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Some field measurements indicate that obvious deformations may occur in retaining structures due to dewatering before excavation. To investigate this problem, a time-dependent analysis method for the interaction between retaining piles and stratified saturated soils with transversely isotropic property due to pre-excavation dewatering (PED) is established by the coupling of the extended precise integration method (PIM) and the finite element method (FEM). Numerical examples are carried out to verify the proposed method and study the influence of some key parameters on the time-dependent behavior of retaining piles, which indicated that the pile deformation and its growth rate are closely related to the incorporate stiffness of retaining piles and the characterization of soils, and the deflection pattern of the retaining pile depends on the pumping depth. [ABSTRACT FROM AUTHOR]

This paper presents the results of field tests performed to investigate the installation effects of pre-bored grouted planted (PGP) pile in deep clayey soil. The variation of horizontal soil displacements, excess pore water pressures and lateral soil pressures was measured in the PGP pile installation process. The test results show that the drilling and grouting process induced large horizontal soil displacements in the soil within a radial distance of 2 d (d is pile diameter), and the maximum horizontal soil displacements induced by the drilling and grouting process were smaller than 15.9 mm when the radial distance reached 4–5 d. Moreover, the horizontal soil displacements decreased along the soil layer depth, as the superficial soil layers were of small deformation modulus and lateral soil pressure. The drilling process brought large excess pore water pressures in the soil when the radial distance was less than 3 d, and the excess pore water pressures induced by the drilling stage were all less than 55 kPa when the radial distance reached 4–6 d. The drilling process also induced some lateral soil pressure increases in the soil within a radial distance of 3 d, while the measured maximum lateral soil pressure increases were smaller than 10.9 kPa when the radial distance increased to 4 d. On the whole, the excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile were much smaller than that induced by the installation of driven PHC pile. Moreover, the horizontal soil displacements, excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile all recovered rapidly after the installation of pile, as the cemented soil in the pile hole was in liquid state after the drilling and grouting stage. [ABSTRACT FROM AUTHOR]

The distribution of temperature in sand soils was measured through laboratory tests, and the temperature influence on friction resistances at the concrete-soil interface was analyzed. Based on the results of laboratory tests, the finite element model was established using the sequential thermal coupling method. The influences of temperature on the bearing characteristics of energy pile were analyzed. The analysis results show that the cyclic temperature will cause additional displacement along pile depth. It is pointed out that if applied vertical loads at energy pile head exceed the value from which nonlinear settlements would be initiated, irrecoverable additional settlement will occur at pile head. Based on the analysis results, a simplified approach was proposed to estimate the zero point of additional displacement along pile shaft and the additional axial pile force. The comparison between the calculated results obtained by the proposed method and that of ABAQUS on single energy pile was given to verify the accuracy of the proposed method. It is shown that reasonable predictions can be obtained without expensive and time-consuming analyses by the proposed method in this paper. [ABSTRACT FROM AUTHOR]

Geomembranes (GMBs) of the landfill composite liners frequently contain long defects, which will form the dominant flow path in the composite liner. The significant differences between the geosynthetic clay liner (GCL) and the compacted clay liner (CCL) lead to distinct flow patterns in the defective composite liners. For GMB/CCL composite liners, the induced flow in the CCL is two-dimensional, thus the existing solution with the assumption of one-dimensional flow significantly underestimates the leakage rate with a maximum relative error of 87% when compared to the results of a 2D finite element model. A new solution for predicting the leakage rate through GMB/CCL composite liners with a long defect is proposed with a consideration of two-dimensional flow in the CCL, with relative errors of leakage rate less than 29% for the cases investigated. The proposed solution also shows a lower relative error for the wetted distance (6–23%) compared to the existing solution (49–77%) for GMB/CCL composite liner cases. The comparisons with numerical results show that the proposed analytical solution significantly reduces the underestimation of leakage rate through the defective GMB/CCL composite liner, thus can help to improve the composite liner design for landfills. [ABSTRACT FROM AUTHOR]

Geothermal energy piles (GEPs) are an innovation technology of vertical ground heat exchangers (GHXs) which can be used for the heating and cooling of building combined with ground source heat pumps. The main barriers to adoption are the inconvenient installation and a lack of the knowledge regarding the potential effect of temperature changes on pile foundations compared to traditional GHXs. The installation process can be facilitated by using pre-bored grouted planted (PGP) GEPs, which simplify the installation of heat exchange pipes and hence reduce the installation time. It is desirable to investigate the thermo-mechanical responses of this GEP for understanding the potential effects of the temperature changes. A PGP GEP was installed in a building during construction that incorporated two heating tests with different conditions (a short-term Test 1 without building load, and a long-term Test 2 with strong structural restraints and building load) to investigate the behavior of the PGP GEP. A fiber Bragg grating (FBG) sensor system was used to evaluate temperature and strain behaviors of the test pile and two adjacent boreholes. The results show that the nonuniform spatio-temporal response of temperature induced the nonuniform thermal-induced stress along the pile depth. The end-restraints had significant effects on the thermo-mechanical response over the full pile. A comparison between the PGP GEP and other types of GEPs were conducted, and the similarities and differences between them were discussed. [ABSTRACT FROM AUTHOR]