冻融循环对桩锚基坑桩间土影响的监测与分析

Monitoring and analysis of the effects of the freeze-thaw cycle on the earth between the piles in pile-anchor foundation pits

通过对某工程冻融循环阶段的现场监测,得到了基坑侧壁桩间的土温、气温、水平土应力以及基坑的变化情况,并将其绘制成曲线。结合气温—土温、水平土应力—土温曲线及现场的位移变化,分析了桩间土水平应力的变化规律。通过分析发现:基坑迎光面与背光面的桩间土应力是不同的,基坑北侧(迎光面)桩间土应力变化过程为2个阶段(稳定阶段和衰减阶段);基坑南侧桩间土应力变化过程为3个阶段(稳定阶段、剧变阶段和衰减阶段)。在此基础上,分析了桩间土各阶段应力变化的原因,对完善季节性冻土地区基坑支护的设计和施工有一定的实际意义。

According to the field monitoring of some proj ects in the freeze-thaw stage, the changes of soil temperature,ambient temperature,horizontal stress and faundation pits have been recorded.The change rule of the horizontal soil between the piles can be obtained based on the ambient-soil temperature curve,the horizontal stress-soil temper-ature curve and the displacement curve.The horizontal stress of the soil in the northern side is quite different from which in the southern side.The horizontal stress of the north-ern side which is under the sunshine during the daytime can be separated into two cate-gories：The stable characteristics and the reduced characteristics.While the southern side in the shadow should be separated into three categories：The stable characteristics,the fast changing characteristics which is different with the northern and the reduced charac-teristics.Based on above-mentioned data,the reason why horizontal stress changes has been acquired in order to provide a theological basis for the design and the construction of the foundation pit in the seasonal frozen earth.