Research On Features Of Driving Force Acting On Anti-slide Piles With Pre-stressed Anchor Cable Based On Force System Monitoring

Study on features of driving force anting on anti-slide piles under the action of prestressing force can make the calculation of the internal force of the piles more reliable, and it is of great significance for the design and calculation theory of the anti-slide pile with prestressed anchor cable. However, the change of driving force under the influence of prestressed anchor cable does not reach agreement at present. To further investigate the problem, soil pressure and anchorage force of anti-s lide piles with prestressd anchor cable were monitored for about two years, with Nanshan landslide treatment in Xinmin No.2 mine, Liliu Coking Coal Group, Shanxi as the research object. According to the monitoring result, the distribution of driving force, ground reaction pressure behind the pile and the changes of soil pressure and prestress were analyzed, based on which the collaborative relationship of soil pressure and cable stress were analyzed selectively and the effect of prestressed anchor cable action on the distribution and variation characters of driving force were studied. Based on the above analysis results, the following conclusions are drawn:1. In the long term, the driving force is mainly influenced by the rainfall and the effect of the prestressed anchor cable; under the influence of the prestressed anchor cable, the driving force and the cable stress show a cooperative change, which is mainly reflected in three stages including stage of cable stretch locking, stage of prestressing loss and stage of coordination deformation of pile and anchor. Among them, the first two stages mainly show the influence of the prestress change on soil pressure. After the first two stages, the loss of prestress reaches the maximum, and the change of the soil pressure and the cable stress reach mutual coordination and finally reach the agreement. In the stage of cable stretch locking, whether soil pressure behind pile appear significant growth with the stretch locking of anchor cable depends mainly on compression deformation of the soil behind pile under the pressure of anti-slide pile. The higher the compression deformation degree is, the more significantly the soil pressure increased.2. The shape of measured driving force distribution along the pile is similar to parabola. The distribution of driving force is mainly affected by the thickness and lithology of landslide mass, deformation difference of adjacent strata and prestressed anchor cable etc. The effect of prestressed anchor cable on the distribution of driving force embodied in the stage of short period of anchor cable stretch locking process on the one hand. In this stage, the influence of prestress on the distribution of driving force is mainly determined by the number of initial prestress and the combination of anti-s lide pile and anchor cable. When the initial prestressing force is small or the structure of anti-s lide pile and anchor cable separation is used, the effect of prestress on the distribution of driving force is not significant in this stage. The influence of prestressed anchor cable on driving force is reflected in the long-term stage of the pile anchor coordination on the other hand. Under the long term effect of the prestressed anchor cable, the force acting point of the driving force is gradually moving downward, and the distribution form of the driving force tends to be more uniform;3. The influence degree of prestressed anchor cable on driving force is mainly related to the rock structure, the thickness of the sliding mass, the number of the initial prestress and the combination of pile and anchor. In the design of anti-s lide pile with prestressed anchor cable, we should evaluate the influence degree of the prestressed anchor cable on driving force in different stages according to the different combinations of the four factors, in order to make the design more reasonable and reliable...