深季冻区高速公路路基边坡固化砂冻融循环试验研究

Research on the Freeze-thaw Cycle Tests of Solidified Sand for the Slope of Highway Roadbed in Deep Seasonal Frozen Area

在深季冻区,使用化学方法固化砂质边坡表层后,由于冻融循环的影响,固结层易发生破坏。为了研究新型固砂剂TD-1固化砂体后的抗冻融特性,从微观方面对其强度形成机理进行分析;使用湿冻法、干冻法对固化砂进行试验,模拟其在有、无雨雪条件下的冻融循环;冻融循环后,通过无侧限抗压强度试验,研究固化砂无侧限抗压强度随冻融循环次数的变化,以及应力随应变的变化。结果表明:(1)使用湿冻法进行冻融循环试验,随着冻融循环次数的增加,试样抗压强度逐渐降低,降低速率由快变慢,之后趋于稳定,试样破坏形式从脆性破坏逐渐向塑性破坏过渡;(2)使用干冻法进行冻融循环试验,随着冻融循环次数的增加,试样抗压强度逐渐增大,增大速率由快变慢,之后趋于稳定,试样破坏形式为脆性破坏。

In deep seasonal frozen area,the solidified layer is easy to be destroyed due to the influence of freeze-thaw cycles after the surface layer of sandy slope is solidified by chemical method.In order to study the freeze-thaw resistance of sand solidified by the new sand consolidating agent TD-1,the strength formation mechanism of TD-1 is analyzed from micro aspects.The solidified sand is tested by the wetfreezing method and the dry-freezing method to simulate the freeze-thaw cycles under the conditions with or without rain and snow.After freeze-thaw cycles,unconfined compressive strength tests are carried out.The changes of unconfined compressive strength of solidified sand with freeze-thaw cycles are studied.The change of stress with strain is studied.The results show that:sand consolidating agent forms bond films on the surface of sand grains,which increases the cohesion between sand grains and forms strength.The freeze-thaw cycle tests are carried out by wet-freeze method.With the increase of freeze-thaw cycles,the compressive strength of the samples decrease gradually,and the rate of reduction decreases from fast to slow,then tends to be stable.The failure mode of the samples changes from brittle failure to plastic failure.The freeze-thaw cycle tests are carried out by dry-freeze method.With the increase of freeze-thaw cycles,the compressive strength of the samples increase gradually,and the increasing rate decreases from fast to slow,then tends to be stable.The failure mode of the samples is brittle failure.