Geometry and Roughness Effect at the RCC Interface-Earth Dam Causing Leakage in Mae Suai Composite Dam, Thailand

Abstract

Mae Suai dam is an earth zone dam with RCC section in the center of downstream slope located at Mae Suai district, Chiang Rai, Thailand. The differential settlement at the joint between RCC spillway and the earth-filled section caused leakage near the crest of the dam. This unusual settlement is the result of a joint where materials of different stiffness are connected, the settlement pattern depends on the shape and interface shear strength of the contact area. In this paper, non-uniform settlement of Mae Suai dam was investigated by 2D & 3D FEM using MIDAS GTS for Fully-Coupled Stress-Seepage analyses. The results of finite element analyses were verified with the geodetic measurements data and observation in rehabilitation processes of Mae Suai dam. Roughness and taper effects were studied by analyzing the settlement along the dam crest using 2D FEM analysis by varying the interface stiffness between the earth dam and RCC spillway to characterize the settlement of each condition and verified with the geodetic measurements. The analysis revealed that the effect of roughness and taper resulted in non-uniform. If these types of dam structures are selected in other projects, the pattern of settlement should be considered in accordance with the guidelines for dam crest design to prevent damage and leakage caused by the non-uniform settlement of the dam.