Study Of The Swell-shrink Fissures Of Improved Expansive Soil And The Effect Of Shear Strength

The expansive soil is made up of strong hydrophilic montmorillonite and illite, it has the obvious swell and desiccation shrinkage phenomenon.This phenomenon is mainly due to climate change in the nature, the hot weather lead to expansive soil water loss, soil began to shrink, rainfall makes the soil expand.Under the effect of both climate alternately, eventually making soil mass crack initiation, expansion. It is because of the generation of crack in the expansive soil, caused the foundation, embankment and dam slope collapse and structural damage, etc.Based on this, this paper mainly with the aid of MATLAB software, through indoor simulation experiment was carried out by different degree of compaction and the dosage of lime and FengHuaSha and the fracture characteristics of reinforced expansive soil of quantitative research, combined with the indoor direct shear strength test, studied the different dosage of lime and FengHuaSha fracture characteristics of improved expansive soil, strength characteristics and the function relation between crack and strength.The results show that:(1) Improved expansive soil cracking formation has important influence on expansive soil fracture after the first dry-wet circulation. With the increase of improved strength, fracture development degree is abate, fracture performance is more small, simple, width is narrower.(2) Improve the degree of compaction, adding geotextile material, mixed with FengHuaSha, lime can effectively inhibit the expansive soil of fracture development degree of the soil sample. By contrast, found that the greater the degree of compaction, reinforcement materials closer to the surface, the greater the differentiation sand proportion and mixing lime dosage, the degree of fracture expansive soil and the complexity is less.(3) Modification by different degree of fracture is not the same, this is mainly because each modified mechanism, the effect of the modified duration is different. Single from the point of view of fracture rate, mixing lime to the fracture effect of improved expansive soil best, reinforcement materials, sanding is poorer, directly improve the compaction effect is the worst.(4) Crack rate is linear increase with the increase of cycling times and improved expansive soil cohesive force and internal friction Angle increased with the increase of cycling times a logarithmic and power function attenuation respectively, the attenuation trend gradually decreases. With the increase of dosage of lime, lime improving expansive soil cohesive force increases gradually, but the trend of increasing process slowed, internal friction Angle is gradually increasing with the increase of the content, but the trend of increase is smaller. FengHuaSha the increase of the content, sand mixing expansive soil cohesive force is decreased after the increases, and the internal friction Angle is characterized by linear increase.(5)It has good exponential relationship between cohesive force and fissure rate, and improve soil the internal friction Angle of and the logarithmic function relationship between fracture rate. The function relation between the fracture and strength, can provide certain theoretical basis to determine the strength of the soil and the slope stability in the future.