| The Yellow River flood plain area distributes silt widely. AS it is pseudo-plastic and lack of toughness meanwhile it has some obvious shakings reflection and the dry strength is very low, the project nature is quite complex. Generally it has insufficient bearing capacity, the medium high compressibility with flexure moved and it is easy to liquefy under the earthquake load function and so on. Especially in highway bridge head place, if does not carry effective processing on the silt ground, it will produce bump at the end of bridges, influencing roadbed and ground stability. The dry jet mixing pile has the widespread usability, usually applied in saturated soft foundation processing. In recent years some practice prove that The dry jet mixing pile was not only suitable for the saturated soft soil foundation reinforcement, but also suitable for saturated or the non-saturated cohesive soil, sandy soil foundation and filled soil foundation reinforcement. Therefore that the dry jet mixing pile reinforces silt foundation has the practical feasibility.This thesis has based on the investigation of the silt distribution in Shandong Heze area , analyzing the silt origin and the physical property .It is carried on the mixing proportion experiment of cement modified soil in local area which has obtained the optimum mixture ratio of cement content of the cement modified soil intensity varying with cement content variation rule. Through the in-site test experiment, by contrasting the dry jet mixing pile composite foundation and the natural foundation , it obtains that the dry jet mixing pile reinforcement silt had the good effect which could reduce the compound settlement of foundation and the lateral deformation effectively. It also obtains the natural foundation and the composite foundation critical filling depth by the actual subsidence curve. The dry jet mixing pile reinforcement silt foundation is able to enhance foundation critical filling depth. The maximum horizontal departure and the settlement have approximate doubling linear relation, when the earth fill achieved critical height, the lateral displacement and the settlement accelerated the speed with its ratio invariable approximately. The dry jet mixing pile processing soft soil foundation enhances the critical filling depth and also delays the lateral deformation fast growth according to the critical filling depth. The pile-soil stress ratio basically becomes the straight line rising fill, increasing along with the depth of fill. When the earth fill achieves certain height, if continued to load, pile-soil stress ratio reduces gradually, approaching certain constant. Through the soil body restraint using the spring unit, it is established the finite element computation model, with the computed result drawing close to actual value which can be used as project examination method. It has established the construction network multi-objective and multi-resources optimization model, embarking from the network planning construction period - cost optimization. Considering the completes time of network planning variable, through calculating the possibility of all kinds of compression construction period under the stipulation construction period, choosing the construction period plan of larger possible for the feasible plan, it has synthesized construction period, the expense and the project quality, the three big goals as appraisal goal of the network planning optimization decision. Using improved analytic hierarchy process to make the network planning optimized decision, optimizing one by one according to the sole resources balanced optimization method, analyzing the importance of each resource using the analytic hierarchy process, it has obtained the influence coefficient of each resources to the most superior operation time and established the model for multi-resources entering the network planning, thus obtaining the best operation date which made all kinds of resources relatively balanced and the whole to be superior. |
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