Research On Coarse Particles And Yield Stress Of Debris Flow By Experiments

Debris flow is a typical solid-liquid vapor mixed complex rheological body of water in the excitation conditions,the outbreak of a sudden,the momentum of violent destruction and strong,worldwide,landslides occur frequently in many mountainous country,to the country and its people resulting in huge losses,mudslides become one of the most common types of mountain hazards.Debris flow hazard not only causing casualties and economic losses,but also cause ecological imbalance in the region,increased soil erosion and desertification process in the region.Mudslides buried silt is one of the main buildings and engineering facilities of harms way,so that debris flow deposition thickness of the debris flow parameters of the most important parameters,but also one of the important parameters of risk assessment and disaster management mudslides mudslides.Debris flows can be obtained through field investigation deposition thickness,density can also be combined with mudslides,yield stress terrain slope and dangerous debris flow deposition thickness range is calculated.However,the current direct calculation of all regions and all types of debris flow deposition thickness model is not perfect,there are many shortcomings.Therefore,it is necessary to study this stage to acquire knowledge of the basic characteristics of debris flow,movement and disaster mechanism,debris flow rheological properties and structural aspects lay the foundation for mudslides and debris flow hazards early warning and forecasting project management.5.12 Wenchuan earthquake,earthquake landslides trench solids accumulate a lot of loose debris flows start critical rainfall decreases,earthquake debris flows reflect the high frequency,mass characteristics.In this paper,the yield stress of the previous research on people-based,coarse particle size,shape,material changes to the conditions for horses Yu,C Ancey other experimental data to validate the data room to siltation segment Huoshaogou typical debris flow field survey data to verify the data field to "indoor laboratory experiment ?indoor data validation? field data validation " is the basic idea.From the analysis of the paper and the coarse nature of the analyzes coarse particle size,shape,and coarse particles affect the grading of the yield stress of the material,and to establish numerical model data with previous laboratory experiments and field debris flow siltation segment data validation,has a certain practicality and universality.Research data through laboratory experiments and field data,third-party verification of data,draw the following conclusions:?1?is an important component of coarse particles of debris flow,the nature of the coarse particles mainly include particle size,particle group gradation,aspects of shape,material properties,and the like.These properties affect the movement of coarse particles of debris flow characteristics,but also on the deposition characteristics of debris flow impact,and rheological properties of debris flow material relationship.Therefore,in this study,in laboratory tests,through the preparation of different coarse debris flow,analysis variables,the relationship between the yield stress and come in coarse particles,the nature of the coarse particles have a significant impact on the yield stress.?2?The results of experimental data analysis,using the same kind of coarse particles in the same size,the more uniform coarse particles,the greater the yield stress,which reflects the composition of the coarse particles of debris more single body,which the greater the yield stress.To characterize the relationship between the curvature coefficient and yield stress grading,when the curvature coefficient closer to 1,graded worse,forming a single coarse particle size,the smaller the yield stress;conversely,vice versa.?3?In the case of coarse particles of the same material,with the same level and in the shape?sphericity??,the larger the particle size,the smaller the yield stress,the yield stress of the coarse particle size inversely proportional relationship.Through the coarse sand particles carried curvature coefficient times the experimental group Cc)and particle size?surface area S?correction can be found fitted and measured values after a good correlation correction,consistent with our interpretation of its mechanism of action and the impact of trends analysis.?4?Since the coarse particles of irregular shape having corners,inlaid better binding between the particles,the stronger structural therefore irregular coarse particles greater yield stress under otherwise identical conditions.After the introduction of sphericity?corrected volume concentration,POM cylinder and fitted values and the measured values of the intensity of the flat ball significantly increased,almost in a straight line,there is a good correlation;glass material also has good correlation.Two sets of data to fully explain the introduction of sphericity ? can be successfully corrected volume concentration of coarse particles reflect the contribution of the shape of the yield stress of the mechanism.?5?the type of coarse particulate materials have different material properties,such as surface energy, water-absorbent,hydrophilic,surface roughness,etc.These factors lead to the type of coarse particulate materials exhibit different properties,yield stress different extent.By introducing a material constant n,to give a better correlation,wherein the glass particles is a constant,the constant PVC material particles is 0.96 to 0.89 constant POM particles which have reached the optimal correlation value.?6?When the volume concentration of less than 0.47 after correction without gradation correction,regression coefficients and correlation coefficients fitted and measured values of the integrated value of the maximum,so the best correlation,which is consistent with the previous section on the ground volume with lower concentrations and conjecture about the impact of the weak 0.47 define.?7?this study found that in experiments when a large volume concentrations?greater than 0.59?,this time,the deposition thickness increased significantly,the measured experimental values have increased dramatically,significantly higher than the fitted values;Ma Yu in 2011 study,when the volume concentration greater than 0.59,the yield stress of the trend line inflection point,significantly increased;Ancey data in 2001 the study also appeared the same phenomenon,the yield stress occurs when a large volume concentration inflection,with a greater tendency to increase.Therefore,in order to better reflect the actual situation,this study volume concentration greater than 0.59 when the proposed new formula will adjust the original formula for the three sections of the piecewise functions.?=?₀C²e^22CP0,?₀=30?,C<.047?,?₀=30e^5?C.0-47?,?.059>C?.047?,?₀=30e^5?C-.047?e^8?C.0-59?,?C?.059?,C=aC₀.?8?fitted through said series of analysis,??? of the final correction factor is determined as follows: wherein : n is a material constant for the different materials have different values;S is the surface area of the coarse particulate material of the average unit?mm2?;Cc is the coefficient of curvature of coarse particles;? of the coarse spherical particles.Correction factor in the formula includes factors shape,size distribution,particle size,material in four areas,by a correction factor for the volume concentration correction can well reflect the nature of the role of coarse particles in the yield stress,reflecting its importance degree.In this paper,there are still many shortcomings to work,the following questions need to be more in-depth study:?1?conduct laboratory experiments is an important direction of research on practical problems,this experiment debris flow composed of a maximum particle size of the solid 16 mm,although the particle size than previous landslides debris flow slurry closer to reality,but the actual still can not match the actual particle size.?2?study the analysis of the material properties of coarse particles is not deep enough,there is no actual data representation for the surface properties of coarse particles,etc.;coarse particulate material properties affect the mechanism of the yield stress is not yet clear,therefore,for the lack of this study,the next further research can continue in-depth study of material properties of coarse particles affect the yield stress the role of the mechanism.