Earth pressure balance shield tunneling is prone to spewing during excavation under conditions of large burial depth and high water pressure. Polymers are generally used as emergency modifiers to deal with spewing. Due to the high cost of polymers and the need for specialized mixing equipment on the ground to mix them into aqueous solutions, there are few cases of their application in soil conditioning. In order to explore the adaptability of water-soluble polymer in improving the formation of medium coarse sand, polymer soil conditioning was carried out for medium coarse sand with different fine-grained contents. Pressure permeability tests, critical spewing pressure tests, and flowability tests were carried out. The results show that: The permeability coefficient of improved soil is greatly affected by changes in fine particle content, while the effect of polymer addition on its permeability coefficient is relatively gentle; The flowability and critical surge pressure of the improved soil increase linearly with the increase of fine particle content; Exploring the adaptability of water-soluble polymers to the improvement of medium coarse sand residue from three aspects: permeability coefficient, critical spewing pressure, and flowability, and determining that polymers are suitable for medium coarse sand formations with a fine particle content of up to 4%; Comparing the economic benefits of the polymer with commonly used bentonite slurry, the results show that the polymer not only has a small impact on construction efficiency but also has certain cost advantages.

The phenomenon of grouting escaping surrounding rock stratum that may occur during shield tail grouting can cause accidents such as incorrect grouting, segment floating, misalignment and cracking, and gushing, which has attracted extensive attention. By designing a self-made shield tail grouting model device for grouting escaping, the effects of grouting properties, gap thickness, and grouting pressure difference on whether or not grouting escaping occurs and the amount of grouting escaping are analyzed, and the critical conditions for no grouting escaping are discussed. The results show that: 1) The grouting pressure and the grouting escaping distance are linearly attenuated. When the grouting consistency is low, the amount of grouting escaping has an approximate linear positive correlation with the gap thickness and slurry consistency, and an approximate linear negative correlation with the shear yield stress of the grouting, and there is an approximate linear positive correlation between the grouting escaping distance and the grouting pressure difference. When the consistency increases, the above relationship will gradually transform into a nonlinear relationship; 2) The range analysis shows that the amount of grouting escaping is most affected by the thickness of the gap between the shield shell and the rock stratum, followed by the difference between grouting pressure and excavation surface pressure, and finally the properties of the grouting itself; 3) Based on the mechanical analysis model and calculation formula for the occurrence conditions of grouting escaping, the occurrence conditions and judgement methods of grouting escaping are obtained, which can be used to guide the preparation of grouting fluid during shield tunneling in stable surrounding rock stratum.

In view of the fact that the sealing rubber is prone to edge warping under compression, which seriously affects the waterproof effect of segment joint, based on the grid mapping technology in ABAQUS/standard, the compression numerical model of hyperelastic rubber gasket is established, and the numerical simulation of axial compression is carried out for 7 kinds of gaskets with different opening shapes, opening rates and hole arrangement. The results show that in the whole process of compression simulation, the stress on the contact surface of elastic gasket meets the multi peak W distribution law of large at both ends and small in the middle; compared with other types of gasket, the maximum average contact stress of the gasket with closed hole of rounded triangle is increased by 86.8%; compared with other types of gaskets with different opening rate, the maximum average contact stress of the gasket with the opening rate of 0.294 increases by 92.6%; the maximum average contact stress of the gasket arranged with staggered holes is 25.2% higher than that of the gasket arranged with opposite holes; compared with the change of open hole configuration, the change of closed hole configuration is more sensitive to the contact stress. The maximum difference of average contact stress between two simulations under the same working condition is 85.2%.