| The self-weight collapsible loess tends to form negative friction around the pile after being immersed in water.The existence of negative friction will reduce the bearing capacity of the pile foundation.In severe cases,it may lead to unbalance and cracking of the superstructure.This problem needs to be solved urgently.After research,the existence of wedge-shaped piles can reduce the drag force of the soil around the pile on the pile,and effectively reduce the negative friction.Therefore,this article uses the waste incineration power generation and sludge disposal project in Liquan County,Xianyang City,Shaanxi Province as the research background to study the negative friction resistance of wedge-shaped piles in the self-weight collapsible loess area,and conduct indoor compression immersion on this issue.Test analysis,numerical simulation analysis,and monitoring of lateral friction resistance of piles caused by on-site flooding.The main tasks and research results completed are as follows:(1)Carry out indoor compression immersion test on the samples taken on site,determine that the soil of the proposed site is self-weight collapsible loess,and make a scatter diagram between self-weight collapsibility coefficient and water content,void ratio,natural density and compressive modulus,And perform curve fitting,make regression equation,analyze the relationship between self-weight collapsibility coefficient and water content,void ratio,natural density and compressive modulus;select mutually independent water content,void ratio,compression modulus The three influencing factors and the self-weight collapsibility coefficient were analyzed by multiple regression analysis,and the relationship between the soil self-weight collapsibility and the physical and mechanical indexes was briefly described.(2)The mechanism of negative friction resistance of pile foundation is studied,the cause of negative friction resistance and related concepts are briefly described,the calculation method of negative friction resistance and reduction measures are described,and then ABAQUS finite element software is used to analyze the wedge-shaped pile under water immersion around the pile.Numerical simulation of load transfer is carried out.The displacement,axial force and side friction of the pile body and the soil around the pile are compared with the simulation results of cylindrical piles under the same conditions.The analysis of the results shows that the wedge-shaped pile is effective Reduce negative friction.(3)Under the condition that the loess around the pile is immersed in water,the pile side friction resistance of the wedge-shaped pile and the cylindrical pile was monitored for 60 days,the ground surface and deep soil settlement were analyzed,and the axial force and lateral force of the two pile-type piles were analyzed.The results of the numerical simulation of friction resistance and the on-site monitoring results are plotted as a curve.The overall trends of the simulation and monitoring results of the two pile types are similar,which verifies the reliability of the numerical simulation results.At the same time,it is pointed out that the wedge-shaped pile can effectively reduce the negative friction resistance.The influence of wedge angle,pile modulus and friction coefficient between pile and soil on the effect of wedge pile in reducing negative friction is studied.The paper has 38 figures,12 tables and 73 references. |
PDF Full Text Request