Variation Regularities Of Water-heat In SH-Reinforced Rammed Earth Used To Fill Unsupported Walls

Songshan Newcastle located in Tianzhu county is an important part of the Great Wall of Ming Dynasty.After more than 400 years of artificial and natural factors' damage,all kinds of diseases have developed seriously.Among those diseases,undercutting and collapse are the most widely distributed ones.The rammed earth used to fill unsupported walls is an effective reinforcement measures to solve the problems of collapse and undercutting.But the fluctuation of capillary water always emerge after the construction of the rammed earth used to fill unsupported walls,resulting the further consolidation and the separate of the rammed earth,which will weaken or even strip the reinforcement effect of the rammed earth.Therefore,it is of great significance to find out the variation regularities of water and heat in the rammed earth after construction.In addition,it is urgent to find a kind of material to solve those problems.Aiming at these problems,SH solution is used as the reinforcement material,and the best concentration of SH solution is determined through laboratory tests.After that,unreinforced rammed earth and reinforced rammed earth strengthened by SH solution are built in Songshan Newcastle.Besides,a minitype weather station is set up and the temperature and volume of water content probes were embedded in the rammed earth.So the variation regularities of environment factors such as temperature,relative humidity,snowfall and rainfall and the fluctuation of water and temperature in the rammed earth.The following conclusions can be drawn through indoor tests and field data analysis.(1)SH solution can obviously improve the unconfined compressive strength of the samples.With the increase of concentration,the reinforcement effect of SH solution becomes more obvious.The SH solution with a concentration of 2.5% can increase the unconfined compression strength of samples about 95.4%.After 15 freezing and thawing cycles,the unconfined compressive strength of 1.5%SH samples is the highest,and the strength loss rate of the sample strengthened by 2.5%SH solution is larger.Thus,it is determined that the 1.5% concentration SH solution is suitable for the consolidation of the rammed earth for Songshan Newcastle.(2)The change of monthly mean value of temperature of the rammed earth is positively correlated with environment temperature and the correlation coefficient is larger than 0.85.The bottom of the rammed body is more sensitive to the air temperature change.The daily variation of temperature of the rammed earth is in a wave form,and there is an obvious rise and fall temperature delay.In a single day,the volumetric water content fluctuation of the middle and bottom of the rammed earth is the most violent,and the top area of the rammed earth is basically the same.(3)It is found that SH solution can obviously reduce the variation coefficient of the temperature of the rammed earth and can reduce the temperature fluctuation in the rammed body.Besides,the SH solution can obviously restrain the water movement in the rammed earth,and the volumetric water content in the rammed earth reinforced by the SH solution is lower than that of the unreinforced one.The results show that SH solution can be used as a reinforcement material for rammed earth used to fill unsupported walls and the effect of reinforcement is remarkable.