Calculation And Optimal Design Of Soft Soil Foundation Treatment By Preloading For Raw Material

The soft soil are widely distributed in large areas of our country,it has manyunfavorable project properties such as high water content，large boid ratio, small shearstrength, huge compression index, low permeability. Soft soil foundation often appears inengineering construction. The strength of natural soft soil foundation is far low to meet therequirements of these buildings for the foundation bearing capacity, some soft grounds orspecial soil foundations often needs foundation treatment. In the1950s people began usingthe method of preloading reinforcement of soft soil foundation. The method of stackpreloading reinforcement of soft soil foundation is developing together with the soilmechanics. After early Terzaghi’s consolidation theory is proposed, an important milestonein the history of the development of soil mechanics had come，and is widely applied in theactual engineering since then. Later on, because of the putting forward of the Biot’consolidation theory and the rapid development of computer technology, finite elementmethod and other numerical calculation methods are used, these makes stack preloadingreinforcement of soft soil foundation soil technology developing very rapidly.Terzaghi’s consolidation theory and the Biot’ consolidation theory have beenreviewed first in this research as well as some stress-strain relation of the foundation soilcommonly used.Then summarizes and analyzes of the three major shear strength theory is made.According to Vesic spherical cavity expansion theory，the saturated soft clay is consideredas a Tresca elastic-plastic material. This research takes the expansion stress of elasticityand plasticity of the pile in soft soil as the example to deduce the change of stress of thecompacted soil and its shear strength by the fomular in both elasticity zone and plasticityzone. Analysis and calculates of the foundation stability and strength increasing underconsidering influence compaction effect are also made.At last, referring to the certain project, a raw material yard, to adopt the method ofpreloading in soft soil foundation. Soft foundation treatment by preloading may appear subsidence and horizontal lateral and changes the stress state of the neighboring buildingsfoundation soil damage to adjacent the foundation of the building. The author analyzed andsolved the problem by using preloading affect the rail foundation. The numerical method isused to analyze the process, and put forward the isolation pile method adopted to solve theabove problems.