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Proceedings of the International Conference on
Advances and New Challenges in Earthquake
Engineering Research, Hong Kong Volume
A SIMPLIFIED METHOD TO EVALUATE LIQUEFACTION
OF SUBSOIL OF BUILDING
Jing Liping and Wu Zhaoying
Institute of Engineering Mechanics
China seismological Bureau, Harbin
Abstract
In this paper, based on the simplified method proposed by Men et al and Martin's model of the
pore water pressure, a new simplified method is presented to evaluate the pore water pressure in
the subsoil of buildings during earthquake. According to the cone model theory the subsoil of
buildings may be approximately divided into three zones, in which the seismic shear stress and
additional dynamic stress can be evaluated with the use of Seed's simplified method and the
cone model. Then the pore water pressures in these three zones may be approximately evaluated
with the use of Martin's model The method could be directly applied to analyze the initial
liquefaction potential of subsoil of building with pore pressure ratio.
Key words subsoil of building, cone model, pore water pressure, seismic liquefaction
Introduction
As is well known up to the present soil liquefaction evaluation methods available have been set
up largely for the free field without building, These methods may be divided into four groups i.e.
(1) Seed's simplified method, (2) seismic response analysis method including both total and
effective stress approach, (3) empirical formulae, (4) probabilistic and statistical method. Since
the 1964 Niigata Earthquake and Alaska Earthquake brought about an extensive damage of soil
liquefaction, many investigators have devoted much attention to study seismic liquefaction
problems and remarkable achievements have been gotten as shown in the methods of four groups
cited above. When buildings are existed the pattern of liquefaction would be different from that
in the free ground. However seismic liquefaction evaluations of subsoil of buildings have not yet
been resolved in such a way that general and practicable methods with sufficient accuracy and
plausibility can be established for the use of engineering design and analysis. This fact may be
due to that (1) building subsoil are much more complicated to deal with in contrast with free
field of ground since the existence of building makes a non-uniform stress field and a
complicated wave propagation pattern due to soil-structure interaction and (2) a variety of
influencing factors relevant to building such as size, shape, rigidity, base area, buried depth of
foundation, dead and seismic loading, etc. have to be considered There have been only limited
results of study on the problem and model tests 1 " 4 , but these studies bring large time and
manpower consumption and could not meet the needs of evaluating liquefaction of subsoil of
building in engineering
Men et al (1997) 5 have presented a new simplified method to evaluate seismic liquefaction of
subsoil of buildings. They have devised the method in such a way that it is simple to handle and
has clear physical insight and sufficient engineering accuracy by taking advantage of Seed's