Research On Interaction Between Surrounding Rock And Support By TBM Techniques

In recent years, with the development of high production high efficiency mine, it needs to improve the transportation capacity and hoisting capacity. The mines newly-built、rebuild and extended gradually began adopting inclined shaft development or inclined-vertical shaft development.To ensure the construction safety of inclined shaft by TBM techniques, the research on interaction between surrounding rock of inclined shaft by TBM techniques and support is performed in the paper. Perturbation solution of axisymmetric round well under unequal compression in two directions is to further study elastoplastic solutions of inclined shaft in uniform stress field and non-uniform stress field; the problem about radial stress transfer law in surrounding rock-backfilling-segment of inclined-shaft by TBM techniques in non-uniform stress field has been studied by utilizing theory of elastic mechanics, which is to determine the load distribution outside the composite lining (segment+ backfilling); the support characteristic curve (SCC) of the composite lining is obtained by theoretical calculation and laboratory test three-dimensional numerical simulation of excavating is performed to gain the longitudinal displacement profile (LDP), which is coupled with the SCC to analyze the complete process of interaction between surrounding rock and support, and to acquire spatial distribution regularity of elastoplastic deformation of inclined shaft. The main contents and conclusions are as follows:(1) The perturbation solution of axisymmetric round well under unequal compression in two directionsThe paper has studied the perturbation solution of axisymmetric round well under unequal compression in two directions, raising the elastic stress distribution considering the second order infinitesimal and analytic dynamics of elasto-plastic boundary line, and analyzing the perturbation solution through engineering examples. The perturbation solution obtained showed that elasto-plastic boundary line is similar to ellipse,σθ and σr are equal in certain angles, and the stabilized value of σr is greater than in-situ stress. The research results are analyzed through the example of project, and compared with (?) A. Galindo solution to prove the reliability of the perturbation method, which are remarkably consistent.(2) Elasto-plasic analysis of inclined shaft (circle tunnel)In the uniform stress field, thick-walled cylinder under linear distributed loads was established for elastoplastic analysis of the spatial model, the solution of which is same to the axisymmeteic tunnel.In the non-uniform stress field, the elastic solution、the elastic-plastic boundary and the perturbation plastic solution based on M-C、D-P yield criterion of inlined shaft are aquired.The stable values of the elastic solution σr、σθ of the inclined shaft vary considerably, and σr+σθ≠2p0; the cross section of inclined shaft turns to ellipse for the non-uniform deformation of the surrounding rock, and the perturbation plastic solution based on M-C、D-P yield criterion are acquired.The parameters initial stress p0、internal friction angle(?)、cohesive force C and inclination β are influencing radius of plastic zone in the inclined shaft。 Usually, cohesive force C is not the principle factor in engineering application。(3) Elastic solution of surrounding rock-backfilling-segment in inclined shaftThe problem about stress transfer in surrounding rock-backfilling-segment of inclined-shaft by TBM techniques under complex stress condition has been studied by utilizing theory of elastic mechanics. Through the force analysis of surrounding rock-backfilling-segment ideally, the problem has been divided into two relatively simple subproblems. It acquired the stress expression and displacement expression of surrounding rock-backfilling-segment of inclined-shaft, and expressing equation of pressure transfer coefficient on the continuity condition of displacement. Bearing capacity of backfilling-segment under the inflation of some factors has been analyzed based on the above expressions. The results show that larger thickness of backfilling, maximum value and minimum value of the elastic modulus of backfilling, inclination of shaft are favourable factors to bearing capacity of backfilling-segment.(4) The support characteristic curve (SCC) of the composite lining① By adopting the freedom distortion circle, the internal force of lining with staggered segment seams was aquired. Based on the idea of the force method, the ring under non-uniform external loads was solved: M= R2/1 (2q1+q2) cos 2(?)/6, N= q0R1 (1=ε cos 2(p)② By introducing parameter ε, an algebraic relationship between external loads was built to acquire the relational expression between internal force and radial pressure p, M-εp1R2/1/2(1+εcos2(?)cos2(?),N-p1R11-εcos2(?)/1+εcos2(?)When λ= 1, in this case, under uniform external loads, there is N= p1R1, which coincides with the existing theories.It verifies the rationality of the above solutions.③ Under different loading rate of a frozen soil experiment machine, the relationship between compressive loading and compression of deformation rubber blanket test specimens was gotten, and then the constitutive relation: σ= 0.3963e3.9068AΔl (0.27MPa<σ< 88.15MPa)④ Based on the stress-strain relation of concrete materials, the relationship between external loads and radial compressive deformation was deduced:(5) The space effect of the working face in inclined shaft① Compared with the horizontal tunnel, the suffering area of the space effect of the working face in inclined shaft (the roof rock) is more larger (x/R0=-6至x/R0=8): the unexcavated part of roof rock causes earlier deformation for it is under more bigger loads than the same part in the horizontal tunnel; the excavated part of roof rock causes deformation at a slow rate for it is under smaller loads than the same part in the horizontal tunnel.② The suffering area in front of the working face is influenced by the position of monitoring point、lateral pressure coefficient and mechanics parameters:The suffering area in front of the working face of roof rock is the most larger, the floor rock is minimum part; The suffering area in front of the working face is more larger with the increasing value of lateral pressure coefficient; For the small value of mechanics parameters, the stability of the surrounding rock is poor, then the suffering area in front of the working face is small.③ The accumulative deformation uR0/uR0 (∞) is different for the variation of lateral pressure coefficient。 When λ=0.5, the value of uR0/uR0 (∞) in the roof and floor is bigger; When λ=1.25 and λ=1.0, the values of uR0/uR0 (∞) are of little change, among which the roof and floor is smaller.④ The relationship of uR0 and x/R0 in uniform stress field is expressed by piecewise function:According to the monitoring results of deformation in monitoring section, the fitted data of a、b、a0、b0 and a1、b1 are acquired, then the relational expression of uR0 and x/R0 are as follows:A、The fitting results in K1zh stratum:B、The fitting results in J2a stratum:C、The fitting results in J2z stratum:D、The fitting results in J1-2y stratum:6、Analysis of complete process of interaction between surrounding rock and support in inclined shaft under elastioplastic deformation condition(1) According to the theory about space effect of the working face, and the fitting function based on the monitoring data of simulation, the paper acquired the spatial distribution regulation of surrounding rock radial elastioplastic deformation in the four stratum s.The results show that: ①If the supporting time is early, the roof rock enters into plastic stage is later than the case that there is no support or later support. But in the four statums, it is too early of the roof rock entering into plastic stage that the combined effect of supporting force p1 and virtual supporting force p2* is of little effect. ②In the premise the support is not out of working, the earlier the supporting time, the better the inhibitory effect to the radial elastioplastic deformation of roof rock.(2) The analysis of complete process of interaction between surrounding rock (roof rock) -support (segment+backfilling) in inclined shaft by TBM techniques in uniform stress field gave the conclusion of interaction between surrounding rock-support in inclined shaft, and analytical solution of complete process of interaction between surrounding rock-supporting inclined shaft.