A simplified numerical procedure for the analysis of negative skin friction on piles in a layered soil deposit is proposed. Pile-soil interface behavior is modeled by nonlinear soil springs. A framework for determining the model parameters from conventional soil tests data has been established. This procedure is used in the back-analysis of seven well-documented test piles in different soil deposits. The good agreement between the computed and the measured values for all seven piles confirmed the validity of the proposed approach.

Long-term monitoring of the behavior of ground anchors constitutes an important aspect of the stability of structures reinforced by such structural members. The present paper describes full-scale tests performed on three instrumented grouted anchors in the laboratory and one other instrumented anchor in the field. Due to the long-term reliability, stability, and accuracy, two types of surface-mounted vibrating wire gauges were used to instrument the anchors. A series of vibrating-wire gauges were microwelded on the anchors at certain intervals along their lengths. The performance of these gauges, the load transfer mechanism, the debonding process, creep behavior, and long-term performance of the anchors under loading, unloading, and sustained loading, were investigated in the laboratory. A practical application and test results of an instrumented anchor at Jeffrey Mine in Asbestos, Canada, are described. The results obtained show that this instrumentation technique of grouted anchors is efficient for long-term monitoring.

This paper describes a new analysis for predicting the tensile stress distribution and load-elongation response in pullout tests performed on thin, extensible, planar soil reinforcements. The proposed formulation is based on shear-lag approximations and assumes elastic properties of the constituent materials (soil and reinforcement), which are linked through a frictional interface. The analysis identifies four successive phases in the pullout response: (1) initial, linear behavior, characterized by a buildup of interface tractions at the active, loading end of the inclusion; (2) nonlinear load-elongation response associated with the progression of a sliding front from the active end; (3) peak pullout resistance, when the interface friction is fully mobilized at the passive end of the inclusion; (4) postpeak reduction in pullout resistance due to a snap-through mechanism, with coalescence of sliding fronts from the active and passive ends of the inclusion. The principal parameters affecting the load-elongation response during pullout are the relative soil-reinforcement stiffness, inclusion length, and interface friction. The proposed analysis shows important limitations in applying limit equilibrium calculations for interpreting interface friction from pullout tests on extensible reinforcements.

This paper presents results of laboratory pullout experiments with planar soil reinforcements that are used to evaluate the proposed shear-lag analyses described in a companion paper. Measurements of tensile stress distributions were obtained for thin steel and nylon 6/6 sheet inclusions embedded in dense Ticino sand. The steel reinforcement is relatively inextensible, with linear stress distribution and load-elongation behavior. The interface friction is well defined from repeatable measurements of the peak pullout resistance. In contrast, the response of the extensible nylon 6.6 reinforcements is highly nonlinear with a pronounced postpeak reduction in pullout resistance. The interface friction can be interpreted reliably from the residual pullout resistance, although these data are affected by stick-slip behavior in tests performed at low displacement rates. The measured data are in good agreement with shear-lag predictions of nonlinear load distributions throughout the test and illustrate very clearly the postpeak “snap-through” mechanism described by the analysis. Further experimental measurements are required to evaluate other aspects of the analyses such as stress concentrations at the sliding front.

A new desiccation theory is developed that provides a rational framework for the consolidation and desiccation analysis of soft fine-grained waste soils. The theory includes four consecutive segments that correspond chronologically to the phases that a soft soil layer undergoes in the field after deposition: consolidation under one-dimensional compression; desiccation under one-dimensional shrinkage; propagation of vertical cracks and tensile stress release; and desiccation under three-dimensional shrinkage. A general form of the finite strain governing equation of the overall consolidation and desiccation process is formulated. It includes the cracking function and the nonlinear constitutive relations. The experimentally obtained consolidation and desiccation characteristics for soft china clay, which are needed for the overall analysis of a given field problem, are presented. The predictions of this theory for the response of a hypothetical soft china clay layer undergoing self-weight consolidation, seepage consolidation, and desiccation due to lowering of the ground-water level or surface drying are presented and discussed.