Experimental study on strength restoration effect of chemically grouted fractured porous sandstone based on temperature gradient
XU Shaodong
ZHANG Lei
PAN Huanxi
LIU Yunhao
Abstract：Investigating the seepage behavior of grout in fractured rock masses and its ultimate restora-tion and reinforcement effects is essential for advancing grouting theory and optimizing engineering grouting parameter design.This study systematically examined the influence of ambient temperature and grouting pressure conditions on chemical grouting processes,designing and conducting a series of laboratory-scale simulation tests.Innovatively employing Low-Field Nuclear Magnetic Resonance(LF-NMR)technology,the tests achieved in-situ,non-destructive,real-time dynamic monitoring of the grout's seepage and diffusion processes within the fracture network of the rock mass.Through in-depth analysis of the T2 relaxation time distribution response characteristics obtained via LF-NMR,this research systematically revealed the specific influence patterns of temperature variations on grout rheological properties,effective grout diffusion range(grout intake volume),and macro-scale permea-bility of the rock mass.Concurrently,direct shear testing on grout-reinforced rock specimens cured under different temperature conditions quantitatively evaluated the critical role of temperature on the final mechanical properties of the grouted body.The results unequivocally demonstrate that tempera-ture is a key controlling factor for grout seepage behavior,with elevated temperatures causing signifi-cant reductions in rock mass permeability,thereby impeding effective grout diffusion;the mechanical performance of the grout-reinforced composite exhibits strong temperature dependency,with its shear strength parameters-angle of internal friction(φ)and cohesion(c)both displaying distinct expo-nential decay trends with increasing temperature.Building upon these core findings,this study further established and validated a mechanical model for the shear strength of the grout-rock interface capable of quantitatively characterizing temperature effects,explicitly incorporating the temperature-dependent evolution of key parameters.The research outcomes provide significant theoretical founda-tions and practical parameter design references for grouting engineering in complex environments such as deep-buried tunnels with high geothermal temperatures.
Keywords：seepage characteristicsstrength repairing effectstemperature LF-NMRmechanical model
Publication Date：2025-12-31
Online Publishing Date：2025-11-25(First online date of this platform, not the publication date of the document)
Pages：10( 36-45 )