圆梁山隧道毛坝向斜段岩溶作用强度模拟研究

On the karstification to the Maoba syncline of Yuanliangshan tunnel

圆梁山深埋特长隧道是重庆至怀化铁路干线的关键性控制工程.在圆梁山向斜核部上二叠统吴家坪组(P3w)和向斜东翼中二叠统茅口组(P2m)碳酸盐岩中,揭露的3个特大型充填溶洞,有异于过去对于深部水循环缓流带只有溶孔和溶蚀裂隙的认识.运用USGS开放式PHREEQC软件,依据各钻孔中地下水水化学、水动力资料对圆梁山隧道毛坝向斜段进行了岩溶作用强度的模拟计算.模拟结果表明,从地层上来看,P3w的岩溶作用强于P2m,T1d(大冶组)的岩溶作用相对较弱;从岩溶发育的位置来看,向斜核部岩溶发育强度明显强于向斜翼部.毛坝向斜地下水系统中岩溶地下水的径流主要受控于断裂的影响,而不是由向斜的一翼径流至核部向另一翼排泄.

Yuanliangshan deep-imbedded and long tunnel is a critical part of the railway from Chongqing to Huaihua.Three large size filling-type karst caves were found in both cores and wings of Maoba syncline,the stratums of which are P3w and P2m respectively.This finding has denied the judgment that only dissolved pores and corrosion fissure can exist in deep slow water cycling zone.Using the USGS software PHREEQC and the hydrochemical and hydrodynamic data of the drill holes,the intensity of karstification in Yuanliangshan tunnel of Maoba syncline was simulated.The results show that the intensity of P3w is stronger than P2m,and the karstification in T1d is very weak.As to the position where karst developed,the karstification of cores is much more intensive to the wings.And the runoff of the groundwater in Maoba syncline is controlled.