We propose a new interpretation procedure based on Gassmann’s theory, to estimate rock properties from seismic P-wave velocity (V_p) and S-wave velocity (V_s) data, mainly for near-surface applications. Rock properties estimated in the procedure are porosity, water saturation, and clay content of rock. Water saturation is first estimated by an analysis of a cross-plot of V_p/V_s and S-wave velocity, based on the concepts of mudrock and dry lines proposed by Castagna et al. [1985. Relationships between compressional-wave and shear-wave velocities in clastic silicate rocks. Geophysics 50: 571–81]. Porosity is then estimated using the extended existing empirical equations. Clay content is estimated from an analysis of the cross-plot of shear modulus and porosity. Finally, effective porosity is estimated using porosity and clay content. We tested this procedure with seismic data acquired in a tunnel abandoned due to deformation of the tunnel walls and to many water leakages. P-wave and S-wave velocity profiles, obtained from a 1,500 m long seismic refraction survey on a paved road in the tunnel, were used to estimate porosity, water saturation, and clay content of the rocks surrounding the tunnel. Rock property estimates were compared to geotechnical observations and measurements in the tunnel, such as deformation of the tunnel walls and water leakage sites. The results of these comparisons revealed that estimated rock property profiles can be used effectively to identify cracks within the rock and fluids in the pores of the rocks around the tunnel. This study demonstrates that the proposed procedure for estimating rock properties from seismic data is a promising technique for visualising subsurface rock properties for shallow engineering applications.

我们提出了一种基于加斯曼理论的新解释程序，从地震 P 波速度 ( V _p ) 和 S 波速度 ( V _s ) 数据估计岩石特性，主要用于近地表应用。在该程序中估计的岩石特性是岩石的孔隙度、含水饱和度和粘土含量。根据 Castagna 等人提出的泥岩和干线的概念，首先通过对V _p /V _s和 S 波速度的交会图进行分析来估计水饱和度。[1985. 碎屑硅酸盐岩中纵波和横波速度之间的关系。地球物理学50: 571–81]。然后使用扩展的现有经验方程估计孔隙度。粘土含量是通过对剪切模量和孔隙率的交会图的分析来估计的。最后，使用孔隙度和粘土含量估计有效孔隙度。我们使用在因隧道壁变形和许多漏水而废弃的隧道中获得的地震数据测试了该程序。P 波和 S 波速度剖面是从 1,500 米长的隧道铺砌道路地震折射调查中获得的，用于估计隧道周围岩石的孔隙度、含水饱和度和粘土含量。将岩石特性估计值与隧道中的岩土观测和测量值进行比较，例如隧道壁的变形和漏水点。这些比较的结果表明，估计的岩石特性剖面可以有效地用于识别岩石内的裂缝和隧道周围岩石孔隙中的流体。这项研究表明，根据地震数据估计岩石特性的拟议程序是一种用于可视化浅层工程应用的地下岩石特性的有前途的技术。