Performance of a geothermal energy deicing system for bridge deck using a pile heat exchanger

In this study, a geothermal energy deicing system for bridge deck using a pile heat exchanger was developed, and the performance of this system was investigated under the conditions of snowfall. The structural response of the bridge deck during the deicing process was also analyzed. The slab temperature, air temperature, inlet and outlet circulating fluid temperature, and slab thermal strain were monitored during the test. The results show that the deicing system developed in this study was capable of accelerating the snow‐melting process even though no heat pump was employed in the deicing system. The deicing system was also suitable for anti‐icing in winter. In addition, the thermal effects of the deicing system on the structural response of the bridge deck could be ignored during the deicing process.     

ACMEG-T: Soil Thermoplasticity Model

This paper addresses an advanced and unified thermomechanical constitutive model for soils. Based on experimental evidence showing the nonlinear and irreversible thermomechanical responses of saturated soils, the constitutive equations of the developed model, Advanced Constitutive Model for Environmental Geomechanics-Thermal effect (ACMEG-T), are presented. In the context of elastoplasticity and critical state theory, the model uses the multimechanism plasticity and bounding surface theory. Nonlinear thermoelasticity is joined with two coupled thermoplastic dissipative processes. The yield functions, the dissipative potentials and the plastic multipliers are introduced. Attention is particularly focused on the coupling between both plastic mechanisms, an isotropic and a deviatoric one, which are in agreement with the consistency condition for multiple dissipation. As far as isotropic mechanism is concerned, a unique thermomechanical yield surface reproduces the thermoplasticity observed at low and intermediate overconsolidation ratios, as well as the plasticity under mechanical loading in an framework unifying mechanical and thermal hardenings. Finally, the efficiency of ACMEG-T is proven by validation tests on drained and undrained thermomechanical paths.     

Advanced compact device for the in situ determination of geothermal characteristics of soils

The in situ thermal response test provides an effective method to determine the ground thermal properties required for the design of a geothermal energy installation. This paper presents a unique compact testing device for in situ thermal response testing based on a previous, trolley-based unit. Modernisations in the presented new apparatus enable the time and cost of the test to be reduced and offer enhanced flexibility and application potential for in situ thermal response testing. The methodology adopted for the test, including the theoretical approach for the evaluation of test data, together with an outline of the design and workings of the apparatus are presented. A case study is also shown for the verification of the quality of the results.     

Prediction and experimental evaluation of soil-water retention behavior of skeletal calcareous soils

Bulletin of Engineering Geology and the Environment - Skeletal calcareous soils refer to soils consisting of skeletal remains of marine organisms. Although calcareous deposits are prevalent along...     

Experimental Investigations of Temperature and Suction Effects on Compressibility and Pre-Consolidation Pressure of a Sandy Silt

Research interest in the thermo-mechanical behaviour of unsaturated soils is growing as a result of an increasing number of geomechanical problems involving both thermal and unsaturated effects. In this framework, this paper addresses a unified thermo-mechanical experimental study of saturated and unsaturated states and, in so doing, contributes to the understanding of the non-isothermal mechanical behaviour of unsaturated soils. The present experimental program has been carried out on a sandy silt called “Sion silt” using two thermo-hydro-mechanical (THM) cells, one isotropic and one oedometric. The characteristics of these two cells are briefly presented, as well as the THM paths followed. The main results are presented and interpreted in the light of a suitable THM constitutive framework. The compressibility of the soil tested appears not to be affected by the temperature but decreases with a suction increase. As far as the apparent preconsolidation stress is concerned, the results show a decrease of the yield limit with increasing temperature, while a suction increase tends to enhance this limit. Finally, an analytical expression is proposed to describe the evolution of the apparent preconsolidation stress with respect to temperature and suction.