Study On Influence Of Columniform And Walled Soil Improvement On Foundation Settlement Distribution

Under a uniform distributed load, the settlement displays a high value near the foundation center and a low one at edge for homogeneous ground, if under the complete elastic and half space condition, the settlement value of the foundation center is two times of that at edge. Based on this theory, this paper attempts to control the differential settlement by adjusting the ground rigidity distribution by regulating the columniform and walled soil improvement configuration, to ensure the stability and long-term use of building.A deep research consists of experimental study and numerical analysis is established to explore the ability of the composite foundation system with columniform soil improvement and another with walled soil improvement to control differential settlement, and the action mechanism between enhanced body and soil of the two kinds composite foundation systems are studied. According to the principle of trapezium distribution, in this study, the longest pile is set under the middle of the foundation and the shortest under the edge, the piles length decreasing from the middle to the edge. Four groups model tests with different pile length configuration, four groups model tests of walled soil improvement configuration and a laboratory test with no soil improvement are proposed, correspondingly. The model tests of different pile length configuration show that the average settlement of the modal foundation are effectively controlled, but the effects of controlling overall and differential settlement are quite different. Under the circumstance of the equal total length of the pile, it’s more effective in controlling the differential settlement of foundation by increasing the length of the piles near the middle properly (rigid increasing). The improved bearing capacity of soil surrounded by the walled soil improvement leads to the effective control of total and differential settlement. However, the effect on improving the bearing capacity and controlling differential settlement is not so obvious by using peripheral walled soil improment only, the ability of controlling total and differential settlement is much improved alter the addition of vertical enhanced body in the peripheral walled soil improment. By the principle of arranging the walled enhanced body depth decreasing from internal to external in the form of trapezium, the effect of controlling foundation differential settlement is more significantly. The result shows that the inflection point of the settlement curve is not obvious, and it indicates that walled soil improment is still working after cracked during loading process.Based on above mentioned conclusion, according to the columniform configuration test scheme, this paper establishes2D finite element models and carries a series of numerical analysis on composite foundation with different pile length configuration. The numerical analysis results indicates the importance of the pile near the center on controlling differential settlement and that it’s available to adjust the foundation rigidity distribution to control the differential settlement by regulating the pile length configuration properly. Model test and numerical analysis results indicate that the controlling of differential settlement and stable settlement can be realized by regulating the foundation rigidity distribution through adjusting the columniform depth or walled soil improvement combination form.