Study On Constitutive Model And Physical And Mechanical Properties Of Outwash Congeries In Linzhi Area

Nyingchi prefecture is located in the southeast of the qinghai-tibet plateau,is a typical modern maritime glacier regions in our country,the influence of ice age,interglacial climate alternation,qinghai-tibet plateau glacier range change is bigger,plenty of rainfall and the growth of ice and snow melt water to water deposit provides favorable hydrodynamic conditions;The outcropped strata are mainly in Cambrian system,devonian system,carboniferous and Triassic-cretaceous and quaternary,lithologic types,more and more appeared different degree of metamorphism,the influence of the regional structure and tectonic movement,the formation of the deposit for the ice water and provides a rich source of solid condition.The typical ice water accumulation bodies in Linzhi area are mostly piled up in sparsely populated high altitude areas,and traffic and construction are not convenient.Before twentieth Century of people accumulation of ice is few,especially on the outwash accumulation engineering mechanical properties are lack of a comprehensive systematic research,both at home and abroad in outwash accumulation on the construction of buildings is very cautious.With the development of the western region in China,it is inevitable for us to contact the ice water accumulation.In this paper,the typical outwash congeries of Linzhi as the research object,on the basis of previous studies,through field geological investigation and remote sensing interpretation means of sedimentary characteristics,outwash congeries particle composition,topography and distribution,degree of cementation are investigated with field investigation and Analysis on the base;a large number of laboratory tests and related research results on the outwash congeries of compaction test,permeability,mechanical properties,temperature and size effects;through the engineering analogy,parameter inversion and other means to obtain a set of outwash macro and micro parameters,based on parameters,using limit equilibrium simulation the numerical method and thought,to do a comprehensive evaluation on the stab ility of ice accumulation slope.This article research results to some extent compensate for the engineering and academia in nyingchi prefecture water deposit on the study on physical and mechanical properties,for the progress of the project and the academic discussion provides a theoretical parameter analysis of the value and its change rule.Technical route of this paper is mainly divided into three stages: the first stage is on the basis of the literature and collect related data,combined with field investigation,field mainly studies the basic characteristics of the deposit in ice water and nyingchi region,methods mainly include the scene of surveying and mapping,a points test,penetration test in situ and some auxiliary methods;The second stage is to utilize the wild take samples accordingly indoor test,the main research deposit in ice water and physical and mechanical properties,the use of test instruments are mainly liquid plastic limit joint meter,multi-function electric compaction meter and ejector,constant head permeability tester,large triaxial shear test apparatus,small triaxial shear test instrument and medium-sized direct shear test apparatus,etc.The third stage is the results of research on the basis of the first two stages,deposit deposit in ice water and constitutive model is established and ice water and slope engineering stability analysis.Through the above research ideas and methods,mainly made the following findings:?1?the Linzhi area outwash congeries in field investigation,a field,permeability and bulk density test,combined with indoor shear test results with different stone content conditions,based on the traditional classification method,the outwash congeries particle composition,cementation degree,permeability and mechanical properties comprehensive classification index method,the outwash congeries body is divided into 3 classes and 5 sub classes.?2?the permeability coefficient of outwash congeries body in generali×10^-3 cm/s,belongs to the medium permeability medium;stability time field pe rmeability test in 2 hours;with grain test,that when fine content is greater than 10% on the accumulation of body permeability influence.The permeability test shows that with increasing of hydraulic gradient,seepage velocity is approximately linear to nonlinear growth,the export flow of water approximately meets the Darcy's law,turbid water obviously does not meet the Darcy's law,but can use the corresponding permeability constitutive relation.?3?The compaction test showed that the same amount of stone under the condition of dry density with increasing moisture content increased first and then decreased,there is obvious peak,there exists an optimum water content and maximum dry density of samples;the same moisture content,dry density increases with increasing the content of stone;the optimal moisture content were overall increases with reducing amount of stone;a boundary stone content of 40% can be used as the ice water accumulation body compaction test.?4?large indoor three axial compression test showed that the outwash congeries the cohesion with the increase of water content increases first and then decreases,and has obvious peak points,and can use the corresponding polynomial fitting;internal friction angle with the increase of moisture content is lower trend in water the rate is 5.07%⁷.84%,amplitude less internal friction angle decreases,the curve tends to be gentle.?5?laboratory three axial compression show that the outwash congeries temperature changes from-10 to ⁵0 DEG C in the process,with the increase of temperature the cohesion increased first and then decreased and tended to be stable,and has a maximum value at 0 DEG C.With the increase of temperature,the internal friction angle has little change,and the fluctuation is within a small range.?6?Under the condition of low confining pressure,the constitutive relation of outwash congeries does not accord with Duncan C hang model.Based on Duncan Chang constitutive model,considering strain softening and expansion of the situation,the tangent modulus and tangent Poisson ratio is corrected,and verifies the correctness of the modified model.?7?Using a variety of physical and mechanical parameters measured,a comprehensive evaluation of the stability of an ice water accumulation slope in the evaluation area is carried out.The numerical simulation software is used to analyze the accumulation of slope failure,and the applicability of the particle flow program PFC^3D to the numerical simulation of the accumulation of bulk media is also verified.In this paper,the water deposit in nyingchi prefecture,physical and mechanical properties of research results,consistent with the general research results of predecessors.O n the basis of predecessors' research results at the same time,make up the deposit related to ice water and in the wild and remote sensing interpretation,engineering classification,engineering characteristics,temperature,and the lack of size effect and so on research.This study mainly aimed at the nyingchi region,water deposit in other areas of research only provides the corresponding research methods and physical mechanics parameter selection of similar material than choose;Study of water deposit constitutive model,this paper only made a model of the strain softening under the condition of correct analysis,and the reality may be there are many shortcomings of,deposit to the ice water for later research of scholars interested in provides a research direction.