Reutilization of Silty Sandstone Shield Spoil for Sustainable Synchronous Grouting: Mechanical Properties and...

Area of Science:

• Civil Engineering
• Materials Science
• Geotechnical Engineering

Background:

• Conventional synchronous grouting materials face challenges like low early strength and poor excavated soil utilization in metro tunneling.
• Efficient and green advancement of shield tunneling technology requires improved grouting solutions.

Purpose of the Study:

• To develop a high-performance grouting material utilizing shield muck and sodium trimethylsilanolate (TMS-Na).
• To systematically evaluate the impact of slag and TMS-Na on grout properties and elucidate the modification mechanism.

Main Methods:

• Orthogonal experiments and range analysis to optimize cement, slag, and TMS-Na content.
• Microstructural analysis using SEM, XRD, FTIR, TG, and MIP to understand TMS-Na's role.
• Field application testing in a trial tunnel section.

Main Results:

• Optimized grout with 8% slag and 0.2% TMS-Na achieved 60.8% shield muck utilization.
• Compressive strength increased by 97.4% (3-day) and 93.3% (28-day); impermeability reached P10.
• TMS-Na accelerated hydration, reduced setting time, and densified the grout matrix by promoting C-S-H formation.

Conclusions:

• The novel grouting material significantly improves mechanical properties and impermeability while enhancing shield muck utilization.
• Field applications confirmed effective cavity filling, water leakage elimination, and ground deformation control.
• The developed grouting material shows strong potential for large-scale metro shield tunneling applications.