Abstract
For roadbed engineering in karst regions and over mined-out areas, improper treatment of underlying voids can readily induce subsidence and other distresses. Grouting reinforcement constitutes one of the common measures for treating karst voids. The typical grouting procedure encompasses drilling, hole sealing, and grouting. Influenced by factors including landform, strata, geological structure, hole sealing quality, and grouting pressure, phenomena such as grout leakage and channeling frequently arise during grouting construction, with the phenomenon of "blind injection and blind evaluation" being prevalent at construction sites, thereby resulting in unsatisfactory filling effectiveness, material wastage, and environmental contamination. The fundamental issue in grouting reinforcement resides in determining the distribution and migration of grout, as well as performing precise evaluation of filling effectiveness. To address the aforementioned problems, this study developed a novel conductive grout material that, while satisfying conventional performance indicators such as fluidity, initial setting time, and water separation, exhibits electrical resistivity significantly distinct from limestone. By exploiting the inherent conductive characteristics of the grout in conjunction with the high-density electrical method, precise tracking and monitoring of grouting construction can be realized, effectively preventing grout channeling and leakage. Through the GIN method grouting control process, GIN value (Grouting Intensity Number) standards are established based on geological conditions, enabling real-time monitoring of the grouting process via P-V curves and F/P-V curves, thereby achieving visualized control throughout the entire grouting operation. The integration of high-density electrical method and transient Rayleigh wave method facilitates rapid detection of grouting reinforcement effectiveness and quantitative assessment of grouting extent and improvement degree. Application of these research findings contributes to advancing the theory and methodology for treating hidden defects in roadbeds, fills relevant technical gaps both domestically and internationally, and holds significant theoretical importance and engineering practical value for the development of new road construction technologies and design theories, as well as for the advancement of construction technology in China.
Full Text
Preamble
Title: Precise Grouting Technology for Treating Underlying Cavities in Subgrade Based on Conductive Cement Slurry Tracking
Authors: Xu Chen¹,², HaoJie Li¹,², Shen Zuo¹,², Jin Li¹,²
Affiliations:
1. Shandong Key Laboratory of Technologies and Systems for Intelligent Construction Equipment, Shandong Jiaotong University, Jinan, Shandong 250357, China
2. School of Transportation and Civil Engineering, Shandong Jiaotong University, Jinan, Shandong 250357, China
Abstract: For subgrade projects in karst and mining areas, improper treatment of underlying cavities can easily induce diseases such as settlement. Grouting reinforcement is one of the common methods for treating karst cavities. The typical grouting process involves drilling, sealing, and injection. However, influenced by factors such as topography, strata, structure, sealing quality, and grouting pressure, problems like grout leakage and channeling frequently occur during construction. This leads to a widespread phenomenon of "blind injection and blind evaluation" at construction sites, resulting in unsatisfactory filling effects, material waste, and environmental pollution. The core challenge in grouting reinforcement lies in determining the distribution and flow direction of the slurry and accurately evaluating the filling effectiveness. To address these issues, this study developed a novel conductive slurry material that, while meeting conventional requirements for fluidity, initial setting time, and water separation, exhibits significantly different resistivity from limestone. By leveraging the inherent conductive properties of the slurry combined with high-density electrical methods, precise tracking and monitoring of grouting construction can be achieved, effectively preventing grout leakage and channeling. Using the GIN (Grouting Intensity Number) method for grouting control, GIN value standards are determined based on geological conditions, and real-time monitoring of the grouting process is implemented through P-V curves and F/P-V curves, enabling visualized control of the entire grouting process. Combined with high-density electrical methods and transient Rayleigh wave methods, rapid detection of grouting reinforcement effects is performed to quantitatively evaluate the grouting range and degree of reinforcement. The application of these research findings contributes to improving the theory and methods for treating hidden diseases in subgrade, fills relevant technical gaps domestically and internationally, and holds significant theoretical importance and practical engineering value for the development of new road construction technologies, design theories, and construction technology advancements.
Keywords: conductive slurry; subgrade; underlying cavity; grouting