施工振动对结构性软粘土路堤稳定的影响

Construction Vibration’s Influence on Stability of Highway Embankment on Structural Soft Ground

研究目的：解决施工振动对结构性软粘土产生破坏的机理，查明施工振动下软粘土路堤失稳原因，为结构性软粘土路堤施工稳定设计验算提供依据。研究方法：基于珠江三角洲结构性软粘土物理力学性状、微结构特征，将冲击碾压施工振动对软粘土结构的破坏作用与强夯冲击振动的破坏作用相比较，同时分析珠三角某软粘土路堤受冲击碾压施工振动后失稳的原因。研究结论：珠江三角洲絮凝结构软粘土的孔隙比大多大于2，灵敏度4～8，属高灵敏性粘土，强度低，内聚力2．36～9．56kPa，内摩擦角1．4°～7．8°；冲击振动软粘土类似于强夯作用，微结构测试参数表明强夯冲击软粘土时增加的孔隙个数是静力堆载的7倍左右；冲击振动下结构性软粘土路堤失稳的原因是重16t、大功率（200kJ）冲击式压路机1d内碾压低路堤10遍，其作用类似于连续的强夯夯击，地基4．7m深度静力触探比贯入阻力值接近于0；建议在结构性软粘土路堤施工稳定设计验算时，对土的抗剪强度参数进行折减或直接采用土的振动强度参数。

Research purposes： The mechanism of fracture of structural soft clay and the reason of failure of highway embankment are found out to provide evidence for design computation of construction stability of highway embankment on structural soft ground. Research methods：The mechanism of fracture of structural soft clay by vibrating road roller is compared to that by dynamic compaction on soft ground. And the reason of failure of highway embankment is analyzed based on the physical and mechanical properties and microstructure characteristics of soft clay in the Pearl River Delta. Research conclusions：The depositional structure of soft clay is mainly characteristic of flocculent structure with high void ratio, lower shear strength and higher sensitivity. Dynamic vibration＇ s effect on soft ground is similar to dynamic compaction＇ s effect. The added number of void ratio by dynamic compaction on soft ground is 7 times as much as that by static load. The reason of failure of highway embankment is that the low embankment is placed by a dynamic vibrating roller with 16 t weight, roller compaction for 10 times. It is suggested that the parameters of shear strength of soft clay should be reduced or doing design computation of construction stability of highway embankment on structural soft ground road in the condition of vibration vibrating.