冻土波速和强度指标下的冻土可钻性分级试验研究

The stage test of frozen-soil drillability under the index of wave velocity and strength

冻土可钻性分级指标及分级研究是目前冻土学术界及冻土工程领域研究的重点课题,冻土波速和强度指标下的冻土可钻性分级研究是该课题研究的重要和关键内容。课题组通过对7 a的试验研究数据进行分析,结果表明,对于以冻土波速、压入硬度、抗压强度、抗拉强度为指标分级时,有如下规律:含水率在13%～25%且一定时,-20℃是可钻性的拐点温度;温度在-1～24℃且一定时,含水率在13%～19%区间,冻土可钻性随含水率的增大而降低。温度在-1℃～24℃且一定时,含水率在20%～25%区间,冻土可钻性随含水率的增大而增强。冻土可钻性一般可分为4级,可钻性一级的冻土表现为较强的塑性;可钻性二级的冻土为塑性向脆性过渡阶段的冻土,冻土温度在-20℃以上时,冻土的塑性较强、脆性较弱,冻土温度为-20℃以下的冻土脆性明显增强;可钻性为三级～四级的冻土表现为较强的脆性。

The step index and stage study of frozen-soil drillability is currently the key subject in frozen-soil academic circles and engineering filed,and the stage test of frozen-soil drillability under the index of wave velocity and strength is the most important research of this subject.The test group makes an analysis to the seven-year experimental data and gets a result.The result shows that when the index of frozen-soil wave velocity,penetration hardness,compressive strength and tensile strength are in index step,there are some regulations as follows：when the water ratio is 13%～25% and fixed,-20℃ is the inflection temperature of drillabilty;when the temperature is-1～24℃ and fixed,and the water ratio is 13%～19%,the drillability will be strengthened as the water ratio is reduced;when the temperature is-1℃～24℃ and fixed,and the water ratio is 20%～25%,the drillability will be strengthened as the water ratio is increased.The frozen-soil drillability can generally be divided into four stages.The frozen soil in first stage shows strong plasticity;the frozen soil in the second stage is the one goes from plasticity to brittleness（when the frozen-soil temperature is above-20℃,the plasticity is strong and the brittleness is weak;when the temperature is below-20℃,the brittleness is clearly increased）;the frozen soil drillability in three or four stage shows strong brittleness.