1、翻译部分原文：Analytical approach for the design of active grouted rockbolts in tunnel stability based on convergence-confinement methodAbstract: Assuming that grouted rockbolts increase internal pressure within a broken rock mass, a new procedure for computation of ground response curves for a tunnel rein
2、forced with active grouted rockbolts is presented, while the effect of distance of bolted section to tunnel face has been also considered. This analytical solution for a circular underground excavation under hydrostatic stress eld , and with consideration of a non-linear strength criterion for rock
3、mass and on the basis of two material behavior models has been developed. In this work, the equation of the ground response curve for a tunnel which has been rein-forced with passive grouted rockbolts is also derived. The proposed model allows one to take, the effect of the distance of the bolted se
4、ction to the tunnel face, the effect of increasing rockbolts spacing, the inuence of increasing pretension load in calculating of the ground response curve, and the effect of increasing the cross-section area of rockbolts, into account. The results show that decreasing rockbolts spacing increase the
5、 support system stiffness rather than preloading of them.Keywords: Analytical solution; Active grouted rockbolts; Tunnel design Convergence-connement ;Reinforcement1. IntroductionThe grouted rockbolts, as passive or as active pretensioned elements improving and conserving the overall rock mass prope
6、rties from within the rock mass, have been widely used to stabilize underground excavations. Passive grouted rockbolts develop load as the rock mass deforms. However, the active types are preloaded before the rock mass deformation.A proper design of grouted rockbolts for reinforcement and sta-biliza
7、tion of an underground excavation lies in a full understanding of the effect of rockbolts in improving the rock mass properties as well as supporting mechanism and effectiveness of rockbolts in tunnel stability on the basis of convergence-connement method.According to the previously researches, the
8、rock bolting effects are summarized as the ground sewing, adding pressure on the tunnel boundary (Bischoff and Smart, 1975), cohesion improving(Grasso et al., 1989), better geomechanical properties (both cohesion and friction angle) of rock mass (Indraratna and Kaiser,1990a), overall variation of ro
9、ck mass properties (Peila and Oreste,1995), and adding internal pressure as a conning pressure within a broken rock mass (Fahimifar and Soroush, 2005).In order to simulate rock bolting effects and modeling as a support system in underground excavations, different numerical, experimental, and analyti
10、cal solutions have been also proposed.Jeng and Huang (1999)performed experimental studies andnumerical analyses to examine the holding mechanisms of the model under-reamed rockbolts subjected to direct pull out loading and pretensioning. They showed that the supporting capacity is related to the ten
11、sile strength of the rock, bolt length and the size of the under-reamed end.Li and Stillborg (1999) developed three analytical models for rock bolts: one for bolts subjected to a concentrated pull load ina pullout test, another one for bolts installed in uniformly deformed rock masses, and the last
12、one for bolts subjected to the opening of individual rock joints. The development of the models is based on the description of the mechanical coupling at the interface between the bolt and the grout medium for grouted rockbolts, or between the bolt and the rock for frictionally coupled bolts.Cai et
13、al. (2004) proposed an analytical model to predict the axial force of grouted rockbolt in the tunneling design. In this approach, the interaction mechanism of the rockbolt and the soft rock mass is described according to their consistent displacement ,and coupling and decoupling behaviors of the roc
14、kbolts around a circular tunnel is analyzed. In this way, a solution is proposed to analyze the supporting behavior of rockbolts.Guan et al. (2007), according to the conventional pullout tests for passive bolts, a spring-slider model adopted to account for the interaction relationship between the bo
15、lt and the rock mass. The proposed method provides a framework to the elasto-plastic ground response analyses with passive bolts reinforcement.Through parameter studies, the inuence of the bolt properties on the reinforcement effect is highlighted.Oreste (2008)presented a new calculation procedure f
16、or the analysis and dimensioning of fully grouted radial bolts in tunnels. This procedure is based on the principle of congruency of the displacements, imposing the condition that the lengthening of the bolt is equal to the expansion in the radial direction of the reinforced rock annulus. The proposed solution is able to analyze the stress and strain state in the rock in details, in the presence of a bolting intervention, and to proceed with its correct
