Foundational Theory And Its Application Of Coated Modification Of Physicochemical Soft Rock

The physicochemical soft rock is a kind of rock in which containing a great amount of clay minerals. Under engineering disturbance conditions, it is easy to produce swell and shrink by wetting and drying and to reduce rapidly its engineering properties. It is one of the biggest rock mechanics problems in geotechnical engineering. Because the physicochemical soft rock is of such physic mechanics properties as hydrate swelling, strength debase and softening disintegration etc, it has brought a great influence to the stability of many important projects.Theory and methods of soft rock engineering stability controls are focused on the passive support and anchor, and the studied focused on the reinforcement of soft rock that has broken or soften. Practice showed that it have obvious control effects for stress-type (high stress squeeze) soft rock and structure-type (jointed and fractured) soft rock, and yet have little effects for physicochemical soft rock as its hydrate swelling, strength debase and softening disintegration. As groundwater, stress and other bad environmental effects, supporting system can't bear enormous expand and disintegration stresses, and an anchor point can't be found in the anchoring system. So that supporting and anchoring system failure in engineering of physicochemical soft rock.On the basis of the systematized study and analysis on the available correlative theories and technologies, conventional passive support and anchor fashion is altered, a thought to eliminate, weaken and slacken changeability of physics and mechanics characters of physicochemical soft rock, and to enhanced stability of soft rock engineering by using modification materials altered physics and mechanics characters of physicochemical soft rock is put forwarded. And aiming at this subject, the following studies are carried out in this paper.1,Based on mineral and chemical composition and microstructure modality of 15 kinds soft rock samples from 8 typical soft rock mines was studied systemically by X-ray diffraction, X-ray fluorescence spectral analysis and scanning electron microscope, two kinds soft rock which is basis composition of montmorillonite and kaolinite were selected as research objects, by some testing methods, such as nitrogen adsorption isotherm, FT-IR spectra, physic chemical experiments of soft rock etc, microstructure properties, surface roughness properties, pore-fracture distribution properties and the surface characters includes surface wetting, surface energy, surface functions and surface electric of two kinds soft rock was studied quantitatively or qualitatively, these offer a minerals surface structure and physicochemical basis for the soft rock coated-surface modification.2,Based on the analysis of the composition of the physicochemical soft rock, the microstructure shape change and swell-shrink mechanism in the drying-wetting process of the clay minerals, the swell-shrink geometrical model and its corresponding equation of the tetrahedral microstructure unit consisting of hard sand and clay minerals tactic strata in the physicochemical soft rock are put forward. This equation offers a theoretical foundation for quantitative research of the swell-shrink property of soft rock.3,A new fashioned solidification at ambient temperature modification materials is synthesized by radical solution copolymerization and sol-gel method in laboratory, coating principle for modification materials on soft rock surface and its structure, hydrophobic property, film fastness, waterproof are studied. At the same time, silane coupling agent selected as modification material for itself excellent property, its waterproof and strength characters was studied by tests, this offers a material foundation for physicochemical soft rock coating modification.4,Based on the study of characters of new fashioned modification material, composition No.3 selected as modification material, Comparative tests on grains free swelling and block disintegration of soft rock for modificated before and after were carried out. Compared with unmodified samples, the grains swelling and block disintegration of modified samples decrease obviously.5,Chemical cohesion principle, cohesion characters and stability of silane; coupling agent, cement and naphthalene-based superplasticizer are studied by theoretical analysis and comparative tests on cement grout fluidity and solidified strength characters of different compositions. The study results applied to the methane emission roadway 12206 workface in Tunlan mine , technical difficulties in roadway support was solved successfully, and achieved remarkable technical, economical and social beneficial results. This offered a new control theory and method for physicochemical soft rock engineering stability.