An Chugong Road Red Rock Slope Stability

The red bed is a clastic sedimentary rock mainly deposit by red continental sedimentation, the rock property is mainly composed by sandstone, mudstone, siltstone and arenaceous shale.It is a famous easy slip stratum.There 2/3 of the An-Chu highway across the red bed area, it is have great influence in superhighway construct because the special engineering characteristic of red bed, especially influence to the cut side slopes.Combine to the engineering actual of An-Chu highway, follow red bed's deposition entironment of sediment, the characteristic of the red bed soft rock geologic strata, the basic regulation structure of geology, the red bed soft rock rock structure characteristic, and pass to investigate analysis, carry on a research of the distortion and steady break mechanism of the road side slope in An-Chu highway area.In accordance with the natural condition of the contracts 8 and 9 along AnChu Expressway and by means of field investigation and analysis, certain subjects are discussed in this paper, including the physical condition of red-bed type deposit, features of red beds and softrock strata in red beds. Basic rides for geological structure, structural features of soft rock nlasses in red beds as well as the failure mechanism caused by deformation a loss of stability of cut side slopes. The main results of this paper can be summed up as follows:(1) The red bed in the middle of YunNan is alternate for the soft rock and hard rock, in existence by alternating layers, the layer combines weak. Had influenced by the regional structure, the layer has great torsion, fold and high angle fault with argillized phenomenon. The ability of red bed soft rock stick up to air slake is weak, has obvious differential air slake and the speed of disaggregation in mudstone is quick. The soft rock strength lowers and argillized seam is very lowe under the satisfied water condition.(2) Because of its special geology structure and the rock mass structure characteristic, After the road side slope digged ,The major factors of stabilityand defomation and failure models are summarized as follows: ①The distortion and steady break mechanism of bedding rock slopes, ②structure planes with disadvantageous combination, ③cut layer in Anti-dip slopes, ④ steady break follows the fracture structure district, ⑤ the slope loosen to move to transform to lose steady.(3) Studies are carried on stability of dip slope. The author suggests using stereographic projection of structure planes to judge the failure modes of dip slope in red beds. Stereographic projection relationship of structure planes with slope is presented. And the stability analysis method such as Engineering Geology analogy, Limited-equilibrium Method, Numerical Analsis.The essential factors involved in stability of slope are presented are given.(4) To analyse the grade ratio and the applicability of defend measures of the red bed slope, sum up the especially request of the red bed slope design and construct.(5) Because special engineering characteristic of red strata has big influence of the road slope, There proper reinforcing measures must be taken, and the reinforcing effects must be evaluated, There for the deformation monitoring of slopes is necessary not only during the construction but after construction.