Analytical and Reliability Study of the Tunnel with Rockbolts in Rock Masses

Abstract

IntroductionRockbolts have been widely used to reinforce the surrounding rock mass in tunnel engineering. A proper design of rockbolts, which depends on the full understanding of the mechanism and effectiveness of rockbolts, is very important to reinforcement, stabilization and safety construction of rock tunnel [1][2][3]. Meanwhile, there are lots of uncertainties in rock tunnel. Uncertainties are critical to design and safety construction due to the complexity of rock mass [4]. Reliability analysis is a widely developed method to determine the uncertainty in engineering system [5]. The stresses and displacements around tunnel is an important problem considering the uncertainty in tunnel engineering.Various analytical, experimental, and numerical methods have been developed to analyze and understand the mechanism of rockbolts in tunnel based on different assumptions and conditions. Analytical models are able to define the stresses and the deformations and have been widely used due to the computational simplicity [6,7]. Hoek and Brown (1980) had presented analytical solutions of tunnel with rockbolts [8]. Brown et al (1983) proposed an analytical solution based on elastic-brittle-plastic material behavior and Hoek-Brown yield criterion [9]. Li and Stillborg (1999) developed three analytical models for rockbolts based on the mechanical coupling at the various interface of the rockbolts, the grout medium and the rock mass

Length Effect on Load Bearing Capacities of Friction Rock Bolts

“…For instance, rock bolts should have enough length to support the plastic zone around tunnels by being inserted in the elastic zone. Besides, the length of the bolt in the elastic zone should be high enough for being able to bear the plastic zone load [23][24][25][26][27][28]. The needed bolt length depends on various parameters like tunnel cross-section shape and size, in situ stress distribution and rock mass quality.…”

Reliability analysis of bolt‐supported tunnels regarded as homogenized structures

“…The basic concept of reliability consists in describing the demand or external actions (represented by S ) and the resistance or capacity (represented by R ) of any structural system through probability density functions (PDFs). The failure probability can be written based on the safety margin $$Z = R - S$$ 32–34 : $$$$\begin{equation}{p}_{\mathrm{f}} = P\left[ {Z \le 0} \right] = {{\Phi}}\left( { - \beta } \right) = 1 - {{\Phi}}\left( \beta \right)\end{equation}$$$$…”

“…The basic concept of reliability consists in describing the demand or external actions (represented by 𝑆) and the resistance or capacity (represented by 𝑅) of any structural system through probability density functions (PDFs). The failure probability can be written based on the safety margin 𝑍 = 𝑅 − 𝑆 [32][33][34] :…”

Research on Supporting Measure at Intersection of Inclined Shaft and Major Tunnel in Highway

“…e research shows that the bolts can effectively control the rock failure and that increasing the number of bolts can improve the reinforcement effect of the surrounding rock. Meng et al [8] considered rock mass and rock bolts as a new homogeneous, isotropic, parameters strengthened equivalent composite material. e research shows that anchor bolt has an important effect on plastic zone size and displacement of the surrounding rock.…”