超前地质预报的物探方法有多种，由于岩溶发育空间分布的复杂性和岩溶含水介质充填物的多样性，单一的超前地质预报方法都具有局限性，如何针对岩溶的地球物理特征，选择适用的地质预报物探方法，以提高预报成果的准确度非常必要。通过对TSP法、地质雷达法、瞬变电磁法等超前地质预报主要物探方法工作原理、有效探测距离和地球物理特征等进行分析，论述岩溶隧道超前地质预报方法的理论依据和方法选择。以九景衢铁路何家隧道为例，详细论述施工过程中采用的几种主要超前地质预报方法以及组合方法，通过对比分析，验证和总结几种主要物探方法预报成果的适用性和准确度。实践成果表明： 1）单一的超前地质预报方法都具有局限性，难以应对岩溶隧道的复杂地质条件和施工高风险，需采取“三结合”措施，选取不同的超前预报方法作为组合方法，相互验证。2）TSP法未能对是岩溶还是断层破碎带进行区分，必须结合其他方法，进行对比验证才能区分； TSP法+地质雷达法长短结合探测方法，是一般简单岩溶隧道通用的组合。3）瞬变电磁法在岩溶隧道探测中效果明显，判译解释准确度高，适合大型岩溶强发育地段； 超前水平钻+瞬变电磁法+地质雷达法+水文监测地质预报组合，是复杂岩溶隧道超前地质预报可采用的有效组合。叠加超前水平钻与瞬变电磁剖面图进行分析，能详细分析出岩溶的空间分布和形态特征。
There are many geophysical methods for advanced geological
prediction. Due to the complexity of spatial distribution of Karst development
and diversity of fillings of Karst waterbearing media, single advanced
geological prediction method has limitations. It is necessary to select
suitable geophysical methods or combinations of geological prediction to
improve the accuracy of prediction results according to the geophysical
characteristics of Karst. The theoretical basis and method selection of
advanced geological prediction method for Karst tunnels are discussed by
analyzing the working principle, effective detection distance and geophysical
characteristics of main geophysical prediction methods such as TSP method,
geological radar method and transient electromagnetic method. Several main
advanced geological prediction methods and combinations used in Hejia Tunnel of
Jiujingqu Railway are discussed in detail during construction. Through
comparative analysis, the applicability and accuracy of prediction results of
several main geophysical prospecting methods are verified and summarized. The
applicable results show that: (1) Single advanced geological prediction method
has limitations and is difficult to cope with complex geological conditions and
high construction risk of Karst tunnels; it is necessary to adopt the measures
of "three combinations" and select different advanced prediction
methods as combinations to verify each other. (2) The TSP method fails to
distinguish between Karst and fault fracture zones, so it must be combined with
other methods to carry out comparative verification in order to distinguish
them; the combination of TSP method and geological radar method is a common
combination for simple Karst tunnels. (3) The transient electromagnetic method
has obvious effect in Karst tunnel detection with high accuracy of
interpretation, and is suitable for large stronglydeveloped
Karst areas. The combination of advanced horizontal drilling + transient
electromagnetic method + geological radar method + hydrological monitoring
geological prediction is an effective combination for advanced geological
prediction of complex Karst tunnels. The analysis of superimposed advanced
horizontal drilling and transient electromagnetic profiles can provide a
detailed analysis of the spatial distribution and morphological characteristics
of Karst.
