Application And Research On The Smw Piles Combined With Anchor Rope Support In A Deep Foundation Pit In Wuhu City

With the rapid development of the social economy,the engineering construction scale updates continuously and the available floor space decreases gradually.Therefore,the underground space is coming to be the objective that human beings intend to exploit.SMW is a support pattern formed by inserting steel with a shape of “H” or other new materials into the cement-mixed piles on the basis of cement mixing method.This method not only has bearing capacity but also seepage-proofing.Moreover,the construction noise is low,which has little influence on the surroundings.This method is well-suited to the loose and soft soil layers mainly composed by soft clay and silty-fine sand due to its reliable structural strength.The curtain wall is unnecessary,because SMW has a high capacity of seepage-proofing.Furthermore,it can be applied to the deep foundation pit combined with anchor rope support,and take place of the underground diaphragm wall under a certain condition.If the “H” steels can be recycled by some measures,the cost would be much less than that of underground diaphragm wall.However,the theory of the support technique has been rarely studied in Wuhu city.It is apparent that the theory study falls behind the engineering practice.Therefore,the paper analyzes the issues involved in design,construction and monitoring during the proceeding of the project using a deep foundation pit in Wuhu City as an example.And deeply discussing the working mechanism of the SMW pile combined with anchor rope support.The main conclusions obtained are shown as follows:(1)Based on the analysis and research on the landform,engineering geology and hydrogeology conditions surrounding the engineering site,the retaining and protection of foundation excavation program are ensured.In the north of the foundation pit,the SMW pile combined with anchor rope support is adopted.While for the other sides of the foundation pit,SMW pile combined with internal support is adopted.(2)On the basis of the investigation report,the security level of the foundation pit is classified as II level.Lizheng software is used to calculate and design the foundation pit support of Jinyulanwan in Wuhu City after selecting the related design parameters of the profile 11-11,and results of all kinds of operating conditions can be obtained.After that,calculating the distributed steel of the fender post and anchor rope according to the operating condition and envelop diagrams.(3)Monitoring results show that the displacement of the pile block changes slightly and the rate of deformation is stable.Accidents such as collapse doesn't take place,which creates a good condition for normal construction.The variations of the axial force of anchor rope can be divided into three phases: declining stage,ascending stage and stable stage.During the stable stage,the axial force reaches at 155 KN that is far lower than the prewarning value.Thus,the foundation pit will be in the safe working condition during this stage.(4)The FLAC3 D software is used to simulate the results of displacement of pile block and axial force of the pre-stressed anchor rope.It is confirmed that the simulation values are higher than that of the measured value,but the variation tendency of the two is similar.Therefore,utilization of FLAC3 D for simulation of the SMW pile combined with anchor rope support can predict the displacement of pile block and axial force of the pre-stressed anchor rope successfully.