Experimental Study On Bearing Mechanism And Group Anchor Effect Of Inflatable Anchor With Several Airbags In Sand Stratum

The inflatable anchor of several airbags as a new type of anchor,which is improvement and innovation on the basis of single balloon inflatable anchor.A large area of soft ground is widely distributed in the coastal areas which are developing at high speed,in the area of engineering construction and the utilization of marine resources,this new type of inflatable anchor with several airbags and single balloon anchor have its special advantages,such as fast and effective reinforcement of the soft foundation area or to provide greater anti float anchor force,and recyclable use etc..The domestic and foreign scholars have conducted research on inflation anchor,gained a lot of achievements,but there is little research and application of inflatable anchor with several airbags,the bearing capacity and the anchoring mechanism is not clear.Therefore,to be on this new type of inflatable anchor with several airbags used in practical engineering,it is also necessary to carry out a lot of research work,such as research on anchor group effect etc..In this paper,indoor model tests are carried out to carry out uplift test of single and multiple with different arrangement forms of inflatable anchor with several airbags in sand soil layer,the change rules of uplift capacity and displacement under different working conditions are studied,and compared with the experimental results of single balloon inflatable anchor,as well as research on it was in the anchor group effect,the main research contents and achievements are as follows:(1)Through the analysis and research of the original designed single balloon anchor rod,a new type of inflatable anchor of several airbags and a set of model test device for single anchor and group anchor pullout test were developed.At the same time,relevant tests were carried out on the selected sand soil samples,and the basic physical and mechanical parameters of sand were obtained.(2)The uplift test of inflatable anchor with several airbags under different inflation pressure,air bag spacing,single capsule length and buried depth is carried out.It is concluded that the air pressure has a significant influence on the ultimate uplift capacity of the inflatable anchor with several airbags.And there is a limit to the influence of the distance between the air bags on the bearing capacity and the displacement.After analyzing the influence of the length of airbag on the bearing capacity and displacement of the inflatable anchor with several airbags,it is concluded that the length of the airbag should be controlled in a reasonable range.With the increase of embedment depth,the bearing capacity of the inflatable anchor with several airbags and the ordinary anchor bolt is greatly improved,but the bearing capacity of the inflatable anchor with several airbags is more obvious than the ordinary anchor.The experimental data were fitted by the least square principle,it is found that the Q-S curve accords with the distribution law of exponential function.(3)For the uplift test of double anchors,the average ultimate bearing capacity increases first and then decreases with the increase of the distance between the anchors,and the effect of the anchor group increases first and then decreases,and the anchor group effect also increases first and then decreases.Under the optimum spacing Ru=35cm and the length of single air sac 120 mm,the uplift test of three anchor and four anchor is carried out on the inflatable anchor of several airbags,finally,it is concluded that the layout form of the four anchors(rectangular)is the optimal arrangement.(4)The bearing capacity of the inflatable anchor with several airbags is theoretically analyzed,and its bearing capacity is mainly composed of two parts: end resistance and lateral friction resistance.Based on the analysis of the theory of cavity expansion and inflatable anchor of several airbags tip resistance and friction resistance,the bearing capacity calculation formula,At the same time,the introduction of the two correction parameters associated with tip resistance and friction resistance,the formula is modified.And the failure modes of inflatable anchor with several airbags are summarized and analyzed.