富水砂卵石地层盾构隧道与地面下伏空洞安全距离计算模型

Calculation Model of Safety Distance between Shield Tunnels and Underground Cavities in Water-Rich Sandy Cobble Stratum

[目的]为保证富水砂卵石地层中盾构隧道穿越地面下伏空洞施工时的安全性,需研究盾构隧道与地面下伏空洞间的安全距离。[方法]以南昌地铁1号线东延伸段隧道工程为例,结合理论计算与数值模拟方法,基于突变理论,针对地面下伏空洞与隧道间的安全距离进行定量分析;结合结构力学近似分析法对现场典型地面下伏空洞与隧道间的安全距离进行计算,建立富水砂卵石地层盾构隧道与地面下伏空洞安全距离的计算模型;以地面下伏空洞与隧道间岩土层系统塑性区是否贯通作为判据,利用Abaqus软件数值模拟方法对所提计算模型的合理性进行验证。[结果及结论]所提富水砂卵石地层盾构隧道与地面下伏空洞安全距离计算模型具有一定的准确性与合理性,可应用于工程实践。隧道与地面下伏空洞间的安全距离随着地面下伏空洞跨度的增加而增加,随着其高跨比的增加而减少,随着围岩影响因子水平的增加而增加。

[Objective]In order to ensure the shield tunnel construction safety in water-rich sandy cobble stratum when passing through underground cavities,it is necessary to study the safe distance between the shield tunnels and the underground cavities.[Method]Taking the tunnel project of Nanchang Metro Line 1 East Extension as an example,combining theoretical calculation and numerical simulation methods,a quantitative analysis is conducted on the safety distance between underground cavities and tunnels based on the catastrophe theory.The above-mentioned safety distance is calculated by combining the structural mechanics approximate analysis method,and a calculation model for the safety distance between the shield tunnels in water-rich sandy cobble stratum and the underground cavities is established.The rationality of the proposed calculation model is verified by the Abaqus software numerical simulation,taking whether the plastic zone of the rock-soil system between the underground cavity and the tunnel is connected as the criterion.[Result&Conclusion]The proposed calculation model for the safety distance between the shield tunnels in water-rich sandy cobble stratum and the underground cavities has certain accuracy and rationality and can be applied in engineering practice.The above-mentioned safety distance increases as the span of the underlying cavity increases,decreases as its height-to-span ratio increases,and increases as the level of surrounding rock influence factors increases.