高速公路穿越岩溶盆地工程地质选线分析

Analysis of Engineering Geology Route Selection in the Karst Basin Area of Expressway

为了达到“减灾防灾、降低造价、确保安全”的选线要求,对开远至建水高速公路小龙潭岩溶盆地区进行工程地质选线研究。通过区域资料收集,现场工程地质调绘、钻探、物探等,重点分析岩溶及岩溶水对隧道方案的影响和新邓尔排土场的稳定性对桥梁方案的影响。当隧道岩溶发育,且与地下管道流及地表河流存在较直接的水力联系时,短时极端突水会对隧道造成极大风险,建议短时极端突水量计算采用历史日最大降雨量的大气降水入渗法;在结合工程地质调绘和分析利用其既有稳定性评价报告的基础上,利用GEO5岩土边坡稳定性分析软件,对新邓尔排土场稳定性进行定量分析。研究表明,若隧道方案于南洞沟岩溶暗河下通过,岩溶及岩溶水风险高,建议规避;新邓耳排土场稳定性良好,风险可控。在综合分析路线方案的工程风险后,推荐规避南洞沟暗河,大跨跨过新邓尔排土场下游的K线方案。

In order to meet the requirements of“disaster reduction and prevention,cost reduction and safety assurance”,the engineering geology route selection study was carried out in the Xiaolongtan karst basin area of the Kaijian expressway.Through collecting regional data,analyzing,geological mapping,drilling and geophysical prospecting,The influence of karst and its water on the tunnel scheme and the influence of the Xindenger dump on the bridge were discussed.When the tunnel karst development was strong,and there was direct hydraulic connection between tunnel and underground pipeline flow and surface river,short-term extreme water bursting of tunnel led great risks,and short-term extreme water bursting calculation using the precipitation infiltration method of historical daily maximum rainfall was suggested.In view of the stability of the Xindenger dump,on the basis of the existing stability evaluation report combined with engineering geological mapping,GEO5 software was used to quantitatively analyze the stability of the geotechnical slope.It is concluded that the tunnel schemes passed under the Nandonggou karst underground river,and the risk of karst and karst water was high and it was recommended to be avoided.The Xindenger dump had good stability and the risk could be controlled.After comprehensive analysis of the engineering risks for the schemes,the K scheme,which avoided the Nandonggou karst underground river and went across the downstream of the Xindenger dump,was recommended.