秦岭特长隧道地区同位素水文地质研究

STUDY OF ISOTOPIC HYDROGEOLOGY IN THE QINLING EXTRA-LONG TUNNEL AREA

氢氧同位素的研究表明 ,秦岭特长隧道地区地下水可分为浅层风化裂隙水和下部构造裂隙水两类 ,两者均接受大气降水补给 ,但前者还接受部分地表水补给。下部水平均补给高度在 2 1 0 0 m(岭南 )和 2 2 0 0 m(岭北 )左右。浅层水的循环深度在 5 0 m以内 ,水交替作用强烈 ;而下部水通常可达 80 0 m范围 ,局部更深 ,水交替缓慢。同位素质量平衡计算表明 , 线平行导坑绝大部分集中涌水点的水量主要来自其自身所在下部含水系统的储存量 ,另一部分来自浅部含水系统地下水的补给量 ,两者的贡献目前大约分别为 66%和 3 4%。综合同位素研究结果 ,概化出隧址区水文地质概念模型。

The study of hydrogen and oxygen isotopes shows that groundwater in the Qinling extra long tunnel area can be classified into two types, that is, the shallow weathering fissure water and deep structure fissure water, which are recharged by meteoric water. The latter has average recharging height of 2100 m over the south slope and 2200 m over the north slope; the former can accept recharge from the surface water besides rain water. There is a circulating depth of about 50 m for shallow water with an intense water alternation and about 800 m for deep water with a slow water alternation. The calculation of isotopic mass balance indicates that the discharge of most of issue points is mainly from the reserve in deep water bearing system, accounting for about 66% and partly from the recharge rate in the shallow water bearing system, accounting for about 34%. A hydrogeologic conceptual model of the tunnel area is generalized on the basis of the results of the environmental isotope study.