| Loess is widely distributed in China,and loess foundation is easily disturbed by external factors,which leads to different degrees of diseases in upper buildings and facilities,so it is necessary to strengthen the weak loess foundation.The efficient foundation treatment method is widely us ed.In order to better realize the splitting grouting reinforcement of loess foundation,the sleeve valve pipe grouting construction technology is introduced,and through the research and optimization selection of casing material ratio in the sleeve valve tube grouting process,It makes sleeve valve pipe split grouting have stronger adaptability in loess.On this basis,a series of research on sleeve valve pipe splitting grouting to strengthen loess foundation is carried out,and control parameters are dete rmined.Through the analysis of mechanical behavior,the effectiveness of sleeve valve pipe splitting grouting in strengthening loess foundation and its influence on loess foundation are verified by practical engineering application.The main contents of t his paper are as follows:(1)The shell material is the key of success of sleeve valve pipe grouting,in order to ensure the loess foundation of sleeve valve pipe grouting reinforcement,analyzed the performance of the shell material of sleeve valve pipe grout ing.First of all,in the engineering mix proportion based on the basic material used by the shell material test the study of simple,determine shell material base material type,and conduct research on the performance analysis,reasonable choice of adding additive,improve the performance ratio,with the adjustment of viscosity.By orthogonal test of different mixing ratio shell material,2h analysis of water rate,strength,dry shrinkage performance,influence analysis of each component on the performance of the shell material,Finally,the best mixture ratio of casing material is selected when sleeve valve tube grouting is used to strengthen loess foundation.Under this ratio,sleeve shell material can play a better role in reinforcing loess foundation wi th sleeve valve tube grouting,and ensure the realization of sleeve valve pipe split grouting to strengthen loess foundation.(2)In this paper,a simulation test was carried out on the loess foundation strengthened by split grouting with sleeve valve pipe.Th e experiment was divided into two parts according to the characteristics of sleeve valve tube being able to be grouting many times,and the actual grouting situation of sleeve valve pipe was simulated in the test simulation box.Single sleeve valve pipe sp lit grouting and multiple sleeve valve pipe split grouting,respectively from grouting pressure,suction volume,stone body and slurry pulse state,This paper analyzes the reinforcement mechanism of loess foundation strengthened by sleeve valve pipe grouting and its action on loess from many angles,such as the change of soil properties,summarizes the grouting law,and determines the control parameters in loess grouting.(3)On the basis of the simulation test,according to the experimental phenomenon,the mechanical behavior of the loess foundation strengthened by sleeve valve pipe grouting and the reinforcement mode of the loess foundation are studied theoretically,and the mechanical behavior of single grouting is mainly studied.According to the change o f action object in grouting process,the grouting process of sleeve valve tube is divided into two steps.The cracking of casing material and the splitting of slurry to loess under the action of slurry.Based on this,the mechanical behavior of each step i s studied in detail according to the experimental phenomena.The formula for calculating the crack pressure of casing material and the calculation formula for the parameters of loess splitting behavior are derived by selecting the appropriate mechanical mo del,and the hydraulic wedge is introduced.The concept of crack is used to analyze and study the splitting behavior of loess foundation strengthened by sleeve valve pipe grouting.Because of the repeatability of the behavior of multiple grouting and multi ple grouting according to the test,Therefore,based on the study of mechanical behavior of single grouting,the mechanical behavior of multiple grouting is studied briefly,and according to the state of stone body after multiple grouting,the performance of composite soil reinforced by sleeve valve pipe grouting on loess foundation is analyzed.An appropriate simplified model is established to analyze the bearing capacity of grouting composite soil,and a formula for calculating the deformation of grouting reinforced composite soil is derived,and the bearing capacity of porous grouting soil is analyzed.(4)On the basis of experimental and theoretical research,the loess foundation is strengthened by sleeve valve pipe grouting in practical engineering.The concrete geological conditions of the site are analyzed,and reasonable grouting parameters are adopted to design the grouting scheme.The feasibility and effectiveness of sleeve valve pipe grouting in strengthening loess foundation are verified by means o f excavation and settlement observation.It is proved that sleeve valve pipe grouting is very effective in strengthening loess foundation.By calculating the settlement rate of foundation after grouting,the influence of sleeve valve pipe grouting on loess foundation is obtained. |
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