地质雷达在溪洛渡—浙西±800kV特高压直流输电线路工程塔基勘察中的应用

APPLICATION OF GROUND PENETRATING RADAR TO TOWER PAD INVESTIGATION OF ± 800KV DC POEWER TRANSIMISSION PROJECT FROM XILUODU TO ZHEXI

溪洛渡—浙西±800kV特高压直流输电线路经过的湘西地区交通极为不便,地形起伏较大,地质条件复杂,在这一地区开展工程钻探工作,困难重重。初勘资料表明,线路经过的灰岩区,岩溶发育强烈,对塔基稳定构成安全威胁,同时线路经过的砂岩区中部分塔基覆盖黏土层中含有风化碎屑,普通麻花钻难以准确判定覆盖层厚度。为了查明塔基下方岩溶发育情况,基岩面埋深等工程地质问题,经综合试验比选,采用地质雷达进行探测。岩溶探测过程中为了进一步查清桩孔基底之下至少5m以内的岩溶情况,除了地面工作外,还进行了桩底探测。钻探及施工开挖结果表明地质雷达能有效探查地下隐伏岩溶、基岩面、风化带、断裂及破碎带等,为合理选择塔位、设计基础深度提供了科学依据,取得了良好的应用效果。

The Xiluodu-Zhexi±800 kV UHV DC transmission line passes through the Xiangxi area where the traffic is very inconvenient,the ground is undulating and the geological conditions are complex.Engineering drilling work carried out in this region is very difficult.Preliminary exploration data show that at the limestone area,karst development is strongly.Tower pad stability can face safety threats.At the sandstone district,the covering clay layer contains weathered debris.Ordinary twist drill is difficult to accurately determine the coverage layer thickness.In order to check the karst development situation and the bedrock surface depth,the ground penetrating radar was used to detect the strata after the pre-test demonstration.In addition to the ground penetrating radar detection on the ground,we also carried out the pile bottom detection in order to further investigate the karst development less than 5m under the bottom of the hole.Drilling and excavation results show that the ground penetrating radar can effectively detect the hidden karst,bedrock surface,weathered zone,fracture and fracture zone.It provides a scientific basis for reasonable choice tower bit and design foundation depth.It achieves a good application result.