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Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacent rock-stratum. The influence of the coefficient of permeability and loading frequency on the soil displacement at the ground surface were studied. The results showed that higher loading frequency led to more dynamic characteristics; and that the effect of the soil permeability was more obvious at higher frequencies.

To explore the modification of rheological behavior of fresh cement paste by in situ polymerization, the rheological properties of fresh in situ polymerization modified cement (IPMC) pastes with various acrylamide (AM) monomer dosages and resting time were investigated by rheology test in this paper. The interaction mechanism between inorganic-organic components of IPMC paste and its influence on rheology are also discussed. The results revealed that the yield stress and plastic viscosity of fresh IPMC paste decreased as the AM dosage increased, and rose rapidly with the resting time when the AM dosage was more than 5%. The time-dependent rheological properties of IPMC paste were associated with various periods of AM polymerization reaction. This paper also found that the dispersing effect produced by the AM adsorption and the flocculating effect generated from the polyacrylamide (PAM) microgels bridging would jointly impact the structural buildup of IPMC paste; the former improved the rheological properties and fluidity, while the latter acted contrary. Our results provide the underlying insights needed to guide the dynamic regulation of rheological properties of cement-based materials by in situ polymerization modification. [ABSTRACT FROM AUTHOR]

The coupled effect of viscosity enhancing admixtures (VEA) and superplasticizer (SP) on the rheological behavior of cement paste was investigated in this work. Two types of VEAs, including hydroxypropyl methylcellulose (HPMC) and Welan gum, and two types of SPs, i.e. polycarboxylate (PCA) and polynaphthalenesulfonate (PNS) were used as admixtures for cement paste. Rheological curves of cement paste and simulated pore solution containing VEA and SP were tested. Simulated pore solution test results show that molecules of different SPs may generate different effects on the viscosity of VEA solutions. Hershel-Bulkley (H-B) model was used to fit rheological curve of cement paste. Strong interaction between PNS and HPMC was observed in this work. [ABSTRACT FROM AUTHOR]