爆炸液化场地上堤坝变形的模型试验研究

饱和砂土地基在地震、爆炸等振动荷载作用下易发生液化,从而使堤坝等上部构筑物发生破坏。开展了爆炸液化场地上堤坝变形的大型模型试验,考虑了筑坝材料以及堤坝地基加固措施对堤坝变形和坝身裂缝的影响。试验表明:堤坝沉降主要发生在场地液化后的1~2 h内,该段时间内产生的沉降占7 d时沉降量的84%~87%;掺加了碎石的堤坝比未加碎石的堤坝7 d时沉降量大24%;地基内采用土工格栅+土工布的加固措施能够有效减少堤坝在液化场地上的沉降,比未加固的堤坝沉降减少了10%。堤坝的裂缝主要出现在细骨料筑成的坝段和不同筑坝材料的交界处,沿坝身开展。总结了国内外规范中对于液化地基沉降的计算及预测方法,根据液化地基上浅基础建筑物沉降图表对试验中的堤坝沉降进行了推算,发现实测沉降与推算沉降比较接近。

Model tests on deformation of embankment in blast-induced liquefied field

A full sandy foundation is prone to be liquefied under an earthquake, explosion or other vibration loadings. As a result, the upper structures such as embankments on the foundation will be damaged. Aiming at the deformation problems of an embankment in a liquefied foundation, the field tests on explosion-induced liquefaction are conducted considering the effects of the embankment materials and reinforcement measures of the embankment foundation on its deformation and cracks. The results show that the subsidence of the embankment mainly occurs within 1 ~ 2 hours after the explosions, which accounts for 84 % ~ 87 % of the total subsidence accumulated in 7 days. The settlement of the embankment with fine aggregate becomes stable after 7 days. The subsidence of the embankment with fine aggregate is 24 % more than that without fine aggregate. The settlement of the foundation reinforced by geogrid and geotextile can be effectively reduced by 10% of the dam settlement in the liquefied ground. The cracks on the embankment body mainly appear in the section with fine aggregate and the interface between two different materials, and they extend along the dam body. The domestic and international specifications for the settlement of structures on a liquefied foundation are summarized. The settlement figure of buildings with shallow footings is adopted as the prediction method for the embankment settlement in this test. The results indicate that the predicted values are close to the measured data.