A comparative study on the physical properties of natural sedimentary loess and manual filling compacted loess

Abstract

With the development of human society, mega engineering projects of removing the tops of hills to in ll valleys began to appear in the loess region. The thickness of the manual lling compacted loess can reach tens of meters. For such large-scale construction projects, studying the properties of compacted loess is essential to ensure the safety and reliability of land creation and arti cial infrastructure. In this paper, the specimens from two exploration well pro les were carried out to study the physical properties of natural loess and compacted loess from the Loess Plateau. Here the natural loess selected was deposited in old ages (Q 2 and Q 1 ) and had strong stability. The natural water content, dry density, speci c gravity, liquid limit, plastic limit, plasticity index, clay fraction, silt fraction, sand fraction, compression modulus, and permeability coe cient have been determined. Statistical theories such as t-test and correlation coe cient checks were used to describe the difference between the two kinds of loess, and the degree of correlation among various indicators. Besides, 14 groups of exploration well data in 8 studies were collected. The variation of natural water content and dry density with well depth was analyzed to supplement the existing data. Results have shown that the manual lling compacted loess is signi cantly different from the natural loess. On the whole, the liquid limit, plastic limit, plasticity index, clay fraction, silt fraction, sand fraction and compression modulus of the compacted loess are smaller. And compared with the natural sedimentary loess with strong stability, it deforms more easily. The difference of compression modulus between the compacted loess and natural loess is mainly controlled by the dry density and the particle composition. Moreover, the heterogeneous level of the manual lling compacted loess is greater than that of the natural loess in the horizontal direction and smaller than that of the natural loess in the vertical direction. Under a combination of external hydrologic conditions and dead weight, the compacted loess will become more stable.

Influence of Moisture Content and Dry Density on the Compressibility of Disturbed Loess: A Case Study in Yan’an City, China

“…Therefore, relevant experimental studies and analyses are urgently needed. By comparing the physical properties of naturally deposited loess and compacted loess, Zhang et al [26] found that the liquid limit, plastic limit, plasticity index, clay fraction, silt fraction, sand fraction, and compression modulus of the compacted loess were smaller, and it was more prone to deformation under external forces.…”

Soil Column Experimental Study on the Effect of Soil Structure Disturbance on Water Chemistry

“…When the flow path changes, the solute flux also changes [ 6 , 13 ]. In disturbed conditions, soil disturbance can damage the soil structure [ 14 ], expose minerals, and change the water flow path [ 6 ]. Therefore, the mechanisms of the water–rock interaction are the key to understanding the influence of water–rock interactions on water chemistry and the evolution of solutes.…”