【作者】 徐小江；

【导师】 毕继红；

【作者基本信息】 天津大学 ， 结构工程， 2008， 硕士

【摘要】 深水基础的施工工艺研究是一个涉及多学科的难题,对于坐落于高岩质边坡的桥梁深水基础而言,复杂的地质条件已经要求了需要对诸如岩石天然结构、水流作用等因素做出相应的研究和讨论。在实际的工程应用中,重大水利工程爆破施工或大型机械的动力作用对岩土边坡的稳定性问题;行车荷载产生的桥梁耦合作用对水下基础产生的局部稳定影响都要求对处于高岩质边坡和深水环境下的桥梁基础在动荷载作用下的力学行为进行深入的理论、数值和实验研究。本文主要围绕在桥梁深水基础钻孔过程中,巨大冲击荷载的作用结合深水静水压力对所在高岩质边坡的稳定性和孔壁及其周围岩体的局部稳定性影响进行展开研究。文中首先分别介绍了基于极限平衡法和基于应力变形理论的有限元强度折减法的岩质边坡静力稳定理论。结合此理论,对襄渝二线流水河大桥南岸岩质边坡进行了数值模拟并给出了稳定安全系数。其次从岩石体动本构模型的选取、冲击振动的简化理论和应力波在岩石体中的传播等方面介绍了冲击动力学的基本理论。最后仍以襄渝二线流水河大桥南岸岩质边坡为例,采用显式动力分析软件LS-DYNA分析大直径灌注桩孔在成孔过程中冲击荷载的影响,从落锤高度、打入深度、冲击次数等多方面因素加以考虑,并根据应力水平、质点振动速率等评价指标得出在一定冲击条件下的岩石边坡的影响程度,从而总结出相关的施工防护措施,为大直径灌注桩成孔过程中相关机具的选择和合适的施工工艺顺序提供了参考。同时也从钻孔过程对孔壁岩石体塑性区的开展情况出发,为合理布置桩距做出相应的理论支持。最后结合拟静力和动力两种分析方法,简单总结了各自的差异和共同点,为今后在这方面的研究打下基础。更多还原

【Abstract】 The research of construct technics of deep-water foundation is one of the marginal problem. For a bridge deep-water foundation which local in high rock slope, some complex geologic condition such as the rock structure and water force should give the corresponding discussion. In practical engineering, reasonable solution of some important and key problem in common, such as the stability of side slope in the explosion of water conservation construction or vibration by large machine; the local stability problem existed in water foundation which from coupling vibration between bridge and vehicle etc., require the thoroughly research on the foundation dynamic mechanics of deep-water and high rock slope under impacting loading from the theories, numerical simulations and experiments.This thesis mainly studied for the stability of high rock slope and jetting of pile forcing by an large impact load combine with hydrostatic uplift when the bridge deep-water foundation was constructed. Firstly the statics stability theory based on the method of limit equilibrium and strength reduction finite element method is been introduced, the safe coefficient in rock slope sited in Liushui river(xiangyuⅡline) is given after numerical simulations. Then the base theory in impact dynamics including the choice of rock dynamics constitutive, impact vibrate theory and something about stress wave transmit in rocks been expounded. The influence exist in foundation when force by hydrostatic uplift is also introduced. Finally using the explicit dynamics finite element software—LS-DYNA to analysis the influence from impact load when in the process of large diameter pile hole. The consider factor including the high of sinker, drill deeper and the number of impact, and then get the conclusion about the slope effect by impact load base on some factor such as stress level and the vibrate velocity of particle. Given the reference in the choice of mechanism and technics process when an large bored pile was being constructed. Also we can build an foundation in this field through the compare between static and dynamics in the future.更多还原