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Full-scale experimental case studies have shown that the induced trench construction method effectively reduces the vertical earth load that is exerted on culverts installed beneath high embankments. Induced trench culverts are traditionally designed on the basis of Marston’s theory; however, various theoretical shortcomings of this formulation have recently come to light. In this paper, a new induced trench theoretical formulation is presented. The proposed analytical model employs inclined shear planes within the embankment fill; such geometry is consistent with experimental findings reported in the literature and leads to positive arching resulting from a reduction in vertical stress and an increase in horizontal stress (thus increasing the lateral earth pressure coefficient within the induced trench zone). A series of parametric studies is performed using finite element software. The proposed theoretical formulation is shown to be in good agreement with the numerical results, and correlations are developed to provide guidance in selecting the appropriate values of (i) the induced trench lateral earth pressure coefficient and (ii) the height to the plane of equal settlement. Two instrumented full-scale induced trench case studies are discussed, and the proposed theoretical formulation is shown to produce results that are in good agreement with the experimental data.

When culverts are installed beneath high embankments, earth loads become excessive and the induced trench construction method is a viable design option to reduce the culvert loads to acceptable levels. However, limited field studies evaluating the performance of induced trench twin culverts are reported in the literature and the practicality and effectiveness of the induced trench construction method (in general) has been subject to recent criticism. This paper describes the performance of twin 3048 mm inside-diameter reinforced concrete culverts constructed with an induced trench beneath 15.3 m of fill. Research instruments and autonomous data acquisition systems were installed during construction to monitor (i) culvert earth pressures, (ii) embankment deformations, and (iii) groundwater elevations in the vicinity of the compressible fill. The experimental observations recorded throughout the construction phase are presented herein; the embankment deformations are indicative of effective positive arching within the induced trench region, and the average earth pressure at the culvert crown was reduced to approximately 48% of the overburden soil pressure. The experimental data are compared with those reported in the literature by others, and the conclusions attained from this study demonstrate the effectiveness of the induced trench construction method.

This paper presents a series of experimental and analytical studies on the ductility requirements of bolted double-angle shear connections. Five full-scale connection configurations were tested, and their load-deformation behaviour was monitored using the digital image correlation technique. The yield line patterns observed from the experiments differ from the assumed pattern used in the derivation of the ductility equations currently available in design guidelines. The identified deformation contours were used as the basis for further development of analytical formulations applicable to the flexibility requirements of connections. The yield line theory was employed to evaluate the induced moment on the connections at the ultimate shear capacity. The details of the experimental setup including test parameters, loading scenarios, and the digital image correlation technique are fully outlined. Finally, the developed formulation was validated through a comparison with previously published experimental results. The results show the proposed solution provides an accurate estimation of the moments induced on double angle shear connections at ultimate capacity rotations.

Sandwich pipe systems can be considered as potentially optimum design configurations for overcoming the shortfalls of single-walled pipes for deep-water applications. This potential design alternative has gained considerable attention in recent years. In this paper the stability of these systems is investigated. The possible equilibrium paths are evaluated and the effect of the various significant parameters on the characteristic behavior of the system is discussed. The Finite Element (FE) software package ABAQUS is used to construct more than 3000 FE models of the sandwich pipes with practical configurations. Four design configurations are considered for the sandwich pipes with respect to the adhesion among the interfaces. The post-buckling behavior of each of these configurations is determined, with emphasis on a wide practical range of parameters. The behavior of these configurations is examined and the efficiency of each system is discussed. Finally, a simplified and fairly accurate equation is developed and recommended for calculating the pressure capacity of sandwich pipes. The parameters of the proposed equation are also fully defined.