车辆荷载作用下钙质砂路基的动态响应试验研究

钙质土颗粒因形状不规则而产生咬合嵌固效应，导致土压力传递特性不同于一般黏性土。为研究不同工况下钙质土地基及挡土墙土压力的分布与响应特征，在某珊瑚礁场地对在建的护岸和道路路基在填土和车辆动荷载作用下的土压力进行了动态监测，重点对填土自重、车辆移动荷载及压路机振动碾压荷载下钙质土中土压力的传递与分布特征进行研究。结果表明：填土过程中钙质土中的侧压力系数为0.2～0.3，平均值为0.25；实际观测到的路基竖向土压力远高于按照理论公式计算的土压力；经过碾压的路基在深度为3.28 m处，重型车辆的附加荷载很小。22 t振动压路机在振动碾压时，地基在深度为2.73 m处附加应力增量极小，因此难以提高该深度处土体的密实度；而浅层土体的土压力增量较大，可有效得到压实。

Experimental study on dynamic response of calcareous sand subgrade under vehicle load

Due to irregular shape, calcareous soil particles are prone to produce interlock, which results in different earth pressure transmission from ordinary cohesive soil. To study the distribution and response of calcareous soil pressure in road foundation and on the retaining wall under different loading conditions, the soil pressure under the vehicle dynamic load was monitored at a coral reef site. The study is focused on the transfer and distribution of earth pressure in calcareous soil under the weight of fill and the moving load of the vehicle and the vibration compaction load of the roller. The results show that the lateral pressure coefficient is 0.2-0.3 and the average value is 0.25. The observed earth pressure on the roadbed is much higher than that calculated according to the theoretical formula. At the depth of 3.28 meter in the roadbed after rolling, the additional load of heavy vehicles is small. The increment of the additional soil pressure in the foundation at the depth of 2.73 meter is extremely small. However, when the 22-ton vibratory roller is vibrated and rolled, the additional stress increment of the foundation at a depth of 2.73 meter is extremely small. Hence, it is difficult to increase the compactness of the soil at this depth. Just the shallow soil can be effectively compacted.