Influence of water contents on shear strength of coal-bearing soil

Coal-bearing soil is weakened when encountering water and its strength is sharply dropped down with increasing water content. Taking coal-bearing soil which ranges along with Guang-Wu Expressway for example, and based on analyzing the physical properties of coal-bearing soil, its shear strength is measured through direct shear test; influence of water contents on shear strength of coal-bearing soil is analyzed; and some suggestions are put forward to treat coil-bearing soil. The results indicate that the shear strength and initial water content of coal-bearing soil have marked correlationship; and the bigger initial water content of coal-bearing soil is, the smaller its shear strength is. With water content increasing, cohesion of coal-bearing soil decreases overall; but its changing trend is of marked characteristic of stage. When water content of coal-bearing soil is under some value, its cohesion changes in small ranges; after water content of coal-bearing soil is over the value, its cohesion decreases with water content increasing; and the interrelationship between the logarithm of its cohesion and water content is linear. Water content of coal-bearing soil has no marked effect on its internal friction angle; but its internal friction angle firstly increases and then decreases, so it has marked peak value.