In the loose and fractured coal seam with particularly low uniaxial compressive strength (UCS), driving a roadway is extremely difficult as roof falling and wall spalling occur frequently. To address this issue, the jet grouting (JG) technique (high-pressure grout mixed with coal particles) was first introduced in this study to improve the self-supporting ability of coal mass. To evaluate the strength of the jet-grouted coal-grout composite (JG composite), the UCS evolution patterns were analyzed by preparing 405 specimens combining the influential variables of grout types, curing time, and coal to grout (C/G) ratio. Furthermore, the relationships between UCS and these influencing variables were modeled using ensemble learning methods i.e. gradient boosted regression tree (GBRT) and random forest (RF) with their hyperparameters tuned by the particle swarm optimization (PSO). The results showed that the chemical grout composite has higher short-term strength, while the cement grout composite can achieve more stable strength in the long term. The PSO-GBRT and PSO-RF models can both achieve high prediction accuracy. Also, the variable importance analysis demonstrated that the grout type and curing time should be considered carefully. This study provides a robust intelligent model for predicting UCS of JG composites, which boosts JG design in the field.

Development of ensemble learning models to evaluate the strength of coal-grout materials

A critical review on the performance of yielding supports in squeezing tunnels

An analytical design method for ductile support structures in squeezing tunnels

A literature review on properties and applications of grouts for shield tunnel

Shield-driven induced ground surface and Ming Dynasty city wall settlement of Xi’an metro

Analytical computation of support characteristic curve for circumferential yielding lining in tunnel design

Deformation control and stability analysis are very important for tunnel construction. Large deformations of the constructed primary support accompanied by lining cracking and spalling occu...

Determination of Deformation Mechanism and Countermeasures in Silty Clay Tunnel

The utilization of highly deformable elements in lining has been proved to be an effective measure to control large deformations occurring in tunnels excavated in severe squeezing rocks. However, t...

Su Qin

Papers

A critical review on the performance of yielding supports in squeezing tunnels

An analytical design method for ductile support structures in squeezing tunnels

Analytical computation of support characteristic curve for circumferential yielding lining in tunnel design

Determination of Deformation Mechanism and Countermeasures in Silty Clay Tunnel

Analytical-Based Assessment of Effect of Highly Deformable Elements on Tunnel Lining Within Viscoelastic Rocks