Soil Mechanics and Foundation Engineering

The results of FEM calculations of the settlement of individual piles and pile groups are presented. A relation is shown between the additional settlements of unloaded piles and the settlements of the soil around loaded piles. The settlements of loaded and unloaded piles are found to decrease with increasing number of piles in a group (reinforcement effect).

The horizontal slice element method for calculating active earth pressure against rigid retaining walls has been extended to the cohesive backfill. The formula of the nonlinear distribution of active earth pressure is derived satisfying the reciprocal theorem of shear stress. According to the Mohr-Coulomb theory, the lateral active earth pressure coefficient can be determined. In order to check the accuracy of the proposed equation; the predictions from the equation are compared with both existing full-scale test results and values from other studies. The comparisons between calculated and measured values show that the proposed equations provide satisfactory results.

We present the results of full-scale and numerical investigations of piles driven and impressed in clay soils. We propose a procedure of application of the data of sounding to the correction of the parameters (specific adhesion and the angle of internal friction) in determining the shear strength of soil along the lateral surface of piles in the numerical investigations.

In the integral bridge, the deck contraction makes the abutment move away from backfill and causes a failure wedge. To inhibit the failure wedge, a new method with connector from each abutment to the unburied piles outside the bridge has been proposed. The soil behavior around laterally loaded stub abutment and unburied piles was studied on laboratory models using the PIV (particle image velocimetry) method. The effects of unburied pile number and soil − pile interaction on the soil deformation pattern were investigated.

Laboratory experiments were conducted to examine the feasibility and determine the optimal voltage gradient of electrokinetic consolidation of Wenzhou clay slurry with a small amount of fine sand. During the process of electrokinetic dewatering using high voltage gradients of 0.5-1.25 V/cm, the current, temperature, drainage, evaporated water, and electrolytic water were monitored in real-time. The results showed that a steady current was achieved under relatively lower voltage gradients (0.5 V/cm), while higher voltage gradients (1 V/cm) reduced the drainage time. Voltage gradients greater than 1.0 V/cm had no significant effect on the drainage rate. A greater reduction in temperature was achieved under higher voltage gradients than using lower voltage gradients, and the evaporated water and electrolytic water increased with increasing voltage gradient. Taken together, the results of this study can be used to optimize engineering practices during land reclamation efforts.

Consistency limits, especially the liquid and plastic limits, are prominent parameters to be determined in geotechnical investigations for classification and identification of finegrained soil. An investigation of the soil suction stress characteristic curve (SSCC) for determination of consistency limits is conducted in this work. The typical SSCC can be divided into five zones according to the state of pore water retention and the mechanisms of solid-liquid interactions. The correspondences between consistency limits of fine-grained soils and characteristic points of every zone in the SSCC are investigated. A detailed discussion of the intrinsic relationships between zones in the SSCC and soil consistency reveals the physical nature of each zone and the critical moisture content. Using experimental data from soil-water characteristic tests of undisturbed loess and disturbed loess, and van Genuchten's soil water characteristic curve (SWCC) model, consistency limits are determined for SSCCs with different void ratios. The feasibility of the presented approach for determining consistency limits of fine-grained soils based on SSCC is demonstrated.

The article considers the Geotechnical Geo-Information System (GGIS) of Astana, Kazakhstan. The GGIS was developed by methods of geoinformatics applied to engineering survey and geotechnical monitoring technologies. A special database program and set of geotechnical zoning maps were created for differentiation by ground bases type, showing the quaternary sediments and bedrock soils distribution, allowing for more efficient field investigations and engineering geological surveys, thus optimizing the length of piles foundations. The GGIS enables engineers to better justify the selection of particular designs, and significantly reduces the time and costs of field investigations and foundation design and construction.

The synergetic effect of the combined supporting system (pile + steel support + anchor) was studied through field tests and finite-element numerical simulation of the foundation’s deformation under "rock-soil layer" conditions, typical for China's Qingdao region. The horizontal displacement of the retaining pile, as well as the ground settlements around the foundation, were studied and compared. The factors were discussed, including excavation steps, pre-stress of steel support and anchor affecting the foundation deformations, pile displacement, pile bending, and shear distribution. The research results can provide a basis for design and construction of deep foundations in the rock-soil layer.

The paper proposes an improved procedure for projecting thermal and stress-strain behavior of the base of an oil tank erected on permafrost soil by taking into account cryogenic heaving of artificially frozen soil. It was shown that the use of just thermal calculations alone (which are conventionally performed when designing buildings in cryolitic zone) is definitely insufficient for providing safety, and that thermomechanical calculations should be performed as well.