Abstract

Several studies have examined the geotechnical behaviour of energy piles; however, the behaviour of piled-raft foundations containing thermal piles is not fully understood. Because piled-raft foundations are optimally designed to bear mechanical loading from the top structure, the energy piles induce extra stress and bending moments on the raft foundation (slab) from the thermal loads, which may cause structural failure. The present study evaluated the thermo-mechanical behaviour of the energy piled-raft foundations using 3D FEM to simulate the geometrical and mechanical parameters of the pile group with an emphasis on slab stiffness. The interaction between the adjacent piles in a group as well as the bending moment induced through the slab have been evaluated. The results showed that, under thermo-mechanical loads, the stiffness of the slab prevented the free expansion and contraction of the energy pile. Increasing in slab thickness from 0.2 to 0.5 m reduced the energy-pile displacement about 50%. It also was observed that a heating load induced more stress than a cooling load along the longer piles. Cooling mechanical loads caused negative skin friction in the longer piles. It was shown that the equivalent pier method is generally applicable for a group of energy piles.

摘要

几项研究已经检查了能量桩的岩土工程行为；然而，包含热桩的桩筏基础的行为尚不完全清楚。由于桩筏基础经过优化设计以承受来自顶部结构的机械载荷，因此能量桩会因热载荷在筏基础（板）上产生额外的应力和弯矩，这可能会导致结构失效。本研究评估了能量桩筏基础的热力学行为，使用 3D FEM 模拟桩组的几何和力学参数，重点是板刚度。已经评估了组中相邻桩之间的相互作用以及通过板引起的弯矩。结果表明，在热机械载荷下，板的刚度阻止了能量桩的自由膨胀和收缩。板坯厚度从 0.2 增加到 0.5 m 可使能量桩位移减少约 50%。还观察到，沿较长桩的热负荷比冷负荷引起的应力更大。冷却机械负载在较长的桩中引起负表面摩擦。结果表明，等效墩法一般适用于一组能量桩。