Application of various grouting methods in reservoirs?

The application of various grouting methods in reservoirs is very important. There are many methods, but the key is application. Only by choosing the most suitable one according to the actual situation can we solve the practical problems better. Zhong Da Consulting Company will explain the application of various grouting methods in reservoirs.

1 project overview

The project scale of a hydropower station is large (2) type, and the project grade is Grade II, which is composed of barrage, discharge structure, power generation and diversion system and workshop.

Engineering grouting mainly includes curtain grouting of dam foundation engineering, contact grouting of steel lining of power station building, backfill consolidation grouting of diversion tunnel engineering, etc. The construction sequence of curtain grouting, consolidation grouting, backfill grouting and steel lining contact grouting is: first backfill grouting, then consolidation grouting and then curtain grouting, and curtain grouting will be carried out after the field production test is completed. Grouting follows the principle of sequential construction and sequential densification. Backfilling grouting and contact grouting are carried out in sections, and consolidation grouting and curtain grouting are carried out in sequence and hole sequence. The consolidation grouting of diversion tunnel is carried out according to the principle of inter-ring order and intra-ring encryption, and the inter-ring order is divided into two orders. Curtain grouting should be carried out downstream before upstream. The same row is divided into three sequences: I, II and III, and grouting is carried out in sequence, and pilot hole construction is carried out in sequence I.

2 construction procedures

The construction process of grouting section is as follows: drilling → flushing → simple water pressing → grouting → circulating the next drilling and grouting → sealing the hole by "replacement and pressure grouting method" after the final hole section is filled.

3 Construction method

3. 1 drilling

3. 1. 1 YGZ-80 disc drill is used for backfill consolidation grouting of diversion tunnel, with an aperture of Ф ф55mm, and the final hole is made according to the design depth; YT-28 hand pneumatic drill is used for backfill grouting, with a hole diameter of Ф ф45mm and a hole depth of 0.10 m..

3. 1.2 The contact grouting hole of steel lining adopts the method of sealing the embedded grouting pipe in sections, and the grouting area of each hole should be controlled at 5 m2. The internal diameter of the embedded pipe is 50 mm, and before grouting, drill holes by hand pneumatic drill. If necessary, you can also use JICZ- 16 magnetic seat electric drill to drill holes with the aperture of 12 mm, and the hole position is determined according to the on-site hammering inspection.

3. 1.3 The bedrock consolidation grouting hole is drilled with XY-2PC geological drill or converted into a pneumatic drill, with a diameter of 56 mm, and the hole is formed according to the design depth.

3. 1.4 XY-2 geological drilling rig and eccentric drilling tool are used for the consolidation hole of overburden, and the casing diameter is 127 mm.

3. 1.5 Curtain grouting holes are arranged in the upstream and downstream rows. The arrangement of grouting holes should be based on the field production test, the rationality of hole spacing and row spacing, as well as grouting materials, slurry mixture ratio and grouting pressure, grouting methods and techniques. The curtain grouting hole shall be drilled in clean water with diamond drilling tools, with the aperture not less than φ76 mm and the final aperture not less than φ 56 mm. The hole depth shall be completed according to the design depth. The drilling equipment is XY-2 and XY-2PC geological drilling rigs.

3. 1.6 diamond clean water was drilled by XY-2 PC drilling rig in the lifting observation well, with a diameter of 9 1 mm and a depth of 30 m.

3. 1.7 The drilling rig used for the inspection hole is the same as the grouting hole, the aperture of the curtain inspection hole is not less than Ф ф76mm, and the backfill consolidation inspection hole is the same as the grouting hole. Static elastic modulus test hole is Ф 76 mm.

3.2 pulping

In order to ensure the engineering quality and efficient construction, centralized transportation is adopted for pulping. The left and right bank abutments are respectively provided with pulping stations, and ZJ-400 high-speed mixer (n= 1 450 r/min) is used for pulping, and low-speed mixer is used for storing pulp, and BW-200/40 is used for pumping pulp, and 0.5∶ 1 cement slurry is used. Send it to the transfer station (1 m3 slurry storage barrel) with a Ф ф50mm slurry delivery pipe, and then send it to the agitator of each grouting unit with a mud pump, and debug it into the mixture ratio required for grouting.

3.3 Grouting construction

3.3. 1 Grouting equipment grouting pump: It is SGB6- 10 three-cylinder piston pump, which can also be filled with cement mortar, which is beneficial to plugging the large leakage layer. Grouting recorder: GY-IV automatic grouting water pressure recorder produced by Hunan Lihe Technology Development Co., Ltd. has strong adaptability to working environment, and the data acquisition accuracy can meet the construction requirements. Hydraulic grouting plug: There are four specifications of φ56mm, φ66mm, φ76mm and φ9 1mm, which can be used for inspection hole grouting and water pressure test, and the maximum pressure is greater than 5 MPa.

3.3.2 Borehole flushing and water pressure test to backfill grouting holes: flushing and water pressure are not needed, and drilling slag can be blown out by wind after drilling. Contact between steel lining and grouting hole: Before grouting, clean compressed air should be used to check the collusion between gaps, and the dirt and water in the hole should be blown away, and the wind pressure should be less than the grouting pressure. Consolidation grouting hole: the consolidation grouting hole needs to flush the hole wall and cracks, and the hole wall flushing can be completed after the backwater is clarified. Flush the cracks with pressure water until the backwater is clear or not more than 20 min, and the flushing water pressure is 80% of the grouting pressure in the grouting section and not more than 1 Mpa. When the geological conditions are complex and the design has special requirements for crack flushing, the flushing method needs to be determined through field test or design. Before grouting, select representative holes for water pressure test, the water pressure is 80% of the grouting pressure, and the number of water pressure test holes accounts for 5% of the total number of holes. The test adopts single point method. Curtain grouting hole: after each grouting section is drilled, drilling and flushing shall be carried out so that the thickness of sediment in the hole does not exceed 0.2 m. Before grouting, the cracks shall be washed with pressure water until the backwater is clean. The flushing pressure is 80% of the grouting pressure, and shall not exceed 1 MPa. Before grouting, simple water pressing can be carried out in combination with fissure flushing, the pressure is 80% of the grouting pressure, not more than 1 MPa, and the water pressing is carried out for 20 min. The water pressing flow is measured every 5 minutes, and the final flow value is taken as the calculated flow, and the result is expressed as water permeability. Guide holes and inspection holes shall be subjected to water pressure test by single-point method or five-point method.

Grouting method

3.3.3. 1 Backfill grouting shall be carried out after the lining concrete reaches 70% of the design strength, and construction shall be carried out in sections, each section is 3 concrete lining sections. Grouting with filling pressure, advancing from low to high, and pouring 0.6 (or 0.5)∶ 1 cement slurry. When the pouring volume is large, cement mortar shall be poured, and the mixing amount of sand shall not exceed 200% of the cement volume. Grouting pressure adopts design pressure. Stop sucking slurry under the design pressure and continue to pour 10 min, and then backfill grouting can be completed.

Contact grouting of 3.3.3.2 steel lining shall be carried out 60 days after concrete pouring. Before grouting, check whether the joints collude with the pressure wind to blow out the dirt and water in the cracks, and whether the wind pressure is less than the grouting pressure. Grouting pressure should be based on controlling the deformation of steel lining not to exceed the design value, generally not greater than 1 MPa. Grouting starts from the lower hole, and the vibrating steel lining is tapped during grouting. After the thick mud is discharged from the upper hole, close the orifice valve in turn, and record the amount and concentration of mud discharged from each hole. Grouting end condition: stop sucking slurry at grouting hole under specified pressure and continue grouting for 5 min.

3.3.3.3 consolidation grouting is generally carried out under self-weight. When the long section is 6 m, it should be grouted in sections and filled with small grouting plugs. Usually, a pump is used to fill a hole. When drilling and stringing slurry, parallel filling with multiple holes should be adopted, and the number of parallel holes should not exceed three. Grouting pressure should be determined according to design drawings or combined with field production tests. Grouting completion standard: under the maximum design pressure of grouting hole (section), when the injection rate is not greater than 1 L/min, grouting can be completed by continuous grouting for 30 min. Hole sealing adopts "full hole grouting method".

Curtain grouting in 3.3.3.4 adopts the method of closed orifice and segmented grouting from top to bottom, with circular grouting in the hole, and the distance between the grouting pipe and the bottom of grouting section shall not exceed 50 cm. During the field production test, the grouting pressure should be adjusted according to the rock characteristics and grouting conditions. The concentration of grouting slurry should change gradually from thin to thick. During grouting, pay attention to control the grouting pressure increase speed, which is coordinated with the injection speed, and shall not exceed the specified value, so as to reduce the damage of rock lifting to buildings, closely monitor the reading of the dial indicator of the lifting device, and take timely pressure reduction measures or stop grouting when the lifting value is ≥200 um. Under the maximum design pressure, when the injection speed does not exceed 1 l/min, grouting can be completed by continuous grouting for 60 minutes. Grouting holes are blocked by "subsection grouting plugging method" or "full hole grouting plugging method".

4 conclusion

Grouting parameters and technology should be improved and perfected according to the field production test results to make them reasonable and advanced; After backfill grouting and consolidation grouting in the tunnel, the seepage flow is obviously reduced and the expected effect is achieved. Contact grouting of steel lining improves the compactness between concrete and steel pipe; After curtain grouting of dam foundation, the water level of piezometer tube is obviously reduced.

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