SMW Method Pile Strength Test And Comparative Analysis Between Monitoring And Numerical Simulation

SMW method pile has the advantages of safety,economic,rapid and environmental protection,so it is used more and more widely in the increasingly competitive market.But there are still problems of mixture ratio and design theory immature.In order to study the application effect of SMW method pile in Guangdong River alluvial geological foundation pit engineering,the foundation pit engineering of Hexin square is chosen as the research object.The following conclusions are drawn from the above research work:1.By changing different water-cement ratio,curing time and cement contentthrough laboratory test,the changes of unconfined compressive strength of mucky clay and fine sand soil-cement are tested.The best water cement ratio of mucky clay and fine sand soil-cement was 1.5.The highest strength ofmucky clay soil-cement is cement content 18% and fine sand soil-cement is cement content 15%.The combination mechanism of sand and cement is similar to cement mortar,which increaseswith the increases of sand-cement ratio.The strength of soil-cement grows along with the curing time and increases obviously after 30 d in the optimum cement content.Soil-cement dry density exist a positive correlation with compressive strength.The cement soil mixing is not uniform and the damage while core pulling cause the in-situ cement-soil strength smaller than the indoor.2.The top horizontal displacement,steel stress,anchor stress,deep soil level displacement,surrounding ground settlement and underground water levels are monitoring during the excavation process of foundation pit,and the change law of the monitoring data during excavation aresummarized.With the increase of depth of the excavation,the top horizontal displacement and anchor stress showed a ladder type growth.The position of the maximum stress of the steel is gradually downward,and soil-cement can share the bending moment of the pile.The drop of underground water levels outside the pit caused by sand and water gushing will make the surrounding ground settlement increases.SMW Method pile could effectively control the deformation of soil around the foundation pit,and cut off the water seepage.3.The GTS Midas finite element software was used to simulate the excavation of Hexin square and compare the calculated results with the measured data.It can be found thatthe deformation data obtained from the finite element simulation calculation are consistent with the actual monitoring data.Because of the sand water gushing,the actual ground settlement is greater than the model calculated settlement.Soil resistance in steel plug process makes calculatedvalues of steel stress less than the measured value.And the analysis shows that considering the condition of soil-cement cracking,the stiffness contribution of non-cracking soil-cement to SMW method pile is about 3%.Through the indoor and outdoor soil-cement strength tests,foundation pit monitoring and Midas GTS finite element analysis,the application of SMW method pile in Guangdong are analyzed,which can provide reference for optimization design of SMW method pile foundation in the future.