弹性波CT技术在桥梁桩基岩溶探测中的应用

Karstic Rock Cavity underneath the Piled Bridge Foundations Detection by the Elastic Wave CT Technique

岩溶地质是桥梁工程建设中的安全隐患之一,探明桥梁桩基础范围内岩溶分布特性对桥梁安全尤其重要。传统的钻孔勘探方法掌握岩溶空间分布是非常困难的,不能精确地确定溶洞的分布范围及边界。依据弹性波在不同介质中的波速差异,井间弹性波CT探测技术直观地展现不同地质体的三维分布状态,特别适合于探测桥梁桩基础落位区域等局部范围内的地下岩溶空间分布情况。通过工程实例分析说明了井间弹性波CT探测技术在拟建基础工程落位区域地下岩溶探测中的有效性。

The karst geology poses a potential safety hazard for the bridge engineering.It is therefore critically important to detect and to evaluate the karst rock cavities underneath the proposed bridge foundations.The conventional test boring method is very difficult to define the karst features as well as the horizontal and vertical limits of the karstic rock boundaries.The crosshole elastic wave Computer Tomography（CT）technique can capture the three-dimensional distribution of the karst features,which is based on the differences of elastic wave prorogating in different geological materials between boreholes.This approach has the advantage of higher accuracy in positioning the space locations,higher resolution and it is well suited in the accurate positioning of the suspected karstic cavities in local areas underneath the bridge foundations.A case history of detecting the karst features underneath a proposed foundation is presented in the paper.