Research On Tensile Characteristics Of Loess

Loess is a kind of special soils, which is widely spread in Northern China. In the construction of some projects, such as roads and high earth dams, loess is often used as the building material. Recent years, building constructions, such as roads, airdromes and high earth dams are rising, which made that the study on tensile characteristics of loess is very significant. Focused on the unsaturated loess, the characteristics of the unsaturated loess such as tensile strength, tensile deformation and effect of sample water content, dry density were scheduled systematic experimental study and deep theory analysis in this paper by means of direct shear, suction and monaxial tension tests. According to the above test results, connections between tensile strength and suction are analyzed, connections between tensile strength and direct shear cohesion are discussed, and formulas expressed these connections are given. Main test research results can be gained as follows: 1.Sample water content and dry density are main affecting factors on tensile strength of loess. With the increasing of water content,tensile strength of undisturbered loess decrease, that of remolded loess increase firstly, and then decrease. In the same condition, tensile strength of undisturbered loess is higher than that of remolded loess. Tensile strength of remolded loess increases with dry density increasing under same water condition. 2.Sample water content and dry density are main affecting factors on tensile deformation of loess. Within test water content, sample tensile deformation decrease first, and second increase. In lower water content section, tensile deformation of undisturbered loess is more than that of remolded loess; In higher water content section, tensile deformation of undisturbered loess is less than that of remolded loess. Tensile deformation of remolded loess increases with dry density increasing under same water condition. 3. The concept of critical void ratio is put forward in analysis on tensile deformation, the value of which is affected by soil kinds, water content and experimentation conditions. Void ratio is increasing during adding loads until critical void ratio or sample destroyed. 4.Connection between tensile strength and direct shear cohesion is linear; Tensile strength is lower than direct shear cohesion. 5.connections between tensile strength and suction is also linear, Suction is much higher than tensile strength. 6.Tensile structural strength bring from connection of cementing material, which can be gotten by tensile strength of undisturbered loess subtracting that of remolded loess. Connections between tensile structural strength and tensile strength of undisturbered loess, direct shear cohesion are discussed, and formulas be given in the paper.