| This dissertation is mainly studying bedding rock cutting slope in Puli-Xuanwei Expressway in Yunnan Province. Considering commonly exsiting problems on bedding rock slope such as slope stability, slope excavation and supporting technology, combined with the National Science Foundation of China research project[51374163] and special technology research project from Transport Department of Yunnan Province[YJK2010(A)07-a], from the bedding slope stability, the dissertation has concentrated on studying and discussing the following aspects: slope stability, the property of structural surface, stability calculation method, blasting excavation and the optimization of slope supporting.The main work is listed as follows:(1)Geologic survey has been finished on bedding rock slope in Puli-Xuanwei Expressway in Yunnan Province, and after the survey it was categorized according to rock property, the structural property of rock stratum, failure mode and slope stability, and the preliminary evaluation on slope stability has been given so as to predict slope constructing problems.(2)According to the engineering geological characteristics of bedding rock slope, the structural surfaces are divided into four types based on their formation mode. A home-made loading device is used to test the compression strength and shear strength of structural surfaces under natural conditions and strength parameter values are obtained by least square linear fitting method, structural surface shear strength parameter values are obtained. By contrasting the equivalent shear strength of Mohr-Coulomb method based on JRC- JCS, the results basically agree with each other and the feasibility of the device is verified. Considering filling thickness, moisture content of filler and other factors based on the different types of slope structural planes, several shear tests were carried out in order to get shear strength parameters relative to structural planes. The test results provide reference data for correct evaluation on the characteristics of structure planes and stability calculation of the bedding rock slope in the next stage. This research has provided a simple test method for the choice of strength parameters relative to structural planes in the test field.(3)Focused on bedding slope with multiple structural surfaces, based on the theory of upper bound limit method, by applying the volume force increment method, and considering the defects of limit analysis model of single sliding surface, arbitrary block model considering the dislocation effects of multiple rock layers which contain structural planes has been built. When the rock mass undertakes ultimate destruction from external load, the work that is done by external loads is equal to the work rock mass absorbs. Based on this premise, relevant equation can be established; thereby the calculation formula of slope stability coefficient can be derived. After analyzing typical numerical examples of slope and contrasting results of discrete element numerical simulation, the feasibility and applicability of this method are verified. Through the calculation of a bedding rock slope located in Puli-Xuanwei Expressway in Yunnan Province, the result shows that the stability coefficient is close to the result of discrete element numerical simulation..The difference between the two kinds of result is analyzed It provides a new calculation method for evaluating the stability of such slopes.(4)Considering surface damage caused by blasting excavation on bedding rock slope, experiment has benn carried out in test field. By applicating sound waves testing technology combined with the method of monitoring vibration velocity, the sound velocity at different slope depths and particle velocity in different locations are acquired. It analyzed injury range of slope under different doses when single and multiple blasts are taken into effect, as well as the attenuation law of the shock wave propagation. It shows that the damage range increases with the increase of vibration velocity and there is a corresponding relationship between the vibration velocity and damage depth of slope at any point of the blasting area.The relationship presents linear for a single blast and presents nonlinear for repeated blasts. Assume 10% decrease in sound velocity as the damage limit and assume the depth of damage as the blasting control value, then the responding critical vibration velocity and damage radius can be acuired under a single blast and repeated blasts respectively. Meanwhile, acoording to Sadov's Formula, the largest single detonation dose is deduced by two blasting methods, it provides guidance for safety control on slope blasting in test field.(5)Though stratum direction and slope plane direction are not consistent in practice, it doesn't take this inconsistency into consideration when referring to anchor bolt support in bedding slope. On this basis, optimal horizontal angle under pre-support of anchor bolt is studied after considering the different angles of stratum direction with slope plane direction, and the calculation model of slope supporting is set up, then the corresponding relational expression is deduced. The results show that the supporting which takes the optimal direction angle of the anchor cable into consideration is much more effective in limiting the stress and deformation of the slope and it can improve the stability of the slope.It provides a reference for actual slope reinforcement design.(6)Instability is common under excavation of bedding slope. Considering potential instability of the bedding rock slope under excavation, such a method is put forward: pre-supporting the slope in reserved area, then excavating the slope stratum by stratum. In this dissertation, concrete analysis process about the excavation method is provided and it verifies its feasibility combined with the numerical example in test field. |
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