In this study,a case study is conducted on the Muzhailing highway tunnel to explore the feasibility and applicable effects of the cantilever roadheader construction method in squeezing rock tunnels based on engineering geological conditions.The types of cantilever roadheader are selected according to the project implementation conditions,and a two-bench excavation scheme for the cantilever roadheader is designed and developed.Furthermore,a comparative analysis is conducted on two-bench excavation by a cantilever roadheader and three-bench excavation for drilling and blasting in a test section in terms of construction efficiency and effect.The main findings are summarized as follows:(1)The selection of the cantilever roadheader should focus on the cutting area and power according to rock strength,excavation cross-section,and work efficiency;(2)The surrounding rocks of the Muzhailing highway tunnel can be divided into two categories and six types based on the applicability of cantilever roadheader;(3)Compared with the construction efficiency of the three-bench drilling and blasting method,the two-bench cantilever roadheader construction method can increase construction advance by 20%and reduce average over-excavation,labor consumption,and shotcrete overconsumption by 150 mm,5-10 persons,and 57%,respectively;(4)Compared with the three-bench drilling and blasting method,the surrounding rock pressure is reduced by 0.01-0.11 MPa using the two-bench cantilever roadheader construction method with a stable and evenly-distributed final surrounding rock displacement and arch frame stress.Moreover,the average stress of the anchor cable is increased by 39 kN.
squeezing rock tunnelcantilever roadheader constructiondrilling and blasting excavationfield test
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