Mercury injection test on Zhanjiang natural soft clay and compressed soil is conducted to obtain the microscopic deformation mechanism of structured soft clay. Evolutions of pore distribution

size

and structural characteristic parameters under different consolidation pressures are analyzed; the pore morphology is further quantitatively analyzed by SEM image

which is explained and testified by fractal theory. The results show that

a positive correlation is shown between the sensitivity of each pore size to external forces and pore volume content. The distribution density of the fine pores might be exaggerated while the one of macro pores might be underestimated in mercury injection test for the bottleneck effect. Pore distribution is affected by structure. When consolidation pressure increases to yield pressure

pores of 0.01-0.50 μm are changing obviously

pore connectivity becomes worse

pore size decreases

isolated pores increase

and limits between pore sizes become unobvious. Zhanjiang soft clay has multi-fractal characteristics

the limits for determining micro-pores

interparticle pores and isolated pores are 0.01 μm and 0.50 μm. Pore size division standard is given.