Research And Application On Deep-hole Pre-injection Technology Of Granite Residual Soil In Pearl River Delta

There are a lot of granite residual soils distributed in the Pearl River Delta region.The properties of the soils are not uniform,and they are easy to be softened and disintegrated by water.Therefore,it is easy to cause engineering accidents when construction works are carried out in water rich granite residual soil area.Through literature research,it is found that there have been many construction accidents in underground engineering in southern China,most of which are caused by not knowing the engineering characteristics of granite residual soil.How to further understand its engineering characteristics,especially the disintegration characteristics,so as to protect its disintegration and properly deal with it is an important issue facing the granite residual soil engineering.Based on the construction background of the tunnel of Chenwu Station-Laoxia Station of Dongguan Rail Transit Line 2,this paper makes an experimental study on the deep hole pre-grouting reinforcement technology for the tunnel excavation in the residual granite soil area.The parameters of the grouting scheme are determined and optimized from the aspects of grouting mechanism analysis and construction technology.The engineering technology ensures the maximum economic benefit under the premise of ensuring the safety of the project,and provides a useful reference for the future underground excavation projects in similar strata.The main contents and achievements of this paper are as follows:(1)Based on the literature investigation of grouting technology and grouting materials,the grouting technology used in the construction of Dongguan Rail Transit Line 2 by mining method is analyzed,and the conclusion that the deep-hole pre-grouting technology can effectively reinforce and control water seepage in tunnel engineering is obtained.(2)The typical engineering geological conditions in the Pearl River Delta region crossed by Dongguan Rail Transit Line 2 are investigated in detail.By studying the special mechanical properties of granite residual soil,the geological hazards such as land subsidence,water inrush disaster and slope instability of foundation pit are explained,and the construction monitoring process is determined.Key indicators.On this basis,the characteristics of granite residual soil layer and pre-reinforcement technology of mine grouting are studied,and the construction technology scheme of forward grouting waterproof curtain is put forward and the technical feasibility is analyzed.(3)The construction monitoring of Dongguan Rail Transit Line 2 shows that there are some problems in the original design of initial support parameters,such as excessive water inflow and land subsidence.Therefore,based on the advanced curtain grouting technology and the deep-hole pre-grouting scheme suitable for this project,the grouting parameters and technology are determined through experimental study.According to the indexes and grouting forms,the technical standards with good operability are put forward for the design and construction of deep hole grouting,thus ensuring the construction safety.Relevant engineering practice verifies the effectiveness and reliability of the results.