Research On The Indoor Model Of Uprooted Foundation Bearing Capacity And Torsion Resistancel

As a new type of variable section pile,the root bond is arranged in the specific position of the pile body to increase the contact area between the pile body and the soil body,so as to improve the bearing capacity of the foundation of the root pile foundation.However,because the relationship between its foundation and soil is too complex,and the construction process is more troublesome than that of the equal-section pile,the research on the root foundation in China mainly remains in the field in situ test and finite element simulation.At present,there are few theoretical studies on uplift and torsion characteristics of the root foundation.Therefore,it is very important to study the uplift and torsion resistance of the root foundation.In this paper,the indoor model test was used to study the unplugging and torsion characteristics of the root foundation as follows:The model box is used to load sand soil,and the research experiments are carried out on the uplift and torsion characteristics of the root foundation from the interface characteristics,the depth of root bond,the number of root bond layers and the arrangement mode of root bond of adjacent layers,etc.,and the strain of pile body,uplift displacement,torsion Angle of pile top and pile body,vertical and circumferential stress of soil body around pile are measured.The results show that the tension and torsion bearing capacity of pile foundation are increased obviously and the tendency of sudden failure is decreased.The ultimate uplift bearing capacity,torsion bearing capacity,axial force change of pile body,torque change of pile body and stress change of soil body around pile are analyzed.The results show that there is a sudden change of axial force at the cross section of the root bond,and the main bearing area of the foundation is located near the buried depth of the root bond.There are differences and similarities in the load-bearing characteristics of the root foundation.Similarity: the increase of root bond makes the bearing capacity of pull-out and torsion resistance obviously better than that of equal-section pile under the same condition,and it can strengthen the ultimate pull-out amount and the maximum deflection Angle of pile tip.Difference: the root foundation is obviously better than the anti-pull-out in the improvement of the anti-torsion property,and the staggered root bond arrangement has better anti-pull-out property,while thenon-staggered root bond arrangement has greater improvement in the anti-torsion property.