ABSTRACT

This article presents the anchoring mechanism of self-locking pre-stressed anchor cable and the design of self-locker. This is based on the following consideration: the current pre-stressed tendon anchor has neglected the energy field in free length stratum so as to result in such defects as too much reaction concentrating in the shallow stratum, too much protection works, too long engineering process and poor economy efficiency in maintenance. The design of self-locker structure is ascertained. Through indoor tests, its effect is checked with numerical test results and the self-locking capability of the pre-stressed anchor cable self-locker is achieved.

1 INTRODUCTION

Pre-stressed anchor fixing technology has been developed in more and more applications and fields progressively and widely, and the geological conditions of anchoring object becomes more and more sophisticated and the structures and types of anchor have improved continuously. Whereas, all current researches of pre-stressed anchor cable structure in application are about the stress field distribution of the fixing end of anchor. It has become a problem demanding prompt solution in engineeringwalks that howto in sophisticated stratums enhance load of anchor cable, improve anchoring system stress field distribution, reduce decreasing speed of anchoring load, prolong life of anchor and save engineering cost. Although there are many types of pre-stressed anchor cable structure and many kinds of anchor fixing end stress field, the stress field of their reaction structure are fundamentally the same, which impact stress concentration on reaction structures in slope and increase protection works. Considering the general types of pre-stressed anchor cable structure, this article presents how to realize pre-stressed anchor cable self-locking by adding self-lockers on the free length with the foundation of free length stratum energy field.

1.1 Basic theory of self-locker

Set self-lockers, which have locking clips inside, in units on the free length crossly. Strands only move in single direction when adding tension, and at the same time the anchor fixing load of the anchor cable will get balanced with the pressure of the cement column in the steel pipe and the boundary adhesive force of the steel pipe holes by self-lockers. Thus, it was realized that adding tension in steps, locking the free length by itself, decreasing the standard of reaction structure or aborting reaction structures. Bi-directional anchoring force model is fundamentally applied in self-locking pre-stressed anchor cable structure, which is easy for both producing and engineering.

1.2 Self-locking theory of pre-stressed anchor cable

Figure 1 introduces the self-locking theory of pre-stressed anchor cable. Compared with other anchor cable structures, self-locking pre-stressed anchor cable has improvements in the reaction structure by adding self-lockers.

2 DETAIL DESIGN OF SELF-LOCKING PRESTRESSED ANCHOR CABLE STRUCTURE

Self-locking pre-stressed anchor cable structure includes: self-locker, fixing end of anchor and reaction structure. This article mainly describes how to design mechanical selflocker structure with the consideration of the solidity of rock/soil body.

2.1 Design of the self-locker structure of self-lockingpre-stressed anchor cable

Figure 2 introduces the mechanical self-locker structure of self-locking pre-stressed anchor cable.

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