The Study Of Karst Tunnel With The Joint Distribution Of The Influence On The Deformation Of Surrounding Rock

In recent years，the construction of the railway go in to the mountains，as therestrictions of reasons such as railway linear, terrain and Geological conditions，thetunnel engineering became one of the most important structure form in the railwayconstruction. In the process of karst tunnel construction, underground engineeringgeological disasters became the main engineering geological problems which affectthe engineering safety. And the karst tunnel floor collapse problems will became veryprominent. The karst geological disasters will make the machines brake and increasethe money and time used in the tunnel projects and then get big trouble for theprojects and will become the potential threats in the post-operation of railway. So theproblems of karst become more and more important.This paper systematically analyzes the joint rock mechanical properties andstructure of surface features. To consult the relevant information on has carried on theinduction summary joint rock mass mechanics and dynamics; Aiming at concealedkarst cave tunnel wall position, this feature are analyzed under different jointgeometric distribution, the impact of tunnel excavation on surrounding rockdeformation, with the introduction of monte carlo random number generationprinciple, generated by random joint program compiled by using matlab software, andapplied it to the fairy cave concealed karst cave tunnel excavation of numericalsimulation。Through the study of this article, preliminary obtained the following conclusions:(1) Through the fairy cave tunnel engineering geological conditions andcharacteristics of karst development survey the fairy cave tunnel karst developmentform is given priority to with vertical development is given priority to thecharacteristics of the horizontal development. (2) Through the fairy cave tunnel excavation of surrounding rock masscharacteristics were investigated, and found the fairy cave tunnel joint development isgiven priority to with steep dip, dip Angle is mainly between60°to90°, andbetween the joint trace length is2m to5m, joint spacing are mainly composed of0.5m to2m, joint rock type integrity is good, part of the karst development insurrounding rock is broken. In the statistical distribution rule on the basis of theexcavation of surrounding grade, found that karst development was a reduced level ofsurrounding rock, rock broken, the main factors of the joints and fissures.(3) Using geological radar detection, found not only in the tunnel karst exposedsection of surrounding rock is poorer, joint fissure development, near the uncoveredconcealed karst cave, surrounding rock is poorer, same concealed karst cave andfissures development brought great hidden trouble to the tunnel surrounding rockstability.(4) Using the state of discrete element numerical simulation software, establishdifferent joint generalized model, the geometric distribution characteristics of tunneland concealed karst cave around different spacing, different Angle and thedeformation of surrounding rock under different combination relationship problemsare studied. Found that when the joint Angle changes, surrounding rock deformationaffected by a certain, when the joint is level to the development, the surrounding rockdeformation, poor rock mass stability. When change joint spacing, surrounding rockdeformation in the larger changes, when the joint spacing is0.5m near cave side ofthe tunnel deformation is spacing is about2times of4m, explain the change of thejoint spacing greatly affected the stability of surrounding rock. When joint and a set ofchanges to two groups, the surrounding rock is obviously increased, and when thejoint combination way not at the same time, the deformation of surrounding rock andtherefore change.(5) Considering in the practical engineering, the development of joint usuallyhave the characteristics of randomness, in numerical simulation, if only by the jointoccurrence, spacing of different structural plane, usually have some differences with the actual situation, this article introduces monte carlo random number generatingmethod, based on the characteristics of structural plane distribution of probability andstatistics, compiled using Matlab software to generate random joint program.(6)Will be concealed karst cave fairy cave tunnel DK12+420as the researchobject. Through field investigation, has carried on the detailed geological analysis ofthe situation of constraints, find out the structure characteristics of the developmentcurrent location advantage. Combining with Matlab and the state of software, moreaccord with the actual situation of the numerical model is established, and analysesthe position of tunnel surrounding rock deformation and the plastic zone, judgewhether the cave in a safe place.(7) Will be the scene of the displacement monitoring data and the theoreticalcalculation of the displacement value, proved the rationality of the theoreticalcalculation.