EXPERIMENTAL STUDY OF ACCUMULATIVE DEFORMATION AND SLAKING LAW OF COMPLETELY DECOMPOSED ARGILLACEOUS SANDSTONE UNDER REPEATED LOADING AND UNLOADING CONDITIONS
(1. Department of Geotechnical and Tunnel Engineering，Changsha University of Science and Technology，Changsha，Hunan 410004，China；2. Guangdong Provincial Changda Highway Engineering Co.，Ltd.，Guangzhou，Guangdong 510620，China)
Abstract：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.
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2013, Vol. 32 
