The deformation modulus of rock mass is an essential parameter for evaluating the bearing capacity and deformations. A deformation modulus obtained through conventional approaches, including empirical equations and in situ tests, cannot present the deformation modulus at representative elementary volume (DREV) due to limited test coverage and technical difficulties in harsh geological or topographic conditions. This study utilized electrical resistivity (ER) tomography and numerical back-analysis to investigate DREV at the Asmari-Jahrum formation. We employed geoelectrical contrasts to detect proper locations for installing extensometers at excavated galleries. The deformations recorded by extensometer were used to back-calculate the DREV values by finite difference numerical modeling. We established a correlation between ER and DREV to predict DREV, which were 30–80 % more accurate than those obtained through conventional approaches at the study site. The tested area, anisotropy, creep, ER inaccuracies, and plastic deformations are evaluated as statistically significant factors that can influence DREV. Our methodology provides a systematical approach to assess DREV, which applies to geoengineering projects within the Asmari-Jahrum formation or similar sedimentary units (ER below 200 Ω⸱m). This methodology is also replicable for other geological formations with harsh geology or limited access without exposing an extreme financial burden or environmental issues.

中文翻译：

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使用电阻率层析成像评估代表性基本体积的变形模量


岩体变形模量是评价承载力和变形的重要参数。通过传统方法（包括经验方程和原位测试）获得的变形模量，由于测试覆盖范围有限，并且在恶劣的地质或地形条件下存在技术困难，因此无法在代表性基本体积 （DREV） 处表示变形模量。本研究利用电阻率 （ER） 断层扫描和数值反演分析来研究 Asmari-Jahrum 地层的 DREV。我们采用地电对比技术来检测在挖掘的巷道中安装引伸计的合适位置。引伸计记录的变形用于通过有限差分数值建模反演 DREV 值。我们在 ER 和 DREV 之间建立了相关性来预测 DREV，这比在研究地点通过传统方法获得的准确率高 30-80%。测试区域、各向异性、蠕变、ER 不准确和塑性变形被评估为可能影响 DREV 的统计显着因素。我们的方法提供了一种系统的方法来评估 DREV，该方法适用于 Asmari-Jahrum 地层或类似沉积单元（ER 低于 200 Ω⸱m）内的地球工程项目。这种方法也可以复制用于地质条件恶劣或通道受限的其他地质构造，而不会暴露出极端的经济负担或环境问题。