EXPERIMENTAL EVALUATION OF SOIL REINFORCEMENTS IN UNPAVED ROAD

In this study, a series of 24 laboratory tests were conducted on a footing resting on crushed stone with 17.68 kN/m3 dry unit weight overlying sandy soils of two relative densities corresponding to (60% and 80%). The subbase layer is of crushed stone with a thickness of 5, 7.5 and 10 cm. Ten tests were conducted under static load with and without geogrid. All the other 14 model tests were carried out under harmonic load which was applied in a sequence determined prior (40% of static load). Tests were conducted at (2) Hz frequency according to the loading value. The process of the loading was continued until the number of cycles reached 104 . The results indicated that, for static load and with the inclusion of the geogrid, as the thickness of the subbase layer increases, the percentage of increase in bearing capacity was reduced. In general, using geogrid reinforcement with subbase thickness of 7.5 and 5 cm causes an increase in bearing capacity approximately 1.5 to 2 times greater than for unreinforced respectively. This means that by using geogrid reinforcement, the thickness of subbase can be reduced which causes a reduction in construction cost.本研究针对承托于干重度为17.68 kN/m³的级配碎石层之上的模型基础开展了24组室内试验，该级配碎石层覆盖于两种相对密实度分别为60%与80%的砂土地基。本次试验的基层（subbase layer）采用级配碎石，厚度分别设置为5cm、7.5cm与10cm。其中10组为静载试验，分别包含布设土工格栅（geogrid）与未布设土工格栅两种工况。剩余14组模型试验采用谐和荷载加载，加载幅值取静载的40%，加载顺序提前预设。试验加载频率设定为2Hz，加载参数依据荷载取值确定。加载过程持续至循环次数达到10⁴次为止。试验结果表明：在静载工况且布设土工格栅的条件下，随着基层厚度的增加，地基承载力的提升幅度呈下降趋势。总体而言，当基层厚度为7.5cm与5cm时，采用土工格栅加筋可使地基承载力相较于未加筋工况分别提升约1.5倍至2倍。这意味着通过采用土工格栅加筋技术，可减小基层厚度，进而降低工程建设成本。