公路地质纵剖面黄土湿陷系数预测及分布规律研究

Prediction and distribution law of the collapsibility coefficient of loess in a geological longitudinal section of highway

摘要:

通过充分挖掘现有黄土湿陷试验资料的价值,建立基于克里金插值法的湿陷系数预测模型。以G244线打庆公路(K1+640~K10+640段)工程为背景,利用少量的湿陷系数实测数据,对湿陷系数进行插值预测并沿其纵剖面绘制等值线图。将湿陷系数预测值与实测值进行对比,并对其二维空间分布规律进行分析。结果表明:(1)基于地质统计克里金法的黄土湿陷系数插值计算方法可行且插值结果合理,能满足工程对于黄土湿陷性的精度和实际应用需求;(2)利用湿陷系数等值线图,采用“0.015”判定法得到黄土湿陷临界深度,湿陷临界深度的变化相对于地表的坡度变化较缓,且沟谷区的湿陷深度(3~8 m)明显小于山岭区的湿陷深度(15~25 m);(3)自地表向下,黄土湿陷系数随着深度的增加先增大后减小,直至小于0.015,即湿陷性消失;(4)在钻孔取样深度相同时,河沟谷区的含水量大于黄土丘陵区,在较低的自重压力时,河沟谷区的湿陷系数大于黄土丘陵区,随着自重应力逐渐增大,黄土丘陵区的湿陷系数逐渐大于河沟谷区。

Abstract:

By thoroughly analyzing existing data from collapsible loess experiments, a predictive model for the collapsibility coefficient based on the Kriging interpolation method was established. Using the Daqing Highway section of the G244 line (from K1+640 to K10+640) as a case study, the collapsibility coefficient of loess was predicted through interpolation, utilizing a limited amount of measured data of the collapsibility coefficient, and then, a contour map was drawn along the longitudinal section. The predicted values of the collapsibility coefficient were compared with the measured values, and the two-dimensional spatial distribution pattern of the collapsibility coefficient was analyzed. The results demonstrate the following: (1) The interpolation method for the collapsibility coefficient of loess based on the Kriging method is feasible, producing reasonable interpolation results that meet the engineering requirements of the accuracy and practical application of loess collapsibility. (2) By utilizing the contour map of the collapsibility coefficient of loess and the “0.015” judgment method, the critical depth of loess collapsibility was determined. The variation in the critical depth of loess collapsibility is relatively gradual compared to changes in the surface slope, with the depth of collapsibility in valley areas (3-8 m) notably less than that in the mountainous region (15-25 m). (3) Moving downward from the surface, the collapsibility coefficient of loess initially increases with the increase in the depth, then decreases until it falls below 0.015, indicating the disappearance of collapsibility. (4) At the same sampling depth, the moisture content in river valleys exceeds that in the loess hilly region. Under low self-weight pressure, the collapsibility coefficient in river valleys is greater than that in the loess hilly region. However, as self-weight stress gradually increases, the collapsibility coefficient in the loess hilly region surpasses that in river valleys.