Steps in grouting construction method of vertical shaft

First, the concept and role of formation grouting

Grouting includes three aspects: water control, ground reinforcement and foundation reinforcement.

Second, the engineering classification of the grouting method and the applicable conditions of various grouting methods

1. According to the order of grouting work, excavation and excavation, it is divided into pre-grouting method and post-grouting method.

1) The pre-grouting method is grouting work carried out before excavation or excavation. According to the different construction sites, the pre-grouting method can be divided into two types: pre-grouting on the ground and pre-grouting on the working face. Ground pre-grouting is usually in the construction preparation period, the working conditions are good, and the construction period is not occupied.

2) Pre-grouting of working face refers to drilling a grouting from the excavation face under the condition that the well is excavated to a certain distance from the aquifer, and the retaining rock cap or pouring concrete retaining pad is reserved. This method takes up construction time.

2. According to the grouting materials used, it is divided into cement grouting, clay grouting, chemical grouting, etc.

3. According to the grouting pressure, it is divided into two categories: static pressure grouting and high pressure jet grouting.

4. According to the action mechanism of the slurry on the soil, it is filled with grouting, penetrating grouting, compact grouting, split grouting and the like.

Third, grouting construction

(1) Grouting construction process content

The process content of grouting mainly includes the selection of grouting method, the selection and installation of grouting equipment, the arrangement of grouting holes, the order of grouting, the determination of grouting control technology, the grouting construction and the effect check.

Taking the ground pre-grouting as an example, the sequence of grouting along the depth of the stratum is divided into three types: segmented down, segmented up, and one full depth grout. The pre-grouting holes on the ground are generally arranged equidistantly according to concentric circles. The number of grouting holes is determined by the overlap of the diffusion radius of the slurry and the diffusion radius required to ensure that the grouting curtain reaches the design thickness. Usually calculated from 1.3 to 1.5 times the diffusion radius).

(3) Principles of grouting material selection

The choice of grouting material should take into account the groutability of the slurry, the controllability of the gel time, the strength and permeability of the stone body, and the stability of the slurry. At the same time, the difficulty of the source of the slurry and the pollution of the slurry to the surrounding environment should also be considered.

1. Cement grouting: It is a slurry prepared purely from cement and water. Commonly used cement types are ordinary Portland cement and slag Portland cement. The advantages are high stone strength and low water permeability; the disadvantages are poor injectionability and stability, long solidification time and difficult to control the solidification time. Additives are usually added to make a modified slurry.

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