Information Design And Elaborate Construction Controlment Of Cutting Slopes

There are some disadvantages of traditional design pattern of cutting slopes in the stages of design, cutting and suppting. Thus could not precisely grasping the aging deformation and evolution features of cutting slopes, and dynamically dealing with the various unexpected situations and slope diseases. Based the key technical problems of Bazhong-Dazhou-Wanzhou highway in red bed region, the methods of engineering geological mechanism analysis, damage mechanics, and unsaturated soil mechanics are adopted to carry on the research. Specifically, the means of engineering geological tracing investigation, indoor rheological test, numerical calculation and monitoring are applied. Every sorts of structure type of cutting slopes, including the joint rock slopes and the accumulation slopes, are systematically researched in the fileds of deformation-failure mode, dynamic stability and deformation-failure features during excavation. On the basis, the optimization mode of supporting measures and construction controlments of every representative structure types are studied and summarized. Specific research results are showed as follows:(1)The representative structure types of cutting slopes are divided into three categories, the flat bedded slopes, the inclined bedded slopes and the accumulation horizontal slopes. Each categorie are further subdivided. The classification scheme of cutting slopes lays a good foundation for follow-up studying.(2)According to the unloading deformation-failure mechanism of cutting slopes, the typical deformation-failure modes of cutting slopes can be divided into two categories, the mode of unloading rebound and the mode of unloading rebound-creep. The mode of unloading rebound could be further divided as the tensile cracking of steep joint, the tensile-shear cracking of joint and the partial slump of accumulation. The mode of unloading rebound-creep could be further divided as the sunken slump, the flat bedded slipping, the inclined bedded slipping, the circular slipping of accumulation and the flat accumulation slipping.(3)Based on the visco-elastic-plastic model provided by FLAC3D, an initial damage tensor describing the geometric feature of rock joints is introduced, and visco-plastic partial strain increment affected by the initial damage tensor is used for calculating the evolution of damage tensor, eventually the equivalent visco-elastic-plastic damage model of joint rocks is achieved. On this basis, combining indoor rheological test results, the representative structure types of joint rock slopes are analyzed by the model. Results show, the different slope types have different deformation evotution features and damage evolution features under the step by step excavation; for the flat bedded slopes, the accumulation of damages are embodied in plastic damage of unloading rebound phase, aging accumulation of visco-plstic damage is relatively small, further showing the maximum damage evolution value increases with the excavation stage as well as the creeping rates; for the consequent bedded slopes, the development of deformation and damage have larger quantity, the accumulation of damages are not any embodied in plastic damage of unloading rebound phase but also the aging visco-plstic damage, showing the creeping rates contunuely increase in the same stage of excavation.(4)For the simulation of seepage field and deformation-failure features of accumulation horizontal slopes, results show that the instability characteristics or deformation failure modes of accumulation slopes have an obvious relation with their hydraulic conditions; the same accumulation slope may appear different deformation failure modes in the different hydraulic conditions; according to the actual geological and environmental conditions, deformation-failure mode will be different again.(5)Taking the level 4 high slope (hard on the soft), located in Bada highway, as an example, three methods of engineering geological tracing investigation, displacement monitoring, and the visco-elastic-plastic damage calculating are used. Dynamic information in the process of step by step excavation is achived. The feedback analysis of dynamic stability and relevant factors is carried on. Further more, combined with the feedback analysis case, the information design mode based on the information feedback is analyzed and summaried.(6) The construction control principles of representative structure types of cutting slopes are summaried. For the flat bedded slopes, the principle of "soft need the elaborate excavation, deep and shallow buried could be supported together, and adverse structure need the extra reinforcement" is put forwarded; for the pouring-out inclined bedded slopes, the principle of "elaborate excavation, early supporting, and medium incline need presupporing" is put forwarded; for the accumulation horizontal slopes, drainage measures should be valued and prior, the follow-up support measures could be implemented according to the evolution of deformation. Eventually, the combination of optimum supporting measures and key points of construction controlments of representative structure types are summeried, which provides the optimization design model.