Underground cavern high side wall uncovered heavy consolidation grouting test method

Abstract

The invention discloses an underground cavern high side wall cover-weight-free consolidation grouting test method. The method comprises the following test steps that firstly, a grouting test is arranged; comprising grouting hole arrangement, deformation monitoring hole arrangement and geophysical prospecting test hole arrangement. 2, a grouting method and a boosting test are carried out; comprising a grouting material, a grouting method and a boosting test. In the pressure boosting test, grouting pressure boosting is adopted, firstly, three rows of grouting holes are formed from top to bottom, three holes are formed in each row, and nine grouting holes are formed in total; secondly, each row is constructed in two sequences, the first sequence holes are constructed firstly, and then the second sequence holes are constructed; secondly, the depth of a grouting single hole is 15 m, grouting is conducted in a segmented mode, and the depth of a lifting observation hole is 17 m; secondly, P.O42.5 ordinary Portland cement is adopted as a grouting material. Compared with the prior art, the method has the advantages that the high side wall arranged in a thin layer, a steep dip angle and a soft shale layer is subjected to consolidation grouting under the condition of no cover weight, surrounding rock has groutability, and the grouting effect is remarkable.

Description

Technical Field

[0001] The invention relates to the technical field of grouting tests, in particular to a method for consolidation grouting tests of high side walls of underground caverns without cover weight. Background Art

[0002] Uncovered consolidation grouting is divided into completely uncovered consolidation grouting (also known as bare rock consolidation grouting) and surface-enclosed uncovered consolidation grouting. The high side walls of the underground powerhouse of Pengshui Hydropower Station adopt bedrock-enclosed uncovered consolidation grouting after surface spraying with 15cm thick steel fiber concrete. Uncovered consolidation grouting is usually used for dam foundation treatment, but in thin layers, steep inclinations, and weak shale layers, the longitudinal axis of the cavern structure is arranged at an angle of 0° to the rock formation. There is no mature experience in consolidation grouting reinforcement treatment of such large underground cavern high side walls without cover.

[0003] Engineering experience shows that consolidation grouting has a significant effect on improving the mechanical properties of rock mass, increasing the bearing capacity and deformation resistance of surrounding rock, especially improving the integrity of micro-cracks or loose and broken rock mass. After grouting, the cracks in the rock mass are filled and compacted, and the mechanical properties of the structural surface change. However, due to the constraints of the karst system, the large underground cavern structure adopts a 0° layout scheme in a thin layer, steep angle, and weak shale layer. The surrounding rock itself has the characteristics of short self-stabilization time, weak weathering resistance, sudden failure mechanism, and is not easy to be captured by monitoring facilities. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the above technical defects.

[0005] In order to solve the above problems, the technical solution of the present invention is: a test method for consolidation grouting of high side walls of underground caverns without cover, comprising the following test steps:

[0006] Step 1: Grouting test arrangement, including grouting hole arrangement, deformation monitoring hole arrangement and geophysical test hole arrangement;

[0007] Step 2: Grouting method and pressure test; including grouting materials, grouting method and pressure test;

[0008] The pressure-raising test adopts grouting pressure-raising, firstly, 3 rows of grouting holes are arranged from top to bottom, 3 holes are arranged in each row, and 9 grouting holes are arranged in total;

[0009] Secondly, each row is constructed in two sequences, first constructing sequence Ⅰ holes, then sequence Ⅱ holes;

[0010] Secondly, the grouting single hole is 15m deep, and the grouting is carried out in sections, and the lifting observation hole is 17m deep;

[0011] Secondly, the grouting material is P·O42.5 ordinary Portland cement;

[0012] Final grouting pressure: 0.1~0.3MPa for the first section (orifice section), 0.3~0.5MPa for the second section (maximum pressure in this section ≤0.5MPa).

[0013] Furthermore, the grouting holes in step 2 are spaced 3m apart and row-to-row distance is 3m. One geophysical exploration hole and one lifting observation hole are arranged in the first and third zones, and one lifting observation hole is arranged in the second zone.

[0014] Furthermore, the grouting material is pure cement slurry, and the cement is P·O42.5 ordinary Portland cement. The water-cement ratio of cement slurry for sequence I hole is tentatively set to 2:1, and the water-cement ratio of cement slurry for sequence II hole is 3:1. The slurry transformation is carried out in the ratios of 3:1, 2:1, 1:1, and 0.5:1.

[0015] Compared with the existing technology, the invention has the advantages that the high side wall arranged in the thin layer, steep angle, weak shale layer is consolidated and grouting is carried out without cover weight, the surrounding rock is groutable, and the grouting effect is significant. DETAILED DESCRIPTION

[0016] The specific embodiments of the present invention are further described below.

[0017] In order to make the contents of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention.

[0018] The test method for consolidation grouting of high side walls of underground caverns without cover weight includes the following test steps:

[0019] Step 1: Grouting test arrangement, including grouting hole arrangement, deformation monitoring hole arrangement and geophysical test hole arrangement;

[0020] Step 2: Grouting method and pressure test; including grouting materials, grouting method and pressure test;

[0021] The pressure-raising test adopts grouting pressure-raising, firstly, 3 rows of grouting holes are arranged from top to bottom, 3 holes are arranged in each row, and 9 grouting holes are arranged in total;

[0022] Secondly, each row is constructed in two sequences, first constructing sequence Ⅰ holes, then sequence Ⅱ holes;

[0023] Secondly, the grouting single hole is 15m deep, and the grouting is carried out in sections, and the lifting observation hole is 17m deep;

[0024] Secondly, the grouting material is P·O42.5 ordinary Portland cement;

[0025] Final grouting pressure: 0.1~0.3MPa for the first section (orifice section), 0.3~0.5MPa for the second section (maximum pressure in this section ≤0.5MPa).

[0026] The grouting holes in the step 2 are 3m apart and 3m apart. One geophysical exploration hole and one lifting observation hole are arranged in the 1st and 3rd zones, and one lifting observation hole is arranged in the 2nd zone. The grouting material is pure cement slurry, and the cement is P·O42.5 ordinary Portland cement. The water-cement ratio of cement slurry for sequence I hole is tentatively set to 2:1, and the water-cement ratio of cement slurry for sequence II hole is 3:1. The slurry transformation is carried out according to 3:1, 2:1, 1:1, and 0.5:1.

[0027] In actual use, after grouting, the inspection hole was subjected to a water pressure test.

[0028] Analysis and evaluation of water pressure test before and after grouting below elevation EL218m, and comparison of water permeability from inspection holes before and after grouting in the test area were carried out, making the uncovered consolidation grouting test method more convincing.

[0029] The present invention and its implementation methods are described above, and such description is not restrictive. In short, if a person skilled in the art is inspired by it and, without departing from the purpose of the invention, designs structures and embodiments similar to the technical solution without creativity, they should all fall within the protection scope of the present invention.

Claims

1. The test method for consolidation grouting of high side walls of underground caverns without cover weight is characterized by: The test steps include: Step 1: Grouting test arrangement, including grouting hole arrangement, deformation monitoring hole arrangement and geophysical test hole arrangement; Step 2: Grouting method and pressure test; including grouting materials, grouting method and pressure test; The pressure-raising test adopts grouting pressure-raising, firstly, 3 rows of grouting holes are arranged from top to bottom, 3 holes are arranged in each row, and 9 grouting holes are arranged in total; Secondly, each row is constructed in two sequences, first constructing sequence Ⅰ holes, then sequence Ⅱ holes; Secondly, the grouting single hole is 15m deep, and the grouting is carried out in sections, and the lifting observation hole is 17m deep; Secondly, the grouting material is P·O42.5 ordinary Portland cement; Final grouting pressure: 0.1~0.3MPa for the first section (hole mouth section), 0.3~0.5MPa for the second section (maximum pressure in this section ≤0.5MPa).

2. The method for consolidation grouting of high side walls of underground caverns without cover according to claim 1 is characterized in that: The grouting holes in step 2 are spaced 3m apart and row-to-row distance is 3m. One geophysical exploration hole and one lifting observation hole are arranged in zones 1 and 3, and one lifting observation hole is arranged in zone 2.

3. The method for consolidation grouting of high side walls of underground caverns without cover according to claim 1 is characterized in that: The grouting material is pure cement slurry, and the cement is P·O42.5 ordinary Portland cement. The water-cement ratio of cement slurry for sequence I hole is tentatively set to 2:1, and the water-cement ratio of cement slurry for sequence II hole is 3:

1. The slurry transformation is carried out in the ratios of 3:1, 2:1, 1:1, and 0.5:1.