Thirty six slopes, which are constituted by limestone, in Longshan Quarry of Anning City have been studied in order to get a new method to determine the shearing strength for limestone. Through comparison the parameter error between the site shearing test and the calculated value that is based on the slope stability, the later has been employed as the substitute of the former to increase the specimen so as to reveal the relationship between the angle of shearing resistance of the rock and the fissuring assembly on the slope together with the coefficient of rock integrity. When the regression analysis is employed, the basic regularity is turned out, which shows the angle of shearing resistance of the rock mass can be determined by the angle of shearing resistance of the rock experimented in laboratory through a discount with the coefficient of its rock integrity.
Site investigation and field observations. Rock material and rock mass property testing (laboratory and in situ).
The shearing strength of rock mass, which has been developed based on the theory of the material strength and the structural strength in the early stage, is a very important parameter for geotechnical design in the engineering construction. Coulomb (1736~1806) is the first scholar who came up with the theory of the maximum shearing strength, which could lead to a broken result of slippage along some certain planes when the force that acts on the slipping zone is greater than the inner cohesion of the material, in the middle of the eighteenth century. It was expounded that the friction caused by the normal stress on the slipping plane should be taken into account besides cohesion in Mohr-Coulomb's strength theory. In twentieth century, many scholars such as Drucker, Bishop, and Hill, who suggested the basic assumptions about yield and proved the outer convex of the yield surface, put forward a lot of strength theories and expressions. With the developing of the construction practice and lucubrating of the theory, the characteristics of rock mass structure plane, together with groundwater occurrence and existence ofweak structure and crustal stress have been realized gradually to be the important influencing factors for the rock mass strength. Patton confirmed the presence of dilatancy effect from the experiment for the first time in 1966, and got the dilatancy formula and bilinear formula. Ladanyi got shearing strength formula that could take the influence of rocky bridge into account in 1970.
