The Calculation of Grouting Diffusion Radius on Based Bingham Fluid for Chunnel That Passes through Fractured Rock Mass

To conduct pro-grouting design and make the prediction of the result of grouting about the chunnel that passes through fractured rock mass, the essay adopts following theoretical formula to calculate the fractured rock mass grouting diffusion radius: Wittke and Wallner Formula、Lombadi Formula and Huang Chunhua Formula. Finally through the analysis of calculation results can conclude: (I) The diffusion radius of the slurry can meet the design requirements under the condition of 3-4 Mpa designed grouting pressure、5 cm grouting holes’ radius and 1800-3600s grouting time. (II) The calculation result of Huang Chunhua Formula is almost the same as Wittke and Wallner Formula and Lombadi Formula, but the margin of grouting diffusion radius’ change as grouting time and grouting pressure growing are different, it’s more close to the real situation.(III) The calculation of these theoretical formula only consider the breadth of fractured rock without considering the variation of its thickness and direction. So all of the calculation results of these formula are generally bigger than the standard.

Download Full-text

Research on Multiple Holes Grouting of Fractured Rock Mass

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.256-259.547 ◽

2012 ◽

Vol 256-259 ◽

pp. 547-551 ◽

Cited By ~ 1

Author(s):

Yong Xu ◽

Wei Hong Peng

Keyword(s):

Rock Mass ◽

Fractured Rock ◽

Distinct Element ◽

Fracture Aperture ◽

Diffusion Distance ◽

Fractured Rock Mass ◽

Grouting Pressure ◽

Universal Distinct Element Code ◽

Distinct Element Code ◽

Multiple Holes

Considering the seepage stress coupling of fractured rock mass, the multiple holes grouting problems were simulated to analyse the spread regularity by Universal Distinct Element Code(UDEC).The results show that the correlation between grouting pressure and the diffusion distance is positive, whereas the correlation between ground stress and diffusion distance is negative; With the raising of grouting holes, the diffusion distance is increasing and becoming more uniform in all directions, and the grout pressure and saturation is falling and attenuation amplitude is decreasing along the direction of grout diffusion; With the increasing of fracture aperture, the grout diffusion distance is increasing, and the grout pressure and saturation attenuation amplitude is decreasing along the direction of grout diffusion.

Download Full-text

Prediction of grout penetration in fractured rocks by numerical simulation

Canadian Geotechnical Journal ◽

10.1139/t02-063 ◽

2002 ◽

Vol 39 (6) ◽

pp. 1384-1394 ◽

Cited By ~ 41

Author(s):

M J Yang ◽

Z Q Yue ◽

P KK Lee ◽

B Su ◽

L G Tham

Keyword(s):

Rock Mass ◽

Fractured Rock ◽

Fluid Pressure ◽

Distribution Patterns ◽

Stochastic Approach ◽

Bingham Fluid ◽

Fractured Rock Mass ◽

Depth Of Penetration ◽

Parametric Studies ◽

Mining Projects

As fractures in rock significantly reduce the strength as well as the stiffness of the rock mass, grouting may be required to improve the performance of the rock mass in engineering or mining projects. During grouting, mortar of cement or other materials is injected into the rock mass so that the fractures can be filled up and the rock mass can act as an integral unit. Unlike water, grouts are usually viscous and behave as non-Newtonian fluids. Therefore, the equations describing the flow of grout are more complicated and the solutions are quite difficult to obtain. The problem is further aggravated by the fact that the fractures are mostly randomly distributed, and it is rarely possible to accurately define the fractures and the distribution patterns. In this paper, a numerical model is proposed for analyzing the grouting process. The model is based on the stochastic approach, and it can provide the depth of penetration and the fluid pressure due to the flow of grout, which is modeled as a Bingham fluid, in the fractured rock mass. Parametric studies have been carried out to investigate the effects of various factors on the depth of penetration, and a regression formula is developed for calculating the penetration depth. Experiments have been carried out and their results are used to validate the present method.Key words: stochastic fractures, fractured rock mass, grout flow, grout penetration.

Download Full-text

The Deviation of Semi-Theoretical and Semi-Empirical Water Inflow Prediction Formula Based on Sphere Coordinate Conversion and a Grouting Excavation Evaluation Method

Applied Sciences ◽

10.3390/app112411956 ◽

2021 ◽

Vol 11 (24) ◽

pp. 11956

Author(s):

Yonghong Wang ◽

Jiabin Li ◽

Chuan Wang ◽

Qin He

Keyword(s):

Numerical Simulation ◽

Rock Mass ◽

Fractured Rock ◽

Water Inflow ◽

Theoretical Formula ◽

Simulation Methods ◽

Confined Aquifer ◽

Fractured Rock Mass ◽

Numerical Simulation Methods ◽

Weight Method

The water in the rock medium is exchanged with the confined aquifer through the fracture, which leads to the water inflow line in the confined aquifer is no longer horizontal. This paper assumes that the aquifuge is a kind of semi-isolation layer, while the first-order derivative of the total head slope line function within the influence of precipitation approaches the slope of the line connecting the top plate of the aquifuge with the spherical center. This hypothesis demonstrates the relationship between the bottom of the well water inflow and the complete well gushing water. Laplace’s equation for the spherical coordinate transformation is used to find the analytical solution of the water inflow for stable flow. The calculation results are in line with reality through actual engineering and numerical simulation methods. The current numerical simulation methods and theoretical methods mostly consider the aquifer in the ideal state, which is difficult to simulate the fractured rock mass. The theoretical formula proposed in this paper can more effectively reflect the actual seepage situation of fractured rock mass than other formulas. In addition, the combination of theoretical derivation, numerical simulation and field measurement can predict the water inflow more accurately than unilateral research. At the same time, for the question of whether the face excavation is grouted or not, this paper using the subjective and objective assignment weight method combined with analytic hierarchy process method and entropy-weight method to take the weight calculation and giving a slurry excavation judgment method based on the proposed formula. Theoretical support is given for the selection of permeability coefficients for each hole in the overrun exploration and this method is validated by different projects, which has some degree of reference value.

Download Full-text