Determination of support pressure for tunnels and caverns using block theory

Prasad, V.V.R.; Dwivedi, R.D.; Swarup, Anil

doi:10.1016/j.tust.2013.03.006

Cited by 13 publications

(7 citation statements)

References 2 publications

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“…025 × e −0.2672Q +1.395 (12) The units of α are kN/m 3 . Therefore, the estimation correlation for surrounding rock pressure based on Q value and span d is obtained as follows (see Equations (13) and (14)):…”

Section: Establishment Of the Estimation Correlationmentioning

confidence: 99%

“…The units of P roof1 and P roof2 in Equations (11) and (12) are kPa, while those of d are m. J n -Joint group coefficient; J r -Joint roughness coefficient. P roof1 = P roof2 when J n = 9; P roof1 > P roof2 when J < 9; P roof1 < P roof2 when J n > 9.…”

Section: Establishment Of the Estimation Correlationmentioning

confidence: 99%

“…4) As shown in the local graph, smaller the Q value, worse is the quality of surrounding rock, and more obvious is the influence of span on the surrounding rock pressure. The units of Proof1 and Proof2 in Equations (11) and (12) are kPa, while those of d are m. Jn-Joint group coefficient; Jr-Joint roughness coefficient. Proof1 = Proof2 when Jn = 9; Proof1 > Proof2 when J < 9; Proof1 < Proof2 when Jn > 9.…”

Section: )mentioning

confidence: 99%

“…Regarding the distance from the inflection point of tangential stress above the arch top to the arch top as an indirect index, which is used to evaluate the stability of surrounding rock in tunnel excavations, Kong [11] analyzed the influence of Geological Strength Index (GSI from 20 to 80), the overburden depth (H from 40 m to 420 m), in-situ stress ratio (k 0 from 0.8 to 3) and excavation roof rise-to-span ratio on the surrounding rock pressure. Based on the block theory, Prasad et al [12] proposed a calculation method for surrounding rock pressure. Scussel et al [13] proposed a new approach to obtain tunnel support pressure for polyaxial state of stress.…”

Section: Introductionmentioning

confidence: 99%

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Study on a Surrounding Rock Pressure Calculation Method for Super-Large Section Highway Tunnels

Gao

Zheng

et al. 2019

Symmetry

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This paper presents new correlations for estimating the surrounding rock pressure of symmetrically shaped tunnels based on a symmetrical numerical model. Surrounding rock pressure is defined as the load acting on the support structure due to the deformation of the surrounding rock after tunnel excavation. Surrounding rock pressure is directly related to the selection of the lining structure and the determination of support parameters. The main challenge in designing and proceeding with the construction process is choosing a calculation method for the surrounding rock pressure for super-large sections, and this has been the focus of research among the tunnel research community. The excavation area of Liantang tunnel of Shenzhen Eastern Transit Expressway (China) is over 400 m2, making it the largest highway tunnel in the world so far. Based on this project, this paper analyses the applicability of various traditional methods of calculating the surrounding rock pressure for super-large section tunnels. In addition, based on the Tunneling Quality Index (Q), the factor of span is introduced into the method of calculating the surrounding rock pressure using the numerical simulation results of super-large symmetrical tunnels with different values of Q and different spans. Additionally, calculated correlations that could quickly estimate the surrounding rock pressure of tunnels are obtained. The comparison of surrounding rock pressures between the estimated and monitoring results of Liantang tunnel and more than 30 projects around the world effectively proves the rationality and universal applicability of the proposed correlations. This method could provide engineers and designers with a quick way to predict the surrounding rock pressure of deep super-large section underground structures during their design and construction stage.

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Section: Establishment Of the Estimation Correlationmentioning

confidence: 99%

Section: Establishment Of the Estimation Correlationmentioning

confidence: 99%

Section: )mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study on a Surrounding Rock Pressure Calculation Method for Super-Large Section Highway Tunnels

Gao

Zheng

et al. 2019

Symmetry

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“…Practice has proved that crossing the block structure in the karst area is not foolproof; for example, Deng [35] determined that the tunnel passing under the underground river, even if there is no fault, is affected by the recharge of the bedding layer and still carries the risk of experiencing great water inrush. From the actual dynamic excavation process, it can be seen from the theoretical analysis of block theory [36] that, under the tunnel excavation, a free surface is created, and that under the action of engineering and self-weight, development of the key block is started because the strength of the sliding surface was insufficient to resist the sliding power, and this may lead to interlocking multiblock instability. We plot the stereographic projections by identifying the occurrence information (according to the preliminary statistical characteristics of the appearance in Figure 5c), as shown in Figure 11; this type of intersection mode is mainly prone to instability and blockage in the vault, easily producing tetrahedral pyramidal blocks, and other types of blocks are generated depending on the fracture spacing [37,38].…”

Section: Basic Characteristics Of the Rock Mass Structure And Developmentioning

confidence: 99%

Study on the Control of Underground Rivers by Reverse Faults in Tunnel Site and Selection of Tunnel Elevation

Zhang

Huang

Liu

et al. 2019

Water

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Along with the need for western economic development, the number of long tunnel projects which go through mountains is constantly on the rise. In the process of construction, various disaster-causing structures are frequently exposed, which leads to many geological disasters. The traditional idea is that the reverse fault is not easily developed for an underground river, which means that the tunnel elevation design is not considered adequately. When some tunnels cross the bottom of the river, the fractures near the fault between the underground river and the excavation space may be activated and then evolve into channels, causing serious water inrush accidents during construction and operation processes. Taking the Qiyueshan Tunnel site as an example, on the premise of the anatomy of the control mechanism of the reverse fault on the development of the underground river, based on the multiperiod typical structural traces of the tunnel and surface outcrop, it was found that stratifications, dip joints, transverse joints, and tension joints of good aperture grade are important control factors. The cut block easily loses its stability and provides space for karst development, while intermittent uplifting of regional structures provides hydrodynamic conditions for the development of the underground river, causing the hydraulic gradient to be inconsistent in the overall underground river. Finally, the rainwater dynamic monitoring and tracer connectivity are data that can be fully utilized to demonstrate that a reverse fracture can control the development of the underground river. The authors further considered the effect of the vertical zoning of the fault structure and the excavation disturbance, and, drawing on the experience of the relative location of the same site in the same field, put forward the suggestion that the construction of the follow-up tunnel in the study area should be slightly higher than the elevation of the underground river. The research results can provide useful reference for similar engineering problems in the future.

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Room Design for Underground Slate Workings: Analysis of Safety Factors for Keyblocks

et al. 2015

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Determination of support pressure for tunnels and caverns using block theory

Cited by 13 publications

References 2 publications

Study on a Surrounding Rock Pressure Calculation Method for Super-Large Section Highway Tunnels

Study on a Surrounding Rock Pressure Calculation Method for Super-Large Section Highway Tunnels

Study on the Control of Underground Rivers by Reverse Faults in Tunnel Site and Selection of Tunnel Elevation

Room Design for Underground Slate Workings: Analysis of Safety Factors for Keyblocks

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