Liquefaction Of Foundation Soils Research Articles

Centrifuge study on the effect of the SCP improvement geometry on the mitigation of liquefaction-induced embankment settlement

Liquefaction of foundation soil causes significant damage to infrastructures. The sand compaction pile (SCP) method is a countermeasure against liquefaction to densify the ground by installing dense sand piles. In recent years, an innovative method has been developed to install sand piles into the ground at any angle. In this study, a series of dynamic centrifuge tests are carried out to investigate the effects of the angle of the SCP improvement zone on mitigating the liquefaction-induced settlement of embankment crests. The lateral displacement beneath the embankment toes is mitigated by the presence of the improvement zone installed in the foundation ground. In particular, the case with a 50° improvement zone is the most effective in mitigating lateral displacement and contributes to the lower settlement of the embankment.

Discriminant Method of Sand Liquefaction

With the proposal of 1.8 billion mus of cultivated land red line and the rise of land reclamation in China, more and more national defense and civil projects are built on poor geological soil, such as reclamation reefs in the South China Sea. The liquefaction damage caused by earthquake, such as water spraying, grouting and surface cracks, has a great impact on such buildings, and poses a threat to people's lives and property. Therefore, it is of great significance to study the liquefaction of sand in foundation soil. Since Academician Huang Wen-xi first proposed to use indoor dynamic triaxial test to study liquefaction, a series of achievements have been made in the liquefaction of foundation soil. The research methods of sand liquefaction have developed from simple single sample of numerical simulation, numerical simulation and test. Referring to the literature at home and abroad, this paper sorted out the discriminant method of sand liquefaction, experimental study of sand liquefaction and post-liquefaction analysis.

Seismic stability of embankments subjected to pre-deformation due to foundation consolidation

It has been reported that the major cause of earthquake damage to embankments on level ground surfaces is liquefaction of foundation soil. A few case histories, however, suggest that river levees resting on non-liquefiable foundation soil have been severely damaged if the foundation soil is highly compressible, such as thick soft clay and peat deposits. A large number of such river levees were severely damaged by the 2011 off the Pacific coast of Tohoku earthquake. A detailed inspection of the dissected damaged levees revealed that the base of the levees subsided in a bowl shape due to foundation consolidation. The liquefaction of a saturated zone, formed at the embankment base, is considered the prime cause of the damage. The deformation of the levees, due to the foundation consolidation which may have resulted in a reduction in stress and the degradation of soil density, is surmised to have contributed as an underlying mechanism. In this study, a series of centrifuge tests is conducted to experimentally verify the effects of the thickness of the saturated zone in embankments and of the foundation consolidation on the seismic damage to embankments. It is found that the thickness of the saturated zone in embankments and the drainage boundary conditions of the zone have a significant effect on the deformation of the embankments during shaking. For an embankment on a soft clay deposit, horizontal tensile strain as high as 6% was observed at the zone above the embankment base and horizontal stress was approximately half that of the embankment on stiff foundation soil. Crest settlement and the deformation of the embankment during shaking were larger for the embankment subjected to deformation due to foundation consolidation.

Design Research and Technical Application of the Multi-Type-Pile Composite Foundation

Through project example, analysis of the multi-type-pile composite foundation (lime pile plus CFG pile) in the practical application of liquefied foundation of high-rise building, especially using the ZFZ construction technology which forwards formed a hole and reverses packed into a compaction pile by a long spiral drilling machine to eliminate liquefaction of foundation soil and improve the bearing capacity of foundation is very notable, in addition, it also produces good economic and social benefits, so it has great value of promotion and use.

Analysis of earth dams affected by the 2001 Bhuj Earthquake

An earthquake of magnitude of 7.6 ( M w 7.6) occurred in Bhuj, India on January 26, 2001. This event inflicted damages of varying extents to a large number of small to moderate size multi-zone earth dams in the vicinity of the epicenter. Some of the distress was due to the liquefaction of saturated alluvium in foundation. Liquefaction was relatively localized for the majority of these dams because the earthquake struck in the middle of a prolonged dry season when the reservoirs behind these dams were nearly empty and shallow alluvium soils underneath the downstream portions of the dams were partly dry. Otherwise, liquefaction of foundation soils would have been more extensive and damage to these dams more significant. Six such dams have been examined in this paper. Four of these facilities, Chang, Shivlakha, Suvi, and Tapar were within the 50 km of epicenter region. These dams underwent free-field ground motion with peak ground accelerations between 0.28 g to 0.52 g. Of these Chang Dam underwent severe slumping, whereas Shivlakha, Suvi, and Tapar Dams were affected severely especially over the upstream sections. Fatehgadh Dam and Kaswati Dam were affected relatively less severely. Foundation conditions underneath these dams were first examined for assessing liquefaction potential. A limited amount of subsurface information available from investigations undertaken prior to the earthquake indicates that, although the foundation soils within the top 2.0 to 2.5 m underneath these dams were susceptible to liquefaction, Bhuj Earthquake did not trigger liquefaction because of lack of saturation of these layers underneath the downstream portions of these dams. These dams were then analyzed using a simple sliding block procedure using appropriate estimates of undrained soil strength parameters. The results of this analysis for these structures were found to be in general agreement with the observed deformation patterns.

An evaluation of the liquefaction potential of the Fraser Delta

Empirical and analytical methods for predicting the occurrence of liquefaction of foundation soils during an earthquake are examined and applied to the Fraser Delta area of British Columbia. The area is diked and at present has a population of about 150 000 people who reside mainly in low-rise buildings. Liquefaction of the foundation soils would cause severe damage to buildings, services, highway and railway links, and the dikes.Application of empirical methods based on blow count values indicates that liquefaction of the foundation soils could occur. Application of analytical methods indicates that liquefaction could occur in the event of an earthquake having a maximum ground surface acceleration of 0.12g (the 100 year value).The effects of various remedial measures are examined and it is shown that densification, drainage, and fill loading serve to reduce the tendency for liquefaction to occur. The presence of a low permeability layer close to the surface may cause liquefaction to occur by impeding the drainage.Construction that involves placing large sand fills with adequate drainage through the surficial low permeability layer to support low rise buildings would seem to be the least hazardous for this region.