膨胀土地区机场跑道的地基处理研究

Foundation Treatment of Airport Runway in Expansive Soil Area

为解决在膨胀土山区修建机场时跑道地基处理的问题,以安康地区膨胀土为研究对象,在对现行石灰改良膨胀土施工控制参数常用方法分析的基础上,进行膨胀土及石灰改良膨胀土的膨胀性能和强度的相关试验。研究结果表明:随着石灰掺量的增加,最优含水率增大,最大干密度减小,胀缩潜势呈降低趋势,石灰掺量与最大干密度呈非线性关系,在石灰掺量达到9%时有荷膨胀率变化的规律性很强;相同石灰掺量改良土的CBR与击实功、含水量等因素有关,并不随着压实系数增加而增大。掺加石灰的比例对石灰改良膨胀土的强度增长影响较大,石灰掺量9%时的CBR值明显大于其他掺量;相同压实系数下石灰掺量3%和6%改良膨胀土的压缩性比较接近,石灰掺量增加到9%时其压缩性明显降低。结合试验结果,提出用石灰改良膨胀土对跑道进行地基处理,并以膨胀性指标作为主要控制指标、强度指标作为验证指标来确定施工参数。

To solve the problem of foundation treatment in the construction of an airport runway in an expansive soil zone,we used the expansive soil in the Ankang area,Shaanxi province as our research obj ect.To determine the construction control parameters of lime-treated expansive soil, we carried out relevant tests on the strength and expansive properties of the soil.The results show that with an increase in the quantity of lime,the optimum moisture content increases,the maximum dry density and the swelling shrinkage potential decreases,and the quantity of lime and the maximum dry density is nonlinear.When the amount of lime is 9%,the regularity of the swelling change rate is strong.The California bearing ratio （CBR）,which is related to factors such as compaction and water content,does not increase with an increase in the compaction coef-ficient.The proportion of added lime had a greater influence on the strength of lime-treated ex-pansive soil.When the amount of lime is 9%,the CBR was higher than for other proportions. Under the same compaction coefficient of expansive soil,with lime dosages of 3% and 6%,the compressibility is relatively similar.When the lime dosage is increased to 9%,the compression significantly decreased.Based on these test results,we propose the use of lime for expansive soil improvement in runway ground treatment,as well as a method for determining the subgrade con-struction control parameters with respect to the expansive properties as the main control indexes, and strength as the confirmation index.