Controlling Effects of Residual Deformation on Pore Pressure: A Loess Soil Case

Kun Liu,Yu Sun,Lanmin Wang,Wentong Tian,Zhenming Wang,Na Li,Junjie Sun

doi:10.1155/2019/7142819

Abstract

What the role of each phase medium plays and how their interactions do work should be essential problems to understand dynamic behaviours of soils. In order to disclose interactions between solid, water, and air phases of soils, we applied loess samples to analyse controlling effects of residual deformation on pore pressure based on three kinds of laboratory tests. We obtained the similarity and difference of mechanical behaviors of soil samples under different water contents and loading. Both process and cause of pore air/water pressures are independent of initial stress conditions or loadings. However, absolute values of pore water pressure depend on the confining pressure, whereas the pore air pressure is contrary. The uniformity of responding process and cause of pore pressure depend upon the interaction mechanism between solid particles and air/water media, but the different absolute values depend upon the permeability and compressibility of air/water.

Highlights

Loess is a kind of uniform, cohesive, and wind-blown sediment within Quaternary period
Dynamic loading correlation between external loading and pore pressure. e result could reveal that the relation between residual deformation and pore pressure is much closer than external loading and pore pressure. is may mean the solid particle structure is the first response medium under external loadings, and it transfers the static/dynamic stress to the two phases of water and air filled in the solid particle structure
E correlation between residual deformation and pore pressure could disclose three facts. e first is solid particle structure of soil transfers the external loading causing the development of residual deformation and pore pressure. e second is residual deformation has a natural relation with pore pressure. ird, during different loading stages the stress origin of pore water and air pressure should be the same, which means the difference between pore water and air pressure is just due to the distinctions of their physical properties such as permeability and compressibility

Summary

Introduction

Loess is a kind of uniform, cohesive, and wind-blown sediment within Quaternary period. In China, the loess area reaches 640,000 km, in which 440,000 km distribute within Loess Plateau. Q3 loess has much higher porosity and weaker cohesion than soils of Q1 and Q2 loess. Under some conditions such as rainfall and earthquake, Q3 loess could cause geotechnical hazards, differing from relative stable soils of Q1 and Q2 loess. If the dynamic loading is large enough, the saturated Q3 loess could suffer liquefaction, as well as seismic subsidence at unsaturated conditions.

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Results

Discussion

Conclusion