摘要
冻土-结构物界面剪切蠕变特性是冻土区桩基及隧道冻结法施工长期稳定性的关键控制因素,当前研究在复杂应力状态下界面蠕变试验和模型构建方面存在明显不足。通过开展不同粗糙度、温度和围压的饱和冻土-钢界面三轴剪切蠕变试验,研究蠕变变形、蠕变速率与时间的变化规律,揭示各因素影响下的界面剪切蠕变机理,并结合Burgers模型建立了可描述加速蠕变阶段的饱和冻土-钢界面数学模型。结果显示:在三轴剪切蠕变分级加载试验中,蠕变曲线依次经历瞬时蠕变、非稳定蠕变、稳定蠕变和加速蠕变阶段;剪应力、温度和粗糙度是影响剪切蠕变的主要因素,剪应力水平主导变形模式,低应力下以稳态蠕变为主,界面长期稳定,高应力下蠕变加剧,界面破坏;温度降低显著地降低了界面的变形量和变形速率;蠕变变形主要呈现随界面粗糙度上升蠕变先减小后增大的趋势,说明存在一个临界粗糙度可最大程度优化界面性能;围压的影响相对较小。本文提出的界面剪切蠕变模型不仅能够表征非加速阶段的黏弹性行为,还能有效描述加速蠕变阶段的位移突变特征。
Under global climate change and China’s Western Development Strategy,engineering construction in frozen soil regions faces significant challenges.In pile foundation in regions with frozen soil,long-term stabil⁃ity issue has become a critical technological challenge for infrastructure development in cold regions.Particular⁃ly,the shear creep effect at the frozen soil-structure interface significantly influences the performance of pile foundations and other engineering systems.Under dynamically varying loads and temperature fields,progres⁃sive damage induced by shear creep at the interface poses serious threats to structural performance.Due to the temperature sensitivity and seasonal deformation behavior of frozen soil,pile foundations are especially affected by freeze-thaw cycles.These foundations are subjected to the combined effects of temperature,stress,and displacement over long periods,which makes the creep behavior at the pile-soil interface increasingly complex.This often leads to a reduced pile bearing capacity and uneven settlement of structures,resulting in engineering deterioration.However,current research on the shear creep at the frozen soil-structure interface has several limi⁃tations.First,traditional experimental devices,such as direct shear and single-shear devices,can generally sim⁃ulate two-dimensional shear conditions,making it difficult to replicate the three-dimensional complex stress state and true mechanical response of pile foundations and other engineering structures.Second,existing studies pri⁃marily focus on the creep characteristics of the frozen soil itself,with limited systematic understanding of the creep behavior and response mechanisms.Third,current constitutive models are insufficient in characterizing the nonlinear accelerated creep phase,making it difficult to accurately predict the creep behavior of interfaces un⁃der different engineering conditions.To address these limitations,this study investigated the mechanical behav⁃ior of the frozen soil-steel interface through triaxial shear creep tests on saturated frozen soil under different sur⁃face roughness,temperature,and confining pressure conditions.The experiments investigated the patterns of creep deformation,creep rate,and time variation,thereby revealing the shear creep mechanism at the interface under the influence of various factors.Additionally,a mathematical model based on the Burgers model was es⁃tablished to describe the accelerated creep phase of the saturated frozen soil-steel interface.The results indicated that in the triaxial shear creep tests with graded loading,the deformation process under different temperature con⁃ditions followed a four-stage evolution pattern:instantaneous creep,primary(transient)creep,steady-state creep,and accelerated creep.Shear stress,temperature,and roughness were identified as the dominant factors affecting shear creep.The deformation behavior was controlled by shear stress levels.Under low stress condi⁃tions,steady-state creep predominated,ensuring long-term interface stability.Under high stress conditions,creep intensified,leading to interface failure.Lower temperatures significantly reduced both deformation magni⁃tude and rate at the interface.Smooth interfaces exhibited rapid increases in shear displacement during initial loading,exhibiting significantly higher creep rates and deformation compared to rough interfaces.Creep defor⁃mation showed a distinct nonmonotonic trend with increasing interface roughness—first decreasing,then increas⁃ing—indicating the existence of a critical roughness that optimized inte rface performance.The effect of confin⁃ing pressure was relatively small.The proposed model effectively characterized the viscoelastic behavior during the non-accelerated phase and captured the displacement jump observed in the accelerated creep phase.The sys⁃tematic analysis of the data revealed the effects of different conditions on the shear creep parameters of the frozen soil-steel interfaces.These patterns provide valuable insights for understanding and predicting interface behavior under similar conditions and offer references for engineering applications.In conclusion,this study provides impor⁃tant experimental evidence and theoretical support for establishing pile foundation design theories that consider interface creep effects and for developing methods for long-term stability evaluation of cold-region engineering.
作者
董旭光
王振波
吕江飞
唐少容
DONG Xuguang;WANG Zhenbo;LÜJiangfei;TANG Shaorong(School of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,China;Ningxia Center for Research on Earthquake Protection and Disaster Mitigation in Civil Engineering,Yinchuan 750021,China)
出处
《冰川冻土》
2025年第6期1666-1678,共13页
Journal of Glaciology and Geocryology
基金
国家自然科学基金项目(52368050
51808302)
宁夏回族自治区自然科学基金项目(2024AAC03126)资助。
