顶管推进引起施工场地竖向附加荷载分析

基于层状体系解析刚度矩阵理论解,结合5节点Gauss-Legendre求积公式,提出了层状地基中顶管施工正面附加推力、掘进机与土体之间摩擦力以及共同作用力引起的附加荷载计算方法,分析了顶管推进引起的土体竖向附加荷载分布规律,也研究了地基等效均质性、土层力学参数、计算点间距以及顶管埋深等因素对顶管施工诱发附加荷载的影响效应。研究结果表明,掘进摩擦力引起的附加荷载在掘进面前方迅速达到压应力峰值,其量值大小和影响范围均要大于正面附加推力,是顶管施工引起临近地层附加荷载的主要影响因素。此外,层状地基土体参数的改变会对顶管施工扰动地层的附加荷载产生一定影响,地基等效均质性、计算点间距以及顶管埋深等因素对附加荷载大小及分布均存在显著影响。成果可为合理制定顶管开挖对周围土工环境的保护措施提供一定理论依据,也可为其他盾构隧道工程提供一定的理论参考。

Analysis of soil vertical additional loads induced by pipe jacking construction

Based on the analytical stiffness matrix solution for layered soil, the calculated method for additional loads induced by the pipe bulkhead additional pressure, and the propulsion friction force between the shield and surrounding soil, and the interaction forces, is derived by means of five-node Gauss-Legendre integral arithmetic. The distribution rule for vertical additional loads induced by pipe jacking construction is analyzed. Furthermore, the influences of equivalent uniform characteristics, soil mechanical parameters, spacing distance for calculation point, and pipe buried depth on additional loads are discussed. The research results show that the peak compressive stress is rapidly achieved ahead by the shield opening according to the additional loads due to the friction force. The value and influence scope of propulsion effects due to the friction force is more obvious than that due to bulkhead additional pressure. The friction force is the main influence factor of additional loads induced by pipe jacking. In addition, the change of layered soil parameters will lead to a certain extent impact on additional loads. The equivalent uniform characteristics, spacing distance for calculation point, and pipe buried depth have distinct influences on the magnitude and distribution of additional loads. The results may provide certain basis to draw up correctly protective measurements of geotechnical environments influenced by pipe jacking construction. The research results can also provide theoretical references to the other projects such as metro tunnel engineering.