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水平定向钻穿越大型河流时,在其出入土端经常会遇到松软地层,为了保证钻进顺利进行,通常使用地质改良或套管隔离等方法提高成孔性能。针对现有套管夯击安装工艺,通过对套管夯击过程力学受力情况分析,利用仿真模拟技术,建立套管夯击过程受力模型,对套管受力情况进行数值模拟,揭示了套管夯击过程中不同因素对夯入深度的影响。根据数值模拟分析结果,增强套管的材料强度可有效增加抗屈曲能力,随着夯击深度的增加,夯击力传递效率迅速下降。同时,结合相关力学理论,参照顶管结构计算方法,通过理论分析与现场施工情况结合,提出套管极限夯击深度计算方法,可为套管有效夯击深度的设计提供参考。
When horizontal directional drilling traverses large rivers, they often encounter loose formations at the entrance and exit ends. In order to ensure the smooth drilling, geological improvement or casing isolation are usually used to improve the hole formation performance. In view of the existing installation process of casing tamping, through the analysis of mechanics stress of casing tamping process, the stress model of casing tamping process is established by simulation technology, and the numerical simulation of casing stress is carried out. Influence of Different Factors on Ramming Depth during Clamping of Bushing. According to the results of numerical simulation, increasing the material strength of the bushing can effectively increase the anti-buckling capacity. With the increase of the tamping depth, the tamper force transmission efficiency decreases rapidly. In the meantime, combining the theory of mechanics, referring to the calculation method of pipe jacking structure and combining the theoretical analysis and on-site construction, the method of calculating the ultimate compaction depth of casing is proposed, which can provide a reference for the design of the effective compaction depth of the casing.