Testing Study On The Moistening Deformation Behaviour Of Gypsum Breccia

Expansive rock has the characters of swell shrinking,over consolidation,fissure and reducing shear strength so that it is considered as one of the world's difficult problems and is taken seriously in geotechnical engineering field.This paper,based on Gypsum breccia that comes from tunnel of railway from ShiJiaZhuang to TaiYuan in TaiHang mountain of SanXi province,studies behaviour on moistening deformation experiments of Gypsum Breccia.After a great deal of the research achievements and document datum in the field is consulted,It's realized that the cardinal nature of expansive rock is its special sensitivity to water and Gypsum Breccia as a new and special expansive rock surely to be influenced by water.The task of this paper is to study the moistening deformation experiments behaviour of Gypsum Breccia.Gain some innovative and engineering refered value acchivments as follow:1)Earn the expansive force of Gypsum Breccia in nature by two expansive force experiment methods named balance load and complete expansion method.The expansive force of Gypsum Breccia increased when it's water content ratio increased,expansive force of Gypsum Breccia is also influenced by it's density to some degree.After analysis,we earn the conclusion that expansive force of Gypsum Breccia in complete expansion method is bigger than that in balance load method.We advised to ues complete expansion method expansive force in engineering design.2)Most of expansive deformation of Gypsum Breccia is cuased by expansive soil in it in test,Breccia has no expansive deformation almostly when it is moistened.Water content ratio and density of Gypsum Breccia determine it's axial expansive deformation ratio in lateral restrict expansive experiment. Axial expansive deformation ratio of Gypsum Breccia is biggest in lateral restrict moistening expansive deformation experiment and secondly in free moistening expansive deformation experiment,smallest in tri-axial expansive deformation experiment.3)Under uniaxial compress condition, Gypsum Breccia's water content ratio deeply influence it's young's modulus and poisson's ratio. Gypsum Breccia shows uniaxial compress memory and recycle uniaxial compress brittleness characteristics.4)In tri-axial compress test,intial water content ratio and cell pressure obviously influence Gypsum Breccia's tri-axial compress characteristics like peek and residual strength,it's tri-axial damage pattern is expand damage.Test tell us that cell pressure can enhance Gypsum Breccia's anti-damage strength.