Study On Deformation And Failure Law Of Surrounding Rock In Swelling Rock Roadway Under The Condition Of Humidity Field

At present,the researches on the deformation rule of the surrounding rock in swelling rock roadways on the condition of humidity field is not comprehensive at home and abroad.Firstly,a model test of similar materials has been designed to explore the deformation variation regular of swelling rock and cave wall around the roadway under the action of the excavation water,the bottom water and initial geo-stress.(1)Under the action of the excavation water,the bottom water and initial geo-stress,the characteristics of the surrounding rock deformation of swelling rock roadways can be concluded as follows.The deformation zone is a comparatively regular shape combined by two arcs,of which the upper part is a semi-circle,the lower part being a semi-ellipse.The two arcs share the same symmetry axis which links the roadway vault and the central line of the floor.(2)The graphs of displacement against time are plotted according to the data collected,from which the side convergence of the roadway wall and the vault subsidence can be observed visually.We can find that the graphs of side convergence of the roadway wall and the vault subsidence are similar.Both of them increased rapidly in the early stage due to the application of load,then they increased slowly and stabilized gradually.Although,the vault subsidence increased slowly in the middle stage,it still had a relatively fast trend.Then,based on the distribution of the humidity field obtained by the project fund,the typical modeling process of the humidity field in ABAQUS is introduced,and the coupling between the humidity field and the ground stress field is realized.The results of the model test and numerical simulation are compared,and the feasibility of the numerical simulation is verified.Finally,the influence of the expansion of the surrounding rock,the lining,the burial depth,the depth-span ratio and the lateral pressure coefficient on the deformation of the surrounding rock of the roadway was systematically analyzed under the condition of the humidity field,and the general law of deformation of the surrounding rock in the roadway of swelling rock was obtained.Some valuable suggestions and references could be provided for the selection of reasonable support scheme and the related design and construction of the swelling rock roadways.(1)Under the same working condition,the anisotropic deformation of the swelling surrounding rock is about 40% larger than the non-swelling surrounding rock.Therefore,in actual engineering,the influence of the humidity field must be considered and the support should be strengthened.(2)Under the conditions of the roadway without expansion surrounding rock,the lining can effectively reduce the vault subsidence of the roadway.While in the case of the roadway of the swelling rock,the effect is particularly evident.Before the lining is applied,the vault subsidence volume 26.9cm and the floor heaves volume 14.3cm,which reduced to 12.0cm and 11.5cm after the lining is applied.So in the actual engineering,it is necessary to consider whether the surrounding rock of the roadway has expansibility.The deformation of swelling rock roadway is large and the lining can reduce the deformation around by 50%.(3)For a straight-wall archway with a high-to-height ratio of 1:2 and the ratio of horizontal stress to vertical stress being 0.5,with the increase of buried depth,two slope deformation increased gradually and the trend increase with time.As a whole,the side displacement increases about 1cm as the buried depth increases 25 m.The greater the depth of the burial is,the greater the vault subsidence and the floor heave will be.In the roadway without expansion surrounding rock,as the buried depth increased by 25 m,the vault subsidence increases about 0.8cm,and the floor heave increases about 0.8cm.In the roadway of the swelling rock,buried depth increased by 25 m,the vault subsidence increases about 2.3cm,and the floor heave increased gradually,which is mainly embodied in the bottom of the roadway.(4)As the burial depth increases,the plastic deformation zone of the surrounding rock expands towards the bottom and both sides.Especially in the swelling rock roadway,the plastic deformation zone leads the bottom vertical deformation trend to be more and more obvious,so the support for the bottom of the two sides must to be strengthened in deep buried roadways.(5)When the depth-span ratio and the stress ratio is relatively small,it is mainly affected by the vertical stress.The vault deformation is large and the floor deformation is small.When the surrounding rock has expansibility,the vault deformation increases by more than 50%.In this case,the vault support structure should be strengthened.When the depth-span ratio and the stress ratio is relatively large,it is mainly affected by the horizontal stress.The roadway is squeezed,and the pressure of both sides are transmitted to the bottom floor,so that the floor deformation is large and the vault deformation is small.When the surrounding rock has expansibility,the floor deformation increases by 30%.In this case,the floor support structure should be strengthened.(6)When the stress ratio increases,the surrounding rock is affected by the horizontal stress more than the vertical stress,and the plastic deformation area of the surrounding rock extends to the top plate and the bottom plate.In this situation,the stress ratio increases by 0.5,the displacement of deformation on the two sides increases by 3cm,and the floor is subjected to horizontal stress.The deformation is particularly obvious.When the stress is relatively large,the deformation of the bottom plate will reach 4 times.The support structure of the bottom plate and the two sides should be strengthened.