Experimental study on bearing capacity of systematic bolt support based on total safety factor method
In view of the absence of bearing capacity analysis method for systematic bolt in the current specifications of tunnels,the total safety factor method proposes a load structure model of bolt-rock bearing arch.This method theoretically enables the quantitative design of bolts but lacks experimental verification.To address this,this paper develops a large-scale tunnel structure model experimental system from a structural experimental perspective.It conducts bearing experiments on bolt-rock bearing arch structures in unsupported tunnel and bolted tunnels with different spacings.By monitoring the stress and strain in the surrounding rock mass,tunnel displacement and bolt strain,the failure state and failure load of surrounding rock and bolt are analyzed.The deformation and force characteristics of the bolt-rock bearing arch and the distribution of bolt forces are investigated.The structural bearing capacity of the model experiment and the calculated bearing capacity of the bolt-rock bearing arch under the total safety factor method theory were compared and analyzed.The results show that the bolts can bear the load together with the surrounding rock mass,effectively increasing the confining stress of the surrounding rock mass and enhancing the compressive strength and bearing capacity.The experimental bearing capacity of the bolt-rock bearing arch is consistent with theoretical calculation results,proving the rationality of the bolt-rock bearing arch theory of the total safety factor method.This method is both safe and conservative.
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