马家树水库大坝防渗土料分散性判别和改性试验

Study of dispersive identification and treatment with lime of dam soil in Majiushu Reservoir

基于分散性土修建挡水建筑物易受破坏而造成工程安全事故等因素考虑,开展双比重计试验、碎块试验、针孔试验、孔隙水阳离子试验和交换性钠百分比试验,对马家树大坝防渗土料的分散性及其改性措施进行研究。试验结果表明,马家树大坝防渗土料属于低液限黏土,易溶盐和饱和孔隙水溶液中含有大量的钠离子,酸碱度呈强碱性或极强碱性;土样中的黏土矿物主要以伊利石为主,含有少量的高岭石、绿泥石和蒙脱石;分散性试验综合判别土料属于分散性土和过渡性土;石灰剂量为0.25%时就对分散性土产生显著改性作用。研究表明,黏性土产生分散性的主因是土体中含有较多的钠离子和酸碱度呈强碱性;石灰是一种有效的分散性土改性剂。

The water-retaining structures built of dispersive clay are so easily destroyed to occur the safety accidents. Considering the safety, the dispersivity and treatment with lime of soil for the Majiashu dam are studied using double-hydrometer test, pore water salts test, pinhole test, crumb test and exchangeable sodium percent test. The results are that the dam soil belongs in the low liquid limited clay; and it has a lot of sodium ions in the easily soluble salt and the saturation pore water; and its pH is the stronger alkalescence or even the strongest alkalescence. Those soil samples had more illite and a few of kaolinite and chlorite and montmorillonoid. The soil samples are transition clays and dispersive clays; and the lime is the effective additive when the content of lime is the 0.25 % with mass ratio the dispersive clay becomes to the non-dispersive clay. It is shown that the key reasons of dispersivity are that the soil of dam has the more sodium ions and the pH is the stronger alkalescence. The lime is the effective additive of the dispersive soil.