The Effect Of Heat And Moisture Coupling Migration Of Ground Structure Without Damp-proof Course On The Indoor Floor Surface Temperature And Humidity

In China,there are still lots of building grounds without damp-proof courses.The distribution of heat and moisture in the soil layer,the coupled heat and moisture migration process are the main ways to affect the wet state of the ground surface and to further affect the indoor wet environment.The change of indoor wet environment is closely related to the human thermal comfort and the energy consumption of the building.Wet accumulation is prevalent in the underlying surface of building grounds in hot and wet areas.When wet accumulation is serious,problems such as flooding,bacterial growth and shortening of building materials life can occur.Therefore,it is very important to analyze the heat and moisture coupling migration of ground without a damp-proof course and to grasp heat and humidity state of the ground surface,which are helpful to calculation of building energy consumption and prevention of moisture accumulation.Taking the effect of the coupled heat and moisture transfer of building grounds without damp-proof courses on the surface heat and moisture state as the goal,the research is carried out by combining spot test,theoretical analysis,experimental analysis and numerical calculation.Based on the mechanism analysis of heat and moisture coupled transfer in building grounds without damp-proof courses,a coupled heat and moisture transfer equation is established.A scale model experiment is carried out,and the applicability of transfer equation is verified by experiment.Based on the model,the changes of heat and moisture state on the ground surface whether considering moisture transfer or not under multiple conditions are studied respectively.The problem of ground condensation is discussed from two aspects of indoor environment and ground heat and moisture migration.And some corresponding mitigation measures are put forward.The main conclusions are as follows:(1)At the beginning of the consideration of the moisture transfer,the surface temperature increases slightly.When reaching a steady state,the surface temperature is lower.The decrease of temperature is related to the factors such as ground,soil and groundwater level.And the reduction,respectively,as follows,the ground structure: 0.1~0.5?;soil type: 0.1~0.3?;underground water: 0.1~0.2?.(2)Considering the moisture transfer,the sensible heat flow through the ground increases.The increase of the sensible heat flux on the ground surface is related to the influence factors such as the ground,soil and groundwater level.The increasing extent is respectively,ground structure: 5.3%~14%;soil type: 0.8%~7.5%;groundwater level: 2.8%~8.8%.(3)Considering moisture transfer,ground have latent heat flow.Its value is related to these factors,such as ground,soil and groundwater level.Under these factors,the multiple which the value of the latent heat compared to the sensible heat flow is as follows: ground structure: 0.9~18.5;soil type: 2~10.4;groundwater level: 2.1~12.1.(4)Considering the moisture transfer,the ground condensation time will increase in plum rain season.The increase is related to the influence factors such as the ground,soil and groundwater level.The increasing extent is respectively,ground structure: 3.7%~9.3%;soil type: 0.4%~4.6%;groundwater level: 2.1%~7.6%;groundwater temperature: 12.7%~14.1%.(5)Aiming at the problem of ground condensation during plum rain season in hot and wet area,three preventive measures are put forward: the surface finishing layer uses the absorbing and releasing moisture materials;a thermal insulation layer of 200 mm of cinder in village building ground;overhead ground.