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隧道进口施工一直是困扰大型隧道施工的技术难题,在偏压地段更是如此,结合张家口至石家庄高速公路北口隧道进口段工程,针对工程开挖后初期支护和坡体产生裂缝这一隧道进口段代表性工程问题展开了专项研究。采用理论分析与监测试验相结合的研究方法,在全面研究偏压隧道进口段工程裂缝发生机理的基础上,提出了非均匀支护控制措施,并通过控制效果监测数据的稳定性评价验证了机理和措施的合理性。研究结果表明:基于围岩压力和隧道开挖后松动圈、塑性区及变形计算理论,通过支护结构特征曲线与围岩支护需求曲线相结合,分析了北口隧道进口段初期支护和坡体裂缝发生机理;在裂缝发生机理研究的基础上,基于支护结构刚度思想确定了非均匀支护参数。
Tunnel construction has always plagued the construction of large tunnels technical problems, particularly in the bias section, with Zhangjiakou to Shijiazhuang North Crossing tunnel entrance section of the project, for the excavation of the initial support and slope cracks generated after the tunnel entrance Section of the representative engineering issues launched a special study. Based on the comprehensive research on the mechanism of cracks in the entrance section of the biased tunnel, the method of theoretical analysis combined with the monitoring test is put forward, and the control measures of non-uniform support are proposed. The stability of the monitoring data is verified by the control method And the rationality of the measures. The results show that based on the pressure of surrounding rock and the loose ring, plastic zone and deformation calculation theory after tunnel excavation, through the combination of the supporting structure characteristic curve and the demand curve of surrounding rock support, the initial support and slope Based on the study of mechanism of crack initiation, the non-uniform support parameters were determined based on the stiffness of support structure.