Research On The Informative Construction Method Of Soil Improvement By Preloading

As a simple but effective soft ground treatment method, the preloading method iswidely used in soft ground treatment engineering. It often occurs during practicalconstruction that loading speed is so quick that the soft soil foundation is unstable anddestroyed. This paper adopts the soft ground informative construction method whichis mainly used for stability control, qualitatively analyzes the influential factors of softground deformation, establishes a soft ground treatment monitoring control indicatorsystem, proposes an integrated stability control method which combines empiricalvalue method and theoretical analysis method, establishes a flow suitable forinformative construction, and develops a soft ground informative constructionmanagement system to guide the construction.Soft ground treatment informative construction is based on site constructionmonitoring which comprises the selection of monitoring item type, layout ofmonitoring point, and the setting of monitoring frequency. After the monitoring itemtype is determined according to deformation control requirements, the monitoringpoints will be laid out at the positions where the deformation of soft ground underpre-loading effect can be reflected sensitively. After the layout, the data will becollected in a regular monitoring frequency and processed into the information whichhas physical meanings.When load-accumulated depth is below critical depth of fill, the soft grounddeformation is mainly the elastic deformation. The soft ground stability coefficientdwindles gradually during load-accumulation, and reaches the minimum when theload-accumulation is completed. And then, with the dissipation of void water, the softground stability coefficient improves gradually. Therefore, the stability control shallbe performed during and after the load-accumulation after load-accumulated depthexceeds critical depth of fill.The influential factors of soft ground deformation under the effect ofload-accumulation are qualitatively analyzed. In connection with the specification andthe deformation data of some projects before collapse, a three-level monitoring control indicator system is established from strict to lenient according to thedifferences of load-accumulation site form and monitoring point position: the firstlevel of control indicators are the specified values in the specification; the secondlevel of control indicators are the monitoring control indicators which are dividedaccording to the differences of load-accumulation site form and monitoring pointposition; and the third level of control indicators are the control indicators determinedaccording to whether there is collapse evidence around the monitoring point.In soft ground treatment, the stability control method based on monitoring data isgenerally determined after the sum-up and analysis of common stability controlmethods. First of all, the monitoring area will be divided according to the monitoringpoint position; then, the selected two-level (or three-level) monitoring controlindicator system is adopted to analyze the monitoring data and preliminarilydetermine the possible unstable area; next, the bearing capacity and stabilitycoefficient of the section corresponding to the possible unstable area are calculated inconnection with practical loading capacity; and finally, the unstable section isdetermined.By combining the empirical value method and theoretical analysis method, thispaper proposes a stability control flow which is suitable for soft ground informativeconstruction. According to the stability problem during construction and thesettlement after construction, this paper develops a soft ground treatment informativeconstruction system.