岩溶山区隧道地下水漏失对植物生长的影响分析及对策

Influence of Groundwater Loss Induced by Karst Tunnel Construction on Growth of Surrounding Vegetation and Its Countermeasures

为研究隧道建设引起的地下水漏失对周围生态环境的影响,依托穿越中梁山山脉通向重庆市区西部的3条重叠相交岩溶隧道(襄渝铁路中梁山隧道、渝遂高速公路大学城隧道和成渝客专铁路歌乐山隧道)的地下水漏失情况,对其影响区内的生态环境及植被生长进行长期监测与综合分析,利用树轮宽度均值探讨地下水漏失对隧址区优势植物(马尾松、杉木)的生长影响,提出基于生态环境保护的隧道地下水"以堵为主、限量排放"的建设思路。研究结果表明:"以排为主"的襄渝铁路中梁山隧道,造成马尾松生物量明显降低(衰退幅度达71.4%),而"以堵为主、限量排放"的其他2条隧道对马尾松的影响则相对小;3条隧道的建设对杉木的生长都产生了不利影响,影响范围在隧道轴线两侧1 km左右;基于马尾松出现生长恢复的时期(1992—1997年),建议将此阶段的最低地下水位作为隧址区地下水生态平衡埋深下限值,进而确定中梁山地区隧道的"以堵为主、限量排放"中限量排放的生态地下水位值,为岩溶山区隧道限量排放的地下水位控制提供参考。

Groundwater loss caused by karst tunnel construction will affect the surrounding residents and the growth of vegetation. In order to study the influence of tunnel construction-caused groundwater loss on ecological environment around,the influence of the groundwater loss on the growth of vegetation is evaluated based on three overlapped tunnels crossing Zhonglianshan（i. e. Zhongliangshan Tunnel on Xiangyang-Chongqing Railway, Daxuecheng Tunnel on Chongqing-Suining Highway and Geleshan Tunnel on Chengdu-Chongqing Passenger-dedicated Line）. The growth conditions of Chinese fir and Masson pine are determined by the average ring width,and limited drainage and preventive measures are found to be an appropriate way for groundwater discharge. The results show that：（1） The Zhongliangshan Tunnel with unlimited groundwater discharge induces a strong impact on the quantity of Masson pine（reduced by71. 4%）; while the other two tunnels with limited groundwater discharge have relatively low impact on the quantity of Masson pines.（2） The growth of Chinese fir is affected by all three tunnels,and the impact range is about 1 km from the centerline of the tunnel.（3） Based on the recovery period of Masson pines（1992-1997）,the lowest water level in this period is suggested to be the lower limit of the buried depth for the balance of groundwater and ecology,and further to confirm the ecological water level by limited discharge of the disease management concept in Zhongliangshan Tunnel,which is ＂ mainly stop and limited discharge＂. The results can provide useful information for the control of water level by limited discharge in karst tunnels.