New Equations for Estimating Radial Loads on Deep Shaft Linings in Weak Rocks

Spagnoli, Giovanni; Oreste, Pierpaolo; Bianco, Luigi Lo

doi:10.1061/(asce)gm.1943-5622.0000657

Cited by 23 publications

(11 citation statements)

References 19 publications

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“…When the convergence confinement method (CCM) is used to estimate the radial loads on the shaft lining, the relationship of the radial ground displacement, U R , and the equivalent internal pressure acting on the rock mass, P i , need to be obtained first. is relationship is represented by the convergenceconfinement curve (CCC), which is important for the analysis of the interaction between the rocks and the shaft lining [25,26]. e CCC of the rocks around the shaft was calculated using the following sequence in the aforementioned numerical model: (i) initiate the model with zero displacement and initial in situ stress, including gravitational loading; (ii) null the shaft elements to be excavated and insert the BDZ after the excavation face passed each section to simulate the damage of rock mass, the extent of the BDZ in numerical analysis was determined based on the result of seismic survey; (iii) apply radial pressure to the excavation surface.…”

Section: Characteristic Curves Of the Shaft Rocksmentioning

confidence: 99%

“…However, for the shaft example presented, the lining is cast close to the shaft face, so the effect of surrounding rock displacement on the distribution of liner loads is significant. Some research shows that the displacement of surrounding rock around the excavation face changes rapidly with the advance of the excavation face [25]. e results mean that the excavation face acts as a constraint on the displacement of the shaft wall near the face.…”

Section: Characteristics Of Internal Force Distribution Along Shaftmentioning

confidence: 99%

“…Accordingly, the effective support pressure provided by the shaft lining (equivalent to the ground load on the lining) can be calculated by the CCM. Taking the intersection between the convergence-confinement curve (CCC) and the reaction line of the support into account, Spagnoli et al [25] proposed new equations for estimation of radial loads on the shaft lining. Combining the CCM and numerical analysis, Spagnoli et al [26] investigated the relationship between the radial loads acting on liner support and the radial displacement of the ground for vertical circular shaft sinking in weak rocks, and they concluded that the lining thickness would affect the radial loads and radial ground displacement.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evaluating the Impact of Blast‐Induced Damage on the Rock Load Supported by Liner in Construction of a Deep Shaft: A Case Study of Ventilation Shaft of Micangshan Road Tunnel Project

Fang

Yao

Walton

et al. 2020

Advances in Civil Engineering

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The rock load acting on the lining of an underground excavation is influenced by multiple factors, including rock type, rock mass condition, depth, and construction method. This study focuses on quantifying the magnitude and distribution of the radial loads on the lining of a deep shaft constructed in hard rock by the so-called short-step method. The blasting-induced damage zone (BDZ) around the shaft was characterized using ultrasonic testing and incorporated into the convergence-confinement method (CCM) and 3D numerical analyses to assess the impact of BDZ on rock loading against the liner. The results show that excavation blasting of shafts is an important controlling factor for the degradation of the rock mass, while the orientation and magnitude of the principal stress had a minimal influence on the distribution of blast-induced damage. The analysis shows that increasing the depth of blast damage in the walls can increase the loads acting on the lining, and the shear loads acting on the liner could be significant for shafts sunk by the short-step method in an area with anisotropic in situ stresses.

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Section: Characteristic Curves Of the Shaft Rocksmentioning

confidence: 99%

Section: Characteristics Of Internal Force Distribution Along Shaftmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluating the Impact of Blast‐Induced Damage on the Rock Load Supported by Liner in Construction of a Deep Shaft: A Case Study of Ventilation Shaft of Micangshan Road Tunnel Project

Fang

Yao

Walton

et al. 2020

Advances in Civil Engineering

View full text Add to dashboard Cite

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“…Beus and Chan [3] described the shaft design in Coeur d'Alene, Idaho, and compared the structural features of circular and rectangular shafts. Spagnoli et al [4] determined the relationship between the key parameters (i.e. cohesion, friction angle and elastic modulus) acting on the shaft lining and the geometric parameters (i.e.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Slightly Degraded Reinforced Concrete Shaft Lining in Thick Topsoil

Xie

2020

Teh. vjesn

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This paper simulates the degradation of a 20 m-tall shaft lining in thick topsoil at the vertical depth of 500 m. The simulation was carried out under the similarity theory. Three reduced scale models were prepared from the original structure. The first model was subjected to circumferential load and then cured naturally, the second model was subjected to circumferential load and then soaked in corrosive solution, and the third model was subjected to circumferential and vertical loads and then soaked in corrosive solution. Without changing the circumferential load, vertical load was applied to the three models until they failed. The three models were found to have similar failure patterns: the uniform cracks first appeared at the top and bottom of the outer lining; the concrete of the inner lining cracked, and the upper part of the shaft lining was crushed, showing a diagonal shear failure. Model 1 had greater cracking load and ultimate load than model 2 and model 3. This is because the coupling between vertical and circumferential loads induces micro-cracks between the inner and outer linings, and thus accelerates the corrosion of the RC shaft lining in the corrosive solution.

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“…Recently, the explorations on the external load estimation, computational methods, and related topics of the shaft lining have been carried out. For instance, for the quick estimation of the stress acting on the lining extrados, the convergence-confinement method (CCM) has been used to calculate both the radial displacements associated with the construction of the shafts and the equivalent loads [1]. In order to resist ground pressure to a shaft lining in creeping rock salt strata, a deformation zone filled with a compressible material is employed between the excavation and permanent lining [2].…”

Section: Introductionmentioning

confidence: 99%

The Unified Strength Theory for Plastic Limit Load Analysis of Vertical Shaft Lining

Guo-fan

Ren

Qiu

et al. 2018

Advances in Civil Engineering

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Plastic limit analysis is a significant application for structural design and failure prediction, implying that the potential bearing capacity of material can be fully considered. Meanwhile, the failure process of structures usually occurs in the deformation of the plastic stage. Hence, it is important to investigate the mechanical properties of structures in the plastic state through proper mechanical models and principles. In this paper, the analytical stress expression and formulas for computing plastic limit load have been deduced based on the unified strength theory. Additionally, the relationships between plastic limit load of the shaft lining and the strength differential (SD) of structural material, the geometrical characteristic (R0/R) and the intermediate principal shear stress (b) have been discussed. Finally, the method of the plastic limit load is adopted for the safety evaluation of the shaft lining through a practical case.

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New Equations for Estimating Radial Loads on Deep Shaft Linings in Weak Rocks

Cited by 23 publications

References 19 publications

Evaluating the Impact of Blast‐Induced Damage on the Rock Load Supported by Liner in Construction of a Deep Shaft: A Case Study of Ventilation Shaft of Micangshan Road Tunnel Project

Evaluating the Impact of Blast‐Induced Damage on the Rock Load Supported by Liner in Construction of a Deep Shaft: A Case Study of Ventilation Shaft of Micangshan Road Tunnel Project

Simulation of Slightly Degraded Reinforced Concrete Shaft Lining in Thick Topsoil

The Unified Strength Theory for Plastic Limit Load Analysis of Vertical Shaft Lining

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