摘要
针对山岭隧道初期支护中钢架和喷混凝土作为组合结构计算受力,不能完全反应两种材料自身强度及其影响的问题,本文对初期支护组合结构的荷载分担进行研究,推导了荷载分担计算公式,提出了应根据两者的材料强度不同,分别计算,并满足相应的强度要求.结合挤压性软弱大变形的工程实际情况,提出大变形等特殊围岩受挤压剪切作用力大的隧道,宜采用H型钢取代工字钢架,在平面内强度相当的情况下,充分利用H型钢架抗剪强度高和平面外抗弯强度大的特点,发挥钢架的空间整体性,结构受力更有利.对目前设计中常用的工字钢架在不同间距下替代的H型钢架给出了建议,可为今后采用H型钢架的决策依据.提出了采用H型钢架,宜配套采用机械辅助架设,严格控制喷混凝土工艺,保证钢架与围岩可靠传力.
Abstract
Aiming at the problem that steel frame and shotcrete as a combined structure in the preliminary support of mountain tunnel cannot fully reflect the strength and influence of the two materials,the force sharing between steel frame and shotcrete is studied in this paper.The calculation formula of load sharing is derived.It is suggested that the force should be calculated according to the two different materials,and they should meet the respective strength requirements.Combining the railway tunnel practice of weak and large deformation surrounding rock,it is suggested that H-shape steel frame should take the replace of I-shape steel frame in the large deformation surrounding rock etc.At the same intensity in the main plane,the features of H-shape frame should be fully utilized which have high shearing strength and high lateral bending resistance.It has better spatial integrity which is advantageous to the stress of extrusion rock.The responsible H-shape steel frame are proposed the corresponding I-shape steel frame with different distances,so as to provide the decisions for using H-shape steel frame.When H beam frames are used,Supporting machinery shall be used and the shotcrete process should be strictly controlled which can ensure the reliable transmission force of steel frame.
维普
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