金川水电站大型地下厂房洞室群施工期围岩质量评价方法

Quality Evaluation Method for Surrounding Rock of Large-Scale Underground Powerhouse Cavern Groupof Jinchuan Hydropower Station during Construction Period

金川水电站地下厂房洞室群规模大且地质构造条件复杂,给施工期带来极大的安全风险,鉴于地下厂房的重要性及特殊性,查明开挖洞室围岩类别及不良地质现象可以为洞室群施工期安全快速施工提供保障,因此本工程迫切需要一种针对地下厂房洞室群在施工期的围岩质量评价方法去解决当下面临的问题。为此,基于前期勘探成果、借助三维地质建模软件建立地下厂房三维围岩质量分级模型,在施工期洞室开挖前采用TGS360Pro系统进行掌子面前方100 m洞段的超前地质预报,对该段的三维围岩质量分级模型进行动态修正,进行地下厂房开挖后地质编录结果和地质预报结果的对比分析。结果表明:采用该方法可深入研究探明局部Ⅳ类围岩等不良地质现象对围岩稳定性的影响,可实现最大限度地降低不良地质部位开挖风险,为工程的顺利修建和安全运行提供技术保障。TGS360Pro超前地质预报技术可以实现精准的超前地质预测预报,进一步查明不良地质现象位置及分布范围,可作为完善地质三维围岩分级模型的重要依据。该围岩质量评价方法及超前地质预报方式对金川水电站大型地下厂房洞室群可实现快速开挖支护提供了技术支撑。

Underground powerhouse cavern group of Jinchuan Hydropower Station is large in scale and its geological condition is complex,which brings great safety risk during the construction period.In view of the importance and particularity of the underground powerhouse,the identification of the surrounding rock type and undesirable geological condition can provide guarantee for the safe and smooth construction of the cavern group.Therefore,a surrounding rock quality evaluation method for the underground powerhouse cavern group during the construction period is urgently required to solve the problem.To this end,based on the preliminary exploration results and with the help of 3D geological modeling software,the 3D surrounding rock quality classification model of the underground powerhouse is established.The TGS360Pro system is used to carry out the advanced geological prediction of the 100 m tunnel section in front of the tunnel before the excavation of the cavern;the 3D surrounding rock quality classification model of the section is dynamically corrected,and the geological cataloging results and geological prediction results after the excavation of the underground powerhouse are compared and analyzed.The results show that this method can be used to study the influence of undesirable geological condition such as local class IV surrounding rock on the stability of surrounding rock,which can minimize the risk of excavation of undesirable geological parts and provide technical support for the smooth construction and safe operation of the project.TGS360Pro advanced geological prediction technology can achieve accurate advanced geological prediction and forecasting,and further identify the location and distribution range of undesirable geological condition,which can be used as an important basis for improving the geological three-dimensional surrounding rock classification model.The surrounding rock quality evaluation method and advanced geological prediction method provide technical support for the smooth excavation and support of the large-scale underground powerhouse cavern group of Jinchuan Hydropower Station.