Model Test Research On Self-anchored Static Load Test Technology Of Foundation Pile

Pile foundation has many advantages such as effectively improving foundation bearing capacity and improving settlement deformation,so it is widely used in engineering.For pile foundation field,it is of practical guiding significance to the project if the bearing capacity of foundation pile can be measured accurately and reliably.The self-anchor static load test technology of the foundation pile is a new method for testing the bearing capacity of the foundation pile.On the basis of reference to the domestic and foreign literature,this paper is based on the theoretical research and analysis,and uses the indoor model test and the finite element ABAQUS software analysis as the means,mainly aimed at the following aspects of in-depth research:Firstly,the existing static load testing methods of foundation piles and the technical principle of static load testing by self-anchoring method are introduced in detail through the research and analysis of relevant references at home and abroad.The load transfer mechanism of pile under vertical load and the calculation method of vertical bearing capacity of single pile are discussed.Based on the minimum logarithmic error square sum of the combined model as the objective function to solve the optimal weighting coefficient,and then the optimal weighted geometric average combined forecasting model is derived to predict the pull-out bearing capacity of the bolt.Based on Meyehof failure mode and arch forming theory,in view of the reinforcement effect of anchor rod on pile end resistance and pile side friction resistance,the mechanism of pile-anchor-soil interaction is further discussed.Secondly,on the basis of the above theory,in order to discuss the interaction of pile-anchor-soil in the static load test of foundation pile,the model test is designed and carried out in the laboratory.Before the model test,the relevant physical geotechnical tests were carried out according to the relevant codes.The conventional static load test and the self-anchored static load test of the foundation pile were completed respectively,the load and settlement curves,and the change of pile body force and the ultimate bearing capacity of the foundation pile under the conventional static load test were obtained.In the self-anchored static load test of foundation pile,the load settlement curve of pile,the change curve of axial force of pile body and the side resistance of pile are studied with different anchorage depth,the same ratio of pile length to diameter and the same anchorage depth,and with different ratio of length to diameter ratio of pile to diameter.The variation is compared and analyzed between the conventional static load test and the self-anchored static load test of thefoundation pile,and the influence of the anchor rod at the bottom of the pile on the load-displacement curve of the foundation pile is discussed at the same time.Finally,using the soil parameters obtained from the indoor test and the collected parameters of the test materials,the numerical simulation of the indoor model test is carried out by using the finite element ABAQUS software,which is used to compare and analyze the indoor model test,aiming at the situation that the indoor model test condition is relatively single.In order to study the relationship between anchor depth of foundation pile and ultimate bearing capacity of pile and elastic slope of pile load settlement curve,the corresponding empirical formulas are obtained by simulating the load settlement curves of foundation piles at different anchorage depths.