Study on CT Scan Technology for Detecting Karst Rock Cavities and Distribution
The electronic-magnetic computed tomography(CT)is an important means and method for the engineering explora-tion of karst cavities.The development type and degree of the underground karst cavities and their distribution characteristics have important reference value for the engineering design.This paper presents a case history of a subway station in Wuhan.The chemical and mineral composition analysis of the soluble carbonate at the site were analyzed to investigate the karst type and development degrees.The CT scan method was used to study the spatial distribution characteristics of the karst from the vertical height of karst anomalies,elevation distribution,and spatial relationship with bedrock.Meanwhile,borehole technolo-gy is used to verify the detection results.The results show that,the structures of the soluble rock are mainly marl,bioclastic limestone and micrite,and the mineral composition is mainly composed of calcite and dolomite,and karst is moderately devel-oped in the field.The locations of the karst anomalies inferred by the geophysical CT are consistent with those revealed by borehole methods.The vertical height of karst anomalies is mainly distributed in 0～4m,and there are few anomalies with the vertical height greater than 4m.The elevation of the karst anomaly points mainly distributed in-27m～-13m,accounting for 70％of the total,while the proportion of karst cavities exposed by the drilling is 60％affected by factors such as the drilling density.Karst anomalies and karst cavities are concentrated within 6m below the bedrock surface,accounting for about 63％of the total,and the number of the karst anomalies and karst anomalies decreases with the increase of the depth.The above re-search indicates that CT detection of karst cavity development and distribution is completely feasible.
Karst Cavity DevelopmentKarst Cavity TypeGeophysical CTSpace Distribution
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