Experimental Study On The Influence Of Water Form On The Thixotropy Of Structural Clay In Zhanjiang Formation

The structural clay of Zhanjiang formation has strong thixotropy,and the interaction between soil and water is an important factor affecting the thixotropy of the structural clay of Zhanjiang formation.The mineral particles of structural clay in Zhanjiang formation are small and the specific surface area is large.The strong hydration reaction occurs when encountering water,which makes the thixotropy mechanism of structural clay in Zhanjiang formation very complex.The existence mode of water has a significant impact on the thixotropy of structural clay in Zhanjiang formation.The main research contents of this paper include three parts: the first part is to obtain the physical and mechanical properties of structural clays of Zhanjiang formation under different sedimentary environments;the second part is to establish the test method of micro water in structural clays of Zhanjiang formation,and judge the composition and content of micro water through the test data qualitatively and quantitatively;the third part is to obtain the physical and mechanical properties of structural clays of Zhanjiang formation under two sedimentary facies The unconfined compression test of structural clay of Zhanjiang group with different micro water content and different curing age was carried out to explore the effect of micro water form and content on the thixotropy of structural clay of Zhanjiang group and its mechanism.Relevant research results are as follows:(1)By comparing the basic physical indexes of structural clays of Zhanjiang formation of two sedimentary facies,it can be seen that both clays have high water content,large void ratio,high liquid limit and high plasticity index.Both of them belong to silty clay,and the clay content of estuarine phase is higher than that of fluvial phase.(2)According to the analysis of unconfined compression test results of structural clays in Zhanjiang formation of two sedimentary facies,it is found that the unconfined compressive strength of both clays decreases with the increase of natural water content,and the strength of fluvial clays is greater than that of estuarine clays.Two kinds of structural clays of Zhanjiang formation belong to high sensitivity clays,and the sensitivity of clays has nothing to do with water content.(3)According to the analysis of NMR test results of structural clays of Zhanjiang formation of two sedimentary facies with different moisture content and different curing age,it is found that the whole hydration process of the two clays can be divided into three stages: the first stage is the transformation stage from free water to combined water;the second stage is the formation stage of strong combined water film;and the third stage is the balance stage of combined water.The hydration process of fluvial clay in the process of thixotropic strength recovery is mainly from the first stage to the second stage;estuarine clay directly enters the second stage of hydration in the early thixotropic stage and reaches the third stage in the late thixotropic stage.(4)Through the comparative analysis of unconfined compressive test data under different water content and different curing age of structural clayey River Soil of Zhan formation of two sedimentary facies,it is found that the unconfinedcompressive strength of river facies clayey soil at the same age increases first and then decreases with the increase of water content.The unconfined compressive strength of estuarine clay decreases with the increase of water content.The thixotropy of fluvial clay decreases with the increase of weak water content.The properties of estuarine clay and fluvial clay are just opposite.The thixotropy of clay increases with the increase of weak water content.