Research And Application Of The Different Method To Predict Settlement On Suizimei Expressway Soft Foundation

In recent years, with the rapid development of economy, more and moreexpressways were built in Western China, especially those that build on softfoundation in mountain areas are expanding. Through many researchers have done aseries of studies on settlement forecast of soft foundation, it needs to be furtherstudied in this area. Reasons can be explained as follows: factors that exert aninfluence on settlement of soft foundation are complicated; as time went by, thereinfluential factors would inevitably undergo a lot of changes; compared with projectsthat were located in soft foundation in coastal areas, there are more difficulties andchallenges to carry out these projects on soft foundation in mountain areas. Thus, itleads to complex situations of the settlement deformation characteristics of softfoundation.Selecting the proper and effective methods to conduct settlement forecasting playa significant role in this research. Each forecasting methods has its applicableconditions, thus results in some discrepancy in data collections for settlementobservation. Moreover, forecasting methods for settlement prediction entails manyassumptions, which may lead to obvious differences between measured data and theresult of settlement forecast.Taking soft foundation in Suizimei expressway as an example, the authorconducts a survey on settlement forecast of soft foundation in mountain area.Procedures of this survey can be described as follows:(1) By long-term site exploration and settlement observation in its constructionperiod, the author analyzes the collecting data of Suizimei expressway TJI-3and thenattempts to explore the causes for soft foundation in mountain ares, characteristics ofsettlement deformation, and features of construction in that area.(2) Features of soft soil and characteristics of soft foundation settlement are takeninto consideration in this research. Based on the theoretical analysis of deformationmechanism of soft foundation and features of its deformation, the author analyzesmeasured data and tries to investigate the underlying factors that affect settlement ofsoft foundation.(3) Methods in this research include curve fitting, gray GM (1,1) MODEL, BP neural model. The author employs the synthetic approach to settlement forecasting insome typical fault and obtains two groups of samples: three-month measurement andsix-month measurement. Data was analyzed by MATLAB program and then theauthor makes comparisons between researching findings, aiming to identifyapplicable conditions of each forecasting method and searching for more properforecasting methods for foundation settlement in Western China.(4) Finally, through the analysis of settlement rate of soft foundation inconstruction period and settlement rate of soft foundation after its construction,settlement rate of index in construction period of Suizimei expressway and settlementrate of index after its construction were described. Findings in this research may behelpful for controlling conditions of foundation settlement in Western China.