既有地铁隧道与基坑的安全距离研究

Study on the Safety Distance Between Existing Subway Tunnel and Foundation Excavation

结合具体工程实例,针对拟建基坑与既有地铁隧道间的安全距离进行深入分析。在常规基坑变形控制条件下,建议隧道结构与围护墙间距≥20m,以便于保护隧道结构的安全。在加强基坑支护刚度的条件下,随着围护墙与隧道结构间距的减小,基坑支护刚度加强所需代价将逐渐增大。当围护墙与隧道结构间距≤12m时,即便花费极大的基坑支护代价提高基坑支护刚度,仍较难以满足隧道结构的安全要求。当围护墙与隧道结构间距>15m时,基坑支护代价逐渐减小,隧道结构的安全更易得到保证。

Combined with the specific engineering, the safety distance between the existing subway tunnel and the foundation excavation was deeply analyzed. On the condition that the deformation control requirements were normal, the relative distance between the tunnel and the retaining wall is not less than 20m, so as to protect the safety of the tunnel structure. When the support stiffness of the foundation excavation is strengthened, the cost of the supporting system will gradually increase with the decrease of the distance between the retaining wall and the tunnel. When the distance between the retaining wall and the tunnel is less than 12m, it is still difficult to meet the safety requirements of the tunnel, even if it takes great cost to improve the support stiffness of the foundation excavation. When the distance is greater than 15m, the cost of the supporting system decreases gradually, and the safety of the tunnel structure is much more easy to be guaranteed.