Volume 55, Nº 1 (2018)

We present the results of investigations aimed at the actualization of the engineering procedure of consolidation analyses of slowly deformed and water-saturated soils. A criterion for the estimation of expediency of the taking into account the time factor in the numerical analyses of basements and foundations is given. A combined procedure of evaluation of the consolidation parameters is proposed. We also describe the engineering method for the evaluation of settlements of water-saturated soils with regard for their primary and secondary consolidations developed at the Gersevanov Scientific-Research Institute of Basements and Underground Structures.

This paper presents an integrated methodology for displacement-based seismic design of homogeneous slopes under typical surcharge loading and slope inclination conditions. Charts developed over the basis of dimensionless parameters are given for both selection of the static safety factor of the slope and determination of the corresponding critical pseudo-static acceleration coefficient in the seismic case. In addition, graphs based on the well-known Newmark's sliding block method are proposed for estimation of slope displacements as a function of the critical seismic coefficient. For this purpose, a series of strong ground motion records from two major Chilean earthquakes grouped by soil conditions were utilized. In this way, a simple and rational design procedure can be followed in order to integrate the desired static safety factor of the slope, the amount of seismic displacement judged to be allowable, and the minimum stability requirements for the slope in the seismic case. The proposed methodology can be used in both preliminary calculations and rapid engineering analyses of homogeneous slopes located at sites with similar seismic characteristics to the Chilean subduction zone.

Experimental observation on unsaturated expansive soils subjected to wetting and drying cycles presents a stabilized limit equilibrium state at the end of the suction cycles. Models developed previously for this behavior introduce a large number of parameters which lead to a time-consuming procedure to calibrate. This paper develops a limit analysis method with the Zarka concept for the mechanical behavior of expansive soils subjected to wetting and drying cycles. The required parameters of the proposed limit analysis method are calibrated by the experimental results obtained for bentonite/sand mixtures subjected to cyclic suction loadings in an odometric test. The comparison between the test results and the model predictions demonstrates the capacity of the proposed method to calculate the limit deformation during suction cycles and simulate the subsequent mechanical behavior of the expansive soils after suction cycles.

We consider the possibility of evaluation of the strength characteristics of rocks in the zones of crushing and elevated jointing. We analyze the relationship between the density and the coefficient of water absorption of a representative sample of dolomite specimens and their ultimate strength via the coefficients of pair and multiple correlations. For the characterization of these rocks, it is proposed to use the methods developed for macrofragmental soils, gruss, and crushed stone.

A solution is proposed for determining the stiffness of the pile foundation of staple slabs at their initial design stage.

Sand-rubber mixtures have the advantages of light weight, high strength, and low price. In this study, three-dimensional finite element simulation was carried out in GTS MIDAS based on the elastoplastic constitutive model to investigate the response of bridge abutments to sand-rubber mixtures backfills under static load condition. Four different backfill materials were used and compared in the modeling. The settlement of abutment foundation, displacements of bridge abutment and foundation pile, and bending moment of the piles were analyzed. The results show that the sand-rubber mixtures backfill can significantly decrease the settlement of foundation, and the displacements of bridge abutment and foundation pile as compared to the backfill soil. Such decrease is more prominent as the rubber content increases. The use of sand-rubber mixtures replacing the soft soil layer or as a backfill material not can only reduce the upper load acting on foundation soils and improve the stability and static performance of bridge abutment, but also solve the problem of waste rubber recycling and potential environmental pollution to meet the increasing demand of road construction materials for the rapid development of highway engineering, resulting in huge economic and social benefits with a wide range of engineering applications.