全风化泥质砂岩强度低,遇水后易崩解、软化,表现出与一般填料不同的工程特性。采用X射线衍射试验分析土样矿物成分,采用压缩试验和平板荷载试验研究重复加卸载条件下土样累积变形与湿化规律,以指导现场压实控制。结果表明:(1)全风化泥质砂岩填土的压缩曲线在固结仪中呈下凹型,在平板荷载试验中呈上凸型,回弹曲线均呈下凹型;(2)第i+1次压缩–回弹曲线均位于第i次曲线下方,线形相似;(3)等载压缩次数增加,沉降增量递减,累积沉降增大,3次压实后,土体的残余变形趋于稳定;(4)超载压缩曲线将回归到首次压缩曲线的延长线上,具有记忆效应;(5)重复荷载越大,单次压缩总变形和永久变形越大;(6)重复荷载作用后的压实填土遇水产生湿化沉降;(7)湿化土的压缩–回弹曲线均呈下凹型,超载越高,相同荷载作用下的变形越小。现场压实过程中,增加压路机能量比增加压实次数可取得更好的压实效果。
Compared with other filling materials,completely decomposed argillaceous sandstone shows some different engineering characteristics like low intensity,easy disintegration and softening after mixing with water.In order to guide the compaction control in field,the mineral components of soil are analyzed by X-ray diffraction test;and the accumulative deformation and slaking law under repeated loading and unloading conditions are studied by compression test and plate loading test.The study results are shown as follows:(1) The compression curves of completely decomposed argillaceous sandstone are of concave type in compression test or convex type in plate loading test;and all rebound curves are of concave type.(2) The(i+1)-th compression-rebound curve is located below the i-th curve,and they have the similar linearity.(3) The more the number of equivalent loading compression,the less the settlement increment,but the more the accumulative settlement.Soil residual deformation tends to be stable after 3 times of compaction.(4) The over-loading compression curve will be back to extension line of the first compression curve,and has memory effect.(5) The larger the repeated load,the larger the single total and permanent deformations.(6) After the repeated loading and unloading,the compacted soils become slaking with water,and produce the slaking settlement.(7) The compression curves of slaking soils are of concave type;and the higher the over-load,the less the deformation under the same pressure.In the practical process of construction,it is better to increase the tonnage of the road roller than to increase the number of compaction operations.