Effects of rock pillar width on the excavation behavior of parallel tunnels

Chen, S.L.; Lee, S.C.; Gui, Meen-Wah

doi:10.1016/j.tust.2008.05.006

Cited by 43 publications

(11 citation statements)

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“…Similar research with 3D-FE analyses targeted to twin mechanized tunneling interaction in soft ground is presented by Do et al Chang et al (1996), based on a case study of twin tunnels in Taiwan, propose a simpli ed method to estimate the safety factor for the pillar and qualitatively analyze measures capable of mitigating the interaction and preventing potential failures. Chen et al (2009) investigate the effects of the rockmass pillar width on the behavior of three and four parallel-branch circular and non-circular tunnels for a case study in Taiwan, via 2D-FE analyses, de ning W/D=2-4, as the critical pillar width to tunnel diameter ratio. Liu et al (2008) examine via 3D-FE analyses the interaction between non-circular, shallow, conventionally constructed tunnels in soft ground for a case study in Sydney, pointing out that the advance of the new tunnel signi cantly affects the existing, with the extent of the in uence depending on the relative distance between the tunnels.…”

Section: Literature Reviewmentioning

confidence: 99%

Three-dimensional Numerical Investigation of the Interaction Between Twin Tunnels

Chortis

Kavvadas

2021

Preprint

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The construction of twin tunnels is an obligatory guideline and a prevailing practice in either conventional or mechanized tunneling. Nevertheless, most of the design methods for calculating the tunnel loads focus on single tunnels, thus, neglecting the potential interaction between neighboring tunnels. The effect of such interaction can be significant, especially for closely-spaced twin tunnels. In this context, this paper investigates via parametric 3D Finite Element (3D-FE) analyses the interaction between deep, parallel-twin, circular and non-circular tunnels excavated with a conventional (non-TBM) method and supported with shotcrete lining. The numerical investigation focuses on the axial forces acting on the primary support of the tunnels by examining the effect of a wide range of geometrical (pillar width, overburden height, tunnel diameter and section (shape), lagging distance), geotechnical (strength and deformability of the surrounding rockmass, horizontal stress ratio), structural (thickness and deformability of the shotcrete lining) and construction parameters (full- or partial- face excavation and support of the tunnels). The results of the analyses indicate that the construction of the subsequent tunnel influences the loads of the precedent. The stress state of the single tunnel is used as the reference for the quantification of the interaction effect. The output is presented in normalized design charts of the quantified interaction effect on the axial forces, versus key geomaterial and geometry parameters to facilitate preliminary estimations of primary support requirements for twin tunnels.

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Section: Literature Reviewmentioning

confidence: 99%

Three-dimensional Numerical Investigation of the Interaction Between Twin Tunnels

Chortis

Kavvadas

2021

Preprint

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“…Mortazavi et al discussed the failure mechanism and studied the influence of geometry and strength parameters on the performance of rock pillar [4]. Chen et al analyzed the width effects of rock pillars in multi-line parallel tunnels and found that the interactions became increasingly obvious with the rock pillar width decrease [5]. Zhang and Goh studied the peak vertical stress in the rock pillar and identified the overlap plastic zones 6.…”

Section: State Of the Artmentioning

confidence: 99%

“…Taking the P-type cross-section tunnel with surrounding rock grade V as an example, the ultimate load on the middle rock pillar can be obtained by using Equation (5). L=4.0 m, a and H are known in the practical engineering.…”

Section: Vertical Stress Calculation Verification Analysismentioning

confidence: 99%

Stability Analysis of Middle Rock Pillar and Cross - Section Optimization for Ultra - Small Spacing Tunnels

Wang¹,

Kunpeng²,

Chen³

et al. 2018

JESTR

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The ultra-small spacing tunnel is a new tunnel type under the urban engineering environment, which not only has high requirements for deformation and settlement control, but also has great difficulty in construction technology. Since the middle rock pillar is the key part in the design and construction of ultra-small spacing tunnels, to explore the stability of the middle rock pillar in the ultra-small spacing (0-200 mm) subway tunnels, this study examined the Gangding-Shipaiqiao ultra-small spacing tunnels on Guangzhou Metro Line 3 in China by using ABAQUS and theoretical analysis, which mainly involved the plastic zone of the surrounding rock, the stress distribution and skew displacement effect of the middle rock pillar by defining the skew coefficient. The tunnel cross-sections of three different types were optimized, and a simplified calculation method was proposed with the load and ultimate bearing capacity of the middle rock pillar. Results show that the theoretical analysis of the bearing capacity of the middle rock pillar is essentially consistent with the results of numerical calculation. The conclusions obtained in the study are of important theoretical value to provide on-site engineering construction guidance.

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“…Such projects are generally deep-buried tunnels [15,19,20]. e tunnel engineering cross section uses a variety of cross types [21,22]: for example, the Russian cross tunnel uses a doublehole double-layer tunnel type; the Italian-Swiss highway in Milan's two-lane cross tunnel-type runs from horizontal to parallel and cross to vertical parallel; the newly constructed east-west Tozai subway tunnel in Japan uses a line pattern similar to the four-hole twist to intersect the existing Keishin line; the first phase of the Shenzhen subway project, from the Guomao Station to the Old Street Station [23] uses left and right overlapping structure of the line; Shanghai Metro Line 2 adopts the way of crossing up and down when crossing with Line 1 [24]. e vertical clear distance between the top and bottom is about 1 m. e above projects cover the main types of cross structures for proximity projects and more difficult studies such as shallow-buried three-dimensional cross tunnels with very large cross sections.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Structural Form and Excavation Model of Urban Metro Cross Transfer Station with Super Large Cross Section and Shallow Excavation

Lin

Chen

Yang

et al. 2020

Advances in Civil Engineering

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The construction of urban underground cross-interchange transfer subway stations often encounters the difficulties of shallow-buried, different surrounding rock, large spans and heights, congested road traffic, and surrounding buildings sensitive to the construction sequence. Therefore, there is a need for an underground project that controls the stability of underground space and ground subsidence. Based on the construction difficulties of a certain station (the maximum excavation area over 760 m2), this paper conducts a comprehensive selection design of the structure, construction mechanics response, and control technology of this type of interchange station structure and construction excavation. First of all, based on the design experience of large-scale underground transfer transportation engineering and taking full consideration of the stratum conditions, an “arch-wall” cross transfer structure method is proposed. The refined numerical analysis shows that the structure can fully utilize the stratum conditions to reduce the ground surface settlement. Then, in view of the stability of surrounding rock during the construction of a large section, based on the traditional large section excavation method, a construction method of “cross rock beam + heading method” was proposed. In order to verify the effect of the construction method, the three-dimensional detailed numerical model was used to simulate the construction conditions, and the mechanical response characteristics and displacement changes of surrounding rock under each excavation step are explored. Simultaneous interpreting with the traditional large section excavation method, the results show that the new method has advantages in controlling the stability of the surrounding rock. Meanwhile, in order to ensure the safe construction of the project, the self-developed multifunctional engineering test system for traffic tunnels is used to carry out a large-scale physical model experiment to simulate the entire process of the “arch-wall” cross transfer structure construction response characteristics. By analyzing the data of measuring points, the results show that the structure form and the excavation method cause the ground surface settlement, stress, and structural forces meet the requirements for safe construction. Finally, the station can be safely constructed under the new structure form and construction method. Therefore, the structure form and method proposed in this paper can be adapted to the large-scale underground structure under construction in complex environments.

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Effects of rock pillar width on the excavation behavior of parallel tunnels

Cited by 43 publications

References 1 publication

Three-dimensional Numerical Investigation of the Interaction Between Twin Tunnels

Three-dimensional Numerical Investigation of the Interaction Between Twin Tunnels

Stability Analysis of Middle Rock Pillar and Cross - Section Optimization for Ultra - Small Spacing Tunnels

Experimental Study on Structural Form and Excavation Model of Urban Metro Cross Transfer Station with Super Large Cross Section and Shallow Excavation

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