Investigation of vertical members to resist surficial instabilities

100 p.This report summarizes the state of the art of using reinforcing structural members to stabilize surficial slope failures. The literature search and review conducted in this study indicated that the use of structural members for stabilizing surficial slope failures is not common practice; however, there is great interest in this methodology. The research team identified the following three innovative methods of surficial slope stability: installing small size structural members by conventional methods; installing launched soil nails, and installing earth anchors. This report includes detailed information regarding the design and analysis methodology for structural members, the material properties of structural members used, construction methods, cost-effectiveness, and case histories. It should be noted that there is little documented information available on this subject. In order to investigate the influence of installing structural members to stabilize surficial slope instabilities in Wisconsin, a comprehensive slope stability analysis was conducted using Wisconsin soil and slope input parameters and various soil strength parameters under dry and saturated conditions. The analysis conducted in this report and by other studies demonstrates the effectiveness of using the structural members in stabilizing surficial slope failures. Based on the information and data available, the methods that have potential merit to stabilize surficial slope failures in Wisconsin in terms of cost-effectiveness and field performance are the small size conventional structural members and the earth anchoring systems. Short-term field performance data demonstrated that plastic lumber is an effective remediation method if installed in closely spaced configuration. Wood lumber and earth anchors also are considered cost-effective. Long-term field performance data on the use of these materials is not available to draw any rational conclusions. Creep of plastic lumber and decay of wood lumber in aggressive environments may impact the behavior of these structural elements in the future and therefore the stability of the slopes they are used to repair

Construction vibration attenuation with distance and its effect on the quality of early-age concrete

456 p.Pile-driving, blasting, and other WisDOT construction activities create air- and ground-transmitted vibration forces that can damage existing and in-construction facilities. Wisconsin limits construction-based vibration levels and the timing of pile-driving near fresh pours based on standards drawn from federal mine-blasting evaluations. This study focuses on pile-driving vibrational effects - both on attenuation of vibrations over distance from source, and on distance and age effects of such vibrations on recently placed concrete - that will be triggered by driving piles during the Marquette Interchange reconstruction. Data emerging from this study will help WisDOT estimate and regulate the impact of pile-driving on adjacent structures and nearby fresh concrete

Development of full scale testing of an alternate foundation system for post and panel retaining walls

127 p.This research will develop and test a new, potentially less expensive and more easily executed design for post-and-panel retaining wall foundations. The design, proposed by several contractors to the Wisconsin Department of Transportation (WisDOT), replaces the use of cylindrical, concrete anchors for retaining wall piles with steel plates welded to piles and driven directly into the ground. This study will examine the feasibility of this proposed system

Evaluation of bridge approach settlement mitigation methods

131 p.Over the past 20 years, extensive research has been conducted to study the causes and mitigation methods of bridge approach settlement or "the bump at the end of the bridge." Many Departments of Transportation are significantly impacted by bridge approach settlement, as it causes unsafe driving conditions, rider discomfort, poor public perception of the state infrastructure, structural failure of bridges, and long-term maintenance costs. The literature has indicated that poor performance of pavement, bridge abutment and type, consolidation of the backfill materials, consolidation of the foundation's soils, and poor drainage are contributors to bridge approach settlement. Many mitigation techniques have been used to control the settlement, but the methods selected depend on the specific site. Techniques to repair the bump include asphalt patching or overlays, slab jacking, and replacement of approach slabs. Because of the considerable amount of money spent on repairing the differential settlement, DOTs and the Federal Highway Administration (FHWA) have funded numerous studies to determine the causes, mitigation methods, and maintenance techniques of bridge approach settlement. This study is part of one of these studies, "Evaluation of Bridge Approach Settlement Mitigation," sponsored by the Wisconsin Department of Transportation. The purpose of this paper is to document the performance and effectiveness of two mitigation techniques, geosynthetic reinforced fill and flowable fill, installed behind four Wisconsin bridges. This study includes an extensive literature review, discussion of the field investigation, and performance evaluation of field results of these four bridges

Investigation of Thermal Loading Effects on Shaft Resistance of Energy Pile using Laboratory-Scale Model

Cyclic temperature changes in an energy pile generate cyclic thermal expansive and contractive strains along the interface, which may impact both the serviceability and the ultimate pile resistance. This paper aims to assess induced changes in the shaft resistance of an energy pile after being subjected to different temperature variation, between 24°C and 34°C. This was done by measuring the load-settlement curve of a laboratory-scale floating energy pile installed in fully saturated normally-consolidated (NC) kaolin. A 10% relative settlement criterion was adopted to define the shaft resistance. Changes in temperature and pore pressure were also monitored in the surrounding clay using embedded thermocouples and a pore pressure transducer. Measurements during thermal loading showed that a positive excess pore water pressure was generated during the first thermal cycle followed by a negative pore pressure (suction) during the same cycle, while subsequent thermal cycles generated a cyclic pore pressure that remained negative regardless of the number of thermal loading cycles. It was also observed that piles subjected to heating exhibited greater shaft resistance than the reference pile tested at room temperature. Although the shaft resistance was considerably influenced by cyclic thermal loading, increasing the number of thermal cycles did not make appreciable differences in shaft resistance

The Mechanisms Underlying Long-Term Shaft Resistance Enhancement of Energy Pile in Clays

Although there are several studies indicating that heating increases the long-term shaft resistance of energy piles, the mechanisms by which heating causes this increase have not been adequately evaluated yet. This article presents a comprehensive analysis and discussion to assess the important factors contributing to this increase by integrating the findings from three recently published papers studying the thermo-mechanical behavior of clay and the clay-pile interface. In these three studies, reconstituted kaolin clay was used, and cyclic and monotonic heat ranging between 24 and 34 °C were applied to the clay and interface. The interface was sheared under two stiffness boundary conditions: constant normal stiffness (CNS) and constant normal load (CNL), where normal stresses varied between 100 and 300 kPa. The analysis presented in this article reveals that the increase in strength of the interface under the CNL condition is primarily attributed to clay stiffening at the interface. However, the increase in shaft resistance under the CNS condition is primarily attributed to the heating-induced increase of effective lateral stress, although clay stiffening at the interface also partially contributes to the total increase of shaft resistance

Determination of typical resilient modulus values for selected soils in Wisconsin

175 p.The objective of this research is to develop correlations for estimating the resilient modulus of various Wisconsin subgrade soils from basic soil properties. A laboratory testing program was conducted on common subgrade soils to evaluate their physical and compaction properties. The resilient modulus of the investigated soils was determined from the repeated load triaxial test following the American Association of State Highway and Transportation Officials (AASHTO) T 307 procedure. The laboratory testing program produced a high quality and consistent test results database. The high quality test results were assured through a repeatability study and also by performing two tests on each soil specimen at the specified physical conditions. The resilient modulus constitutive equation adopted by National Cooperative Highway Research Program (NCHRP) Project 1-37A was selected for this study. Comprehensive statistical analysis was performed to develop correlations between basic soil properties and the resilient modulus model parameters k sub i. The analysis did not yield good results when the whole test database was used. However, good results were obtained when fine-grained and coarse-grained soils were analyzed separately. The correlations developed in this study were able to estimate the resilient modulus of the compacted subgrade soils with reasonable accuracy. In order to inspect the performance of the models developed in this study, comparison with the models developed based on the Long-Term Pavement Performance (LTPP) database was made. The LTPP models did not yield good results compared to the models proposed by this study. This is due to differences in the test procedures, test equipment, sample preparation, and other conditions involved with development of both LTPP and the models of this study

Experimental Evaluation of Shear Strength of Kaolin Clay under Cyclic and Noncyclic Thermal Loading

The soil response to daily temperature variation imposed by an energy pile is critical for estimating the energy pile\u27s capacity and serviceability. It is, therefore, necessary to determine the temperature-induced effects on mechanical properties of soils. This article presents the results of an experimental study on the effects of thermal loading on shear strength of reconstituted kaolin clay. The study was performed using a triaxial testing apparatus capable of applying thermal loading. Different cyclic and noncyclic thermal loadings, with temperatures ranging between 24 ⁰C and 34 ⁰C, were applied. In addition, two theoretical mechanisms defining force distribution at the interparticle level were used to analyze the shearing behavior of clay under thermal loading. Both experimental and theoretical results indicate that the influence of temperature variation on the shear strength of clay is primarily controlled by stress state and stress history

Influence of Temperature on Soil-Pile Interface Shear Strength

Geothermal piles are subjected to daily and seasonal cyclic temperature changes during their life spans. These temperature changes (heat cycles) induce cyclic expansion/contraction along the soil–pile interface that may affect interface properties such as shear strength. A series of direct shear tests was conducted using a temperature controlled direct shear test apparatus to evaluate the effects of heat cycles on soil–pile interface strength. The interface temperature was cycled between 24 ° C and 34 ° C to simulate the real thermal conditions that an energy pile may experience. Non-cyclic and cyclic thermal loading were applied under different stress states and histories. It was found that the shearing behavior of interface under thermal loading is described through thermally induced changes in Mohr–Coulomb\u27s parameters of the interface. Moreover, the thermally induced changes in interface strength are mainly controlled by the soil stress state and the soil stress history