# Optimization of Thixotropic Slurry Ratio and Drag Reduction Effect Test for Circular Pipe-Jacking Construction in Pebble Stratum

## TL;DR

This study finds that adding shell powder to slurry improves pipe-jacking construction in gravel strata by reducing friction and preventing collapse.

## Contribution

A novel slurry formulation using shell powder is proposed to address high friction and instability in gravel strata during pipe-jacking.

## Key findings

- The optimal slurry mix includes bentonite, shell powder, and other additives, reducing soil friction by 35.6%.
- Shell powder enhances slurry sealing and stratum stability due to its porous structure.
- The optimized slurry formulation improves anti-seepage capacity and reduces jacking resistance in gravel strata.

## Abstract

What are the main findings?
The optimal thixotropic slurry materials and  mix proportions  (including bentonite, shell powder, etc.) applicable to pipe-jacking construction in pebble strata were established.The porous structure of shell powder significantly enhances the slurry’s sealing performance and stratum stability.The optimized slurry can reduce the soil friction coefficient by about 35.6%, effectively addressing the issue of high jacking resistance.

The optimal thixotropic slurry materials and  mix proportions  (including bentonite, shell powder, etc.) applicable to pipe-jacking construction in pebble strata were established.

The porous structure of shell powder significantly enhances the slurry’s sealing performance and stratum stability.

The optimized slurry can reduce the soil friction coefficient by about 35.6%, effectively addressing the issue of high jacking resistance.

What are the implications of the main findings?
An economical and efficient slurry optimization scheme is proposed, utilizing conventional materials such as shell powder, facilitating widespread application.It simultaneously addresses challenges in pebble–gravel strata, including high friction, slurry leakage, and stratum instability.It provides a successful case for the design of “site-specific slurry” in complex strata, promoting the development of refined construction technologies.

An economical and efficient slurry optimization scheme is proposed, utilizing conventional materials such as shell powder, facilitating widespread application.

It simultaneously addresses challenges in pebble–gravel strata, including high friction, slurry leakage, and stratum instability.

It provides a successful case for the design of “site-specific slurry” in complex strata, promoting the development of refined construction technologies.

Circular pipe-jacking construction in gravel strata faces significant technical challenges, including high frictional resistance, elevated permeability, and susceptibility to collapse. Optimizing the formulation of thixotropic slurry is crucial for improving the construction quality and efficiency of such projects. This study, based on the Ruyang Water Supply Project of the North Main Canal in the Qianping Irrigation Area, Henan Province, China, systematically investigated slurry formulation using bentonite, soda ash, sodium carboxymethyl cellulose (CMC), polyacrylamide (PAM), and shell powder as raw materials. An orthogonal experimental design was employed to optimize the mix proportions, and the friction-reduction performance was validated through drag-friction model tests. The results indicate that the optimal slurry formulation is: bentonite 8%, soda ash 0.3%, CMC 0.2%, PAM 0.15%, shell powder 4%, and water 87.35%. This formulation exhibits excellent fluidity and thixotropy, facilitating the formation of a stable slurry film. Consequently, the friction coefficient between concrete specimens and gravel soil was reduced by 35.6%. The inclusion of shell powder significantly enhanced the slurry’s cohesiveness and improved the anti-seepage capacity of the surrounding stratum due to its filling effect. The optimized thixotropic slurry effectively mitigates frictional resistance during pipe jacking in gravel strata and enhances the formation’s resistance to collapse. The findings of this study provide a viable technical reference for pipe-jacking projects under similar geological conditions.