Due to the complex rock formations, the dam's abutments, especially the left abutment require reinforcement to enhance the dam's overload safety. The reinforcement is presented and its effect on overload safety discussed. The mechanism of reinforcement after geomechanical model test and FEM analysis are given. Both model test and numerical calculation show that the overload safety factor has increased from the original 3.0 to more than 5.0 as a result of the reinforcement.
Das ce document a ete faite une analyse d'elemt limite de trois dimensions dn fondement de construction de roche faisant appel au modele de l'endommagement à fracture, analyse appliquee an fondement du bar ragevoute de Lijiaxia. Ce document decrit le test de modele geomecanique integral pour le barrage-voûte de Lijiaxia L'ampleur du modele en question constitute l'une de plus importantes en China. lls correspondent par faitement anx calculs des resultats.
In der Verliegenden Arbeit wird ein integrater geomechanisch Modellversuch fuer Lijiaxia Bogenstaumauer Vorgesstellt. Die Bogenstaumauer liegt aut der komplizerten felsformationen. Der Zerstoerungsmechanismus, die Stabilitaetsfaktoren und die Interaktion zwischen der Bogenstaumauer und den Seiltichen. In der Vorliegenden Arbeit wird eine dreidimensionale finite element analyse fuer die seitlichen. Gestein sauflager mittels dem Bruchmodell Vorgestellt, da fuer Lijiaxia Bogenstaumauer angewandet wird. Ein Bruch mechanismus modell einschliesslich der statistischen parameter der Gesteinfes tigkeit wird entauckeit.
Lijiaxia hydropower station is located on the upper reach of Yellow River in Qinghai province, China. Its layout is shown as Figure 1. The 165m-high arch dam is situated on a complex rock formation with migmatite metamorphic rock. There exist many weak intercalations and faults in the overlapped migmatite and dolomite. Developed infillings are found in the bedrock. The fault ditribution on the site is shown as Fig 1.
The limit analysis of the arch dam by FEM showed that the original overload safety factor (S.P.) was 3.0, because there are weak zones and unfavorable faults band in the left bank, shown
(Figure in full paper)
as Figure 1. Some mechanical parameters of the rock masses are given in Table 1. Anchors need to be installed to enhance the dam's overload safety.
(Figure in full paper)
Study on the overload safety of the arch dam was carried out by FEM. Rock zones including both the upper and lower reaches at rock abutments were taken into consideration. The finite element mesh is shown as Figure 2. The loading steps were as Table 2.
A progressive I failure process appeared in the numerical simulation. Figure 3 and Figure 4 are the dam's deformation and its yield zone distribution. In case that the dam had no reinforcement, the upper dam heel began to fracture at 1.5P0, and here P0 is the. normal water load the dam. is subjected to. The gravitation dam abutment failed due to sliding at 2.0P0, and at 3.0P0, the dam was considered to have collapsed as shown in Fig 2. Hence, the overload S.F. = 3.0, which couldn't satisfy the requirement.
