南宁地铁2号线岩溶风险分析和处理原则

岩溶地区城市地铁修建过程中,岩溶地质灾害问题严重威胁着地铁施工和后期运营的安全,由于受到地质条件和人类工程活动等多因素影响,需要综合分析各影响因素的作用,进而制定岩溶处理原则。以南宁地铁2号线石子塘车站和石子塘站—大沙田站区间为例,分析岩溶洞穴几何特征以及空间分布规律,针对不同岩溶塌陷风险等级的影响范围和危险程度,确定相应岩溶处理原则。石子塘车站岩溶塌陷可以划分为高风险区、中等风险区、低风险区,其岩溶处理范围分别为隧道轮廓线两侧围护结构处基岩界面以下15、10、6 m,处理措施分别为采用注浆帷幕以及钻孔灌注桩+内支撑体系的围护结构,注浆帷幕以及围护孔和中立柱桩加固,注浆以及围护孔和临时立柱桩。基于不同岩溶塌陷风险等级的岩溶处理原则考虑岩溶场地的复杂性,具有较大实际工程意义,对今后岩溶地区城市隧道的施工有一定参考价值和借鉴意义。

Risk Analysis and Principle of Management of karst in Nanning Metro line 2

With the development of urban subway construction in karst areas,karst geological disasters seriously affect the safety of metro construction and later operation. Due to complex geological conditions and human engineering activities,comprehensive analysis of the impact of the influence factors should be conducted to formulate the principle of karst treatment. Taking the Shizitang station and the section between Shizitang and Dashatian on Nanning subway line 2 as an example,corresponding karst treatment measures are implemented by determining the influence range and hazard level of different karst collapse risk grades and analyzing the geometrical characteristics and spatial distribution of the karst caves. The karst collapses of Shizitang station are classified into high risk,medium risk and low risk with treatment ranges of 15 m,10 m and 6 m respectively below the bedrock interface on both sides of the tunnel contour.Corresponding treatment measures are taken such as the enclosure structure with grouting curtain and bored pile plus an inner support system, the grouting curtain and enclosure and neutral pillar reinforcement grouting,and the enclosure holes and temporary pillars. The karst treatment principles based on karst collapse risk level take into account the complexity of the karst site and have great engineering significance and they are of certain reference value and significance for future construction of urban tunnels in karst areas.