Advanced Geotechnical Investigation and Data Interpretation for Complex Underground Structures-Paper

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The paper presents a multiphase geotechnical investigation framework for complex underground structures, emphasizing that careful site characterization and timely interpretation can reduce cost overruns, improve safety, and prevent overly conservative design.<br /><br />The proposed program combines investigations before excavation—geological surface mapping, seismic refraction and cross-hole tomography, borehole drilling and testing, and borehole televiewer surveys—with investigations during construction, including 3D face mapping, probe drilling, and drift mapping. These methods provide complementary information on stratigraphy, rock structure and quality, groundwater, in-situ stresses, and material strength.<br /><br />The authors stress that data should be interpreted collectively rather than in isolation. Geological mapping and borehole results are correlated with geophysical surveys and observations from excavations to build and update a geological model. Discontinuity orientations can be assessed stereographically to identify potential wedge failures and inform excavation alignment and support design. Groundwater conditions and stress magnitudes and directions also require assessment because they can significantly affect stability.<br /><br />Rock-mass classification systems such as Q and GSI, alongside laboratory and in-situ test results, are used to estimate design parameters including strength, cohesion, friction angle, and deformation modulus. Investigation findings should be confirmed and revised as excavation exposes actual ground conditions.<br /><br />Overall, the framework aims to provide reliable geotechnical inputs throughout design and construction, enabling appropriate support systems, more economical design, and fewer unexpected or hazardous conditions underground.

Keywords

geotechnical investigation

underground structures

site characterization

seismic tomography

borehole drilling

geological mapping

groundwater conditions

rock mass classification

wedge failure

excavation support design