Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force, especially for deep-buried pipes. To better reflect the soil arching effect resulting from the excavation of rectangular jacked pipes and the distribution of the earth pressure on jacked pipes, we present an analytical solution for predicting the vertical earth pressure on deep-buried rectangular pipe jacking tunnels, incorporating the tunnelling-induced ground loss distribution. Our proposed analytical model consists of the upper multi-layer parabolic soil arch and the lower friction arch. The key parameters (i.e., width and height of friction arch B and height of parabolic soil arch H1) are determined according to the existing research, and an analytical solution for Kl is derived based on the distribution characteristics of the principal stress rotation angle. With consideration for the transition effect of the mechanical characteristics of the parabolic arch zone, an analytical solution for soil load transfer is derived. The prediction results of our analytical solution are compared with tests and simulation results to validate the effectiveness of the proposed analytical solution. Finally, the effects of different parameters on the soil pressure are discussed.

The pipe jacking method has been increasingly applied to a variety of tunnel projects. Investigating the ground disturbance characteristics during pipe jacking is of great significance to ensure accurate safety assessment and timely ground deformation control. This paper developed a three-dimensional model to simulate the entire pipe jacking process of a shallow-buried cross passage tunnel in soft strata. A key contribution of this research is the development of an element shear failure approach, combining element failure method with shear failure modeling. Meanwhile, the dynamic cutter excavation effect and the soil shear failure were considered in the numerical modeling. Through the comparison with the field monitoring results and traditional numerical simulation approach, the effectiveness, reliability, and superiority of the proposed approach were well demonstrated. Moreover, based on the numerical results, the ground deformation characteristics along with the stress-strain state of the cutter head during the soil excavating process were thoroughly analyzed. The proposed approach and its application in the ground disturbance analysis will offer useful references and guidance for numerical studies in similar pipe jacking projects in near future.

This study presents a series of centrifuge model tests that were conducted to investigate the grouting mechanism and its effect during rectangular pipe jacking in soft soil. A new jacking grouting device was developed to simulate the entire grouting process in the centrifuge model tests. The influence of grouting on the friction at the lining-soil interface and vertical displacement of the tunnel lining was analysed. In addition, the impact of the grouting slurry's viscosity and fluid loss on ground surface settlement and the friction at the pipe-soil interface was also examined. The results indicate that grouting plays a significant role in mitigating the friction and vertical displacement of the tunnel lining caused by excavation. Furthermore, the study shows that reducing the viscosity of the grouting slurry can reduce the friction coefficient at the pipe-soil interface, thus facilitating the advancement of pipe jacking. The use of a low fluid loss grouting slurry is also recommended to improve control over ground surface settlement. These findings are crucial for enhancing the efficiency and safety of rectangular pipe jacking in soft soil.

The shear behavior of the pipe-soil interface determines the frictional resistance of pipe jacking. In the interfacial direct shear tests of well-graded dense sand against steel pipe under both unlubricated and lubricated scenarios, the shear stress initially exhibits hardening followed by softening. The shear band forms in the hardening stage, and significant morphology of the shear band varies in the softening stage. Eventually, the shear band exhibits a bell-shaped distribution in the pattern of horizontal displacement influenced by boundary conditions and fabric anisotropy. Coarse particles exhibit greater displacement and more intense softening due to larger initial void ratios and rotational radius, while specimens with more fine particles possess smaller maximum vertical displacement away from the interface and larger critical interface friction angle. Increased normal stress restricts particle displacement, resulting in larger shear displacement at peak state, more severe particle breakage, reduced shear band thickness, and increased peak interface friction angle. The shear stress reaches the critical stage earlier with bentonite slurry (omega = 6 %) due to reduced dilatancy and particle breakage. When the slurry concentration exceeds 14 %, overall sliding of particle displacement occurs instead of the layered distribution with increased vertical particle movement and noticeable stress softening. Continuous accumulation of irreversible dilation might induce forward movement of overlying soil. Moreover, excessive slurry concentration increases hardening and interfacial friction coefficient.

Ensuring construction safety and promoting environmental conservation, necessitate the determination of the optimal jacking force for rectangular pipe jacking projects. However, reliance on empirical calculations for estimating jacking force often resulted in overly conservative results. This study proposed a modified Protodyakonov ' s arch model to calculate the soil pressure around the jacked pipe considering the critical damage boundary. A three-dimensional log-spiral prism model, based on limit equilibrium method was applied to analyze the resistance on the shield face. The determination of jacking force integrated factors such as soil pressure around jacked pipes, friction coefficient between pipe and soil, and shield face resistance. By utilizing Suzhou ' s jacking-pipe engineering as a practical context, the accuracy was validated against field monitoring data and existing jacking force calculation models of varying specifications. Parametric analysis indicated the jacking force is linearly correlated with the soil unit weight and pipe-soil friction coefficient. However, the jacking force decreases significantly with increasing internal friction angle. As the internal friction angle rose from 25 degrees to 50 degrees , the soil arch height gradually diminished from 8.91 to 2.59 m. Notably, a complete arch structure failed to form above the jacked pipe when the cover depth ratio was less than 0.5. The heightened predictive precision of the proposed model enhanced its suitability for practical shallow buried tunnel jacking force predictions.

Pipe jacking construction is a commonly employed trenchless technique for laying underground pipes in urban areas. However, the conventional support structure for pipe jacking shafts poses challenges, including difficulty in reserving pipe jacking holes, susceptibility to tilting, low bearing capacity, and the potential for failure during construction. Taking the 5# pipe jacking shaft of the pipe jacking construction for diverting the Yellow River through the river at Niukouyu in Zhengzhou City as the research background, investigates the soil settle deformation around the working shaft and the mechanical response law of the supporting structure during the shortdistance, long-distance and second long-distance pipe jacking construction by combining the practical engineering field test and finite element numerical simulation, and carries out a sensitivity analysis on the main design parameters affecting the stability of the supporting structure through orthogonal test. The findings reveal that during the second pipe jacking construction, stress and deformation of the supporting structure are higher than those observed in the first pipe jacking. Notably, support piles and waist beams at the entrance of the pipe jacking experience greater force, and the back and side walls undergo increased force and deformation in the later stages of pipe jacking, and support pile spacing is the main control factor affecting the mechanical performance of the novel support structure. The study concludes that monitoring and protection measures should be reinforced, particularly in areas prone to failure and damage during construction. The insights gained from this research can serve as a reference for designing, optimizing, and safely monitoring novel assembled pipe jacking shaft support structures.