Relationship Between Pore Characteristics And Texture Of Q₃ Malan Loess

Loess is a kind of structural soil material with multi-pores and weak cementation,which was transported and deposited in the land environment by wind in arid and semi-arid climate since Quaternary in geology.It has the characteristics of mainly silt,followed by clay.Silt and clay particles constitute the special columnar joints and macroporous structure of loess,which provides convenience for the structural deterioration process of loess under stress and water disturbance.With the expansion of engineering construction in loess area,the influence of porosity on engineering stability becomes more and more prominent,such as land subsidence,deformation and failure of earth dam foundation,deformation and failure of slope surface,etc.As the main place of structural damage,pore space is the objective basis of structural impact.It is of great significance for theoretical research and engineering practice to explore its specific impact mechanism.The special pore space of loess is very complex,so it is difficult to study quantitatively with traditional Euclidean geometry.Fractal theory puts forward a new cognitive method.It is of new cognitive significance to explore the relationship between pore fractal dimension and structural parameters.In this paper,samples of natural Q₃ Malan loess from two different topographical and landform sampling areas(zone I and zone II)were taken to carry out basic physical property tests in the laboratory.The natural loess samples were obtained by mercury intrusion test(MIP),SEM scanning and high-precision?CT scanning to get pore characteristics,and analyze the difference in pore development of natural loess samples in the two sampling areas.Unconfined compression tests were carried out on natural?remolded loess samples under the conditions of natural moisture content,and the saturated loess sample is subjected to the unconfined compression test,and the loess is calculated by the compressive strength The structure index of the sample.The results show:(1)The pores and structure of the natural loess sample in the sampling area of the sampling area?are relatively low(7-10%),the content of clay particles is not high(15-21%),the particle size distribution is similar,and the pores are uniform distribution.The relationship between degree indexes Gou-du is the closest,and a mechanism explanation model is established in which large and medium pores affect water stability and then structural degree indexes Gou-du.(2)Apply fractal theory to quantify the pore composition of the loess sample,and combine the high-precision?CT image box dimension and gray dimension,the content of large and medium pores or the content of small and micro pores to verify various calculations of pore fractal dimensions based on MIP data The applicability of the model,the volume fractal dimension and thermodynamic fractal dimension that are involved in large,medium,small,and some micropores are more reasonable to describe the pore space complexity of loess,and it has a good index-like relationship with the structure index.(3)It is discussed that the calcium carbonate content and distribution position of the sample II loess sample,and the clay cementation around the large and medium pores may affect the main influence of the original pores on the texture.(4)Based on fractal theory,comprehensive physical characteristics,and gray scale theory to build a gray correlation model of pore volume fractal dimension,lower limit of pore size corresponding to effective porosity,and structure index,which is important for research and evaluation of structure index from the perspective of pores.Significance,to make an important reference value for revealing the influence mechanism of soil compactness on soil structure from the perspective of porosity...