1、翻译部分英文原文Distinct analysis of fully grouted bolts around a circular tunnel considering the congruence of displacements between the bar and the rockAbstractThis paper presents a new calculation procedure for the analysis and dimensioning of fully grouted radial bolts in tunnels. This procedure is base
2、d on the principle of congruency of the displacements, imposing the condition that the lengthening of the bolt, added to the displacements due to the shear strains in the boltrock interface, is equal to the expansion in the radial direction of the reinforced rock annulus. A comparison of the results
3、 obtained using this procedure with those obtained using the traditional numerical modelling method, which is more costly in computational terms, has led to satisfactory results.The application of the procedure to a real case has given results that are comparable with the in situ measurements. The p
4、roposed instrument is able to analyse the stress and strain state in rock in detail, in the presence of a bolting intervention, and to proceed with its correct dimensioning with the objective of improving the degree of stability of the rock around the tunnel.1. Introduction Fully grouted radial bolt
5、ing is an intervention that is commonly used in the field of tunnelling in rock, as it is easy to carry out, reliable and efficacious in controlling the radial displacements of the tunnel walls and in improving the degree of stability of the rock around the tunnel. It is generally adopted in a syste
6、matic manner in rock masses with medium to good geomechanical quality (RMR varying from 35 to 70); in rock of optimal quality, spot bolting is instead used in order to stabilize any individual potentially unstable rock blocks. This method involves the use of no pre-stressed rigid steel elements that
7、 are completely adherent to the medium into which they are inserted due to the mortar injected into the hole or through friction produced by the high contact pressures of the element on the hole walls ( swellex and split-set bolts ). They are arranged in a radial manner around the perimeter of the t
8、unnel and are usually installed close to the excavation face. They are initially unloaded and it is only with the subsequent advancement of the face that they become loaded and they begin to function statically. In civil infrastructure tunnels , where it is necessary to guarantee the functionality o
9、f the bolts for a sufficiently long time, fully grouted bolts are generally used . The cemented mortar usually has a water/ cement ratio of 0.30.35 and it has the duty of connecting the element to the surrounding rock and protecting it from the actions of corrosive agents . Many different authors ,
10、starting from back in the 1980s, have studied the behaviour of passive radial bolts arranged in a systematic way around the perimeter of a circular tunnel 19 an d they have formulated both analytical and numeric al calculation method s that are able to evaluate the effect of the bolts on the stress
11、and stra in behaviour of the rock around the tunnel. Unfortunately, however, the complexity of the problem and the necessity of always considering new aspects to adequately simulate the boltrock interaction have made such calculation methods difficult to use.Further more, most of the aforementioned
12、methods refer to a continuous equivalent medium and do not allow the maximum force induced inside the bolts to be evaluated, a value that is necessary to obtain their correct dimensioning. In this work, starting from a study of the results of an extensive parametrical analysis developed using a nume
13、r-ical calculation method and from experimental evidence in tunnels , the typical trend of the axial force along a bolt when the head of the bolt is constrained in a correct way on the tunnel walls, was first identified , from a qualitative point of view . Once the qualitative trend of the axial for
14、ce was obtained, a calculation procedure was developed that is able to evaluate the stress and strain state in rock and the maximum force inside a bolt. For this purpose an iterative process was developed, comparing the lengthening of the bolt produced by the stresses induced on the inside of it wit
15、h the radial expansion of the reinforced rock annulus around the tunnel. The lengthening of the bolt increases and the expansion of the reinforced annulus diminishes with an increase in the maximum force inside the bolt. The lengthening of the bolts and the expansion of the reinforced rock an nulus
16、should be identical, less a difference due to the shear strains at the boltrock interface, due to congruency of the displacements. The set up calculation method, which has been implement ed in the Matlab programming language , was compared to a traditional numerical method that discretizes the continuous medium in great detail. The program can be accessed at http:/staff. polito.it/pi erpaolo.orest e/. A comparison of the results of the eighty-one analys
