摘要
寒区岩体长期经受荷载与冻融的共同作用,若不考虑冻融过程对其长期力学行为的影响,将会给寒区工程建设和安全运营带来重大的安全隐患。为此,以寒区某边坡工程砂岩为研究对象,通过开展不同冻结温度下的冻结/解冻过程单轴分级加载蠕变试验,使岩石在同一应力状态下处于冻结和解冻过程,真实再现寒区工程岩体长期力学响应特征。以此研究冻结/解冻过程对岩体长期力学特性的影响,并对其蠕应变、稳态蠕变速率及长期强度等宏观力学指标进行量化分析。结果表明:(1)砂岩冻结过程先后经历冷缩阶段、冻胀阶段和稳态蠕变阶段,解冻过程只经历融缩阶段和稳态蠕变阶段;冷缩阶段和融缩阶段砂岩发生收缩变形,冻胀阶段则发生膨胀变形;(2)冻结/解冻温度为-5℃/25℃、-10℃/25℃、-15℃/25℃时,砂岩蠕应变较常温状态下蠕应变增幅范围分别为102%~193%、81%~126%、105%~194%,解冻后稳态蠕变速率较冻结前最大增长3.65倍、4.31倍、5.56倍,冻结/解冻过程蠕变砂岩的长期强度是常温状态下长期强度的96.33%、88.52%、75.44%;(3)应力对冷缩、冻胀变形的产生起抑制作用而对融缩变形的产生起促进作用;冻结温度越低,冻胀变形和解冻后融缩变形越明显。文章提出的将蠕变与冻融过程相结合的试验方法能较为真实地反映工程实际,该方法为寒区岩体工程长期稳定性评价提供新途径。
The rock mass in cold regions is always subjected to the load and freeze-thaw.If the impact of longterm freeze-thaw mechanical behavior on sandstone mass is neglected,it would lead to significant hazards to the construction and safe operation of engineering in cold regions.This study focused on the sandstone from a slope engineering in the cold region.The realistic long-term mechanical response characteristics of engineering rocks in cold regions was presented by uniaxial graded loading creep tests for the freezing/thawing process at different freezing temperatures and the same stress state.Then the effect of the freezing/thawing process on the long-term mechanical properties of the rock mass was investigated,and the macroscopic mechanical indexes,such as creep strain,steady-state creep rate,and long-term strength,were analyzed quantitatively.The results indicate that sandstone undergoes the stages of cold shrinkage,frost heave,and steady-state creep during the freezing process,and the stages of thaw consolidation and steady-state creep during the thawing process.Sandstone shrinkage deformation occurs during the cold shrinkage and thawing stages,while expansion deformation occurs during the frost heave stage.At freezing/thawing temperatures of−5℃/25℃,−10℃/25℃,and−15℃/25℃,compared to the creep strains at room temperature,the creep strains of the sandstone are amplified by 102%−193%,81%−126%,and 105%−194%,respectively.The steady-state creep rate after thawing increases by 3.65,4.31,and 5.56 times compared to the steady-state creep rate at room temperature.The long-term strength of the sandstones in the frozen/thawed state are 96.33%,88.52%,and 75.44%of the long-term strength at room temperature,respectively.Stress inhibits the generation of cold shrinkage and freezing deformations and promotes the generation of thawing deformations.The freezing temperature affects frost heave deformation and thaw shrinkage deformation after thawing.As the freezing temperature decreases,the deformation increa
作者
宋勇军
操警辉
程柯岩
杨慧敏
毕冉
张琨
SONG Yongjun;CAO Jinghui;CHENG Keyan;YANG Huimin;BI Ran;ZHANG Kun(School of Architecture and Civil Engineering,Xi’an University of Science and Technology,Xi’an,Shaanxi 710054,China;China Metallurgical Group Northwest Geotechnical Engineering Co.Ltd.,Xi’an,Shaanxi 710061,China)
出处
《水文地质工程地质》
CAS
CSCD
北大核心
2024年第6期93-103,共11页
Hydrogeology & Engineering Geology
基金
国家自然科学基金面上项目(11972283,42277182)。
关键词
蠕变特性
冻结/解冻过程
冷缩应变
冻胀应变
融缩应变
creep characteristics
freezing/thawing process
cold shrinkage strain
frost heave strain
melting shrinkage strain
