为揭示硬质岩公路隧道不同高跨比断面形态对结构力学响应与围岩压力特征的影响,基于典型深埋隧道工程,采用数值模拟方法对六种高跨比断面进行了系统分析,并对比了普氏理论、公路隧道设计规范等传统计算方法与数值结果的差异。现有经验公式在非标准断面及高地应力条件下存在偏差,难以反映断面形态效应。针对Q系统模型的局限性,建立了高跨比与围岩压力的定量耦合关系,提出了基于Q法的围岩压力修正模型。结果表明:随着高跨比由 0.2 增至 1.0,拱顶沉降降低 87.4%,围岩压力峰值下降 57.6%,当高跨比大于 0.6 时,结构变形趋于稳定;修正模型与实测数据拟合良好,验证了方法的合理性与工程适用性。研究成果完善了硬质岩隧道形态效应理论,可为复杂地质条件下的结构设计与围岩压力快速估算提供依据。

To reveal the influence of different depth-span ratio cross-section shapes on the structural mechanical response and surrounding rock pressure characteristics in hard rock highway tunnels, this paper conducts a systematic analysis of six depth-span ratio sections based on a typical deep-buried tunnel project using numerical simulation methods. Differences between traditional calculation methods, such as Protodyakonov's theory and the theory of highway tunnel design, and the numerical results are compared. Existing empirical formulas exhibit deviations under non-standard cross-sections and high in-situ stress conditions, failing to adequately reflect the cross-section shape effect. Addressing the limitations of the Q system model, a quantitative coupling relationship between the depth-span ratio and surrounding rock pressure is established, and a modified surrounding rock pressure model based on the Q-method is proposed. Results indicate that: As the depth-span ratio increases from 0.2 to 1.0, the crown settlement decreases by 87.4%, and the peak surrounding rock pressure drops by 57.6%. When the depth-span ratio exceeds 0.6, structural deformation tends to stabilize. The modified model shows good agreement with measured data, validating the rationality and engineering applicability of the proposed method. The research findings enhance the theory of shape effects in hard rock tunnels and provide a reliable basis for structural design and rapid estimation of surrounding rock pressure under complex geological conditions.