Of Deep Mixing Composite Foundation And Practical Settlement Calculation Method And Sand Cushion Mechanism Theory Analysis

Since the 1980s when the technology of composite foundation of deep mixing piles was introduced into our country, and with the development of our infrastructure construction of the past few years, this technology has been widely applied. However, partly because of the so far immature study of composite foundation of deep mixing piles, and partly because of the complex geography, the designing often fails to agree with the practical application, which would lead to great waste or various accidents. In light of that, this paper makes further study and analysis of the mechanism of composite foundation of deep mixing piles. The following is the main contents of this paper.1. The mechanism, especially the destruction-mode, of composite foundation of deep mixing piles is further studied with the help of the calculation and analysis of practical projects.2. A practically applicable method of settlement calculation for mixing piles is produced in the light of the transitional area's impact between the piles and the earth, together with the above-analyzed destruction-mode, and the typical unit theory. This method has been validated by field observation.3. This composition foundation produces a reinforce-body collectively functioned by both the piles and the earth, which greatly diminishes its compression deformation. The produced composition serves as a connecting link to decrease the settlement of substratum because of its "whole" effect.4. This paper introduces the limit-destruction theory to study and analyze the function-mechanism of sand cushion in the collective function of the piles and the earth, and then brings forward the regulating-equation of the stress ratio between the up-pile-soil and the top of pile concerning the sand cushion. Its final calculating result basically tallies with the practical function conditions. This provides an alternative approach to the study of sand cushion.