湿陷性是安哥拉红砂的典型工程特性,研究其影响因素对红砂地区岩土工程勘察评价具有重要意义。基于安哥拉红砂原状土与重塑土的室内压缩试验,探讨了压力、含水率、结构性、干密度和细粒土含量对红砂湿陷性的影响规律。试验结果表明:试验压力>100 kPa时,红砂重塑样湿陷系数约是原状土的2.0倍;红砂湿陷系数与试验压力和细粒土含量呈正相关关系,随压力和细粒土含量增加而增加但存在峰值压力和峰值细粒土含量,峰值压力为300 kPa,峰值细粒土含量为60%～80%;红砂湿陷系数与干密度和含水率整体上呈反比关系,原状红砂湿陷性消除和完全丧失的界限含水率分别为9%和13%;重塑土湿陷性消除和完全丧失的界限含水率分别为11%和13%,界限干密度分别为1.80 g/cm³和1.90 g/cm³,对应的压实系数分别为0.92和0.97。湿陷性红砂地区工程建设可通过提高干密度消除其湿陷性。

Collapsibility is a typical engineering characteristic of Angola red sand. It is of great significance to study its influencing factors for geotechnical investigation and evaluation in red sand area. Based on laboratory compression tests of undisturbed and remolded Angola red sand specimens, the effects of structure, pressure, moisture content, dry density and fine-grained soil content on the collapsibility of Angola red sand were examined. Test results show that when the pressure is larger than 100 kPa, the collapsibility of remolded red sand is 2.0 times that of the undisturbed red sand. The collapsibility coefficient of red sand has a positive correlation, i.e. to increase with increasing test pressure and fine-grained soil content, with peaking pressure and fine-grained soil content reaching 300 kPa and 60%-80%, respectively. Contrarily, the collapsibility coefficient of red sand is, in general, negatively correlated with dry density and water content. The critical moisture content for eliminating and completely losing the collapsibility of undisturbed red sand is 9% and 13%, respectively, and those of remolded soil 11% and 13% respectively. The critical dry density of remolded soil is 1.80 g/cm³ and 1.90 g/cm³ respectively, and the corresponding compaction coefficient is 0.92 and 0.97 respectively. For engineering construction, the collapsibility of red sand can be eliminated by increasing dry density.