Random Reliability Analysis Of The Settlement Of Dry Jet Mixing Pile Composite Foundation

Reinforcement of soft soil with dry jet mixing pile is a commonly used method, this method can use the capacity and other performance of the undisturbed soil the best, the formed soil-cement after reinforced has high-intensity and good-stability, it will has a good application prospect in our country which the geological conditions is complex and the soft soil lies very board. For DJM composite foundation, settlement and capacity issues are equally important. However, the calculation of the composite foundation involving several disciplines, and geological conditions and the physical and the mechanical properties of soil are closely related to the project, it becomes a foundation engineering problems still no good way to make it consistent or close calculation of theoretical and experimental results of the settlement. Based on the original calculation method, combined with the reliability theory and the confidence interval theory, method for calculating the random reliability and confidence interval of the fuzzy reliability was proposed, this method can be used as the basis for the adjustment of the design of composite foundation, not only it is safe and suitable, durable, but also more economical.First, through the study of properties of DJM composite foundation and combined with reliability theory, a reliability analysis method suit to the composite foundation was chosen; second, through the analysis of the existing calculation method of composite foundation, the basic random variables which can impact the settlement of the DJM composite foundation was established, the limit state equation for the settlement of the DJM composite foundation was calculated, a method to get the random reliability of the composite foundation with JC method was proposed, and through an example with MATLAB for supporting calculation, the correctness of this method was verified; third, combined with an example project, impacts on the reliability index which was caused by changes of the variation coefficient of the random variables and number of pile and the allows settlement were analyzed, variables which have greater impact on the reliability index were found in order to guide the practice; finally, fuzzy reliability confidence interval of the composite foundation was presented, method for solving a certain confidence interval under a certain confidence degree was investigated for designers to judge the reliability of the design programs.