5 research outputs found
Analysis of rock burst event in deep TBM excavation of Pahang-Selangor raw water transfer tunnel
No full textTunnelling under high overburden and high in-situ stress can pose a major threat to the tunnel
construction due to the phenomenon of rock burst. Rock burst is a typical phenomenon caused
by underground excavation due to stress release and rock explosion where the rock masses
broken in large or small pieces. Thus, predicting the occurrence of this phenomenon and its
mechanism is important especially in determining suitable tunnel support system. In this study,
the event of rock burst phenomenon at the Pahang-Selangor Raw Water Transfer Tunnel
which is evaluated between the Chainage of 13 to 27 km beneath the Titiwangsa Main Range.
This is the most criticaal section because of the high overburden up to 1200 m and presence
several fault zones. Stress-strength method was used to analyse the tunnel behaviour under
high overburden stress based on strength factor and tangential stress. Analysed results show
that section with high overburden have high possibility of rock burst. Furthermore, it allows a
reasonable prediction of the tunnel behaviours under different rock conditions, support systems
and overburden stress which serves as a tool in the observational design and construction
method for the deep tunnel excavation
Numerical Analysis of TBM Tunnel Lining Behavior using Shotcrete Constitutive Model
Get PDFShotcrete is a fundamental support element for tunnels and underground constructions. Shortly after application, shotcrete linings undergo a high load while the ordinary concrete is not fully hardened yet. Therefore, the time-dependent behaviour of the shotcrete material must consider. Traditional approaches assume a linear elastic behaviour using a hypothetical young modulus to model this time-dependency and creep effects. In this paper, a new constitutive model of shotcrete is applied to evaluate the time-dependent behaviour of TBM tunnel lining under high in-situ stress state. The Shotcrete model is based on the framework of Elasto-plasticity and designed to account for non-linear and time-dependent behaviour for concrete material more realistically. A parametric study of the time-dependent behaviour of the shotcrete lining, using the shotcrete model, is performed. To achieve this, the influence of the lining thickness, tunnel diameter and tunnel depth on the development of the stresses and displacement of the shotcrete lining with time is investigated. The results showed that the development of the lining tensile stress with time at tunnel crown increases by increasing the lining thickness and tunnel depth, whereas it decreases by increasing of the tunnel diameter. At the tunnel sidewall, the lining compression stress with time increases with the increase of the tunnel depth and diameter, while higher lining thickness decreases the lining compressive stresses. However, the results showed the ability of the shotcrete model to simulate the structural behaviour of the shotcrete lining with time.</jats:p
