1, curtain grouting
Curtain grouting is a grouting project in which grout is poured into cracks and pores of rock mass or soil layer to form a continuous waterproof curtain to reduce seepage and seepage pressure.
2. Consolidation grouting
Consolidation grouting is pumping high-grade cement slurry or chemical slurry into rock mass through drilling holes to seal cracks, enhance the integrity of bedrock and achieve the purpose of improving the strength and stiffness of rock mass.
Second, the role is different.
1, curtain grouting
Curtain grouting of rock foundation of concrete dam is carried out in the flat tunnel on both sides of dam abutment and in the gallery of dam body. Curtain grouting of rock foundation of earth-rock dam, some are carried out at the top of rock foundation first, and then the dam body is filled; Some of them are carried out in the corridors of dams or dam foundations. Its advantages are that it does not interfere with dam filling, and after completion, it can monitor the curtain operation and make up the curtain.
The borehole grouting of curtain grouting is gradually compacted according to the designed order. Curtains with two or more rows of holes are mostly drilled and poured downstream, then drilled and poured upstream, and finally drilled and poured in the middle. The same row of holes is drilled and poured in three sequences. All grouting methods are full-hole segmental grouting.
2. Consolidation grouting
① Improve the integrity and uniformity of rock mass.
② Improve the compressive strength and elastic modulus of rock mass.
③ Reduce the deformation and uneven settlement of rock mass.
For concrete gravity dam, the whole dam foundation area is consolidated grouting; For concrete arch dams or gravity arch dams, consolidation grouting should also be carried out for the abutment arch support rock mass with greater stress; For hydraulic tunnels, rock mass consolidation grouting is often carried out after lining.
When excavating a tunnel in a broken rock stratum, in order to avoid rock collapse or concentrated leakage, a certain range of inclined holes or horizontal holes can be consolidated in advance before excavation.
When a concrete cushion is set at the bottom of the impervious body of an earth-rock dam, it is often necessary to consolidate and grout the rock mass below the cushion. In order to ensure the grouting quality, it is necessary to pour a certain thickness of concrete cover plate or concrete on the surface of rock foundation before consolidation grouting.
Third, the construction methods are different.
1, curtain grouting
1) borehole inclinometer: use small-caliber geological rotary drilling rig and diamond bit to drill holes, fix them with "two-point method" ground anchor before opening holes, and use angle ruler and geological compass to correct the vertical axis of the drilling rig. After grouting in 1 section, the buried depth of orifice pipe is 2m to bedrock, and the orifice pipe is φ73mm seamless steel pipe. KXP-I inclinometer is selected for borehole inclinometer, which is generally measured every 10m 1 time.
2) Borehole flushing and simple water pressing: high-pressure water pulse flushing is adopted, and the flushing time is not less than 30 min, with backwater 10 min. Simple water pressure test was conducted before grouting, and the water pressure was 65438±0.0 MPa.
3) Pulping and detection: centralized pulping is adopted, and pulp is supplied by different parts. The slurry is ground in series by a wet mill and then sent to a mixing barrel. The admixture is UNF-5 superplasticizer, and the dosage is 7%. Use standard funnel viscometer to detect mud concentration, and the funnel viscosity is required to be less than 30s；; ; The fineness is mainly checked by sedimentation method and laser particle size analyzer. Cement inspection is required every 10 t 1 time.
4) Automatic recording: All grouting records are completed by automatic recorder.
5) Grouting pressure control: In order to avoid uplift damage during construction, the relationship between injection rate and maximum grouting pressure is established.
2. Consolidation grouting
Grouting hole construction is carried out according to the principle of sequential encryption, which can be divided into two-sequence construction or three-sequence construction. Each hole should be drilled in sections from top to bottom, grouted in sections or grouted after drilling the last hole.
When the bedrock section of the grouting hole is less than 6m, the whole hole grouting can be completed at one time. When the geological conditions are not good or there are special requirements, grouting can be carried out in sections. For projects with grouting pressure not greater than 3MPa, grouting holes should be grouted in sections.
Baidu encyclopedia-curtain grouting
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