Modal Experimental Study And Numerical Analysis Of Cement Mixing Pile Composite Foundation

Silt soil-sand mixed soft soil is more and more common in the mountain valley. As with other soft soil, it not only has low strength and high compressibility, but also occur large deformation or damage in highway loading. Because of the particularity of its components, engineering properties, selection of foundation treatment method, design calculation and testing evaluation method. Therefore, it is necessary to research deeply.This paper takes the science and technology project of the ducumemt of Jiangxi province "granite mountain stream in the engineering properties of soft soil and foundation treatment technology research" as the background, and does the relevant indoor simulation study with the composite foundation in engineering aiming at Jing-mu highway’s silt-sand mixed soft soil composite foundation engineering case. Here are the main contents and conclutinns of this paper:(1) The contact area of work of pile-soil interface has been tested in direct shear and the study shows that common interface shear strength of piles and soil is influenced by normal stress, the properties of mixed soil, etc. While the water content is certain,with the increase of sand content the friction coefficient of contact surface increased first and then decreased regularity. While the sand content is certain, the friction coefficient of contact surface decreased as the water content increase.when the normal stress incerase the friction coefficient of contact surface is slowing down and finally tends to be stable.(2) Based on the similarity theory, two groups of eight model experiment have been designed and completed, and the experimental studys on the sand content of different pile Numbers and different conditions, the relationship between the settlement of composite foundation and the stress ratio of pile-soil. The Study have shows that the increasing of the replacement rate is helpful to improve the bearing capacity of composite foundation and reduce the total settlement of the foundation. The increase of silt medium sand content could improve the bearing capacity of foundation.(3) According to the engineering properties of mixed soil, using ANSYS finite element analysis software, a simulation study was carried out on composite foundation, it points out that numerical simulation is necessary to consider the contact surface friction, and the model test of soil and sand mixed in different proportion were studied by numerical simulation, verified the model test of composite foundation under the conditions of different sand content of the pile body change laws of additional stress. Combined with the Jing-mu highway project site, using the ANSYS site settlement of foundation of numerical calculation, the result shows that the finite element used to calculate the settlement of composite foundation tallies with the in-situ test and finite element calculation method is a reliable method of calculating settlement of composite foundation.