Grouting technology has been widely used in all fields of geotechnical and civil engineering. Prospective engineering objectives including reinforcement of rock mass and groundwater leakage treatment can be achieved by grouting which will change the mechanical parameters of rock mass such as strength, elastic modulus, coefficient of permeability, and etc. In this paper, rock mass is assumed as a composite material consisting of rock particles and random micro cracks initially. Since part or all of the cracks will be filled with cement slurry after grouting, rock mass consists of rock particles, grout condensate and some or no random micro cracks after grouting. The damage constitutional law of the mesoscopic element is established based on the theory of mesoscopic damage mechanics. With the heterogeneity of the components of rock mass considered, the variation of mechanical characteristics of rock mass is studied before and after grouting. And the influence mechanism of grouting on rock mass is investigated at meso-scale level.
Grouting is a technique that makes use of pressure to inject slurry into the rock cracks or cracks in buildings, in order to improve the physical mechanical characteristics. It has been applied in almost all the domain of rock and civil engineering and its functions are enhanced gradually with the growing grouting technique. Grouting can obtain the objectives of reinforcement of rock mass and groundwater leakage treatment by filling, pressing, conglutinating and solidifying.
Since 1802, when grouting technique was used for the first time to restore the gravelly soil foundation of a tide gate, which is eroded by water stream, by the France civil engineer Charles Berigny, the technique has been developed for more than 200 years and great progress has been made.
Yin Suhong and Wen Ziyun(2002) studied the properties and reaction mechanism of dolomite limestone-water glass grout; Ge Jialiang(2006) studied the development and prospect of chemical grouting techniques; Tang Degang(2006) introduced the application of grouting technique to treatment of limestone cave surge; Chen Hao(2003) has expounded high pressure grouting technique for fault stabilization treatment at karstic ground, and analyzed action mechanism of high pressure grouting and means of grouting pressure control;Hao Zhe(1999), Yang Mijia(2001), Luo Pingping(2005) studied crack grouting in rock mass and has developed the corresponding computer simulation procedure respectively; Li Jiuhong(2007) et al. proposed the overall evaluations of crack grouting effect in concretes dam; Li Ning(2002) et al. has discussed numerical modeling of grouting in geoengineering. Present theory and practice research mainly concentrates the grouting material, craft, technology, grouting and its influence and flow quality of cement slurry in rock mass cranny, but it is seldom to see the research about how grouting improves the mechanical characteristics of rock mass. This article attempts in this aspect to make the preliminary study.
The current research of material characteristics is mainly focused on three scales which are micro, meso and macro scales. It is generally considered that the mechanical characteristics of materials in a scale can be analyzed and explained in a lower scale(Zhu et al. 2007).