干湿循环条件下泥岩颗粒料破碎机理及渗透特性研究
发布时间：2018-10-05 16:44
【摘要】：选取三峡库区砂、泥岩颗粒料作为研究对象,进行在荷载及干湿循环组合作用下的渗透固结试验及颗粒筛分试验。选取上覆荷载、土体干密度、粗颗粒含量为试验的影响因素。采用自制的颗粒破碎细观试验系统,试验系统由有机玻璃试验桶、上游供水装置、下游出水装置、热气源进气装置、砝码、量测设备(上下水头测压管、百分表、下游集水箱、高精度试验天平)组成。通过对试验数据进行分析比对,获得的结论及研究成果有:(1)在干湿循环作用下,研究干密度、上覆荷载、粗颗粒含量对泥岩颗粒料的影响,总结了干湿循环条件下泥岩渗透特性及固结特性的变化规律。岸坡土体渗透特性的变化,必然会对岸坡渗流场产生影响,通过分析岸坡深度为0.5m、1m、2m、3m的土层渗透系数的变化,揭示了渗透特性演化对岸坡稳定性的影响。基于泥岩土样的空隙比和渗透系数的变化,利用Kozeny-Carman公式揭示了泥岩颗粒崩解破碎的破碎机理。在干湿循环效应下,泥岩同时受到固结作用和破碎作用的影响,试验前期以固结作用为主,当主固结作用的完成后则以颗粒破碎作用为主。(2)通过对渗透固结试验结束后的泥岩颗粒料进行筛分,比较试验前后泥岩颗粒料各粒径组的颗粒含量变化的情况,发现2~5mm是颗粒含量增加最多的粒组,将2~5mm作为特征粒径组,衡量粗颗粒的破碎性能。采用hardin破碎势Bp对试验前后的泥岩颗粒级配进行量化,研究了在干湿循环效应下,干密度、上覆荷载、粗颗粒含量对泥岩颗粒料破碎程度的影响。基于熵增原理,使用基础熵NB对泥岩颗粒级配进行量化,建立泥岩颗粒组成演化模型,并对渗透系数K与基础熵NB进行拟合,发现渗透系数K与基础熵NB之间具有良好的相关性,则可通过土体渗透系数变化反映颗粒在干湿循环作用下的破碎情况(3)对在水位反复升降的情况下砂泥岩质岸坡渗流稳性进行讨论,发现随着水位升降次数的增加,砂泥岩混合料孔隙平均粒径Do逐渐减小,小于混合料孔隙平均粒径Do的颗粒含量不断增加。建立了基础熵NB与小于土体平均孔隙直径的细颗粒含量的关系模型,提出了通过基础熵NB预测砂泥质岸坡发生渗透破坏的方法,揭示了粒组演化对码头岸坡渗流稳定性的影响。
[Abstract]:Sand and mudstone granular materials in the three Gorges reservoir area were selected as the research object. The osmotic consolidation test and particle screening test were carried out under the combined action of load and dry-wet cycle. Overburden load, soil dry density and coarse particle content were selected as the influencing factors. The test system is composed of plexiglass test barrel, upstream water supply device, downstream outlet device, hot air intake device, weight, measuring equipment (up and down water head pressure measuring pipe, percentile, downstream water collecting tank, etc.) High precision test balance. Through the analysis and comparison of test data, the conclusions and results obtained are as follows: (1) under the action of dry-wet cycle, the effects of dry density, overburden load and coarse particle content on mudstone pellets are studied. The changes of permeability and consolidation characteristics of mudstone under dry and wet circulation are summarized. The change of soil permeability characteristics will inevitably affect the seepage field on the bank slope. By analyzing the change of soil permeability coefficient with a depth of 0.5 m ~ 1 m ~ 2 m ~ 3 m, this paper reveals the influence of the evolution of seepage characteristics on the stability of bank slope. Based on the variation of void ratio and permeability coefficient of mudstone samples, the mechanism of mudstone particle disintegration and breakup is revealed by using Kozeny-Carman formula. Under the effect of dry-wet cycle, mudstone is affected by consolidation and fragmentation at the same time. After the completion of the main consolidation process, the effect of particle fragmentation is dominant. (2) by screening the mudstone particles after the osmotic consolidation test, the particle content changes of each particle group of mudstone particles before and after the experiment are compared. It was found that 2~5mm was the group with the largest increase in particle content. 2~5mm was used as the characteristic particle size group to evaluate the crushing property of coarse particles. The particle gradation of mudstone before and after the test was quantified by hardin breakage potential Bp, and the effects of dry density, overburden load and coarse particle content on the crushing degree of mudstone particles were studied under the dry and wet cycle effect. Based on the principle of entropy increase, the basic entropy NB is used to quantify the gradation of mudstone particles, and the evolution model of mudstone particle composition is established, and the permeability coefficient K is fitted to the basic entropy NB. It is found that there is a good correlation between the permeability coefficient K and the basic entropy NB. The change of soil permeability coefficient can reflect the fragmentation of grain under the action of dry and wet circulation. (3) discuss the seepage stability of sandy and mudstone bank slope under the condition of repeated rise and fall of water level, and find that the seepage stability of sandy mudstone bank slope increases with the increase of water level rise and fall times. The average pore diameter Do of sand mudstone mixture decreases gradually, and the particle content of Do smaller than the average pore diameter of the mixture is increasing. The relationship model between basic entropy NB and fine particle content smaller than the average pore diameter of soil is established. A method of predicting seepage failure of sandy and muddy bank slope by foundation entropy NB is proposed, and the influence of grain group evolution on seepage stability of wharf bank slope is revealed.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45
[Abstract]:Sand and mudstone granular materials in the three Gorges reservoir area were selected as the research object. The osmotic consolidation test and particle screening test were carried out under the combined action of load and dry-wet cycle. Overburden load, soil dry density and coarse particle content were selected as the influencing factors. The test system is composed of plexiglass test barrel, upstream water supply device, downstream outlet device, hot air intake device, weight, measuring equipment (up and down water head pressure measuring pipe, percentile, downstream water collecting tank, etc.) High precision test balance. Through the analysis and comparison of test data, the conclusions and results obtained are as follows: (1) under the action of dry-wet cycle, the effects of dry density, overburden load and coarse particle content on mudstone pellets are studied. The changes of permeability and consolidation characteristics of mudstone under dry and wet circulation are summarized. The change of soil permeability characteristics will inevitably affect the seepage field on the bank slope. By analyzing the change of soil permeability coefficient with a depth of 0.5 m ~ 1 m ~ 2 m ~ 3 m, this paper reveals the influence of the evolution of seepage characteristics on the stability of bank slope. Based on the variation of void ratio and permeability coefficient of mudstone samples, the mechanism of mudstone particle disintegration and breakup is revealed by using Kozeny-Carman formula. Under the effect of dry-wet cycle, mudstone is affected by consolidation and fragmentation at the same time. After the completion of the main consolidation process, the effect of particle fragmentation is dominant. (2) by screening the mudstone particles after the osmotic consolidation test, the particle content changes of each particle group of mudstone particles before and after the experiment are compared. It was found that 2~5mm was the group with the largest increase in particle content. 2~5mm was used as the characteristic particle size group to evaluate the crushing property of coarse particles. The particle gradation of mudstone before and after the test was quantified by hardin breakage potential Bp, and the effects of dry density, overburden load and coarse particle content on the crushing degree of mudstone particles were studied under the dry and wet cycle effect. Based on the principle of entropy increase, the basic entropy NB is used to quantify the gradation of mudstone particles, and the evolution model of mudstone particle composition is established, and the permeability coefficient K is fitted to the basic entropy NB. It is found that there is a good correlation between the permeability coefficient K and the basic entropy NB. The change of soil permeability coefficient can reflect the fragmentation of grain under the action of dry and wet circulation. (3) discuss the seepage stability of sandy and mudstone bank slope under the condition of repeated rise and fall of water level, and find that the seepage stability of sandy mudstone bank slope increases with the increase of water level rise and fall times. The average pore diameter Do of sand mudstone mixture decreases gradually, and the particle content of Do smaller than the average pore diameter of the mixture is increasing. The relationship model between basic entropy NB and fine particle content smaller than the average pore diameter of soil is established. A method of predicting seepage failure of sandy and muddy bank slope by foundation entropy NB is proposed, and the influence of grain group evolution on seepage stability of wharf bank slope is revealed.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45
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