Study On Consolidation And Conservation Of Earthen Sites In Moisture Circumstances

The consolidation and conservation of earthen sites in moisture circumstances is one of the technical problems recognized at home and abroad. The thesis carried out the research work for the purpose of the completion of national scientific research projects, with the conservation of Liangzhu sites group (3300B.C.-2100B.C.) form environmental science to materials science.First of all, the disease type, the ruin mechanism, the conservation methods and protective materials of earthen sites were analyzed and discussed. In the view of determination of the status of earthen sites by only atmospheric relative humidity or soil water content, after the Liangzhu Culture sites survey, three determination parameters were identified separately, including the environmental determination parameter, local environmental determination parameter and small environmental determination parameter, on the base of three parameters including soil water content, atmospheric relative humidity and humidity coefficient. The conception of moisture circumstances, which is one of the most important conceptions in the field of earthen sites conservation, was defined quantitatively. This definition could cover all kinds of complicated environmental conditions of earthen sites.Secondly, two profiles of Liangzhu Tangshan sites, 500 meters away from each other but with quite different preserving status, were chosen as the inspection targets and investigated systematically. The factors about preserving status were discussed by the comparison and analysis of the building technique, the environmental conditions, the ground status, the water table and the vegetation of the two profiles. It was found that when the environment could not be changed, the preserving status of earthen sites could be improved by some small environmental conditions, such as more appropriate vegetation planting, better ventilation, more sunlight and smoother drainage system. And then the objective of slowing ruin rate could be achieved. This concept has a universal significance.Thirdly, in order to consolidate the moist soil, a kind of room temperature vulcanizing silicones solution (RTV) was designed made up of short-chain hydroxyl terminated polysiloxanes, teraethyl silicate, and etc. according to the characters of silicones materials. We conducted an experiment applying RTV to two moist soil samples of different specifications with moisture content of 11.7-21.7% and a soil sample with a water content of 18.4%. The results showed that the compressive strength of soil samples increased by 0.1-0.7 times. The testing results in appearance, water-resistivity, permeability, compressive strength, artificial weathering and freezing-smelting led us to find the best two solutions for soil samples, i.e. RTV- II -2 and RTV- I -4 (RTV-1 and RTV-2). Both solutions were then put into field conservation operations and proved to have good water-resistivity. Our SEM analysis revealed their working mechanisms of consolidation and water-resistivity.In the end, the field tests were implemented on the two profiles of Liangzhu Tangshan sites in situ. Except for the RTV-1, PS (p otassium silicate), WD-10 (dodecyl trimethoxyl silanes), WD-S (oligo-methoxyl silanes), WD-W252, W-W102, and WD-W02 etc. were applied as Controlled trial. The field results of Two years showed that the RTV-1 was of great performances with better consolidation and water-resistivity effects. RTV materials could be tested for the consolidation and conservation of earthen sites in moisture circumstances.