Numerical simulation of working characteristics of energy pile group under thermo-mechanical coupling

In order to study the working characteristics of energy pile groups, based on the Abaqus finite element simulation, assigns the average temperature of the heat transfer stable stage to the pile body for steady-state thermo-mechanical coupling calculation, and proposes a simplified analysis method for the bearing characteristics of energy pile groups.The reliability of this research method is verified through the comparative analysis with field data.Combined with an example, this method is used to analyze the bearing characteristics of energy group piles under the action of pure mechanical load and thermal coupling.The results show that the non-uniform settlement of the distributed symmetrical arrangement of energy piles in the pile group foundation is significantly less than that of the centralized arrangement, and the layout has a great influence on the response characteristics of the pile foundation structure.Under the condition of equal stiffness of pile foundation, the control effect of pile group tilt is better by increasing pile diameter and decreasing pile spacing.The research results of this paper can provide some reference value for the engineering application of energy pile group

Operational Performances and Enzymatic Activities for Eutrophic Water Treatment by Vertical-Flow and Horizontal-Flow Constructed Wetlands

In this study, pilot-scale vertical-flow constructed wetland (VFCW) and horizontal-flow constructed wetland (HFCW) were constructed to treat eutrophic water, and dissolved oxygen (DO) distributions, decontamination performances and key enzymes activities were compared under different influent loads. The influent load increase caused reductions of DO levels and removal efficiencies of chemical oxygen demand (COD), total nitrogen (TN), NH4+−N and organic nitrogen, but it had no remarkable effect on the removal of NO3−−N and total phosphorus (TP). The interior DO concentrations of VFCW were higher than those of HFCW, indicating a vertical hydraulic flow pattern was more conducive to atmospheric reoxygenation. The VFCW and HFCW ecosystems possessed comparable removal capacities for TN, NO3−−N and TP. VFCW had a remarkable superiority for COD and organic nitrogen degradation, but its effluent NH4+−N concentration was higher, indicating the NH4+−N produced from organic nitrogen degradation was not effectively further removed in the VFCW system. The activities of protease, urease and phosphatase declined with the increasing depth of substrate layers, and they were positively correlated with DO concentrations. The enzymatic activities of VFCW were significantly higher than that of HFCW in the upper layers. Taken together, VFCW and HFCW presented a certain difference in operational properties due to the different hydraulic flow patterns