Research On Reasonable Spacing Between Prestressed Anchor Cables In Rock Slope Engineering

Prestressed anchor cable used in stabilizing high slope is a kind of advanced, efficient, economical and practical geotechnical reinforcement technology, currently it is widely applied in slope reinforcement projects, and has achieved great success. However, the theoretical research of prestressed anchor still lags behind engineering application, and it is always a difficult problem to determine the reasonable distance of anchor cables. The current common practice is to use engineering experience of geological analogy method, which is diseconomy or even unsafe sometimes. So, this paper deals with problems for the reasonable distance of prestressed anchor cables, and the main research work carried out as follows:1) According to the characteristics of tension and pressure dispersion-type anchorage cable, the anchoring mechanism of these two kinds of anchor cables are analysed by numerical simulation, which include stress state of grout in the interior bond section of prestressed anchorage cable and rock mass among the interior bond section of prestressed anchorage cable.2) By using the Mindlin’s solution, this paper obtained the stress of rock mass among the interior bond section of tension anchor cable at any point. At the same time, this paper deduced the stress solution of Thick Wall Cylinde under uniform load, and obtained the stress formula of rock mass among the interior bond section of pressure dispersion-type anchor cable at any point with the stress solution. Compared the stress solutions of Mindlin and Thick Wall Cylinde with these two kinds of anchors, the paper found that the former is more suitable for tensile type anchor cable, and the latter is more suitable for pressure dispersed anchor cable.3) According to the stress solutions of rocks among the interior bond section of a single anchor, analysis of the stress state of rock mass in the anchor group effect with the Superposition Principle. By using the limit equilibrium theory and studying on mechanism of the anchor group, the paper obtained the theoretical solution of different types of anchor spacing, and got the quantitative expressions, then analysed specific examples of projects with them.4) Considering the anchorage strength and deformation parameters, rock strength and deformation parameters, cable tension and anchorage length, their effect on the spacing between prestressed anchor cables is analyzed.This paper based on the analysis of tension and pressure dispersed anchor cable mechanism, derived two kinds of rock anchor stress solutions, and deduced the anchors spacing expression of these two different kinds of anchor cables. The research results can provide theoretical guidance and reference for the design of prestressed anchor cable in rock slope.