Physico-mechanical properties of loess-paleosol sequence from Q₄ to Q₁ strata in the Chinese Loess Plateau

With the rapid development of the Chinese Loess Plateau, engineering projects built in the deep loess strata may be concurrently constructed in the Q₄, Q₃, Q₂, and Q₁ strata from top to bottom. However, the physico-mechanical properties of the loess-paleosol sequence from Q₄ to Q₁ strata have been unclear. In this paper, the physico-mechanical properties of the loess-paleosol sequence in the Zaosheng profile of Eastern Gansu were determined, and the relationship between chemical properties, microstructures, and physico-mechanical properties was discussed. The results showed that the dry density, specific gravity, saturation, liquid limit, compressive modulus, characteristic value of foundation bearing capacity, and cohesion of loess and paleosol exhibited an overall increasing trend from Q₄ to Q₁ strata, and their values tended to fluctuate regularly with depth. These parameters of the paleosol were larger than those of the underlying loess, while the fluctuation pattern between the internal friction angle and depth was opposite to the above. The fluctuation pattern of water content from Q₄ to Q₁ strata was bounded by the groundwater level. Moreover, the increase in chemical weathering intensity from northwest to southeast Loess Plateau would, therefore, contribute to lower (higher) clay content, liquid limit, and plastic index of the loess and paleosol in Q₄ to Q₁ strata in the northwest (southeast), and decreasing sand content in the corresponding direction.