摘要
夯击参数比选是决定强夯地基处理经济性与加固效果的关键环节,当前主要依靠试夯结果确定停夯标准及参数调整。对此,建立了非辐射平面发射型一维强夯应力波传播模型,推导了单次夯击作用下波阵面应力沿土体深度的分布,揭示了地基压密变形、剪切波横向扩散和土体阻尼特性3种独立因素耗能作用的机制,基于应力衰减规律探讨了加固深度分层标准、应力波传播与能量耗散过程。结果表明:当静接地压力由40.8 kPa增至122.3 kPa时,地基加固深度显著增加,同等静接地压力下提高落距和增大夯锤半径对地基加固效果提升有限;采用偏重锤低落特征的夯击参数组合对应力波向土体深层传播更为有利;随着土体深度增加,应力波时程依次呈现冲击加固、振动密实与弹性振动特征,冲击加固区深度可参照5%体应变等值线包络地基范围估计;依据任意拉格朗日-欧拉法仿真结果对单次强夯理论解进行修正,得出了连续夯击地基加固深度计算流程;通过对比现场检测结果可优化夯击参数,提高施工效率及经济性。
The selection of tamping parameters can be the vital procedure for economic efficiency and ground reinforcement effect of dynamic compaction treatment.At present,stop-tamping criterion and parameters adjustment mostly depended on in-situ test result of dynamic compaction.In this study,a one-dimensional stress wave propagation model with non-radial plane emission was developed;the distribution of wavefront stress along soil depth under single tamping was derived;the mechanism of three independent energy-consuming factors,including compression deformation of foundation soil,lateral diffusion of shear wave and soil damping,were revealed;and classification standard for ground reinforcement depth(GRD)was proposed based on the rule of stress attenuation,which was then used to characterize stress wave propagation and energy dissipation process.Research results indicate that GRD can be notably increased as static ground pressure increase from 40.8 kPa to 122.3 kPa,while excessive increase of drop height and tamper radius has limited influence on GRD under equivalent static ground pressure conditions.Parameters combination of dynamic compaction characterized by heavier-tamper and lower-drop height,can be more beneficial to stress wave propagation deeper.Time-history curves of stress wave show various characteristics at different depths,including shock reinforcement,vibration compaction and elastic vibration.The shock reinforcement depth can be estimated by using the result of ground area enveloped by 5%volumetric strain isogram.The theoretical solution under single tamping is modified by using arbitrary Lagrange-Euler method-based simulation results,then calculation procedure of GRD under continuous tamping can be derived.Therefore,dynamic compaction parameters can be optimized through comparison with in-situ test results so as to improve construction efficiency and economy.
作者
刘文俊
李岳
蔡靖
戴轩
水伟厚
董炳寅
LIU Wen-jun;LI Yue;CAI Jing;DAI Xuan;SHUI Wei-hou;DONG Bing-yin(School of Transportation Science and Engineering,Civil Aviation University of China,Tianjin 300300,China;Engineering Research Center of Intelligent Construction and Industrialization,China Airport Construction Corporation,Tianjin 300456,China;Beijing Dadi Geotechnical Engineering Company,Beijing 100176,China;Guangdong Dadi Geotechnical Engineering Company,Guangzhou,Guangdong 510700,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2023年第S01期427-435,共9页
Rock and Soil Mechanics
基金
天津市自然科学基金(No.21JCQNJC00850)
中央高校基金项目(No.3122022043)
天津市研究生科研创新项目(No.2021YJSS133)。
关键词
强夯
应力波
夯击参数
任意拉格朗日-欧拉法
参数比选
dynamic compaction
stress wave
tamping parameters
arbitrary Lagrange-Euler method
parameters comparison
