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11.
Summary The mechanical behaviour of reconstituted normally consolidated Boom clay was examined in a series of laboratory triaxial stress path tests. The aim was to establish some basic characteristics of this soil. The compressibility of the reconstituted Boom clay was found to be moderate, corresponding to the soils of the same plasticity. The results indicated also that the destructured Boom clay exhibited a brittle behaviour. The undrained secant stiffness was found to vary with strain level and also to be dependent on the consolidation pressure. 相似文献
12.
This paper focuses on using urea hydrolysis as a bio-grouting process to increase the strength of crushed aggregates commonly used in stone columns. Various reagent phases (2, 4, 6 and 12 phases) consisted of alternately percolating solutions containing bacterial suspension and cementation solution through the soil column. In addition, a multi-soil lift strategy with options of up to four soil lifts was undertaken to test the applicability of bio-grout to cement crushed aggregate columns. While the average amount of calcium carbonate precipitation was roughly unchanged in both techniques, the distribution within the crushed aggregate columns was heterogeneous. However, the distribution of the precipitated calcium carbonate is almost uniform in crushed aggregates treated by a two-soil lift strategy and a four-phase treatment strategy. It is also deducted that both techniques can be combined to gain a uniform calcium carbonate and strength along a long sand/stone column. Furthermore, a one-soil lift resulted in higher strength than using multi-soil lifts, and a maximum strength of approximately 2.3 MPa was achieved using 4-reagent phase treatment strategy. Scanning electron microscopy and electron dispersive spectroscopy analysis validate that calcium carbonate was deposited as white crystals on the surface of the crushed aggregate particles. 相似文献
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Abdelmalek Bouazza Asadul Haque Dong Mei Wang 《Geotechnical and Geological Engineering》2009,27(1):115-121
The generation of massive volume of slimes from sand mining industry ascertains the need for effective waste treatment. The
application of slimes in landfill barrier construction works has been identified as one of the processes that can be used
to reduce their volume, enabling in this way the rehabilitation of dangerous sites. This article presents a modified triaxial
cell specially built to investigate high water content soils and discusses the results obtained from the investigation of
the hydraulic properties of two slimes. The results of laboratory filter cake tests show that the slimes have reasonably good
sealing capacities due to the formation of a cake layer on other porous materials upon draining. A relatively low hydraulic
conductivity (1.5–3 × 10−9 m/s) was achieved, once the cake layer was formed. This is close to the prescribed 1 × 10−9 m/s required by the local environmental governmental authority for a landfill hydraulic barrier material, indicating their
potential suitability as landfill barrier. 相似文献
14.
Unconfined compression tests have been carried out on a highly plastic clay using three different strain rates: fast, medium and slow. Results of the t strength with increased strain rate for both the undisturbed and remoulded soil, although the increase was more pronounced in the undisturbed cases tha leading to an increase in sensitivity. It is therefore recommended that sensitivity be defined for a particular strain rate, or that an acceptable incr rate be defined for both undisturbed and remoulded soils. 相似文献
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16.
E. Laville B. Delcaillau M. Charroud O. Dugué L. Ait Brahim G. Cattaneo P. Deluca A. Bouazza 《International Journal of Earth Sciences》2007,96(3):497-515
The South Middle Atlas front constitutes a northeast-trending shear zone, located north of the Neogene Missour basin and east
of the Taza Guercif basin. This paper analyses the Southern Middle Atlas Fault Zone (SMAFZ) deformation since the Pliocene.
The set of structures observed suggests that reverse and thrust faulting along the central part of the SMAFZ are combined
with left-lateral slip along N–S striking faults of its south-western termination and right-lateral faulting along E–NE striking
faults of the east–northeast termination. Thrusts and oblique thrust-related anticlines of the two lateral ramps partly accommodate
north-west directed motion of the African plate. The Thrusts probably resulted from rejuvenation of Jurassic normal faults;
they were active during the Upper Miocene–Pliocene and the Pleistocene. The geometries of positive inversion structures and
buttressing effects are clearly dependent on the geometry and sedimentology of the original basin-controlling fault system
and on the presence of a décollement level. Field mapping is integrated with Landsat imagery and a digital elevation model
to investigate the morphotectonic evolution of the south-eastern range front of the Middle Atlas. Geomorphological features
provide significant information on the processes that govern lateral propagation of active anticlines. Both suggest that the
deformation front may have been active since Pliocene. 相似文献
17.
The effect of grain size distribution on the unconfined compressive strength (UCS) of bio-cemented granular columns is examined. Fine and coarse aggregates were mixed in various percentages to obtain five different grain size distributions. A four-phase percolation strategy was adopted where a bacterial suspension and a cementation solution (urea and calcium chloride) were percolated sequentially. The results show that a gap-graded particle size distribution can improve the UCS of bio-cemented coarser granular materials. A maximum UCS of approximately 575 kPa was achieved with a particle size distribution containing 75% coarse aggregate and 25% fine aggregate. Furthermore, the minimum UCS obtained has applications where mitigation of excessive bulging of stone/sand columns, and possible slumping that might occur during their installation, is needed. The finding also implies that the amount of biochemical treatments can be reduced by adding fine aggregate to coarse aggregate resulting in effective bio-cementation within the pore matrix of the coarse aggregate column as it could substantially reduce the cost associated with bio-cementation process. Scanning electron microscopy results confirm that adding fine aggregate to coarse aggregate provides more bridging contacts (connected by calcium carbonate precipitation) between coarse aggregate particles, and hence, the maximum UCS achieved was not necessarily associated with the maximum calcium carbonate precipitation. 相似文献