Papers by Author: Yong Wang

Abstract: Experiment study on shallow gassy unsaturated sand under different confining pressure with GDS triaxial system's 4D stress path module is carried out. Different SWCC shapes under different confining pressures are analyzed. The results show that unsaturated sand's water retention capacity declines gradually with confining pressure infliction and accretion. Finally, shallow gassy sand's gas reservoir pressure characteristics with SWCC are analyzed and forecast, and it's conservative if the same thing is done based on SWCC without confining pressure.

Abstract: Taking steel-plastic composite reinforced band (CAT) and gravelly soil as the test materials, the pullout tests of reinforced band in gravelly soil with different water contents have been carried out by the laminated shear test instrument. The interface friction characteristics between reinforced band and gravelly soil are studied, and the influences of water content on the interaction characteristics are also discussed. Results show that (1) the extraction of reinforced band is a gradual process. The anchor end began to move firstly because of the extensibility of reinforced belt itself. As interface friction gradually transfer backward by, the free end start to move onward, then displacement schedule curves of the anchor end and the free end are gradually parallel, the whole movement of reinforced belt happens immediately. (2) Pulling force and displacement curve of the pullout friction test displays obviously nonlinear characteristics. Pulling force of the reinforced band increases greatly with increasing displacement at the beginning of the test, then decrease with the increasing displacement after the peak value is reached, the force-displacement curves generally exhibit strain soften characteristics. But it present strain hardening trend under greater normal stress, and pullout frictional strength increases with the increasing normal stress. (3) The pullout friction coefficient of the interface is sensitive to water content. It decreases linearly with the increasing water content.

Abstract: This study has been carried out to determine how the fines content affects the post liquefaction strength and deformation characteristics of sand. With the GDS dynamic triaxial system, a series of monotonic undrained compression tests of the sand after liquefaction with variation in fines content from 0 to 40% were conducted, and effects of fines content on the post liquefaction strength and deformation characteristics of sand were analyzed. Results show that with the addition of fines up to a fines content of 30%, the stress-strain curve moves downward and axial strain at low intensive stage is increased, beyond this critical value of fines content the trend is reversed. However, shear strength of post-liquefied sand first decreases with increasing fines content, and beyond the critical value of fines content it increases with increasing fines content at the strength recovery stage when are subjected to monotonic loading. At the same time, the strength recovery rate decreases firstly and then increases with the increasing fines content.

Abstract: Considering the influence of atmosphere action, field test of swelling force on expansive soil is carried out in Nanning Guangxi. The test sustains a whole rain season. The testing results show that swelling force is closely linked to the process of rainfall. The phenomenon, that long drought turns the rain, induces a sudden change of swelling force. But the persistence of rainfall brings different influence on vertical and horizontal swelling force. The results of field test can provide reference to optimize the engineering design.

Abstract: Considering adverse effects of shallow gas geology on Hangzhou Metro construction, based on the fluid-solid coupling analytical method of multi-phase media, effects of shallow gas on diaphragm wall trenching construction were examined by using FLAC-2D software. In combination with the diaphragm works of a typical subway station in the region buried shallow gas, the deformation on slurry trench of diaphragm wall were analyzed under working conditions using different specific gravity slurry. Results show that shallow gas escape of the stratum significantly affects stability of the groove wall, easily leading to collapse of the soil and resulting in the concrete diaphragm wall with quality problems such as honeycomb, reducing diameter, bulging, breaking zone and etc. In trenching construction of the diaphragm wall, increasing the specific gravity of slurry appropriately is an effective way to reduce adverse effects of the shallow gas, but it should not be too large. A suitable range of mud weight varies from 1.06 to 1.10.

Abstract: In order to analyze the effect of subsoil liquefaction on the seismic response of pile foundation, typical computation model in liquable ground was set up. Based on different constitutive models of the foundation soil before and after liquefaction and considering the nonlinear relation of pile-soil interaction, the dynamic finite difference analysis of group piles was carried out by using FLAC3D. The dynamic response characteristics of pile foundation considering liquefaction during earthquake are studied. Results show that the peak value of pore pressure ratio is different in different depth of the soil around pile, and the arriving time of the peak value of pore pressure ratio is later than that of the peak value of earthquake acceleration. At any time during the earthquake whether before or after the liquefaction the top moment of pile are larger than that of the pile shaft when the top pile is solidly embedded.