摘要
高寒高海拔地区常年受冻融循环作用影响,裂隙岩体冻胀现象普遍存在。为探究冻胀力在裂隙冻胀变形中的演化规律,揭示裂隙岩石的冻胀损伤机制,利用分布式压力薄膜传感器、温度传感器和应变仪组成的测试系统,对不同裂隙宽度的饱和裂隙红砂岩试样的冻融过程进行实时全面监测,获得裂隙冻胀力、温度和裂隙应变随时间变化的曲线。试验结果表明:在冻融过程中,饱水裂隙红砂岩裂隙内20 mm处出现恒温平台,标志着裂隙水发生冻结,且裂隙宽度越大,恒温平台出现时刻越早;岩石表面应变与温度变化拐点同步,裂隙应变拐点滞后于温度拐点,但裂隙应变与最大冻胀力的变化同步;在恒温平台出现时,岩石表面应变快速上升,主要是岩石骨架收缩和岩石孔隙水冻胀共同作用引起的;岩石表面温度变化比裂隙内温度变化更快,导致裂隙水的冻胀有所滞后;在融化过程,冻胀力和应变均再次爬升,并出现次高点;对于宽度在2~4 mm范围内的裂隙,最大冻胀力峰值随着裂隙宽度增大而增加;在整个冻融过程中,冻胀力的分布是不规则的、冻胀力由四周向内部递增,四周的冻胀力大小基本保持不变;冻融机制分析表明:岩块周边首先形成冻结层,然后裂隙水发生冻结逐渐形成冰塞,当冰塞不再滑移、达到完全密闭状态,裂隙应变急速上升、冻胀力骤然上升到最大值,裂隙尖端应力集中,产生微裂纹。在融化时,岩石表面融化,裂隙内产生二次冻胀。试验初步分析了裂隙岩体中孔隙水和裂隙水的冻结规律,为合理分析裂隙岩体冻胀损伤机制提供依据。
Alpine and high altitude areas are affected by freeze-thaw cycles throughout the year,and frost heaves in fractured rock masses are widespread.In order to explore the evolution law of frost heaving force in fracture frost heaving deformation and reveal the frost heave damage mechanism of fractured rock,using the test system of distributed pressure film sensor,temperature sensor and strain gauge to fully monitor the freeze-thaw process of saturated cracked red sandstone samples with different crack widths in real time,then the curves of crack frost heave force,temperature and crack strain with time were obtained.The experimental results show that during the freezing and thawing process,a constant temperature platform appears at 20 mm in the water saturated red sandstone fracture,indicating that the fracture water is freezing,and the larger the fracture width is,the earlier the constant temperature platform appears;The strain of rock surface is synchronous with the inflection point of temperature,the inflection point of fracture strain lags behind the inflection point of temperature,but the change of fracture strain is synchronous with the change of maximum frost heaving force;When the constant temperature platform appears,the strain of rock surface rises rapidly,mainly caused by the joint action of the shrinkage of the rock skeleton and the frost heaving of the rock pore water;The change of temperature on the rock surface is faster than that in the fracture,which leads to the lag of frost heaving of fracture water;During the thawing process,the frost heaving force and strain both climb again,and appear the secondary peak;For cracks with a width of 2–4 mm,the maximum frost heaving force increases with the increase of crack width;In the whole process of freezing and thawing,the distribution of frost heaving force is irregular,the frost heaving force increases from the four sides to the inside,and the frost heaving force around basically remains unchanged;The analysis of freeze-thaw mechanism shows that:a frozen layer is first formed around the rock mass,and then the fracture water freezes and gradually forms an ice plug.When the ice plug no longer slips and reaches a completely closed state,the fracture strain rises rapidly,the frost heaving force rises to the maximum,and the stress concentration at the fracture tip leads to microcracks.During melting,the surface of the rock melts and secondary frost heaving occurs in the fracture.and secondary frost heaving occurs in the fracture.The test preliminarily analyzes the freezing law of pore water and crack water in the fractured rock mass,which provides the basis for reasonably analyzing the frost heaving damage mechanism of fractured rock.
作者
田镇
李银平
王贵宾
马洪岭
张君岳
毕振辉
TIAN Zhen;LI Yinping;WANG Guibin;MA Hongling;ZHANG Junyue;BI Zhenhui(State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China;State Key Laboratory of Rock and Soil Mechanics and Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2022年第S01期2857-2868,共12页
Chinese Journal of Rock Mechanics and Engineering
基金
国家重点研发计划(2018YFC0808401,2018YFC0808402)
关键词
岩石力学
裂隙岩体
冻胀力
冻胀变形
冻胀损伤机制
rock mechanics
fractured rock mass
frost heaving force
frost heave deformation
frost heave damage mechanism
作者简介
田镇(1995–),男,硕士,2018年毕业于福州大学采矿工程专业,主要从事矿业工程中岩石力学问题方面的研究工作。E-mail:1373570901@qq.com
