Experimental Study on the Effect of Hydroxyethyl Cellulose on the Friction-Reducing Performance of Thixotropic Slurries in Pipe Jacking Construction.

In pipe jacking construction, thixotropic slurry critically governs lubrication, friction reduction, and ground support. This study evaluated slurry performance through six parameters: specific gravity (SG), pH, fluid loss (FL), water separation rate (WSR), filter cake thickness (FCT), and funnel viscosity (FV). Orthogonal experiments optimizing bentonite, carboxymethyl cellulose (CMC), and sodium carbonate (NaCO) ratios established 10 wt.% bentonite, 0.3 wt.% CMC, and 0.4 wt.% NaCO as the optimal formulation. Subsequently, to address performance limitations in challenging conditions, this study introduces hydroxyethyl cellulose (HEC) as a novel additive, with potential advantages under high-salinity and variable pH conditions. Comparative experiments demonstrated that HEC, as a non-ionic water-soluble cellulose, not only significantly increases FV and reduces FL while maintaining SG, FCT, and WSR within acceptable thresholds, but also exhibits superior pH stability compared to CMC. Based on the aforementioned results, interface friction characterization tests were conducted on representative slurry formulations with varying FVs, quantitatively demonstrating the viscosity-dependent friction-reduction performance. Complementary scanning electron microscopy (SEM) analysis of three distinct thixotropic slurry compositions systematically revealed their microstructural characteristics, with microscopic evidence confirming the excellent compatibility between HEC and thixotropic slurry matrix. These findings highlight HEC's potential as an effective alternative in pipe jacking, particularly in demanding geological environments.