CN114411640B - Construction method for reinforcing and repairing rock-fill core wall dam - Google Patents
Construction method for reinforcing and repairing rock-fill core wall dam Download PDFInfo
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- CN114411640B CN114411640B CN202210238736.7A CN202210238736A CN114411640B CN 114411640 B CN114411640 B CN 114411640B CN 202210238736 A CN202210238736 A CN 202210238736A CN 114411640 B CN114411640 B CN 114411640B
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- 238000010276 construction Methods 0.000 title claims abstract description 47
- 230000003014 reinforcing effect Effects 0.000 title claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 62
- 239000002002 slurry Substances 0.000 claims abstract description 59
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000002131 composite material Substances 0.000 claims abstract description 23
- 230000003068 static effect Effects 0.000 claims abstract description 19
- 238000005516 engineering process Methods 0.000 claims abstract description 10
- 230000035699 permeability Effects 0.000 claims abstract description 8
- 230000010349 pulsation Effects 0.000 claims abstract description 8
- 230000000630 rising effect Effects 0.000 claims abstract description 4
- 238000005553 drilling Methods 0.000 claims description 42
- 238000013461 design Methods 0.000 claims description 22
- 238000011144 upstream manufacturing Methods 0.000 claims description 22
- 238000002347 injection Methods 0.000 claims description 19
- 239000007924 injection Substances 0.000 claims description 19
- 239000004568 cement Substances 0.000 claims description 18
- 239000004927 clay Substances 0.000 claims description 15
- 238000012360 testing method Methods 0.000 claims description 15
- 238000007689 inspection Methods 0.000 claims description 14
- 238000007789 sealing Methods 0.000 claims description 12
- 230000008569 process Effects 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 9
- 239000011435 rock Substances 0.000 claims description 8
- 239000000654 additive Substances 0.000 claims description 6
- 230000000996 additive effect Effects 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 6
- 239000003607 modifier Substances 0.000 claims description 6
- 230000000694 effects Effects 0.000 claims description 5
- 230000008859 change Effects 0.000 claims description 4
- 230000002265 prevention Effects 0.000 claims description 4
- 239000011398 Portland cement Substances 0.000 claims description 3
- 230000004888 barrier function Effects 0.000 claims description 3
- 230000000903 blocking effect Effects 0.000 claims description 3
- 238000007906 compression Methods 0.000 claims description 3
- 238000009792 diffusion process Methods 0.000 claims description 3
- 239000003673 groundwater Substances 0.000 claims description 3
- 239000005416 organic matter Substances 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 3
- 230000037452 priming Effects 0.000 claims description 3
- 230000002035 prolonged effect Effects 0.000 claims description 3
- 239000004576 sand Substances 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 230000035515 penetration Effects 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims description 2
- 230000002787 reinforcement Effects 0.000 abstract description 12
- 230000008439 repair process Effects 0.000 abstract description 5
- 230000008901 benefit Effects 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 2
- 238000004904 shortening Methods 0.000 description 2
- 238000009412 basement excavation Methods 0.000 description 1
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- 238000003973 irrigation Methods 0.000 description 1
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- 230000004048 modification Effects 0.000 description 1
- 230000003204 osmotic effect Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B7/00—Barrages or weirs; Layout, construction, methods of, or devices for, making same
- E02B7/02—Fixed barrages
- E02B7/04—Dams across valleys
- E02B7/06—Earth-fill dams; Rock-fill dams
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B3/00—Engineering works in connection with control or use of streams, rivers, coasts, or other marine sites; Sealings or joints for engineering works in general
- E02B3/16—Sealings or joints
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
- E02D15/04—Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
- E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
- E02D19/18—Restraining of underground water by damming or interrupting the passage of underground water by making use of sealing aprons, e.g. diaphragms made from bituminous or clay material
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
- Y02A10/11—Hard structures, e.g. dams, dykes or breakwaters
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Abstract
The invention discloses a method for reinforcing and repairing a rock-fill core wall dam, and belongs to the technical field of water conservancy and hydropower construction. A rock-fill core dam reinforcement and repair construction method comprises the following steps: s1, dam crest: dismantling and rebuilding to ensure that the dam top elevation meets the current standard requirements; s2, sinking and rising parts of the dam slope: repairing and recovering appearance quality; s3, dam: adopting controllable composite paste slurry high-pressure pulsation grouting; s4, a main river bed dam foundation: grouting by adopting static pressure; s5, dam foundations and dam abutments of two banks: grouting by using a curtain; s6, foundation along overflow weir: grouting by using a curtain; s7, downstream foot protection: reinforcing and recovering drainage; s8, separating the leaked spillway chute bottom plate into seams for anti-seepage treatment. According to the invention, a proper grouting reinforcement method is selected aiming at different dam segments under the condition of meeting the permeability coefficient of the dam body required by the current specification, and the seepage-proofing coefficient of the dam body is improved by a composite grouting reinforcement technology.
Description
Technical Field
The invention relates to the technical field of water conservancy and hydropower construction, in particular to a method for reinforcing and repairing a rock-fill core wall dam.
Background
The rock-fill core wall earth-rock dam is widely applied in the current world due to the advantages of convenient material taking, strong adaptability, flexible construction, simple structure, economy, high safety, reliability and the like. Numerous earth-rock dams are built in China, but the earth-rock dams are aged to different degrees after long-term operation; the permeability coefficient of the dam body does not meet the current standard requirement, and the normal operation is directly affected.
At present, in order to maintain the original functions of flood control, irrigation, cultivation, power generation and the like of a reservoir, reconstruction, repair, curtain grouting and other reconstruction, reinforcement and lifting technologies are adopted on the dam body of the existing reservoir. However, the method is not economical and environment-friendly and has long construction period.
The partial dam body dismantling reconstruction and restoration technology needs to handle water environmental protection procedures, local materials need to be obtained to find a material source site and a spoil site, and the ecological environment is greatly influenced; the construction period is longer; the curtain grouting technology is not economical in the longitudinal direction of the whole dam section.
Disclosure of Invention
The invention aims to solve the problems of insufficient economy, environmental protection and long construction period in the prior art when a dam body is reinforced and repaired, and provides a rock-fill core wall dam reinforcing and repairing construction method.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a rock-fill core dam reinforcement and repair construction method comprises the following steps:
s1, dam crest: dismantling and rebuilding to ensure that the dam top elevation meets the current standard requirements;
s2, sinking and rising parts of the dam slope: repairing and recovering appearance quality;
s3, dam: adopting controllable composite paste slurry high-pressure pulsation grouting;
s4, a main river bed dam foundation: grouting by adopting static pressure;
s5, dam foundations and dam abutments of two banks: grouting by using a curtain;
s6, foundation along overflow weir: grouting by using a curtain;
s7, downstream foot protection: reinforcing and recovering drainage;
s8, separating the leaked spillway chute bottom plate into seams for anti-seepage treatment.
Preferably, in step S3:
the grouting axis of the dam body is parallel to the axis of the dam near the upstream of the core wall;
the middle dam section is provided with two rows of holes, the two dam abutment sections are provided with single-row grouting holes, and the two rows of grouting holes are arranged in the upstream row; the first row of holes is arranged at a position 1.2m upstream of the dam axis, and the second row is arranged at a position 0.5m upstream of the dam axis; the grouting holes are arranged in three sequences, wherein the interval between the first sequence holes is 4m, the interval between the second sequence holes is 4m, and the interval between the third sequence holes is 2m;
the grouting depth is deeper than 1.0m below the dam foundation contact surface, and the method adopts bottom-up small-section pure pressure grouting; the primary grouting pressure is 1.5-3.0 MPa, the range of 5m below the dam crest is to prevent damage to the core wall, stable slurry is filled, and the primary grouting pressure is 0.5MPa;
during construction, constructing a downstream row firstly and then constructing an upstream row;
grouting completion requires the effective thickness of the anti-seepage body: the double row holes are not smaller than 1.3m, the single row holes are not smaller than 0.5m, and the permeability coefficient is not larger than 1.0X10-5 cm/s.
Preferably, in step S3, the method further includes:
carrying out a productivity test before construction;
selecting a relatively high dam section in the left bank and the right bank for testing to verify the pourability of the high-pressure pulse grouting technology in the project and influence on a core wall and a filter material; obtaining a corresponding paste diffusion range and a corresponding penetration coefficient;
the core wall powder clay has poor pourability, and the cohesive force of grouting slurry is reduced as much as possible on the premise of meeting the requirement.
Preferably, in step S3, the method further includes:
the accurate positions of high culvert and low culvert are ascertained before construction, and controllable composite paste high-pressure pulse grouting is not allowed to be carried out within the range of 1m around the pipe.
Preferably, the mixing ratio of the paste slurry is as follows:
the low-fluidity paste comprises the following components in percentage by mass of 100 parts of clay, 100 parts of cement, 15 parts of additive, 5 parts of pre-setting structural agent, 160 parts of water and 5 parts of modifier;
the stable composite paste comprises, by mass, 100 parts of clay, 100 parts of cement, 12 parts of additive, 6.5 parts of pre-setting structural agent, 160 parts of water and 3.5 parts of modifier.
Preferably, the paste material quality requirements are:
clay has clay content of not less than 25%, plasticity index of more than 14, sand content of not more than 5% and organic matter content of not more than 3%;
the cement adopts ordinary Portland cement, and the grade adopts PO425 grade.
Preferably, the physical and mechanical indexes of the paste slurry are as follows:
density >1.45g/cm3;
the fluidity is 60-140 mm;
the water separation rate is less than 1%;
initial setting time is 5h;
final setting time is 12h;
the strength of the calculus body 28d is 1.5-3.0 MPa;
the initial yield strength is more than or equal to 150Pa;
the elastic modulus is 100-3000 MPa.
Preferably, in step S3, the method further includes:
proportioning and conversion of slurry:
the slurry fluidity is controlled to be 60-140 mm, and the slurry fluidity is changed from large to small; the initial fluidity of the slurry is 90-140 mm, if the grouting pressure cannot reach the design pressure for a long time, the fluidity of the slurry can be changed to 60-90 mm;
grouting method and construction sequence:
adopting a 'controllable extrusion-in composite paste anti-seepage grouting method', and implementing slurry self-blocking and small-section pure-compression grouting in a drilling hole from bottom to top; each grouting section has the length of 0.5m, and when the grouting section meets the grouting end standard, the next grouting section can be used for grouting;
the controllable grouting hole construction sequence is carried out according to the principle of sequential encryption by firstly constructing a downstream row and then constructing an upstream row; the single-row controllable grouting is firstly constructed into a pilot hole, then a first-order hole is constructed, then a second-order hole is constructed, and finally a third-order hole is constructed;
wherein, part of the first-order holes are used as pilot holes;
after grouting of the corresponding part is finished for 14d, performing inspection hole construction;
grouting end standard:
the controllable grouting reaches one of the following conditions, and the grouting section can finish grouting:
(1) when the orifice pressure gauge reaches the lower limit of the set pressure, and the unit injection amount reaches the maximum grouting amount, the next section of grouting can be performed;
(2) when the orifice pressure gauge reaches the upper limit of the set pressure, and the unit injection amount reaches the minimum grouting amount, the next section of grouting can be performed;
(3) when the unit injection amount reaches 600L/m and the design pressure lower limit is not reached, grouting of the next stage can be performed.
Preferably, in steps S4, S5:
the drilling hole is coaxial with the upstream row axis of the dam body controllable composite paste high-pressure pulse grouting; arranging single row of holes, wherein the hole pitch is 2.0m; the three-order hole spacing is 8m, the two-order hole spacing is 8m, and the three-order hole spacing is 4m.
Curtain grouting is controlled 1m below the upper limit line of the weak permeable lower belt;
the pilot holes are arranged before construction, the pilot holes are selected from a sequence of holes, the distance between the pilot holes is 16-24 m, or the pilot holes are arranged according to 10% of the number of the holes; the static pressure grouting depth is determined through pilot hole test, and the principle of not penetrating the dam foundation water-resisting layer is adopted;
static pressure grouting drilling dam foundation below 5m, and drilling in 1m small sections;
the rock stratum change condition is concerned at any time, and the drilling speed and the backwater condition are concerned at any time in the drilling process; once the drilling speed is suddenly increased or the water return is turbid, the drilling is stopped immediately, and the phenomenon that a water barrier is penetrated to a goaf in the dam foundation grouting process is prevented.
Preferably, in steps S4 and S5, the steps include:
1) Drilling:
the deviation between the drilling position and the design position is not more than 10cm, and the depth of the hole accords with the design rule;
2) Grouting method:
when the length of the bedrock section of the grouting hole is smaller than 6m, adopting a full-hole one-time grouting method; when the size is larger than 6m, a top-down sectional grouting method is adopted;
3) Grouting pressure and slurry shift:
the curtain grouting pressure is 0.8-1.2 MPa, and the static pressure grouting primary grouting pressure is 0.3-0.5 MPa;
after curtain grouting and pore-forming, adopting static pressure grouting at the dam foundation surface before grouting so as to enhance the seepage-proofing effect of the contact zone of the dam foundation; ensuring that the overlap joint length of the dam foundation grouting and the dam body controllable composite paste slurry high-pressure pulse grouting is not less than 1m, and the overlap joint is good at the contact part of the dam foundation;
grouting should reach the design pressure as soon as possible, but should step up when the injection rate is large; the concentration of the grouting slurry is changed from thin to thick step by step; the cement ratio of the curtain grouting slurry can be 5:1. 3: 1. 2: 1. 1: 1. 0.8: 1. 0.6: 1. 0.5:1 seven ratio steps; the ratio of the water to the ash of the priming water can be 5:1, a step of;
in the grouting process, when the grouting pressure or the injection rate suddenly changes greatly, the reason should be immediately ascertained, and corresponding measures are adopted for treatment;
4) Grouting end standard and hole sealing method:
when the grouting section is under the maximum design pressure, the grouting can be finished after the grouting rate is not more than 1L/min and the grouting is continued for 30 min; when the geological conditions are complex, the groundwater flow speed is high, the injection quantity is high, and the grouting pressure is low, the continuous grouting time should be prolonged properly;
after the full-hole grouting is finished, replacing slurry or accumulated water in the holes with fresh ordinary cement slurry with the water-cement ratio of 0.5, and sealing holes by adopting a full-hole grouting hole sealing method;
hole sealing grouting pressure: when the top-down sectional grouting method and the bottom-up sectional grouting method are adopted, the full-hole Duan Pingjun grouting pressure is 2MPa;
during grouting, the grouting and slurry leakage are found, and caulking, surface blocking, low pressure, thick slurry, current limiting and limiting are adopted according to specific conditions:
5) And (3) engineering quality inspection:
the curtain grouting inspection hole water pressure test is carried out after curtain grouting is finished for 14 days; the number of the inspection is 10% of the total grouting holes, and the design requires that the pressurized water test q <5Lu in the inspection holes is a qualified standard.
Compared with the prior art, the invention provides a method for reinforcing and repairing the rock-fill core wall dam, which has the following beneficial effects.
1. According to the invention, a proper grouting reinforcement method is selected aiming at different dam segments under the condition of meeting the permeability coefficient of the dam body required by the current specifications, and the seepage-proofing coefficient of the dam body is improved by a composite grouting reinforcement technology, so that the purposes of reducing the construction cost, shortening the construction period and playing social benefits as soon as possible are achieved.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows; and will be apparent to those skilled in the art in part based upon a review of the following; alternatively, the teachings may be directed to practice of the present invention.
Drawings
Fig. 1 is a schematic diagram of concrete construction of reinforcement and repair of a rock-fill core dam.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.
A rock-fill core dam reinforcement and repair construction method comprises the following steps:
s1, dam crest: dismantling and rebuilding to ensure that the dam top elevation meets the current standard requirements;
s2, sinking and rising parts of the dam slope: repairing, namely repairing by adopting a method of backfilling after excavation, and recovering appearance quality;
s3, dam: adopting controllable composite paste slurry high-pressure pulsation grouting;
s4, a main river bed dam foundation: grouting by adopting static pressure;
s5, dam foundations and dam abutments of two banks: grouting by using a curtain;
s6, foundation along overflow weir: grouting by using a curtain;
s7, downstream foot protection: reinforcing and recovering drainage;
s8, separating the leaked spillway chute bottom plate into seams for anti-seepage treatment.
Referring to fig. 1, a specific construction of a reservoir is taken as an example.
Wherein, the dam body grouting axis is parallel to the dam axis near the upstream of the core wall.
As shown in the figure, the starting point of the left dam abutment is connected with the grouting end point of the spillway curtain, the right dam abutment is the intersection point of the rock-soil dividing line, which is shifted downwards by 1m and 495.82m, and the total length is 360.00m.
Two rows of holes are arranged at the joint of the dam section with the middle dam height of more than or equal to 30m and the flood spillway; row spacing is 0.7m, hole spacing is 1.0m, and quincuncial arrangement is realized; a single-row grouting hole is arranged at a dam section with the height of the two dams being less than 30 m; an upstream row, the first row of holes being disposed 1.2m upstream of the dam axis, the second row being disposed 0.5m upstream of the dam axis; the grouting holes are arranged in three sequences, wherein the distance between the first sequence holes is 4m, the distance between the second sequence holes is 4m, and the distance between the third sequence holes is 2m.
The grouting depth is deeper than 1.0m below the contact surface of the dam foundation, and the grouting is divided into small sections from bottom to top for pure pressure grouting. Wherein the aperture of the drilling final hole is not less than 91mm.
The primary grouting pressure is 1.5-3.0 MPa, the range of 5m below the dam crest is to prevent damage to the core wall, stable slurry is filled, and the primary grouting pressure is 0.5MPa.
It can be understood that during construction, the grouting pressure is checked and corrected according to the actual drilling grouting data in the grouting process; at the same time, the grouting pressure is not allowed to exceed the critical breaking pressure so as not to influence the grouting effect.
Productivity tests were performed prior to construction.
Specifically, in the engineering, a dam section with a higher right bank is selected for testing; to verify the pourability of the high-pressure pulse grouting technology in the project and the influence on the core wall and the filter material; and obtaining key parameters such as the diffusion range, the permeability coefficient and the like of the corresponding paste.
Because the core wall powder clay has poor filling property and high reservoir water level during filling, the cohesion of the filling slurry is reduced as much as possible on the premise of meeting the requirement.
During construction, the downstream row is constructed first, and then the upstream row is constructed.
Grouting completion requires the effective thickness of the anti-seepage body: the double row holes are not smaller than 1.3m, the single row holes are not smaller than 0.5m, and the permeability coefficient is not larger than 1.0X10-5 cm/s.
It should be noted that the accurate positions of the high culvert and the low culvert, especially the coordinates and the elevations of the intersection positions of the culvert pipes, the dam body and the grouting axes of the dam foundation, need to be ascertained before construction; in order to ensure that the original culvert pipe structure is not influenced when the dam body is grouted, the controllable composite paste high-pressure pulsation grouting is not allowed to be carried out in the range of 1m around the high culvert pipe and the low culvert pipe.
In the dam body seepage prevention construction of the dam by adopting controllable composite paste high-pressure pulsation grouting, the paste slurry mixing ratio is as follows:
the low-fluidity paste comprises the following components in percentage by mass of 100 parts of clay, 100 parts of cement, 15 parts of additive, 5 parts of pre-setting structural agent, 160 parts of water and 5 parts of modifier; the stable composite paste comprises, by mass, 100 parts of clay, 100 parts of cement, 12 parts of additive, 6.5 parts of pre-setting structural agent, 160 parts of water and 3.5 parts of modifier.
As shown in the table below.
Physical and mechanical indexes of the paste slurry are shown in the following table.
Wherein, the paste material quality requirement:
clay has clay content of not less than 25%, plasticity index of more than 14, sand content of not more than 5% and organic matter content of not more than 3%;
the cement adopts ordinary Portland cement, and the grade adopts PO425 grade.
In drilling: adopting a 300-type rotary drilling machine to perform hole forming, wherein the hole opening aperture is 150mm, and the final hole aperture is not less than 91mm; in construction, hole inclination is strictly controlled, observation on the hole inclination is enhanced, the hole inclination is measured once every 5-10 m of drilling, the drilling direction is corrected in time, and the maximum allowable deviation of drilling is not more than 0.8m.
Grouting pressure and grouting amount control criteria are shown in the following table.
In construction, the proportion and the change of slurry are controlled.
The slurry fluidity is controlled to be 60-140 mm, and the slurry fluidity is generally changed from large to small; the initial fluidity of the slurry is 90-140 mm, if the grouting pressure cannot reach the design pressure for a long time, the fluidity of the slurry can be changed to 60-90 mm.
Grouting method and construction sequence:
adopting a 'controllable extrusion-in composite paste anti-seepage grouting method', and implementing slurry self-blocking and small-section pure-compression grouting in a drilling hole from bottom to top; each grouting section has a length of 0.5m, and when the grouting section meets the grouting end standard, the next grouting section can be used for grouting.
The construction sequence of the controllable grouting holes is carried out according to the principle of sequential encryption by firstly constructing a downstream row and then constructing an upstream row.
The single-row controllable grouting is firstly constructed into a pilot hole, then a first-order hole is constructed, then a second-order hole is constructed, and finally a third-order hole is constructed; wherein, a part of the first-order holes are used as pilot holes.
And after grouting of the corresponding part is finished for 14d, performing hole inspection construction.
Grouting end standard:
the controllable grouting reaches one of the following conditions, and the grouting section can finish grouting.
(1) When the orifice pressure gauge reaches the set pressure lower limit, the unit injection amount reaches the maximum grouting amount, and the next section grouting can be performed.
(2) When the orifice pressure gauge reaches the upper limit of the set pressure, the unit injection amount reaches the minimum injection amount, and the next section of grouting can be performed.
(3) When the unit injection amount reaches 600L/m and the design pressure lower limit is not reached, grouting of the next stage can be performed.
The dam foundation seepage prevention adopts main riverbed dam segment static pressure grouting and two-bank dam abutment curtain grouting, and the drill hole and the upstream row axis of the dam body controllable composite paste high-pressure pulsation grouting are coaxial, namely, the upstream 1.2m position of the dam axis; arranging single row of holes, wherein the hole pitch is 2.0m; the three-order arrangement is adopted, the first order hole spacing is 8m, the second order hole spacing is 8m, and the third order hole spacing is 4m.
Curtain grouting is controlled 1m below the upper limit line (5 Lu line) of the weak permeable lower belt.
The pilot holes are arranged before construction, the pilot holes are selected from a sequence of holes, the distance between the pilot holes is 16-24 m, or the pilot holes are arranged according to 10% of the number of the holes.
The static pressure grouting is low-pressure thick slurry grouting, the depth of the static pressure grouting is determined through pilot hole test, and the maximum depth is not more than 8m on the basis of not penetrating a dam foundation water-resisting layer; static pressure grouting drilling dam foundation is below 5m, and 1m small section drilling is recommended.
The rock stratum change condition is concerned at any time, and the drilling speed and the backwater condition are concerned at any time in the drilling process; once the drilling speed is suddenly increased or the water return is turbid, the drilling is stopped immediately, and the phenomenon that a water barrier is penetrated to a goaf in the dam foundation grouting process is prevented.
And performing dam foundation and dam abutment seepage prevention construction by adopting static pressure grouting and curtain grouting, wherein the method comprises the following steps.
1) Drilling.
The deviation between the drilling position and the design position is not more than 10cm, and the depth of the hole accords with the design rule.
The grouting holes are preferably small in aperture, and the wall of the drilled holes is flat and complete, so that the accuracy of the hole direction is ensured; the drilling machine is installed flatly and stably, the drill holes are embedded with orifice pipes, and the direction of the vertical shaft of the drilling machine is consistent with the direction of the orifice pipes and the designed hole; the drilling adopts a longer thick-diameter drilling tool, and the drilling pressure is properly controlled.
The grouting holes should be measured for hole inclination, and the deviation is found to be over the requirement and should be corrected or remedied in time.
2) The grouting method is a grouting mode.
When the length of the bedrock section of the grouting hole is smaller than 6m, adopting a full-hole one-time grouting method; and when the size is larger than 6m, adopting a top-down sectional grouting method.
3) Grouting pressure and slurry shift.
The curtain grouting pressure is 0.8-1.2 MPa, and the static pressure grouting primary grouting pressure is 0.3-0.5 MPa.
When in construction, the grouting pressure should be checked and corrected according to the actual drilling grouting data in the grouting process; at the same time, the grouting pressure is not allowed to exceed the critical breaking pressure so as not to influence the grouting effect.
After curtain grouting and pore-forming, adopting static pressure grouting at the dam foundation surface before grouting so as to enhance the seepage-proofing effect of the contact zone of the dam foundation; the overlap joint length of the dam foundation grouting and the controllable composite paste slurry high-pressure pulsation grouting of the dam body is not less than 1m, and the overlap joint is good at the contact part of the dam foundation.
Grouting should reach the design pressure as soon as possible, but should step up when the injection rate is large; the concentration of the grouting slurry is changed from thin to thick step by step.
The cement ratio of the curtain grouting slurry can be 5:1. 3: 1. 2: 1. 1: 1. 0.8: 1. 0.6: 1. 0.5:1 seven ratio steps; the ratio of the water to the ash of the priming water can be 5:1.
in the grouting process, when the grouting pressure or the injection rate suddenly changes greatly, the reason should be immediately ascertained, and corresponding measures are adopted for treatment.
4) Grouting end standard and hole sealing method:
when the grouting section is under the maximum design pressure, the grouting can be finished after the grouting rate is not more than 1L/min and the grouting is continued for 30 min; when the geological conditions are complex, the groundwater flow speed is high, the injection quantity is high, and the grouting pressure is low, the continuous grouting time should be prolonged appropriately.
After the full-hole grouting is finished, the slurry or the accumulated water in the holes is replaced by fresh ordinary cement slurry with the water-cement ratio of 0.5, and a full-hole grouting and hole sealing method is adopted for hole sealing.
Hole sealing grouting pressure: when the top-down sectional grouting method and the bottom-up sectional grouting method are adopted, the full-hole Duan Pingjun grouting pressure is 2MPa.
During grouting, the grouting and slurry leakage are found, and caulking, surface blocking, low pressure, thick slurry, current limiting and limiting are adopted according to specific conditions:
5) And (6) checking engineering quality.
Curtain grouting inspection hole water-pressing test is performed 14 days after curtain grouting is finished.
The number of the inspection is 10% of the total grouting holes, and the design requires that the pressurized water test q <5Lu in the inspection holes is a qualified standard.
The osmotic coefficient was measured to be 0.86×10 -5cm S, less than design criteria; can be widely popularized and applied in earth-rock dam and earth-rock cofferdam reinforcement engineering construction, and has strong applicability.
Aiming at the defects of the traditional technology, the invention provides a method for reinforcing and repairing a rock-fill core wall dam; according to different dam segments, under the condition of meeting the permeability coefficient of the dam body required by the current specifications, a proper grouting reinforcement method is selected, and the seepage-proofing coefficient of the dam body is improved by a composite grouting reinforcement technology, so that the purposes of reducing the construction cost, shortening the construction period and playing social benefits as soon as possible are achieved.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (8)
1. The construction method for reinforcing and repairing the rock-fill core wall dam is characterized by comprising the following steps of:
s1, dam crest: dismantling and rebuilding to ensure that the dam top elevation meets the current standard requirements;
s2, sinking and rising parts of the dam slope: repairing and recovering appearance quality;
s3, dam: adopting controllable composite paste slurry high-pressure pulsation grouting;
s4, a main river bed dam foundation: grouting by adopting static pressure;
s5, dam foundations and dam abutments of two banks: grouting by using a curtain;
s6, foundation along overflow weir: grouting by using a curtain;
s7, downstream foot protection: reinforcing and recovering drainage;
s8, separating the leaked spillway chute bottom plate into slits for seepage prevention treatment;
wherein:
in step S3:
the grouting axis of the dam body is parallel to the axis of the dam near the upstream of the core wall;
the middle dam section is provided with two rows of holes, the two dam abutment sections are provided with single-row grouting holes, and the two rows of grouting holes are arranged in the upstream row; the first row of holes is arranged at a position 1.2m upstream of the dam axis, and the second row is arranged at a position 0.5m upstream of the dam axis; the grouting holes are arranged in three sequences, wherein the interval between the first sequence holes is 4m, the interval between the second sequence holes is 4m, and the interval between the third sequence holes is 2m;
the grouting depth is deeper than 1.0m below the dam foundation contact surface, and the method adopts bottom-up small-section pure pressure grouting; the primary grouting pressure is 1.5-3.0 MPa, the range of 5m below the dam crest is to prevent damage to the core wall, stable slurry is filled, and the primary grouting pressure is 0.5MPa;
during construction, constructing a downstream row firstly and then constructing an upstream row;
grouting completion requires the effective thickness of the anti-seepage body: the double row holes are not smaller than 1.3m, the single row holes are not smaller than 0.5m, and the permeability coefficient is not larger than 1.0X10 -5 cm/s；
In step S3, further comprising:
proportioning and conversion of slurry:
the slurry fluidity is controlled to be 60-140 mm, and the slurry fluidity is changed from large to small; the initial fluidity of the slurry is 90-140 mm;
if the grouting pressure can not reach the design pressure for a long time, the fluidity of the slurry is changed to 60-90 mm;
grouting method and construction sequence:
adopting a 'controllable extrusion-in composite paste anti-seepage grouting method', and implementing slurry self-blocking and small-section pure-compression grouting in a drilling hole from bottom to top; each grouting section has the length of 0.5m, and when the grouting section meets the grouting end standard, the next grouting section can be used for grouting;
the controllable grouting hole construction sequence is carried out according to the principle of sequential encryption by firstly constructing a downstream row and then constructing an upstream row; the single-row controllable grouting is firstly constructed into a pilot hole, then a first-order hole is constructed, then a second-order hole is constructed, and finally a third-order hole is constructed;
wherein, part of the first-order holes are used as pilot holes;
after grouting of the corresponding part is finished for 14 days, performing inspection hole construction;
grouting end standard:
the controllable grouting reaches one of the following conditions, and the grouting section can finish grouting:
(1) when the orifice pressure gauge reaches the lower limit of the set pressure, and the unit injection amount reaches the maximum grouting amount, the next section of grouting can be performed;
(2) when the orifice pressure gauge reaches the upper limit of the set pressure, and the unit injection amount reaches the minimum grouting amount, the next section of grouting can be performed;
(3) when the unit injection amount reaches 600L/m and the design pressure lower limit is not reached, grouting of the next stage can be performed.
2. The method for reinforcing and repairing a rockfill core dam according to claim 1, further comprising, in step S3:
carrying out a productivity test before construction;
selecting a relatively high dam section in the left bank and the right bank for testing to verify the pourability of the high-pressure pulse grouting technology in the project and influence on a core wall and a filter material; obtaining a corresponding paste diffusion range and a corresponding penetration coefficient;
the core wall powder clay has poor pourability, and the cohesive force of grouting slurry is reduced as much as possible on the premise of meeting the requirement.
3. The method for reinforcing and repairing a rockfill core dam according to claim 1, further comprising, in step S3:
the accurate positions of high culvert and low culvert are ascertained before construction, and controllable composite paste high-pressure pulse grouting is not allowed to be carried out within the range of 1m around the pipe.
4. The method for reinforcing and repairing the rock-fill core dam according to claim 1, wherein the mixing ratio of the paste slurry is:
the low-fluidity paste comprises the following components in percentage by mass of 100 parts of clay, 100 parts of cement, 15 parts of additive, 5 parts of pre-setting structural agent, 160 parts of water and 5 parts of modifier;
the stable composite paste comprises, by mass, 100 parts of clay, 100 parts of cement, 12 parts of additive, 6.5 parts of pre-setting structural agent, 160 parts of water and 3.5 parts of modifier.
5. The method for reinforcing and repairing the rock-fill core dam according to claim 4, wherein the mass requirements of the paste material are as follows:
clay has clay content of not less than 25%, plasticity index of more than 14, sand content of not more than 5% and organic matter content of not more than 3%;
the cement adopts ordinary Portland cement, and the grade adopts PO425 grade.
6. The method for reinforcing and repairing the rock-fill core dam according to claim 4, wherein the physical and mechanical indexes of the slurry are as follows:
density of>1.45g/cm 3 ；
The fluidity is 60-140 mm;
the water separation rate is less than 1%;
initial setting time is 5h;
final setting time is 12h;
the strength of the calculus body 28d is 1.5-3.0 MPa;
the initial yield strength is more than or equal to 150Pa;
the elastic modulus is 100-3000 MPa.
7. The method for reinforcing and repairing a rockfill core dam according to claim 1, wherein in steps S4 and S5:
the drilling hole is coaxial with the upstream row axis of the dam body controllable composite paste high-pressure pulse grouting; arranging single row of holes, wherein the hole pitch is 2.0m; the three-order hole spacing is 8m, the two-order hole spacing is 8m, and the three-order hole spacing is 4m;
curtain grouting is controlled 1m below the upper limit line of the weak permeable lower belt;
the pilot holes are arranged before construction, the pilot holes are selected from a sequence of holes, the distance between the pilot holes is 16-24 m, or the pilot holes are arranged according to 10% of the number of the holes; the static pressure grouting depth is determined through pilot hole test, and the principle of not penetrating the dam foundation water-resisting layer is adopted;
static pressure grouting drilling dam foundation below 5m, and drilling in 1m small sections;
the rock stratum change condition is concerned at any time, and the drilling speed and the backwater condition are concerned at any time in the drilling process; once the drilling speed is suddenly increased or the water return is turbid, the drilling is stopped immediately, and the phenomenon that a water barrier is penetrated to a goaf in the dam foundation grouting process is prevented.
8. The method for reinforcing and repairing a rockfill core dam according to claim 7, wherein in steps S4 and S5, the method comprises the steps of:
1) Drilling:
the deviation between the drilling position and the design position is not more than 10cm, and the depth of the hole accords with the design rule;
2) Grouting method:
when the length of the bedrock section of the grouting hole is smaller than 6m, adopting a full-hole one-time grouting method; when the size is larger than 6m, a top-down sectional grouting method is adopted;
3) Grouting pressure and slurry shift:
the curtain grouting pressure is 0.8-1.2 MPa, and the static pressure grouting primary grouting pressure is 0.3-0.5 MPa;
after curtain grouting and pore-forming, adopting static pressure grouting at the dam foundation surface before grouting so as to enhance the seepage-proofing effect of the contact zone of the dam foundation; ensuring that the overlap joint length of the dam foundation grouting and the dam body controllable composite paste slurry high-pressure pulse grouting is not less than 1m, and the overlap joint is good at the contact part of the dam foundation;
grouting should reach the design pressure as soon as possible, but should step up when the injection rate is large; the concentration of the grouting slurry is changed from thin to thick step by step; the cement ratio of the curtain grouting slurry can be 5:1. 3: 1. 2: 1. 1: 1. 0.8: 1. 0.6: 1. 0.5:1 seven ratio steps; the ratio of the water to the ash of the priming water can be 5:1, a step of;
in the grouting process, when the grouting pressure or the injection rate suddenly changes greatly, the reason should be immediately ascertained, and corresponding measures are adopted for treatment;
4) Grouting end standard and hole sealing method:
when the grouting section is under the maximum design pressure, the grouting can be finished after the grouting rate is not more than 1L/min and the grouting is continued for 30 min; when the geological conditions are complex, the groundwater flow speed is high, the injection quantity is high, and the grouting pressure is low, the continuous grouting time should be prolonged properly;
after the full-hole grouting is finished, replacing slurry or accumulated water in the holes with fresh ordinary cement slurry with the water-cement ratio of 0.5, and sealing holes by adopting a full-hole grouting hole sealing method;
hole sealing grouting pressure: when the top-down sectional grouting method and the bottom-up sectional grouting method are adopted, the full-hole Duan Pingjun grouting pressure is 2MPa;
during grouting, the grouting and slurry leakage are found, and caulking, surface blocking, low pressure, thick slurry, current limiting and limiting are adopted according to specific conditions:
5) And (3) engineering quality inspection:
the curtain grouting inspection hole water pressure test is carried out after curtain grouting is finished for 14 days; the number of the inspection is 10% of the total grouting holes, and the design requires that the pressurized water test q <5Lu in the inspection holes is a qualified standard.
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