| The shear strength parameters of rock-soils are very important to evaluate the slope stability.In the actual projects,many slopes become instability because of the angle of internal friction with a small deviation only 1 to 2 degree.Ensuring the accuracy of the shear strength parameters of rock-soils is the primary task during the period of slope stability calculation and engineering design.On the basis of the collaborative optimization algorithm,a new approach that takes advantage of collaborative back analysis to obtain the shear strength parameters of complex structure slope has been proposed.The so-called complex structure slope means that the location of its potential failure surface is unknown and there are many kinds of soil need to be inversed.As there is no exact steady state of slope,two typical loading cases such as the design storm condition and the natural condition have been selected for the inversion.The back analysis of shear strength parameters have been done in several typical profiles of a practical slope project under the natural and storm conditions.According to the inversion recommend shear strength parameters,the slope stability has been analyzed and compared in two stages of before and after reservoir impoundment by the limit equilibrium method and the finite element method.Meanwhile,the mechanical properties of reinforcement measures have been evaluated and analyzed reasonably based on internal force and deformation analysis of the pre-stressed anchor cables and anti-slide piles.The conclusions are listed as follows:(1)The shear strength parameters which are obtained from back analysis are consistent with the geological recommended parameters no matter in the natural condition or storm condition.It means that the hierarchy and parallelism of collaborative optimization is an effective way to reduce the influence among the inversed soils and the calculated profiles.Meanwhile,it also can improve the problem that the inversed parameters are always having no unique solution.The collaborative optimization method can provide a new way for the shear strength parameter back analysis of complex structure slope.(2)The result of slope stability analysis shows:no matter useing limit equilibrium method or finite element method,reservoir water impounding is the main factor.After impoundment,the heavy rain has the most serious impact on slope stability and leads to the least safety factor among the occasional cases of rapid drawdown,heavy rain and earthquake under operation.So the security monitoring of slope stability should be enhanced particularly when encountering rainstorm.(3)According to the mechanical properties analysis results of pre-stressed anchors:the axial force value and variation features of pre-stressed anchors in quasi-three-dimensional numerical calculation are consistent with the results of the three-dimensional numerical calculation.The axial force values of pre-stressed anchors increase sharply in heavy rain conditions.The prestress of some pre-stressed anchors are reduced in different levels.Overall,its primary support function can be normal executed.(4)According to the mechanical properties analysis results of anti-slide piles:the maximum internal forces and deformations of anti-slide piles appear in different design conditions,the maximum internal forces appear in storm conditions,while the maximum deformations occur in earthquake conditions.In addition,the force situation of anti-slide piles is different form each other as the change of its spatial distribution,the anti-slide piles with larger force are located in the center profile of the slope,while,the internal force of anti-slide piles which are built in both sides of slope is relatively small.Overall the reinforcements are reasonable and practicable. |
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