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Abstract At present，the combined support method of long anchor cable and bolt shotcrete mesh is widely used in deep soft surrounding rock，but it is very deficient in understanding on bearing behavior of the combined supporting structure；and it still lacks quantitative analytical formulae especially for bearing capacities of primary supporting and secondary supporting. In allusion to the united supporting characteristics of anchor，spray net and cable of deep wall rock，the mechanical model of overlap arch bearing body were put forward based on rock mechanics theory，which are composed with the main compression arch(bolt supporting) and the secondary compression arch(intensive cable supporting). By means of elastoplastic theory，neutral point theory of bolt and force transferring mechanism of cable，strength equations of the bearing body of primary supporting and second supporting were deduced. Community composed of wall rock and supporting structure is regarded as an equivalent coupling surrounding rock；and relation equations of rock mechanics parameters of surrounding rock with release displacements(yield displacements) were obtained from the method of elastoplastic mechanics. Computational results of engineering indicate that the peak intensity and bearing capability of rock mass were enhanced obviously for the breaking cavity of Jinchuan Mine III after the support of overlap arch；the limit bearing capacity of equivalent coupling surrounding rock can reach 513.34 kN；the value of can reach 47.54º and the value of can reach 1.37 MPa. Monitoring data also show that deformations of surrounding rock supported by overlap arch bearing body trend to be stable，convergence rate of which is less than 0.1 mm/d.
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Received: 15 January 2010
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2010, Vol. 29 
