Study On The Micro Mechanism And Structural Parameters Of The Reinforced Soil

With the development and the rise of geosynthetic materials, a new type of composite soil, reinforced soil, is gradually applied to different fields including highway, water conservancy, civil engineering and the other territories in recent years. With the wide use of reinforced soil in different fields, It is particularly important to understand and research the microcosmic mechanism of the reinforced soil. Researchers do a large number of researches on microscopic properties of reinforced soil, but there is not a relatively perfect theory summarizing the microcosmic mechanism of the reinforced soil based on the complex interaction of soil and geosynthetic materials. So far, the study on micro mechanism of the reinforced soil is slow, far behind the engineering practice. In this paper, digital image correlation method is applied to microscopic mechanism research, and all analyses done have a certain theoretical significance and engineering application value for the theory designing and the engineering research of the reinforced soil.Nowadays, digital image correlation method(DICM) as a kind of relatively mature experimental mechanics observation technology, is applied in many fields. Digital image correlation method is based on digital photography and digital image processing technology. Digital image correlation methods a kind of full optical measurement method that is non-contact and efficient. And the method now has been widely used in the measurements on displacement field and strain field among microstructure particles. Especially in the process of measurement, digital image correlation method with advantages of high precision, non-contact and full measuring, makes up for the deficiency of the traditional measuring method.The microscopic test of reinforced soil this paper uses is based on the digital image correlation method combining with reinforced soil direct shear test. In the microscopic test, shear strength indexes is obtained under different vertical pressure. And the three other microstructure parameters including plane porosity, rate of anisotropy and directional frequency of the pictures chosen using the DICM and Matlab are obtained. In this paper, plane porosity, rate of anisotropy and directional frequency is analyzed in the test process. And the three micro structure parameters together with the shear strength indexes, are analyzed to obtain the interaction of the soil and reinforcements under the microscopic structure. The experimental study of this paper will provide some research foundation of the soil and the reinforcements under the vertical pressure in the level of the microstructure. And further discusses on the micro mechanical properties of reinforced soil. And the main microscopic parameters are analyzed.The content and conclusions of this paper is as follows:(1)The shear strength parameters and the three microstructure parameters of reinforced soil of standard sand and clay under different vertical pressure is calculated. And the interaction and change of these parameters is analyzed. The study lays a foundation for the theory study of reinforced microscopic mechanism under the load.(2)Based on different layer reinforced(without reinforcement, one layer reinforced and two layers reinforced), microscopic test of reinforced specimen of standard sand and clay is calculated. The paper studies the interaction mechanism of soil and reinforcement materials under the certain vertical pressure on the microstructure level.(3)The results show that, with the increase of reinforcement layers, the cohesion of the standard sand and clay decreases, and the internal friction angle of the standard sand and clay increases.(4)Standard sand and clay tested has three types including no reinforcement, one layer reinforced and two layers reinforced. On a certain reinforcement condition, the plane porosity of the specimen decreases and anisotropic rate of the specimen increases and the probability entropy of the specimen decreases gradually under a vertical pressure(50kPa,100 kPa,200kPa and 400kPa). The changes make the mutual attraction between adjacent particles in the specimen slightly reduced, and make the friction force on the surface and the bite force among soil particles increased. And the cohesion slightly lows, while the internal friction angle of specimen increases.