| The ancient tomb sites in the Yangtze River Basin are greatly affected by the extreme rainfall and drought environment in the south.Under the influence of rainfall and evaporation and repeated fluctuation of groundwater,they are in a state of dry and wet alternation for a long time,which is easy to cause the strength reduction and deformation of the soil,and then threaten the long-term stability and safety of the ancient tomb body and the tomb chamber structure.Therefore,it is necessary to systematically study the deformation and strength of the undisturbed clay in the ancient tomb sites,which is of great significance for enriching the protection theory of the ancient tomb sites in the Yangtze River Basin and guiding the preventive protection of the ancient tomb sites.Based on the current situation of structural research,this paper takes the underground anti-seepage project of Zhuran Tomb Site in Ma’anshan City,Anhui Province as the background and research object,and conducts a series of indoor geotechnical tests and analysis on the natural clay of Zhuran Tomb Site.It is proposed to prepare undisturbed soil from compacted soil by dry-wet cycle,in order to reveal the strength and deformation characteristics of natural structural clay in Zhuran tomb,and also provide a basis for the subsequent protection of Zhuran tomb.The main work and research results of this paper are as follows :(1)Study on engineering geological characteristics of Zhuran tomb clay.Through the study of the engineering geological characteristics of the clay in the Zhuran tomb site,the geological properties of the local strata in Ma ’anshan were mastered.Through field investigation,the geological conditions in the study area were studied in depth,and a series of indoor geotechnical tests were carried out on the clay of Ma ’anshan site,and the basic physical index data of the clay of Ma ’anshan site were obtained.(2)Study on the dry-wet cycle in the environment of Zhuran tomb site.The dry-wet cycle method can better simulate the dry-wet alternating state of Zhuran tomb site under natural conditions.The dry-wet cycle remolded soil was prepared with compacted soil,and through the study of its swelling and shrinkage characteristics,the swelling and shrinkage characteristics of the dry-wet cycle remolded soil and the compacted soil are obviously different,and it has a certain structure.For the difference of clay structure,a generalized model of micro-change of Zhuranmu clay is proposed.The clay of Zhuran tomb site is in the stable stage of expansion and contraction for a long time.(3)Study on compression characteristics of Zhuran tomb clay.Unidirectional compression tests were carried out on the remolded soil of Zhuran tomb site,and the deformation parameters of Zhuran tomb site clay were obtained.The compression properties of Zhuran tomb clay were obtained by comparing and analyzing the remolded soil and compacted soil.The e-lgp curves of remolded soil under different dry-wet cycles have inflection points,which are different from the properties of compacted soil and similar to other undisturbed soils.Through the analysis of compression characteristics,it is concluded that the soil compressibility of Zhuran tomb site remains stable for a long time.At the same time,a mathematical model method is introduced to determine the preconsolidation pressure of Zhuran tomb undisturbed clay.(4)Study on strength and deformation characteristics of clay in Zhuran tomb site.The deformation and strength characteristics of Zhuran tomb clay were studied by conventional triaxial compression test and direct shear test.Among them,the stress-strain relationship and the influence of strength indexes c and φ of clay dry-wet cycle samples and compacted soil in Zhuran tomb site were studied by conventional triaxial compression test.Through the direct shear test and consolidation shear test on the cyclic samples and compacted soil of Zhuran tomb site,the influence of consolidation on the soil structure of Zhuran tomb site was explored.Under the long-term time and low-load stage,the shear strength of structural clay in Zhuran Tomb Site tends to be stable,and the change of strength index is consistent with the hypothesis of Zhuran Tomb clay generalization model.Consolidation has little effect on the clay of Zhuran tomb site. |
