【摘要】 黄土隧道在开挖过程中经常发生支护结构破坏或过度变形。依托某黄土隧道，提出一种新型组合结构支护体系(π形拱架),采用理论计算对比了π形拱架与传统工字钢提供的支护反力，结合现场监测和数值模拟分析了不同支护体系下围岩控制效果，优化新型组合结构的构造参数，同时基于正交试验探究了构造参数对围岩支承效果影响显著性大小。结果表明：π形拱架提供的支护反力是型钢钢架的3.14倍，具有强度大、承载力高的优势；建立对比分析模型，较传统支护体系相比，新型支护体系下的拱顶沉降降幅达到53.8%,等效塑性应变减少约64.4%,初期支护最大压应力和拉应力分别减少约35.3%、35.9%;进而建立参数优化模型，通过对围岩竖向位移和塑性区的综合评估，建议拱架壁厚取6 mm,灌浆强度选择C30,翼板长度以200 mm为宜；结合正交试验结果，各因素影响程度由小到大依次为因素B(灌浆强度)<因素A(钢管壁厚)<因素C(翼板长度)。本研究可进一步促进新型拱架在黄土隧道施工支护中的应用。更多还原

【Abstract】 During the excavation of loess tunnel, the supporting structure is often damaged or excessively deformed.Based on a loess tunnel, a new combined structure support system(π-type arch) is proposed.The support reaction provided by π arch and traditional I-steel is compared by theoretical calculation.Combined with field monitoring and numerical simulation, the control effect of surrounding rock under different support systems is analyzed, and the structural parameters of the composite structure are optimized.Meanwhile, combined with the orthogonal test, the significance of the influence of structural parameters on the supporting effect of surrounding rock is explored.The results show that the support reaction force provided by π-type arch is 3.14 times that of I-steel frame with the advantages of high strength and high bearing capacity.A comparative analysis model is established,and compared with the traditional support system,the settlement of the arch crown under the new support system is reduced by53.8%,the equivalent plastic strain is reduced by about 64.4%,and the maximum compressive stress and tensile stress of the initial support are reduced by about 35.3% and 35.9% respectively.Then the parameter optimization model is established.Through the comprehensive evaluation of the vertical displacement and plastic zone of surrounding rock,it is suggested that the arch wall thickness should be 6 mm,the grouting strength should be C30,and the flange length should be 200mm.Combined with the results of orthogonal test,the influence degree of each factor from small to large is:factor B(grouting strength)<factor A(steel wall thickness)<factor C(flange length).This study can further promote the application of the new arch in the construction support of loess tunnel.更多还原