Study On The Landslide Mechanism And Support Scheme Of The High Slope Behind Qianwei Hospital In Sichuan

There are many high slopes in some projects such as communication engineering, mining engineering, hydraulic engineering and national defence construction etc. In order to keep these projects well developing and operating, it is important to make these high slopes stability during the time of construction and operation. In this paper, the high slope is taken as an example, which is behind the outpatient building of Qianwei people hospital in Sichuan province. According to the theory and methods which are from Engineering Geology, Rock Mass Mechanics, and Numerical Simulation etc., the author analyses the deformation damage mechanism and stability of the slope, and provides some optimizing support-scheme to make the slope long-time stability. The acquired results are as follows:1,On the basis of the mechanics analysis principle of Engineering Geology, the author analyses the deformation damage mechanism and establishes the model of destruction of the slope. The results show that the leading cause of deformation and destruction lies on a low dip angle siltized intercalation, the shallow weathering and deformation of soft silty sandy mudstone, and two sets of high dip angle joint planes that are nearly parallel and perpendicular to slope strike. Firstly, two sets of high dip angle joint planes among derrick thick sandstone are opened and the differentia deformations occur in soft underlying stratum because of stress-release and rebound deformation, while the slope is dug. Then, pore water pressure on joint planes is augmented and the mechanics characteristic of siltized intercalation is further weakened, while rainwater seeps in the opening joint planes. Finally, the slope mainly slips downward in above disadvantage circumstance.2,According to imbalance thrust force method (ITFM) and Spencer method, which are from limited equilibrium method, the author analyses the stability of the slope and evaluates its stabily state. It is indicated that the slope is hardly to maintain its stability in the bad circumstance. In order to discuss the reliability of theoretical hypothesis which is deduced by ITFM, the relationship between the dip angle of inter-slice force and stability factor is fully analyzed. The results show that the dip angle of inter-slice force has a great influence on stability factor. ITFM has been widely used in the field of slope stability analysis, so the author adopts QieJiao method (the unfit node is continuously divided) to improve ITFM. The error between QieJiao method and Spencer method is ignored during calculating stability factor of the slope.3,Based on the deformation damage mechanism and stabily state of the slope, a reasonable support-scheme including the systemic draining and the prestressed cable frame beam is put forward. According to the previous research fruits and the practical project, the author brings up optimizing design for the prestressed cable frame beam and improves on some optimizing methods.4,Through comparing the results obtained by Fast Lagrangian Analysis of Continua in Three-dimension (FLAC^3D) with the mechanics analysis of Engineering Geology, it is indicated that the latter is almost accordant to the former. In light of numerical simulation method based on strength reduction theory, the author works out stability factor that is almost equal to the results by limited equilibrium method. In order to evaluate the support-scheme of the slope, the author analyses the difference of stress and displacement in two state (reinforce and non-reinforce) by the structural elements model of FLAC^3D. The results show that the prestressed cable frame beam is an effective support-scheme.