A review of shear and tensile strengths of the Malan Loess in China

Loess deposits cover about 640,000 km2 of China, equivalent to about 6.7% of the total area of the country. The Loess Plateau alone covers approximately 317,000 km2, making it the largest bulk accumulation of loess on the Earth. Land instability hazards in the Loess Plateau are frequent and varied, among which the cracking-sliding (Beng-hua, in Chinese) failure is a typical mode. Cracking-sliding failures commonly occur in the Malan Loess at volumes of the order of 100 m3 and cause more than 100 deaths per year. As the tension in the upper part of the failure plane and shearing/sliding along the lower part mobilize cracking-sliding failures, this failure mode demands an investigation into the tensile and shear strengths. This paper presents a review of these properties based on a large collection of literature. Both tensile and shear strengths of the Malan loess decrease with water content and increase with dry density, resulting in close multi-regression correlations. Large differences between undisturbed and disturbed tensile strengths of the loess indicate the significance of its structure. Shear strength of the loess is direction dependent, indicating strong anisotropy of the loess structure. Test method, sample size and loading rate all influence the measured tensile strength.