| A true triaxial apparatus is a testing system measuring the mechanics characteristics of soil under three-dimension principle stress condition.A new true triaxial apparatus with a new structural cell was developed by the geotechnical engineering institute in Xi'an University of Technology.By comparison loading ways of different true triaxial apparatuses both at home and abroad,the new true triaxial appratus's charateristics was summarized as following:A kinds of hydraulic/Variable apparatus with stepper motor servo-driven was developed,which was used to load independently principal stress,and the corresponding automatic control system was developed.Furthermore,the true triaxial testing of remolded loess was executed on the new true triaxial apparatus,the characteristic of the stress-strain curve of the true triaxial testing of remolded loess and the the strength of the Loess remodeling was analyzed under different water content.Through the above research work,some points as following:(1)In this paper,the rigid axial loading,lateral load biaxial are flexible,lateral adjacent biaxial between the use of hydraulic radial capsule flexible scalable,flexible rotation of planar thin-walled steel effective segregation of the three independent axial loading system was used on the Xi'an university of technology true triaxial apparatus;and servo stepper motor driven hydraulic / variable load controller was used,the loading process of the independent three principal stress was realized,Noninterference direction stress and strain can be forecasted.(2)The true triaxial apparatus can to complete various types of conventional and special test pilot,the pilot project are:①The stress path test and the strain path test with the constant middle principal stress ratio b;②constant mean stress test;③and Unloading Stress test on cycle path;④lateral unloading test;⑤creep test;⑥stress-induced anisotropy test.(3)By analysis the experimental datas of remodeling loess under the conditions of adoption of different initial moisture content of consolidation pressure,the same consolidation pressure and moisture conditions,with the increase of the ratio of axial stress,stress-strain curve of the hard-liners gradually hardening into a weak ideal or plastic;the same consolidation pressure and the ratio of axial stress conditions,as the moisture increases,the stress-strain curve from weak sclerosis or idealism into hard plastic;the same moisture content and the ratio of axial stress conditions,as the consolidation stress increases,stress-strain curve from weak or hardened into a tough idea plastic state.(4)through analysis the remolded loess the Strength change rule,under the different strain condition,on theπplane,of the the yield curve of remolded loess and damage curve was basic similar;Under the different moisture content condition in theπplane,the loess damage curve is similar,and along with moisture content enlargement,the curve contracts inward,through to destroy path's fitting analysis,on theπplane,the failure curve was well described by function which Yi-chuan Xing proposed,this failure curve located at mole of coulomb line and outside loose hillock Yuan SMP criterion curve,under same condition Mises circle.(5)on theπplane,through analysis the stress space failure change rule analysis of the remolded loess with the different water content,the application generally Mises criterion and the SMP criterion has established the description different water content loess intensity failure plane criterion;the transformation stress space method proposed by Yang-ping Yao etal was quoted to revises the Cambridge model and to establish the elastoplasticity model,which can reflect the deformation properties of remolded loess with water content change on the three dimensional stress space. |
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