| With the rapid development of all kinds of engineering construction, dam,underground engineering, slope and tunnel engineering rock mass will develop to larger, wider and deeper direction. Therefore, when we analysis the slope stability of highway, railway, open-pit mining and water conservancy industry,we have to face a more and more complex geotechnical engineering geological environment problems.The highway line form Ziyuan to Xing’an pass through a large number of cuesta which is affected by the tectonic,so the geological condition is very complicated. Based on the slope engineerin of the highway from Ziyuan to Xing’an(K21+638~ 810) this paper start a research about the Structural cuesta siliceous rock structure and rock mass slope stability. On the basis of understanding the Ziyuan regional geological environment situation and the engineering geological conditions, a detailed study of siliceous rock structure of cuesta was carried out; and by using the finite element numerical simulation software Midas GTS NX, we can make a Two-dimensional numerical simulation analysis for the slope before excavation,during excavation,after excavation and after applying supporting structure,draw the following conclusions:(1)The cuesta strike here perpendicular to the Xingning-Ziyuan tension-torsion fault strike because of Caledonian movement and the neocathaysian structural system.The gradient of the cuesta and strata inclination are almost same.The tension-torsion fault(F1) has a great influence on the development characteristics of rock mass discontinuity.(2)According to the statistical results of the rock mass structure, the strata inclination of the rock is between 290° to 305°, and the dip angle is between 20° to 30°.The first set of joints are mainly distributed in the 115° to 115°, Angle are mainly distributed in 60° to 70°;The second set of joints are mainly distributed in 295° to 300°, Angle are mainly distributed in 70° to 80°. And the development the first set of joints are more advantage than the second set of joint.(3)According to the engineering geology classification of the rock mass structure, it is concluded that Ⅲ structure plane generally spent poor combination, medium spacing, medium width to wide, low to medium continuity are more advantage. Ⅳ class structure plane generally spent poor combination, medium spacing to wide spacing, medium width, dominant low to medium continuity have an absolute advantage.(4)The thickness of the weak structural plane are mainly distributed between 100 mm to 300 mm, the packing material mainly is rock, debris clamps mud, close-grained degree are mainly composed of osteoporosis and loose, and the groundwater characteristics is mainly for(local) water penetration.It’s structural plane alteration is relatively serious,and has been badly embroidered basically, and it has the poor cementation.(5)According to the available data and laboratory test results, the rock Severe gamma is 27 kN/m3, the shear strength of cohesive force is 105 kPa, internal friction Angle is 48°, poisson’s ratio is about 0.17, elastic modulus of about 78 GPa. Rock mass discontinuity shear strength of cohesive force is 3 kPa, internal friction Angle is 32°elastic modulus of about 31 GPa. The weak discontinuity shear strength of cohesive force is 18 kPa, internal friction Angle is 23°, poisson’s ratio is about 0.25, elastic modulus of about 4.8 GPa.(6)With no supporting mode before excavation,the whole slope is stable.As excavation step by step,the state of the slope changes from stability to instability. Because of the sliding surface deepen and shear stress concentration in rock mass discontinuity and the bottom of the slope,the slope has a trend of sliding along the discontinuity.(7)The whole slope is stable as the excavation and supporting step by step under original design.Part of the slope would slide along rock mass discontinuity if there is no supporting in the process of excavation. As the same time, the stress and strain of anchor cable are increased above the excavation slope.slope creep deformation may occur.Slope would has creeping deformation as the action continues.(8)The numerical simulation result is consistent with the field of slope deformation development situation, shows that in this numerical simulation,the establishment of the model,the selection of material parameters,the selection of structure model,the selection of constitutive model and meshing are reasonable and feasible,and the results can provide reference for similar slope engineering design in the future. |
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