1、翻译部分英文原文ANALYSIS OF IN SITU ROCK BOLT LOADING STATUSD. H. S. ZouDept. of Mining Engineering, Dalhousie University, CanadaAbstract: Rock bolts are widely used in rock engineering for ground stabilization. The anchorage quality, the loading status and the bolt integrity are of most concern in the fiel
2、d. Rock bolts performance is currently assessed by pullout or torque wrench tests. These methods are destructive or inaccurate and cannot provide all the required information. Consequently some research is directed to non-destructive testing methods. However, due to the complex ground conditions and
3、 the loading mechanism of rock bolts, it is still a challenge to monitor the rock bolt performance in situ quantitatively and accurately. The tension distribution along a bolt for various types of bolts is often not well understood. The condition of the surrounding rock mass and the varying field st
4、resses further complicate the problem. This article will thoroughly analyze mobilization of the anchoring force and distribution of the bolt tension for mechanically anchored, grouted, pre-tensioned and un-tensioned rock bolts. The terms load bearing capacity and anchorage quality of rock bolts will
5、 be clarified. The effects of ground movement will also be examined with an insight into the future direction for rock bolt testing and monitoring.Keywords: rock bolt tension, non-destructive test, load capacity, anchorage quality.1 IntroductionRock bolts are widely used for ground support in rock e
6、ngineering, such as in highway slopes, hydro dams, underground mine workings and open pit highwalls. Based on installation, rock bolts may be classified as mechanically anchored, fully or partially grouted (with resin or cement) and friction bolts. The grouted bolts may also have a bearing plate wit
7、h initial tension. The primary function of rock bolts is to hold the rockmass together and increase or maintain the ground stability. In the field, the anchorage quality, the loading status and the bolt integrity are most concerned.At present the common practice of assessing anchorage quality is by
8、pullout test (Choquet 1991) and sometimes by torque wrench test (Seeber 1992). Both methods have limited capability and can not provide all the needed information. They are time consuming and destructive or inaccurate. Other researchers (Thurner 1988, Hirao et al 2001, Beard and Lowe 2003) have been
9、 trying to use non-destructive test technique to monitor rock bolts in the field. However due to the complex ground conditions and the loading mechanism in a rock bolt system, the technology can not be applied directly. It is still a challenge to monitor the rock bolt performance quantitatively and
10、accurately. First of all, mobilization of the anchoring force and distribution of the bolt tension for various types of rock bolts are not well understood. The condition of the surrounding rockmass and the varying field stresses due to excavation activities further complicate the problem. In the fol
11、lowing, the anchorage force and tension distribution together with other relevant issues will be discussed thoroughly.Since the anchorage of friction bolts depends on the random contacts between the bolt and the non-smooth borehole rock, the anchoring force is difficult to determine and it has littl
12、e meaning to predict its distribution at this point. Therefore the following discussions will be focused on the mechanically anchored and grouted bolts.2 Clarification of terminologyFor the clarity of discussions, some technical terminology relevant to rock bolting needs to be defined first:Anchorag
13、e: the mechanism that bonds the bolt and the rockmass together. For mechanical bolts, it is the anchor at the hole bottom. For grouted bolts, it is the combination of the grout, the interface between the bolt and the grout, and the interface between the grout and the rock.Rock bolt failure: the fail
14、ure of any component of the rock bolt system: steel bolt, anchorage or rock around the borehole. The failure of the bearing plate at the collar is excluded.Anchorage strength (Tas): the maximum tension tolerable per unit length of a grouted bolt before the anchorage fails.Anchoring force: the tensio
15、n mobilized at the anchored end of a mechanical bolt, or the total tension mobilized along a segment of a grouted bolt.Anchorage capacity (Tac): the maximum anchoring force of a bolt before the anchorage fails.Anchorage quality: the quality of anchor installation for mechanical bolts (measured by th
16、e anchorage capacity), or the quality of grouting for grouted bolts (measured by the anchorage strength and its consistency along the bolt). For grouted bolts, the anchorage quality is also called bond quality or grouting quality.Bolt tension (T): the actual tension in a bolt at a particular location.Load bearing capacity (LBC): the maximum tension tolerable by the rock bolt system. It is understood (Choquet 1991) that a rock bolt system ma
