Effect Of Soil Improvement On Deformation Of Foundation Pit In Soft-clay Area

In recent years, with the rapid development of China’s construction, excavationscale tends larger, deeper and its surrounding environment has become more complex.In soft soil region, there are many construction accidents caused by large deformationof excavations. For this reason, engineers are paying more attention to thedeformation control design of foundation pits. Engineering Practice has proved thatsoil reinforcement in passive zone can effectively control the lateral displacement ofthe retaining structures and the settlement of surrounding ground, and it is also able toincrease the capacity of anti-uplift deformation of the excavation bottom. To this end,many scholars and engineers, home and abroad, have been studying the impact factorsof deformation and a lot of targeted measures and countermeasures are proposed. Butso far the problem on how to decide reinforcement parameters quantitatively in theconstruction has not yet been well resolved, and soil improvement is also lack ofcorresponding codes and regulations. Therefore it is the existence of practicalsignificance to carry out the study of impact of soil improvement parameters ondeformation induced by excavation.Based on mechanical analysis and numerical computation of foundation pits, thispaper has studied the parameters of soil improvement, the main contents are asfollows:(1) At first, mechanical of deformation induced by excavation has been analyzed,the main factors of the deformation have been discussed and the main methods topredict the deformation have been introduced and compared.(2) The main soil reinforcement way in excavation engineering has beenintroduced, the applicability and arrangement form has been studied. And it resear-ched the physical and mechanical properties of reinforced soil and its influencingfactors.(3) Based on mechanical analysis of the retaining structure and reinforcement infoundation pit, the earth pressure in passive zone before and after soil improving isobtained and compared. The results show that the displacement control effects ofpassive zone improvement are significant. By means of analyzing the formulaobtained, we can conclude that the depth of reinforcement, the degree ofreinforcement, the area ratio of reinforcement and m value of the soil are the fourmain influencing factors of the effect of soil improvement. (4) By applying the nonlinear finite element software ADINA, the impact of soilimprovement arrangement form and parameters (such as cement mix ratio, horizontalreinforcement rate, improvement depth, etc.) on deformation induced by excavationhas been analyzed. And we can get reasonable values of reinforcement parameters indifferent reinforcement form.(5) Finally, the conclusion of theoretical analysis and numerical calculations areverified by two project cases which are in high deformation control protection level.