Experimental Study On The Reinforcement Of Fly Ash Foundation By Dry Jet Mixing Pile

China is a "poor oil-rich coal" developing country,and its rich coal resources determine its dominant position in China’s energy consumption.The coal consumption field is mainly concentrated in thermal power generation,and the incidental fly ash of thermal power generation in China.The comprehensive utilization rate is low.The fly ash that has been stored in the outdoor ash yard for a long time naturally forms a fly ash stratum.The fly ash stratum is a weak foundation.The construction of the fly ash yard must first be reinforced according to the specifications.DJM pile technology is a kind of composite foundation reinforcement technology which is widely used in theoretical research and engineering practice.At present,the special soft soil layer which is stabilized by DJM pile method is less in experimental research and engineering application.Based on the engineering project of Shang yao Old City Reconstruction and Resettlement Area in Shang yao Town of Huai nan City,this paper analyzes the influencing factors of the strength of the DJM pile and determines the optimal dosage of cement fly ash through laboratory tests,and analyzes the static load test of DJM pile composite foundation on the spot.The force characteristics of piles and composite foundations are combined with static load test to establish a finite element three-dimensional model.The settlement deformation of the DJM pile under vertical force is analyzed,and the settlement displacement of each position of the pile is obtained to prove the static load test..This paper provides an important reference for the design and construction of large-volume deep-thickness fly ash stratum by DJM piles.The main results of this paper are as follows:(1)The material composition and particle gradation characteristics of fly ash in the ash field of the tender section were analyzed.The sampling test showed that the content of calcium oxide in the fly ash accounted for 3.87%,which belonged to low calcium fly ash and the proportion of loss on ignition.1.44%,belonging to the first grade ash,the average value of the natural water content sample is 46.5%,and the foundation reinforcement depth is about 15m.All the conditions can meet the construction site requirements of the composite foundation of the DJM pile.(2)The indoor test is an important basis for the design of cement fly ash formation by DJM pile.Through the laboratory test analysis of cement fly ash test block,some basic mechanical parameters of cement fly ash test block are obtained.The amount of cement,age,The variation of the shape of the sample and other factors on the strength of the fly ash test block.Laboratory test research before engineering application can help to determine the amount of DJM pile powder,which also has great significance in saving economic costs.(3)Based on the static load test on site,the bearing capacity of composite foundation of DJM pile and DJM pile is determined.Based on the analysis of load-settlement curve of static load test,the formula of hyperbolic function is determined by curve fitting.It is found that the formula can accurately calculate the bearing capacity of the DJM pile and the composite foundation.The hyperbolic method greatly saves the workload of the test.It provides a certain theoretical reference value for the design stage before the construction of the DJM pile.(4)Based on the bearing capacity test of composite foundation of powder jetting pile,the ANSYS simulation analysis software was used to model the pile-soil of the DJM pile,and the deformation displacement and compounding of the piles under the vertical pressure were simulated.The settlement of the foundation,the numerical analysis results of the numerical analysis are larger than the test results,but the overall change trend is consistent.Considering the interaction between the actual DJM piles,the simulation results can explain the correctness of the field test,and also explain the utilization.The finite element modeling and analysis of the composite foundation of the DJM is reasonable and feasible.Figure 34 Table 15 References 68...