Research On The Effect Of Anchor Cable Prestress Loss On The Performance Of Pile-anchor Support Structure Of Foundation Trench

With the gradual expansion of the scale of foundation pit engineering in China,the safety of pile anchor support structure has been paid more and more attention by the public.However,in practice,there is still a lack of relevant theoretical and experimental research.The prestress loss of anchor cable is an important factor affecting the safety of foundation pit.Whether the anchor cable can provide enough prestress will greatly affect the safety of foundation pit.By using finite element software and taking a pile-anchor support project as the research object,the changes of anchor cable prestress on horizontal displacement,soil displacement behind pit and soil pressure behind pile are analyzed,which shows that the upper anchor cable plays an important role in controlling the deformation of the whole support structure.Relevant research contents are as follows:(1)Through numerical simulation of a section of the project,it is found that the monitoring data of the deep horizontal displacement of the supporting structure is slightly larger than that of the finite element software simulation,but the trend of the two is the same,which proves that the model can further simulate the pile anchor supporting structure.(2)By simulating the prestress loss of each layer of anchor cable,it is found that no matter the horizontal displacement of supporting structure,the vertical displacement of soil behind the pit,or the change of active earth pressure behind the pile,the influence of the upper layer of anchor cable is greater than that of the lower layer of anchor cable,so in the project,it is important to monitor the prestress of the upper layer of anchor cable.(3)The horizontal displacement of the supporting structure will gradually increase and the active earth pressure after the pile will gradually decrease with the prestress loss of the anchor cable.The change rule is related to the position of the anchor cable.With the increase of prestress loss of anchor cable,the supporting pile may break first in the middle and upper part.By monitoring the horizontal displacement of the crown beam of the supporting structure,the deformation of the supporting structure can also be predicted.