Prestressed Cable Landslide Reinforcement Works

The applications of prestressed cable technique in engineering are studied in this paper. Based on consulting a large amount of reference material, a comprehensive study is made on the basic theory, developing features, design theory and prestress losses of prestressed cable technique. Combined with the stability analysis and safty monitoring of the 2~# landslide which located in chuan-zang road 102 landslide-group, the work has been done as follows:1. The progress of the deforming and destroying of slope is complicated, dynamic, and from the quantitative change accumulated to the qualitative change, from the little deformation to large deformation progress. So far, there is no a mathmatics-mechanics model which can describe this progress accurately. So the problem of the little deformation can be solved with the finite element method(FEM).As for the problems of large deformation, the DEM can be used. In 2D-FEM computing, the beam element and the truss element can be used to simulate the cable while the truss element can only bear pulling force and the beam element can bear axis force, shear force and moment. This is independent of the angle with the slip surface. In 2* landslide, the prestressed cable intersect the slip surface with a big angle, so the forces worked on the cable are not only the axis pulling force but also the shear force and the moment. Through analysing and computing, it is indicated that computing cable with beam element is close to actual condition.2. Based on the achievements of predecessors, through analyzing the large amount of monitoring data and the variation law of prestress load, the factors, steel relaxation, strength and character of rock, quality of construction, structure of cables and environment change, which influenced the prestress of cables, are discussed comprehensively. The result of study indicated that the load variations can be described as three phase: the stage of instantaneous losses of load, the stage of load fluctuating, the stage of load losing with uniform rate in long time. The main factors affecting the long -term performance of prestress cables are rock deformation ,steel fiber relaxation and temperature chage. The formula that calculate the loss of prestress coming from temperature change is modified in this paper. The results is well tested in the reinforce of the 2~# landslide.3. 2~# landslide is made up of large scale loose deposits, and based on the example of reinforcing 2~# landslide, the problems of stress response, capability of cables holding, prestress attenuation and group cables effects have been studied.In all, the application of the prestressed cables not only improve the bearing condition of the structure, but also make full use of the material strength and save project cost. It can be reduce cost ,convenience the construction ,speed the schedule.So it is of benefit to society and economy.