• Title/Summary/Keyword: urban tunnelling

Search Result 162, Processing Time 0.021 seconds

Ground behaviour according to ground water locations due to tunnelling below shallow foundation by laboratory model test (실내모형시험을 통한 얕은 기초 하부에서 터널굴착 시 지하수위 위치에 따른 지반거동)

  • Lee, Hyun-Gu;Kong, Suk-Min;Oh, Dong-Wook;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.20 no.3
    • /
    • pp.575-592
    • /
    • 2018
  • Tunnelling is getting more important solutions for problems induced by the growth population in urban areas. Many studies on tunnelling below existing structure are carried out by many researchers. In general, however, ground water condition is ignored for most of researches using laboratory model test, so far. In case of ground behavior, error can occur if the result of effective stress related to hydraulic condition can't be taken into considerations. In this study, therefore, laboratory model test and the close range photogrammetry were conducted to investigate behaviour of ground and shallow foundation using newly device drainage system which is available to express the ground water condition. Also, numerical analysis was carried out to compare to results from the laboratory model test, and was performed with two methods, one is plastic and the other one is fully coupled analysis. Results from those two methods were compared to that of the laboratory model test.

Analysis of pile load distribution and ground behaviour depending on vertical offset between pile tip and tunnel crown in sand through laboratory model test (실내모형시험을 통한 사질토 지반에서 군말뚝과 터널의 수직 이격거리에 따른 하중분포 및 지반거동 분석)

  • Oh, Dong-Wook;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.19 no.3
    • /
    • pp.355-373
    • /
    • 2017
  • Tunnelling in urban areas, it is essential to understand existing structure-tunnel interactive behavior. Serviced structures in the city are supported by pile foundation, since they are certainly effected due to tunnelling. In this research, thus, pile load distribution and ground behavior due to tunnelling below grouped pile were investigated using laboratory model test. Grouped pile foundations were considered as 2, 3 row pile and offsets (between pile tip and tunnel crown: 0.5D, 1.0D and 1.5D for generalization to tunnel diameter, D means tunnel diameter). Soil in the tank for laboratory model test was formed by loose sand (relative density: Dr = 30%) and strain gauges were attached to the pile inner shaft to estimate distribution of axial force. Also, settlements of grouped pile and adjacent ground surface depending on the offsets were measured by LVDT and dial gauge, respectively. Tunnelling-induced deformation of underground was measured by close range photogrammetric technique. Numerical analysis was conducted to analyze and compare with results from laboratory model test and close range photogrammetry. For expression of tunnel excavation, the concept of volume loss was applied in this study, it was 1.5%. As a result from this study, far offset, the smaller reduction of pile axial load and was appeared trend of settlement was similar among them. Particulary, ratio of pile load and settlement reduction were larger when the offset is from 0.5D to 1.0D than from 1.0D to 1.5D.

Analysis on the behavior of shield TBM cable tunnel: The effect of the distance of backfill grout injection from the end of skin plate (뒷채움 주입 거리에 따른 전력구 쉴드 TBM 터널의 거동 특성 분석)

  • Cho, Won-Sub;Song, Ki-Il;Ryu, Hee-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.16 no.2
    • /
    • pp.213-224
    • /
    • 2014
  • 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.

A Study on the Pile Behaviour Adjacent to Tunnel Using Photo Imaging Process and Numerical Analysis (Photo Imaging Process 기법 및 수치해석을 이용한 터널주변 파일기초거동에 대한 연구)

  • Lee Yong-Joo
    • Journal of the Korean Geotechnical Society
    • /
    • v.21 no.9
    • /
    • pp.87-102
    • /
    • 2005
  • In the congested urban areas, tunnelling close to existing structures or services often occurs due to the lack of surface space so that tunnelling-induced ground movements may cause a serious damage to the adjacent structures. This study focused on the two dimensional laboratory model pile-soil-tunnelling interaction tests using a close range photogrammetric technique. Testing equipments and procedures were Introduced, particularly features of aluminium rods regarded as the frictional granular material. The experimental result showed that the photo imaging process by the VMS and EngVis programs proved to be a useful tool in measuring the pile tip movements during the tunnelling. Consequently, the normalised pile tip movement data for the influence zones can be generated by the laboratory model tests using the Photogrammetric technique. This study presents influence zones associated with the normalized pile tip settlements due to tunnelling in the cohesionless material. The influence zones were Identified by both a laboratory model test and a numerical analysis. The normalized pile tip movements from the model test were in good agreement with the numerical analysis result. The influence zones proposed in this study could be used to decide the reasonable location of tunnel construction in the planning stage. However, the scale of model pile and model tunnel sizes must be carefully adjusted as real ones for practical application considering the ground conditions at a given site.

Developments of monitoring system to measure sound absorbing coefficient and structural stability of sound absorbing panel on the concrete track in the urban train tunnel (도시철도 터널 내부 콘크리트 도상 국소공명흡음판의 흡음계수 및 구조안정성 평가를 위한 계측시스템 개발)

  • Oh, Soon-Taek;Lee, Dong-Jun;Lee, Dong-Hoon
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.19 no.1
    • /
    • pp.1-9
    • /
    • 2017
  • In this study, a test-bed system simulated a tunnel and concrete track is tested on cite and invested an allowed limit of multi-layered sound absorbing panel for reducing noise reflected on the concrete track in train tunnel considering the criteria and limitation on the theoretical back ground. The studied results are an effective evaluating system of the sound absorbing coefficient influenced fluid effects depending on the vehicle speed in the urban train tunnel and measuring not only structural behaviors of maximum displacement and acceleration of the panel but also dynamic characteristics of damping ratio and natural frequency.

Influencing factors for abrasive flow rate and abrasive flow quality of abrasive injection waterjet systems for tunnel excavation (터널굴착용 투입형 연마재 워터젯 시스템의 연마재 투입량과 유동성에 미치는 영향 인자)

  • Joo, Gun-Wook;Oh, Tae-Min;Cho, Gye-Chun
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.16 no.4
    • /
    • pp.417-430
    • /
    • 2014
  • A new rock excavation method using an abrasive waterjet system is under development for efficiently creating tunnels and underground spaces in urban areas. In addition, an appropriate abrasive flow rate and abrasive flow quality are important for the new rock excavation (cutting) method using an abrasive waterjet system. This study evaluated the factors influencing the abrasive flow rate and abrasive flow quality, specifically the abrasive pipe height, length, tortuosity and inner diameter, through experimental tests. Based on the experimental test results, this study suggested optimal conditions for the abrasive flow rate and abrasive flow quality. The experimental results can be effectively utilized as baseline data for rock excavation methods using an abrasive waterjet system in various construction locations such as tunnels near urban surroundings, utility tunnels, and shafts.

Applicability examinations of induced drainage system for reduction of uplift pressure in underpass structures: Numerical study (지하차도 부력저감을 위한 유도배수공법의 적용성 검토: 수치해석적 연구)

  • Jo, Seon-Ah;Jin, Gyu-Nam;Sim, Young-Jong;Cho, Gye-Chun
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.15 no.2
    • /
    • pp.123-134
    • /
    • 2013
  • Urban underground structures at low ground elevations (i.e. shallow substructures) unlike typical tunnel structures are subjected to low overburden and high water pressures. This often causes the underground structures to become damaged. Various conventional methods for the urban underpass structures such as dead weight increasement, round anchors, and tension piles, are significantly conservative and provok concerns about the costly, time-consuming installation process. Recently, permanent drainage system becomes to widely use for supplementing the conventional method's shortcomings, but, it is applied without the considerations for ground conditions and water table. In this study, therefore, numerical analyses are performed with various parameters such as groundwater level, wall height, and ground conditions in order to establish design guidelines for induced drainage system which is a kind of the permanent drainage method constructed at the Y-area. According to the numerical results, the induced drainage system is very effective in reducing the uplift pressure that acts on the base of underpass structures.

Study on key safety hazards and risk assessments for small section utility tunnel in urban areas (도심지 소단면 터널식 공동구의 핵심 안전 위험요소 및 위험성 평가 연구)

  • Seong, Joo-Hyun;Jung, Min-Hyung
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.20 no.6
    • /
    • pp.931-946
    • /
    • 2018
  • In line with the increased usability of utility pipe conduits in urban areas, construction and R&D activities of utility tunnel, incorporated with the shield TBM method, are actively under way. The utility tunnels are installed through underground excavation, and thus are relatively weak in terms of construction safety. However, hazards associated with the utility tunnel construction have not been properly identified, despite the introduction of a policy to the 'Design for Safety' for the purpose of reducing accident rates in the construction industry. Therefore, in this study, following the derivation of hazards associated with utility tunnel, these hazards were then used as the basis to uncover key safety hazards requiring extensive management in a field, which were then used to conduct a risk assessment having applied the matrix method so that the results can be utilized in risk assessment during the stages of utility tunnel planning, design, and construction, while also serving as a data reference.

A study on the machine load on shield advancing between soil ground and mix ground included core stone (토사지반과 핵석이 포함된 복합지반에서 쉴드TBM 굴진 시 장비부하에 관한 연구)

  • Kim, Ki-Hwan;Kim, Hyouk;Mun, Cheol-Hwa;Kim, Young-Hyu;Kim, Dong-Ho;Lee, Jae-Yong
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.20 no.6
    • /
    • pp.1039-1048
    • /
    • 2018
  • In urban tunnel construction, most of the Shield TBM method is applied to secure the safety of buildings and to minimize risks. On the other hand, in the urban development process, landfills are often embanked or improving in many cases, so that the boundary between the surface and the rock is often heterogeneous. In case of ground condition such as alluvial soil, granite, decomposed granite, core stone and rock with various layers, datas on shield TBM advancing according to each ground condition are analyzed, The characteristics of machine load were compared and analyzed. As a result, it can be predicted that the change of ground condition can be predicted by the tendency of discharge volume, thrust force and cutting wheel torque when the cutter is checked and replaced regularly on advancing under maintaining the design slurry pressure.

A study on the fire smoke diffusion delay strategy in a great depth underground double deck tunnel junction (대심도 복층터널 교차로 화재연기 확산지연 방안 연구)

  • Shin, Tae-Gyun;Moon, Jung-Joo;Yang, Yong-Won;Lee, Yun-Taek;Han, Jae-Hee
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.21 no.1
    • /
    • pp.115-126
    • /
    • 2019
  • Recently, in order to solve the traffic congestion in urban areas and to improve the peripheral environment, research on the design and construction technology development of great depth underground double-deck tunnel is under way by using the underground space in the urban area. The network type double-deck tunnel is in the form of an intersection with a small cross section and a steep slope as per construction at the base of a flatland, so that the fire smoke spreads rapidly in case of fire, which is expected to cause damage of human life. Therefore, this study is analyzed the delay effect of fire smoke diffusion according to the installation and non - installation of delay system for fire smoke diffusion at the intersection. Fire fumes were delayed up to 270 seconds when the delay system for fire smoke diffusion was installed at the intersection and it is analyzed that the greater the operating area of the delay system for fire smoke diffusion, the more preventable the damage of human life of the intersection.