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为研究刀盘开口率对盾构土舱内、外压力的影响,利用土压平衡盾构模型机,在多种不同刀盘开口率条件下进行模拟掘进试验,监测刀盘开口处土压力和土舱压力,分析不同刀盘开口率条件下的土舱内、外压力的变化规律,试验结果表明,随着刀盘开口率的增加,土舱压力传递系数逐渐增大,土舱内、外压差逐渐减小。借鉴黏性流体理论,针对盾构施工渣土运动过程中的应力变化建立力学模型,提出土压力变化公式,考虑土体运动过程中的沿程损失和刀盘结构处的局部损失,使计算过程更加贴近于实际状况,可以定量分析刀盘开口率、隧道洞径、土体参数、附加应力等参数对土舱内、外土压力变化的影响。根据该力学公式可得,土体内摩擦角和黏聚力越大,盾构土舱内、外土压力差值越大;盾构刀盘开口率越大、隧道直径越大,盾构土舱内、外土压力差值越小。为确认理论分析的合理性和适用性,将理论计算公式和实际工程的监测数据、离散元模拟结果以及模型试验结果进行了对比分析,进一步论证了计算理论的合理。
In order to study the influence of cutter opening ratio on the internal pressure and external pressure of shield soil, a tunnel boring machine was used to simulate the tunneling test under a variety of different cutter opening rates to monitor the earth pressure and The pressure in the soil tank and the pressure in the soil tank under different conditions of cutterhead opening rate were analyzed.The results showed that with the increase of cutterhead opening ratio, Pressure drop gradually reduced. According to viscous fluid theory, a mechanical model is established for the change of stress in the process of shield muck, the formula of earth pressure variation is proposed, and the loss along the course and the local loss at the structure of cutter head are considered, Closer to the actual situation, quantitative analysis of cutter opening rate, tunnel diameter, soil parameters, additional stress and other parameters on the soil inside and outside the earth pressure changes. According to the mechanical formula, the larger the friction angle and cohesion, the greater the pressure difference between the inside and the outside of the shield soil. The larger the shield cutter opening ratio, the larger the tunnel diameter, Inner and outer soil pressure difference is smaller. In order to confirm the rationality and applicability of theoretical analysis, the theoretical calculation formula is compared with the actual project monitoring data, discrete element simulation results and model test results to further verify the rationality of the calculation theory.