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Mechanical properties of ageing dams and rock foundations can differ significantly from those design values used during construction. It is necessary to conduct the inverse analysis of mechanical parameters of dam and rock foundation. However, it is inconsistent with the actual situation by utilising the conventional inversion method for structural analysis, as the conventional method can only inverse the integrated elastic modulus. Therefore, a new inversion method is proposed in this paper, which utilises adjustment coefficient to inverse initial elastic modulus, and introduces the adjoint method combined with DFP quasi Newton method in order to inverse zoning elastic modulus of dam and rock foundation. The adjoint method calculates the gradients in a much more efficient way, as it can avoid the repeated computation of large stiffness matrix. Therefore, the time consumption is reduced greatly and the computational efficiency increases significantly. Combined with project case, the feasibility and validity of the proposed method are verified. [ABSTRACT FROM AUTHOR]

The shear strength of the concrete-rock interface is a key factor to justify the stability of a hydraulic structure foundation. The Mohr-Coulomb failure criterion is usually used as shear strength and evaluated by extrapolating shear tests results carried out in a laboratory on small-sized samples. This paper presents an experimental study on the concrete-rock interface shear behavior. The effect of rock surface morphology on shear behavior was studied by performing laboratory direct shear tests on prepared square samples with a previously characterized rock surface. The scale effect and the test conditions were also studied by comparing the results to those obtained by performing usual laboratory shear tests on cored samples at lower scale. The tested interfaces were composed of the same concrete and granite and have a natural rock surface. The results displayed that the peak shear strength is strongly dependent on the concrete-rock bonding, the rock surface morphology and the applied normal load. A new surface morphology description tool was developed in order to characterize the main waviness. Moreover, the concrete-rock shear behavior at medium scale was reproduced by a 2D finite elements model to study the stress distribution along the sheared interface. Under low normal load, the concrete-rock adhesion is thus progressively mobilized according to the waviness on the rock surface and the local shear failure mechanisms depend on the type of this main waviness. Consequently the shear strength of a concrete-rock interface must be analyzed with respect to the various morphology aspects on its rock surface. [ABSTRACT FROM AUTHOR]

The technique of strength and sustainability analysis of earth and underground hydro technical structures taking into account physical and mechanical parameters of soil properties and design features of Tupolang dam (Uzbekistan) offer in this issue. Structures behaviours under dynamic loading by elastic and nonlinear approach by 2D schemes are considered. [ABSTRACT FROM AUTHOR]

The article presents an analysis of the subgrade modulus aspect of geocell-reinforced sand foundation beds. It examines the influence of geometry and position of placement of the geocell layer to the sand foundation's subgrade modulus through a series of laboratory model tests. The study uses a multiple-variable data regression in establishing a relation between the effect of reinforcing in terms of subgrade modulus improvement factor and the parameters that the scheme of reinforcement.

Waterstops are installed in the body of concrete (to a depth of 30–60 cm) during the construction of hydraulic structures to minimize or eliminate all possible leaks at construction joints. However, they often deteriorate as a result of the thermal variations and hydrostatic pressure to which hydraulic structures are subjected over their lifetime. Since repairing or replacing deteriorated waterstops is very complicated and costly, they are normally left in place and new ones installed close by. Various new products and methods have now been developed for this purpose, but their performance is not well documented. Eighteen different products were initially chosen and subjected to a battery of laboratory tests (viscosity, chemical compatibility with water, and freeze–thaw cycling) at 23 °C, 15 °C, and 5 °C. Four of the 18 products were subsequently tested for permeability and apparent adherence in a specially designed setup. The test data showed that the waterstop that best fulfilled the criteria was a two-component polyurethane resin. [ABSTRACT FROM AUTHOR]

A comparative study of performance of various isolation systems for liquid storage tanks is investigated under real earthquake ground motions. The various base isolation systems considered are the laminated rubber bearings (with and without lead core) and sliding isolation systems (with and without restoring force). The isolated liquid storage tank is idealized with three-degrees-of-freedom associated with convective, impulsive and rigid mass under uni-directional earthquake excitation. Since the force-deformation behavior of the isolation systems is non-linear, as a result, the equations of motion are solved numerically by step-by-step method. In order to measure the effectiveness of the isolation systems, the seismic response of the isolated liquid storage tanks is compared with the corresponding response of non-isolated tanks. Further, the effectiveness of the isolation is also explored for wide range of practical liquid storage tanks considering the influence of tank aspect ratio. It is observed that the isolation systems are quite effective in attenuating the earthquake acceleration transmitted to the tank, which reduces the design seismic forces significantly. Further, it is also found that the sliding type isolation systems are more effective in controlling the response of liquid storage tanks in comparison to the elastomeric bearings. Among the various sliding systems, the resilient-friction base isolator is found to be most effective for seismic isolation of the tanks. [ABSTRACT FROM AUTHOR]