Jianliang Deng

Ageing and viscous effects on the deformation of clay in 1D compression

Ageing and viscous effects on the stress -strain behaviour of kaolin and their interactions were evaluated by performing special constant-rate-of-strain 1D compression tests on air-dried and saturated kaolin without and with cement-mixing. The yield stress that was higher t han the stress at which curing was made developed by ageing effects associated with cement hydration, which became larger with an increase in the curing period. The stress -strain behaviour of saturated cement -mixed kaolin after monotonic loading continues for some strain range following the start of yielding was rather independent of the stress at which cementation developed. The viscous properties of kaolin was evaluated by measuring the stress jump v �� � taking place upon a sudden change in the strain rate from before v ) (�& to after v ) (�& at the instantaneous stress v v � � � � / } ) /( )

VISCOUS PROPERTY OF KAOLIN CLAY WITH AND WITHOUT AGEING EFFECTS BY CEMENT-MIXING IN DRAINED TRIAXIAL COMPRESSION

The viscous property of kaolin and the ageing effect on its stress-strain behaviour as well as their interactions were evaluated by performing a series of drained triaxial compression (TC) tests on air-dried and saturated specimen with and without cement-mixing. The axial strain rate was changed stepwise many times as well as drained creep and relaxation tests were performed during otherwise monotonic loading (ML). Different types of viscous properties (called Isotach type as well as weak and strong TESRA types) were observed depending on test conditions. The ageing effects by hydration of cement, interacted with the viscous property, were observed with saturated cement-mixed kaolin. It is shown that the effects of viscosity property and ageing, which interact with each other, can be simulated by a non-linear three-component rheology model modified from the original one to account for ageing effects.

Effects of Excess Pore Water Pressure on the Displacement of Failed Dip Slopes in 2004 Niigata-Ken Chuetsu Earthquake

The effects of excess pore water pressure on the behavior of earthquake-induced dip slope failure were evaluated by field investigation, laboratory tests and numerical calculation. Two dip slopes which failed in the 2004 Niigata-ken Chuetsu Earthquake were investigated intensively. One is at Yokowatashi, Ojiya, and the other is at Yamakoshi Village (currently Nagaoka City). In both cases, the sliding plane was mainly along a weak thin layer. Laboratory test results showed that excess pore water pressure possibly increased during earthquake and/or during sliding. The displacement calculation was executed by using extended Newmark and Janbu method which considers the effects of irregular geometry of the sliding plane and the excess pore water pressure increase or the strain softening property of the weak layer. The calculation results showed very significant effects of excess pore pressure or strain softening.