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边(滑)坡体的破坏属于破坏力学范畴,当滑面上每点都达到极限应力和极限应变状态时,材料进入破坏,此时岩土体抗剪强度得到充分发挥,这就是破坏力学中的破坏准则。通常当有支挡结构与岩土介质共同作用时,滑面上土体一般不处于极限平衡状态,而可能处于弹性平衡或者局部塑性极限平衡状态。这种受力状态不是设计情况下的受力状态。多年来,岩土工程设计一直采用极限状态设计方法,即传统方法中计算得到的支挡结构上的岩土侧压力是在坡体整体破坏且岩土体强度充分发挥时的岩土侧压力,也就是土体处于极限平衡状态且支挡结构有充分位移时作用在支挡结构上的岩土压力,按此设计既能保证坡体安全,又能最大限度地节省经费。因此,采用有限元强度折减法来考虑岩土介质与支挡结构的共同作用时也应遵循这一原则,即要求作用在支挡结构上的岩土侧压力与传统方法计算得到的岩土侧压力大体相当,在此条件下根据岩土介质与支挡结构的共同作用来确定支挡结构的内力。按照此原则,采用有限元强度折减法,不但得到了滑坡推力的大小和分布,而且通过有限元桩-土共同作用模型计算得到了抗滑桩的弯矩和剪力,并与传统方法进行了比较。算例表明采用有限元强度折减法来计算抗滑桩的内力是可行的,该方法增大了支挡结构设计的可靠性和经济性。
The failure of the side (slip) slope belongs to the category of destructive mechanics. When each point on the slip surface reaches the limit stress and the ultimate strain state, the material will enter and destroy, and the shear strength of the rock and soil body will be brought into full play. The destruction of the guidelines. Usually when there is a support structure and geotechnical medium interaction, the soil on the sliding surface is generally not in the limit equilibrium, and may be in elastic equilibrium or local plastic limit equilibrium. This state of stress is not the state of stress in the design situation. For many years, the design method of limit state has been adopted in geotechnical engineering design. The lateral pressure of the rock on the support structure calculated by the traditional method is the lateral pressure of the rock mass when the whole slope is damaged and the strength of the rock mass is fully exerted. That is, when the soil is in the state of limit equilibrium and the supporting structure has sufficient displacement, the rock-soil pressure acting on the retaining structure can ensure the safety of the slope and save the maximum expense. Therefore, the strength reduction method using finite element method to consider the joint action of geotechnical media and retaining structure should follow this principle, which requires the lateral pressure on the retaining structure of rock and soil calculated by the traditional method side The pressure is roughly the same, and under this condition, the internal force of the retaining structure is determined by the joint action of the geotechnical medium and the retaining structure. According to this principle, not only the magnitude and distribution of landslide thrust are obtained by finite element strength reduction method, but also the bending moment and shear force of anti-slide pile are calculated by the finite element pile-soil interaction model and compared with the traditional method Compare The examples show that it is feasible to calculate the internal forces of anti-slide piles by the strength reduction method of finite element method. This method increases the reliability and economy of the support structure design.