Study On Calculation Methods Of Landslide Thrust And Their Distribution

The phenomenon that rock soil on the slope moves down as a whole along a certain weak belt or surface is called landslide. Along with the economic development and environment geology condition worsening, landslide geology disasters in our country have been more serious in recent years. And it brings people's widespread attention. The magnitude of landslide thrust and its distribution are primary factors which decide the project choice of the landslide control design and the mechanical characteristics of retaining structures. However, for ages, for technicians of landslide prevention and control, how to determine the landslide thrust and its distribution forms acting upon the anti-slide support structures are still two big difficult problems. Because of geo-materials multiplicity, complexity of sliding process and the landslide body as well as its strength properties changing along with the outside factors, it is very difficult to estimate accurately the actual landslide thrust and its distribution forms. The two primary influences on the computation accuracy of landslide thrust are the selections for strength parameters of sliding-zone soils and calculation methods for landslide thrust. Based on the project of the Kaotang landslide, the back-analyses on the shearing strength of sliding-zone soils are studied by using the limit equilibrium method and the finite element method. When using the limit equilibrium method, the proposal that combining multi-sections to carry out the calculations by adopting the different strength parameters according to the difference of the matter components of sliding-zone is given. When using the limit element method, the strength reduction technique is used. Repetitive computation trials will be performed by replacing parameters until the traversing plastic zone occurs or computation is not convergent. At this time the parameters can be transformed into the back-analysis indexes. The results by utilizing the two methods are compared and analyzed. The existing calculation methods of landslide thrust are discussed and the finite element method for computing landslide thrust is presented. In addition, considering the advantages of the finite element method that can reflect stress, strain and their variation processes as well as satisfy automatically force equilibrium and moment equilibrium conditions, the distribution forms of lateral landslide thrusts of the circular slip surface and the irregular curve slip surface are studied by using the finite element method. The work done in the paper is to improve the computation accuracy of landslide thrusts and people's understanding to their distribution laws and explore the new methods and means that can be the reference to landslide control design.