Research On Composite Grouting Technology Of Water Rich Fault Fracture Zone

As urban construction is developing rapidly,a growing number of traffic problems are taking place in the cities,thus the construction of subway is put forward.It is inevitable to pass through bad geologic segments during the process of construction,among which water-saturated faulting fracture zone is more common.With the characteristics of large scale difference,complex material composition,abundant groundwater and mechanical catastrophe,the water-saturated faulting fracture zone is more easily occurring engineering geological disasters such as collapse,water-bursting and mud-bursting and so on during the construction of subway.In engineering practice,grouting is usually used for water stop and reinforcing.Since the grouting theory currently is way far behind engineering practice,it is critical to study the grouting technology theory.Taking No.2 construction shaft of Shandong Road South Station of Qingdao Metro Line 8 as the background,this paper analyzes the requirements of grouting technology in the water-saturated faulting fracture zone.Based on the analysis of characteristics and cases,a composite grouting technology of the water-saturated faulting fracture zone and a new composite grouting material are put forward.The feasibility of the technology is verified through the application in engineering,and the grouting effect of the new composite grouting material is further studied by simulation.The specific research contents are as follows:Through literature research,we are aware of that the characteristics in the water-saturated faulting fracture zone and there are construction risks.The reason why big settlement occurred in the surface of water-saturated faulting fracture zone during process of shaft construction is analyzed through the analysis of surface subsidence monitoring data,and the grouting technical requirements for the water rich faulting fracture zone is proposed.(1)The grouting technical requirements for the water rich faulting fracture zone is proposed by combing engineering characteristics and practical experience of water rich faulting fracture zone.The technology is divided into two steps.Step 1,through infiltration and filling grouting,the large gap is blocked and the slurry running problem is solved;step 2,through compaction and splitting grouting,the bearing capacity of the stratum and the impermeability of the surrounding rock are improved.We chose corresponding grouting materials based on the analysis of the performance requirements of composite grouting.In the first step,a new composite grouting material is used,which consists of portland blast-furnace slag cement,fly ash,compound thickener and water glass;in the second step,ultra-fine cement slurry is used.(2)Through the orthogonal test,the performance of the new composite grouting material was determined.Through the comprehensive analysis of various influencing factors,the best formula proportion was determined as follows:water binder ratio:0.8:1;fly ash:10%;compound thickener:0.3%;water glass:10%.Through above formula,it is found that the viscosity and 28d have great performance on the compressive strength,such as rheological property and bond strength of serous calculus,which can meet the performance requirements of grouting materials in the first step of grouting.(4)The application of composite grouting technology in engineering has good performance and achieved expected goal,which verifies that the technology is feasible in the construction.Numerical simulation software is used to analyze the performance of new composite grouting material and cement slurry in the water rich faulting fracture zone,which shows that new composite grouting material can effectively control the deformation of surrounding rock and the range of plastic zone after excavation,and the grouting effect is better than that of cement slurry.