Based on the fundamental solutions due to Dirac's d function for transversely isotropic media, a numerical scheme for wave propagation in two-dimensional orthotropic media is developed within the boundary element method in the time domain. Criteria for selection of the time and space discretizations for convergent and accurate results are established. The applicability and accuracy of the scheme are verified by a number of benchmark problems including dynamic responses of an orthotropic half plane under uniform harmonic surface loadings and a circular cavern in slightly orthotropic media under the incidence of pseudo-P and-SV waves. The procedure is then applied to examine wave propagation for an underground tunnel with different ratios of orthotropy in the media. The effects of different wave parameters and ratios of orthotropy on dynamic response of the tunnel are presented.

Based on the dynamic theory for saturated porous media by Biot (Journal of the Acoustical Society of America 1956; 28:168–178), a numerical model is presented to analyse the resection behaviours of reservoir sediment and compared with those from the visco-elastic model. It is concluded that the two models give very similar results of resection coefficient α within the frequency range of interest. Then, using the two models, the change of the resection coefficients α with various sedimentation parameters and excitation frequencies are studied in detail. The results are further used in the analysis of response functions of hydro-dynamic pressures on, and structural displacements of the Xiang Hong Dian arch dam, for which some results from a Celd vibration test are available. It appears that e2ects of water compressibility with sediment resection on hydro-dynamic pressures and structural response are not signiCcant for this speciCc case. Copyright

A comprehensive study of non-linear seismic response of arch dams with contraction joint opening and joint reinforcements has been conducted. A numerical model of contraction joint reinforcements is presented for optimization control of the joint opening. The objective of this control is to reduce the joint opening and expectantly to balance the sustained loads between the horizontal and the vertical components of the dam, thus avoiding an overstress in the cantilever while retaining the release of arch tensile stresses to some extent. Several parameter studies such as critical element size and required number of joints to be simulated for convergence are also performed. As an engineering application, a 292-m high arch dam (the Xiaowan arch dam) and the Big Tujunga dam are analysed in detail. The results demonstrate that the joint opening and the corresponding load transfer from the arch to cantilever components of the dam during strong earthquakes are substantial. It is also evident that by providing su$cient strength and reinforcement #exibility, the joint opening can be controlled to some extent. However, the stress redistribution due to reinforcement control is not su$cient to avoid the overstress in the cantilever for the Xiaowan arch dam. Thus, alternative measures are discussed. Copyright

Strain controlled uniaxial tensile and compressive tests of rolled compacted concrete ~RCC! are conducted to establish the constitutive relationship of RCC. Complete stress-strain constitutive curves including strain-softening behavior of the material have been obtained. To satisfy the test requirements for obtaining the strain-softening behavior of the material, the stability conditions on specimen parameters and machine rigidity are described based on the concept of strain localization. By using test results of RCC, a 200-m high RCC gravity dam, Longtan Dam, is analyzed for earthquake resistance using the procedure of nonlinear fracture mechanics and the compression-shear failure mechanism for concrete. A safety evaluation of the dam's ability to resist the design earthquake under different reservoir elevations is performed.

The earthquake behavior of arch dams is studied including dam-canyon interaction and nonlinear response of dams due to contraction joint opening and joint reinforcements. Significant effects of canyon radiation damping, non-uniform free-field excitations and nonlinear joint behavior on dam response have been confirmed.