| In China,the distribution of soft rock is very wide,which is an inevitable type of rock in civil engineering construction.With the rapid development of civil engineering,the soft rock problems involved in the engineering construction have become increasingly prominent and have become a major problem in geotechnical engineering.The engineering stability of soft rock is greatly affected by the aqueous solution,The slaking characteristics of the rock are greatly influenced by water,which can lead to the cracking of the entire rock mass,the problems of related road construction,foundation treatment,tunnel construction,stability of slope plagued people.The soft rock and the engineering damage caused by it are also rapidly paid great attention by the majority of scientific researchers.Therefore,it is of great theoretical significance and application value to explore the physical and chemical mechanism of soft rock slaking and to analyze the mechanism of slaking on the bonding characteristics of rock-concrete interface.This paper mainly focused on the following aspects:(1)In order to overcome the problem that the traditional method can't be used to prepare a prototype specimen of standard cylindrical soft rock of specific size,a method of hand-making a soft specimen of standard cylinder of soft rock is proposed and applied to indoor rock mechanics tests.(2)Taking soft rock in Taihu County,Anhui Province as an example,three sets of samples(mudstone and sandstone)are chosen to perform laboratory tests of slaking in different soaking times and many wetting and drying cycles.The dissertation focuses on the mineral composition and microstructure characteristics of rock,the mechanism of soft rock in water disintegration are explored.The results show that its mineral composition,especially clay minerals,cement composition of microstructure and other interior factors are the decisive factors in the slaking characteristics.(3)Taking the two kinds of soft rock(tuff)in Huoshan County,Anhui Province for example,some laboratory tests of slaking in pH=2?pH=7?pH=12 solutions were performed in wetting and drying cycles.The phenomena and characteristics of slaking of the two rocks,under different pH solutions,were observed and recorded.And the trend of mass fraction of particle with different sizes and ion concentration of the aqueous solutions during slaking process were analyzed.Combined with X-ray diffraction(XRD)results,the physical and chemical mechanisms of rock disintegration were investigated under different pH solutions.The study showed that the pH value have an strong impact on tuff slaking.The smaller the pH value,the more obvious variation the mass fraction of particle with different sizes and ion concentration of solution,also the stronger the disintegration.The chemical action of water on rock occurred during the process of rock submerging and its chemical effect was stronger when pH = 2.Also,the disintegration of rock was the strongest.(4)According to the slaking characteristics of soft rock,a test method and test specimen for the bonding characteristics of the interface between soft rock and concrete are provided.Taking two kinds of red sandstone as an example,the bonding experiment of soft rock and concrete under dry state and saturated water saturation was designed.The effect of water on the bonding properties and frictional properties between red sandstone and concrete were studied by laboratory tests.The results show that the bond strength and frictional strength of the disintegrating soft rock-concrete interface are related to the disintegration of the soft rock,the disintegration results in a decrease in the bond strength and frictional strength.Bonding and frictional strength of the interface between no-disintegrating soft rock and concrete are also related to the condition of rock soaking. |
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