| Deformation of underground project may be more serious as its adjoining rock masses being soft rock or showing soft rock features along with increase of mining depth.That how to restrain the floor heave effectively has been an important method to stability of soft rock roadway.There are lots of theories about the excavations in the soft rock,but at present,that havetn't systematic and appropriate support theories of soft rock excavations.The deformed destruction of soft rock is led by many reasons,such as the low intensite itself,the exploiting press,underground water,support and the quality of support etc.This paper combines elements of the soft rock roadway engineering in Xin'an coal mine of Huaning Group, the mechanism of floor heave of the roadway is profoundly exposed.The factors resulting in its floor heave are analyzed, as well as the components of the floor heave deformation and the developing process of the floor heave are discussed.On the basis of the experience summed up by our predecessors,propose the combined supporting which is made of flexible inverted arch structure.The mechanism of composite structure for flexible inverted arch has been discussed.Uniaxial and triaxial compression tests about soft rock roadway and grouting specimens of flexible pore cushion were executed on SAW-2000 Electro-hydraulic Servo-controlled Rock Mechanics Testing System manufactured in Kexin testing instrument corporation.Complete process strain-stress curves and mechanism of rock failure for specimens were obtained,and mechanical parameters included peak strength,elastic modulus,Poisson's ratio, and so on.The physical mechanics of the grouting specimens changed rapidly with the confining pressure and grouting effect.The factors of floor heave for the belt blind inclind shaft at -800 level and return-air roadway at -600 level including the nature of rock,water,geological structure,tectonic stress,roadway layout and supporting the form of six factors.The interaction of these factors makes the opening floor heave serious.Among them, the nature of rock,water,support means and tectonic stress are major factors.Numerical simulation using FLAC software calculated the stress distribution,wall rock's displacement and plastic strain distribution of the three programs:the bare wall,the common rigidity arc,combination of flexible inverted arch structure combined bolting-grouting support.The absence of support in the bottom of the case,the tunnel show a large deformation,concentrated expression of the vault settlement,two groups of restrained,from the floor heave.The ordinary rigid composite structure against the end of Arch and flexible inverted arch could significantly control the deformation of surrounding rock,which composite structure flexible inverted arch effect was more obvious especially in the amount of floor heave control.The numerical simulation proved that the roadway at the complex rock condition uses the combined supporting of soft rock may control the stability of soft roadway well.The supporting project has successfully been put into practice ,Pre-construction plan for the repair problems on the program's parameters,structural design , supporting the choice of materials , construction organization,set the corresponding measures,vast economic profit and technological effect has been achieved,as well as a good method to control the floor heave of similar roadway has been given.
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