Research On The Characteristics And Mechanism Of Water Softening Of Schist In Tongjie-Manjiazhai Mining Area

In the 1950s,Soviet scholars proposed the Water-Rock Interaction(WRI).For decades,researchers at home and abroad have studied the mechanism of water-rock interaction on sandstone,mudstone,and slate,and made breakthroughs.Schist belongs to special soft rock,and its mechanical strength is higher in natural state.After immersion in water,the mechanical strength is reduced to the soft rock standard.This article relies on the special engineering geological research project of Tongjie-Manjiazhai open pit,to the widely distributed green mud schist in the mining area.,Eryun schist and Eryun quartz schist,carried out a large number of outdoor and indoor point load tests,using SEM electron microscopy,EDS spectrum analysis,XRD diffraction means and binary regression to explore the physical and chemical aspects of the above three schist The softening mechanism,the main research contents and conclusions of the article are as follows:(1)The uniaxial compressive strength of the rock is obtained through a large number of point load tests.The results show that: green mud schist and diorite schist are soft rocks,and diorite quartz schist is softer rock;the uniaxial compressive strength of the three schists are all the same as Buried depth and RQD have a positive correlation;(2)According to a large number of on-site immersion tests,it is found that with the increase of rock mass quality index(RQD),the softening coefficient of green mud schist and dolomitic schist has an overall upward trend.;The higher the degree of weathering of the green mud schist and the dolomitic schist,the lower the softening coefficient.The softening coefficient at the bottom of the full-strong weathering layer is the smallest.There is no obvious correlation between the softening coefficients of the three schists in the medium-micro weathering layer;The correlation between the softening coefficient and the burial depth is poor,but it has a certain correlation with the structure.The fault is developed,the schist softening coefficient is low,and the amplitude is small;(3)Indoor immersion softening tests were carried out on green mud schist,diorite schist,and diorite quartz schist,and the uniaxial compressive strength,water content and immersion time of the three schists were obtained: the longer the immersion time,the more The higher,the lower the rock compressive strength;(4)XRD diffraction analysis of schists with different water immersion durations shows that: green clay schist and dolomitic schist are the main ones,and the main minerals that affect the softening are montmorillonite,chlorite,illite,muscovite and other clays Minerals,and through linear fitting,the content of montmorillonite is negatively correlated with the softening coefficient;(5)Carry out SEM electron microscope scanning,EDS energy spectrum analysis,combined with the results of hydrochemical analysis,and obtain the microscopic mechanism of schist softening: clay mineral expansion,disintegration,dissolution and dissolution,ion exchange,and hydration lead to rock structure Changes,the mechanical strength decreases.