| Based on the project of the NSFC,"Research on the damage and stability control of surrounding rock of deep large deformation roadway",on the basis of classifying and mechanics analysis of surrounding rock of layered roadway,the paper studies the distribution and failure mechanism of plastic zone in surrounding rock of layered roadway,and the law and characteristics of plastic zone expansion of surrounding rock of layered roadway.This paper analyzes the principle and principle of surrounding rock control of layered roadway,and puts forward the method of "full section anchor cable + steel bracket + net jet grouting" to strengthen the support scheme and put it into practice,the application of this scheme has achieved good support effect on the spot.According to the theory of fracture mechanics,elastoplastic mechanics and mine pressure,the types and characteristics of surrounding rock of layered roadway are summarized,and the mechanical characteristics and failure mechanism of surrounding rock of layered roadway are analyzed,and the influencing factors of plastic zone of surrounding rock of layered roadway are understood.According to the research,the main factors of bedding inclination angle are classified into three categories,which are horizontal layer roadway surrounding rock,inclined layered roadway surrounding rock,and staggered roadway surrounding rock.The damage form and mechanism difference of the surrounding rock of the layered roadway with different inclination angle are obvious.The factors influencing the plastic zone of surrounding rock of layered roadway include thickness h,rock mechanics parameter,bedding inclination angle and so on.By using FLAC3 D numerical simulation software,the surrounding rock calculation model of 10 kinds of layered roadways is established,and the surrounding rock of horizontal layered roadway is calculated by simulation(upper hard lower soft,upper soft lower hard,middle soft),inclined layered roadway surrounding rock(upper hard lower soft,upper soft lower hard,middle soft),staggered layered roadway surrounding rock condition of plastic zone shape,It is considered that in the upper hard and soft layer,the plastic zone,regardless of the thickness of the delamination or the dip angle,always expands the hard rock part in the soft rock,but the plastic part of the hard rock has obvious deformity characteristics.The influence of the dip angle of the bedding layer on the plastic zone expands the range of the plastic zone,which expands in two directions in the upper and lower layers along the inclined direction of the bedding plane,which seriously affects the stability of the surrounding rock of the roadway.In the upper soft and hard layer,it cannot be simply understood as the reverse of the upper hard soft layer,it has two obvious characteristics one is that the plastic zone of the soft rock is larger than that of the bottom plate,and the other is inclined along the dip angle of the bedding plane,and the plastic zone expansion in soft rock is elongated in relation to the upper hard soft case.These obvious characteristics make the damage of surrounding rock more serious,especially the roof.Under the stratification of middle-weak type,the plastic zone of roadway surrounding rock is the most abundant in the middle weak interlayer,and the plastic zone surrounding development is most obvious.The surrounding rock of the staggered stratified roadway is a special part of the surrounding rock of the layered roadway,the soft rock in the plastic zone of the surrounding rock of the roadway expands fully,but there is little expansion in the hard rock.The plastic zone expansion of surrounding rock mass of layered roadway usually undergoes four periods,such as developmental distortion period,malignant rapid expansion period,malignant slow expansion period and extended stable period.Plastic zone from one rock to another to break through the formation of distortion out of the present developmental distortion stage,the malignant rapid expansion period plastic zone will first along the distortion direction of the tip breakthrough depth of a certain distance,and associated with cutting-edge branches.The stage of deformation of the surrounding rock can be increased by the malignant slow expansion period.The external morphology of plastic zone in the extended stable period is basically unchanged.The plastic zone of surrounding rock of layered roadway has three prominent characteristics,such as breakthrough,surrounding development and development of interlayer.On the basis of the above research,according to the engineering situation,this paper puts forward the "full-section anchor cable + STEEL bracket + NET Jet grouting" step joint and graded reinforcement support scheme.The results of data monitoring show that the scheme has achieved good control effect by using the scheme in engineering practice. |
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