动静组合加载下颗粒迁移与沉积特性试验研究

Experimental study on migration and deposition of particles under alternating dynamic and static loads

悬浮颗粒在路基中迁移和沉积运动规律研究对揭示翻浆冒泥病害孕育、发展与致灾机制具有重要的理论意义和应用价值。通过开展动-静组合荷载下分层砾石-砂粉土柱翻浆试验,探究了动荷载加载强度、静荷载间歇时长、以及动静组合加载重复次数等对颗粒迁移和沉积行为的影响规律,并结合试样动水力响应特征分析了诱发颗粒迁移的驱动机制。试验结果表明:颗粒在动水力作用下发生悬浮迁移而在静荷载段受重力作用发生沉降,从而造成砾石层内泥浆浊度呈现波动型增长特征。随动静组合加载重复次数增加,每一个重复周期内的颗粒悬浮增量趋于降低,且悬浮颗粒逐渐堵塞砾石孔隙并在一定程度上抑制翻浆发展。提高动载频率和动应力会进一步降低砂粉土表层的内部稳定性,但相比于增大平均动应力,提高加载频率对增大颗粒迁移量和竖向迁移距离更加显著。

The study on the migration and deposition of suspended particles in subgrade is important to reveal the generation and disaster-causing mechanism of mud pumping.The effects of magnitude of dynamic loads,intermittent duration of static loads and repetition number of alternating dynamic and static loads on the migration and deposition of particles are studied by carrying out the mud pumping tests on the layered gravel-sandy silt column.According to the hydrodynamic response characteristics of specimens,the driving mechanism of particle migration is analyzed.The test results show that the suspended particles migrate upward under hydrodynamic force and settle under gravity during the interval of static loads,which results in the fluctuating growth of slurry turbidity in the gravel layer.The particle suspension increment tends to decrease with the increasing repetition of alternating dynamic and static loads,and these particles gradually clog gravel pores and inhibit mud pumping to a certain extent.Increasing the dynamic frequency and stress can further reduce the internal stability of the sandy silt surface layer.However,compared with increasing the dynamic stress,increasing the loading frequency is more beneficial to increase the particle migration mass and vertical migration distance.