Study On The Deterioration And Disintegration Law Of Ruihai Olive Basalt Under Water-Rock Reaction And Its Application

Ruihai gold mine is the deepest seabed metal mine in China,with a maximum burial depth of 1700 m.In this paper,aiming at the typical engineering phenomenon of water collapse of olivine basalt surrounding rock in the development roadway of Ruihai Gold Mine,the uniaxial compression test and synchronous acoustic emission test of Ruihai olivine basalt under different soaking time are carried out to reveal the apparent characteristics,mechanical properties and acoustic emission activity evolution law of Ruihai olivine basalt under water-rock interaction.By means of thin section identification,X-ray diffraction whole rock analysis and inductively coupled plasma atomic emission spectrometry,the degradation and disintegration mechanism of Ruihai olivine basalt under water-rock interaction was explored.The numerical simulation method was used to analyze and optimize the surrounding rock support scheme of Ruihai olive basalt under water-rock interaction and explore the influence of water-rock interaction on the stability of surrounding rock of Ruihai olive basalt under different geostress levels.The main understanding of this article is as follows :(1)Under the influence of water-rock interaction,the elastic modulus and uniaxial compressive strength of Ruihai olivine basalt decreased with the extension of soaking time.When the soaking time was 2,6,12 and 20,the average elastic modulus decreased by 38.84 %,42.99 %,54.26 % and 90.81 % respectively,and the average elastic modulus decreased by15.85 %,14.74 %,18.65 % and 93.07 % respectively.The brittleness index Bi of Ruihai olivine basalt also decreases with the progress of water-rock interaction.After soaking for 20 hours,the brittleness index Bi is only 6 % of the brittleness of Ruihai olivine basalt in natural state.The curves of elastic modulus,uniaxial compressive strength and brittleness index Bi with time all show ’ S ’ type.(2)After soaking for different time,the uniaxial loading process of Ruihai olive basalt has obvious changes : with the extension of soaking time,the total energy released by acoustic emission activity decreases,and the total energy released by acoustic emission activity after soaking for 20 hours is 96.7 % lower than that in the unsoaked state.The acoustic emission activity increases in the elastic deformation stage and the plastic stage,and the high-energy rate acoustic emission activity changes from only appearing in the compaction and failure stage to appearing at any stage during the loading process.The b value of acoustic emission increases gradually,and the b value of acoustic emission increases by13.4 % after soaking for 20 h,indicating that the ratio of acoustic emission small energy events to large energy events increases during the loading process of Ruihai olivine basalt under the influence of water-rock interaction.(3)Ruihai olive basalt has strong heterogeneity and high clay mineral content compared with common olive basalt.Under the action of water-rock,the sodium ions in the solution increase with the increase of soaking time,and the dissolution and dissolution of albite are obvious,which leads to the weakening of the cementation force of Ruihai olive basalt and has a certain effect on the deterioration of Ruihai olive basalt under the action of water-rock.The clay minerals dominated by saponite are expanding and changing obviously.The main reason for the deterioration of Ruihai olive basalt under water-rock interaction is that the clay minerals dominated by saponite swell to form pores,and then the pores gradually develop into cracks and connect with each other with the extension of soaking time.(4)Based on the deterioration law of Ruihai olive basalt under water-rock interaction,the numerical simulation of the typical roadway of surrounding rock collapse in Ruihai gold mine is carried out.The simulation results are in good agreement with the field failure.On this basis,the control effects of different lining thickness and bolt length on surrounding rock are analyzed respectively,and the support optimization suggestions are given.The results show that the increase of in-situ stress will amplify the influence of water-rock interaction on the stability of roadway,and the influence of Ruihai olivine basalt rock mass with performance deterioration is particularly prominent.The support of Ruihai olivine basalt part which is easily affected by water-rock interaction under high in-situ stress conditions should be strengthened in roadway construction.