couplings of a large-section cable tunnel were optimized through experiment on actually laid-out cables. For the section layout of a large-section cable tunnel, it is believed that the double-deck scheme prevails over the single-deck scheme, and such a cable-splicing scheme can meet the cable-laying requirement.

Computational Fluid Dynamics Simulation of Ventilation Effect of a Large Cross-Section Cable Tunnel

The finite element software ADINA was employed in this paper to study the ventilation effect of a large cross-section cable tunnel by using a computational fluid dynamics method. The temperature and ventilation zoning inside a cable tunnel were determined according to the characteristics of the large cross-section cable tunnel. With the ambient tunnel characteristics and tunnel cross-section layout being taken into consideration, a three-dimensional model for large cross-section cable tunnels was established; the computations indicate that the main influential factors of ventilation effect of large cross-section cable tunnels are intake airflow rate, intake air temperature, exhaust airflow rate, ventilation duration, tunnel length, fire door layout, and so on. The average air velocity in the tunnel was about 60 % of the intake airflow rate. The intake air temperature has much impact on tunnel temperature distribution within a range of 30 m away from the tunnel origin, as shown by a significant cooling effect when intake air temperature falls; whereas the intake air temperature has less impact on tunnel temperature distribution beyond 30 m from the tunnel origin.

The Study on Analog Module of Underground Cables Environmental Monitoring System Based on CAN Bus

In order to online real-time monitor of underground cable tunnel environment and running state, the timely discover and preclude troubleshooting that may occur, and to ensure the safety and reliability of the cable running. This article describes the underground cable environment online monitoring system platform based on CAN bus technology, and which is in its application layer using a common international CANopen protocol. This paper focuses on the realization of analog modules. It provides timely and effective monitoring method for real-time monitoring of the underground cable environment.

基于线型感温火灾探测器的电缆隧道火灾实验

The engineering suitability of typical linear heat detectors for early fire detection in cable tunnels was explored.In cable tunnel environments,an experimental platform was established based on exiting linear temperature fire detectors,including temperature sensing cables,fiber Raman detectors and fiber grating detectors,then two different fire experimental scenes were set up,and the temperature variation and fire detector response time were recorded in the processing of fire simulation.The experiments show that only directly contacting heat detectors can give an alarm response and other non-contact detectors are unable to respond the small-scale fire because a small amount of thermal radiation has no flame for the beginning of the fire.Furthermore,for massive fire,the alarm response time of both fiber Raman sensing heat fire detector and fiber grating sensing fire detector is about 30 s,the temperature over the fire recorded by a thermocouple is less than 35 ℃ in 60 s,while the temperature rising is more than 5 ℃ / min within the range of ± 3 m.According to the technical characteristics of the three detectors,the engineering suitability of the typical linear heat detectors in cable tunnels early fire detection is analyzed,which can provide technical support for establishing the design specifications of fire alarm.

Research on Safety Inspection of Electric Cable Tunnel with Masonry Structure

According to inspection and assessment technology and method for the ground masonry structure, this paper presents the inspection method and results for an electric cable tunnel with masonry structure. The contents of the inspection include masonry bricks strength grading, masonry mortars strength grading, concrete strength for crest slab, reinforcement of crest slab and appearance of masonry structure. And the technologies for identification are introduced. Therefore, the key problems for safety inspection of electric cable tunnel with masonry structure are solved. The inspection items, process and identification technologies presented in this paper are effective and applicable for electric cable tunnel with masonry structure.

A Study of a Fire Behavior in a Miniature Simulation of a Cable Tunnel - from the viewpoint of fire detection -

A Study of a Fire Behavior in a Miniature Simulation of a Cable Tunnel - from the viewpoint of fire detection -

Simulation Study on Value of Cable Fire in the Cable Tunnel

The cable tunnel fire spreads rapidly, the high-temperature toxic smog accumulates, and the fire fighting is of great difficulties. Once the fire hazard occurs, serious economic losses and casualties will be caused. Through the numerical simulation of the cable tunnel fire process, and the analysis and summary of simulation results, conclusions are drawn of flue gas spread situation and the section temperature changes during the generating process of cable tunnel fires. Then the best fire fighting time is proposed, which provides references for development of fire-fighting measures and selection of the fire protection system.