冻融循环条件下岩体-喷层结构模型试验研究

MODEL TEST STUDY OF ROCK-SHOTCRETE LAYER STRUCTURE UNDER FREEZING-THAWING CYCLES

针对南方地区极端冰雪灾害下的边坡岩体和支护体的变形破坏现象,提出在冻融循环条件下岩体-喷层结构一体的室内模型试验方法。选取砂岩-混凝土一体化试样,置于自行研制的高低温环境试验箱中进行冻融循环条件下的模型试验。利用静态应变测试系统和光纤光栅测试技术同步采集应变数据,分析冻融循环过程中砂岩、混凝土、砂岩-混凝土胶结面的变形及原因。岩石表面应变花数据表明,当温度降至0℃以下时主应变增大,升温后主应变减小;混凝土表面应变花数据表明,该点处主应变随温度升高而增大,随温度降低而变小。2种测试手段均测得胶结面处应变同时受岩石和混凝土的影响,是两者共同作用的结果。据此拟合出胶结面处最大应变与冻融次数的关系表达式,归纳出岩体-喷层结构一体化在冻融循环作用条件下的冻胀损伤机制。

Aiming at the deformation and failure of slope rock mass and supporting structure under extreme ice-snow conditions in south China,an indoor model test of rock-shotcrete layer structure is put forward to conclude the deformation laws under freezing-thawing cycles.Sandstone-concrete integration sample is placed in the self-developed high-low temperature environmental test chamber.Static strain testing system and fiber bragg grating（FBG） testing method are used to synchronously monitor the strain of sample.Deformations and deformation reasons of sandstone,concrete,sandstone-concrete cementation face under freezing-thawing cycles are analyzed.The strain data on rock surface show that principal strain increases when the temperature dropped below 0 ℃ and decreases with the increasing temperature.The strain data on concrete surface show that principal strain increases with the increasing temperature and decreases with the decreasing temperature.The two monitoring methods both show that the strain data on cementation plane are the combined action of rock and concrete.Based on the coincident data,the fitting relationship formula of maximum strain and freezing-thawing cycles are formulated.The mechanisms of freezing-thawing damage of sandstone,concrete and cementation plane between rock and concrete are concluded.