CN116971338A

CN116971338A - Methods for rapid construction of rock-fill self-compacting concrete gravity dams

Info

Publication number: CN116971338A
Application number: CN202310954516.9A
Authority: CN
Inventors: 蔡东波; 柴少强; 李春早; 张汉; 刘小强; 闫东杰; 苏克静; 姜竣博
Original assignee: CCCC Seventh Engineering Co Ltd
Current assignee: CCCC Seventh Engineering Co Ltd
Priority date: 2023-07-31
Filing date: 2023-07-31
Publication date: 2023-10-31
Anticipated expiration: 2043-07-31
Also published as: CN116971338B

Abstract

The application relates to the technical field of hydraulic engineering, and discloses a method for rapidly constructing a self-compacting concrete gravity dam of a rock-fill, which comprises the following steps: s1, treating a bedrock surface and preparing a cleaning field, and pouring a concrete cushion layer after the bedrock surface is treated; s2, installing a template; s3, screening and warehousing of piled stones; s4, producing and transporting self-compacting concrete; s5: pouring self-compacting concrete; s6, curing the self-compacting rock-fill concrete; and S7, checking the safety performance of the stepped gravity dam body through a numerical simulation method and a rigid body limit balance method. The technical scheme of the application can reduce the risk of safe operation and the construction cost, and simultaneously improve the construction efficiency and shorten the construction period.

Description

Method for rapidly constructing rock-fill self-compacting concrete gravity dam

Technical Field

The application relates to the technical field of hydraulic engineering, in particular to a method for rapidly constructing a rock-fill self-compacting concrete gravity dam.

Background

The rock-fill concrete is a novel large-volume concrete construction mode developed on the basis of self-compacting concrete technology, and the characteristics of high fluidity, good separation resistance and self-flowing of the self-compacting concrete are utilized to randomly fill rock-fill gaps in the rock blocks with larger grain sizes to form complete and compact concrete.

The dam body surface of the existing gravity dam back water surface is designed into a slope type, the back water surface of the slope type gravity dam is usually provided with a back frame type high-strength formwork, when the back frame type high-strength formwork is installed, a tower crane is required to hoist the back frame type high-strength formwork, a storage formwork is required to be reserved as a supporting female die, the back frame type high-strength formwork is supported, and meanwhile, internal pulling reinforcing steel bars are required to reinforce the back frame type high-strength formwork. The problems with slope gravity dams in construction are: 1. when the back frame type high-strength template is reinforced, the body of an operator is in an inclined operation state, so that the risk of safe operation is increased; 2. the use of the internal pulling reinforcing steel bars increases the use of the steel bars, and meanwhile, the internal pulling reinforcing steel bars occupy the space of the stone stacking layer, so that the stone stacking rate is reduced, the use amount of concrete is increased, and the construction cost is increased; 3. because when installing back-up frame formula template that excels in, need adopt the tower crane to hoist and mount to need reserve a storehouse template as supporting the master model, for back-up frame formula template that excels in provides the support, consequently, increased the input of master model and tower crane, increased construction cost, reduced the efficiency of construction simultaneously, prolonged construction cycle.

Disclosure of Invention

The application aims to provide a rapid construction method of a self-compacting concrete gravity dam for a rock-fill, so as to reduce the risk of safe operation and the construction cost, improve the construction efficiency and shorten the construction period.

In order to achieve the above purpose, the application adopts the following technical scheme: the method for rapidly constructing the rock-fill self-compacting concrete gravity dam comprises the following steps:

s1, treating a bedrock surface and preparing a cleaning field, and pouring a concrete cushion layer after the bedrock surface is treated;

s2, installing a template, wherein the template comprises an upstream surface template and a back surface template, the upstream surface template is fixed through an installing support, the back surface is designed in a step mode, the on-line positions of a step external corner connecting line and an original slope surface are consistent, namely, a step is retracted towards the inside of a dam body relative to the original slope surface, the step size is 1.6mx2.0m, the back surface template is a single-layer template, and the single-layer template is reinforced by adopting a recyclable back frame implanted anchor ground steel bar and a bolt;

s3, screening and warehousing of piled stones;

firstly, screening and cleaning the rock piles, wherein the particle size range of the rock piles is 30-160 cm;

secondly, placing the piled stones into a bin, namely arranging the bin from the upstream surface to the downstream surface by adopting a reverse method, and piling the piled stones in a space which is 50cm away from the upstream surface template;

s4, producing and transporting self-compacting concrete, and mixing the self-compacting concrete in a field mixing mode, wherein the water-cement ratio change range is controlled within-0.02-0.01 during mixing;

s5, pouring self-compacting concrete;

firstly, pouring an anti-seepage panel;

secondly, pouring self-compacting concrete of the rock-fill layer;

s6, curing the self-compacting rock-fill concrete;

and S7, checking the safety performance of the stepped gravity dam body through a numerical simulation method and a rigid body limit balance method.

The beneficial effect of this scheme is: compared with the prior art, the technical scheme has the following advantages:

1. because the back surface adopts the ladder formula design, and ladder external corner connecting wire is unanimous with former slope surface on-line position, and the ladder is for the inside indentation of dam body of former slope face promptly, consequently, this technical scheme's gravity dam has practiced thrift construction cost, has reduced the construction degree of difficulty, has improved the control of efficiency of construction, be convenient for construction quality.

2. Because the technical scheme adopts the recyclable back frame to implant the anchor ground steel bars and the bolts to strengthen the back surface template, the technical scheme omits the internal pulling strengthening steel bars, reduces the using amount of the steel bars and reduces the construction cost; meanwhile, the technical scheme omits the internal-pulling steel bars, so that the space of the stone stacking layer is not occupied when the back surface template is reinforced, the stone stacking rate is improved, the using amount of concrete is reduced, and the construction cost is further reduced.

3. The back surface is designed in a stepped manner, and the step size is 1.6mX2.0 m, so that when the back surface template is installed, a female die is not required to be supported, the investment of the female die is saved, a tower crane is not required to be used for hoisting the template, the cast-in-situ step surface is taken as a reference to install the back surface template, the height of a working surface is reduced, and the potential safety hazard existing in high-place operation is reduced; meanwhile, the technical scheme omits the procedure of installing the template by the tower crane, and the step-type slope does not need to be constructed in a reverse bevel, so that the working face is large, the turnover efficiency of the template is high, the construction efficiency is improved, and the construction period is shortened.

4. In the aspect of installation and disassembly of the step section back surface template, the template is easy to reinforce, the stability is good, meanwhile, the rockfill is easy to put and the base surface is easy to clean, the thickness of the concrete protection layer of the downstream surface is easy to control, the self-compaction concrete of the step surface is filled more compactly, and the pouring quality is improved.

5. And checking the safety performance of the stepped gravity dam body by a numerical simulation method and a rigid body limit balance method, wherein the stepped gravity dam meets the safety requirement.

According to the technical scheme, the stone layer is piled in a space which is 50cm away from the upstream face template, so that when the impermeable panel is poured, the non-poured stone layer is used as the template, the formwork supporting process of the template on the inner side of the upstream face template is omitted, the construction procedure is simplified, the construction cost is reduced, the construction progress is improved, and meanwhile, the impermeable panel can resist the impact of the osmotic water pressure, so that the impermeable effect is achieved; compared with other concrete pouring for the seepage-proofing panel, the seepage-proofing panel is poured by self-compacting concrete, so that the aim of pouring the self-compacting concrete of the rock-fill layer can be fulfilled, the process of mixing other concrete is omitted, meanwhile, the self-compacting concrete has the advantages of good fluidity and good separation resistance, and the seepage-proofing effect of the dam can be improved.

The water-cement ratio variation range is controlled within-0.02-0.01, and the fluidity of the concrete is fully maintained at a proper range value on the basis of ensuring the solidification quality, so that the self-compacting concrete is uniformly filled in the rock-fill layer.

Further, in S2, the template still includes the indent template, and the indent template is the L type, and the indent template is including connecting portion and the shaping portion that connects gradually, and connecting portion installs in the upper end of upstream face template, and one side and the prevention of seepage panel contact of shaping portion, the width of shaping portion is 15 centimetres, and the lower extreme of shaping portion stretches into in the rock-fill layer.

The beneficial effect of this scheme is: due to the arrangement of the pressing groove template, when the self-compacting concrete of the stacking layer is poured, a groove with the width of 15 cm is formed on one side close to the anti-seepage panel, the grain diameter of the stacking stone is larger than 30cm, the stacking stone cannot be filled into the groove of the upper dam body when the stacking stone layer of the next dam body is stacked, pure self-compacting concrete is filled into the groove when the next dam body is poured, and under the double-layer protection of the anti-seepage panel and the groove, the anti-seepage effect of a construction joint is improved; in the process of rock-fill, a face of the rock-fill is just attached to the base surface of the self-compacting concrete of the rock-fill layer in the dam body of the previous layer, and the self-compacting concrete can not penetrate into the face attached to the rock-fill layer, so that the risk of dam leakage is increased, and the grooves are formed, when the dam body of the next layer is poured, the self-compacting concrete can flow into the attached face through the grooves, and the risk of dam leakage is reduced; if water on the upstream surface passes through the seepage-proofing surface through the interlayer construction joint and flows to the groove part, the water needs to pass through the groove part, and then the water needs to turn to flow to the bottom of the groove and then flow to the upper part of the groove, so that the seepage-proofing effect is achieved.

Further, in the first step of S5, a water stop sheet is provided at the downstream of the impermeable panel, the water stop sheet includes an upper connection portion, a water stop portion and a lower connection portion which are sequentially connected, a clamping groove is provided at the bottom of the connection portion, the upper connection portion is clamped in the clamping groove, the lower connection portion is integrally poured with the impermeable panel of the upper dam body, and the upper connection portion is integrally poured with the impermeable panel of the lower dam body and is mutually perpendicular to the interlayer construction joint.

The beneficial effect of this scheme is: if no clamping groove is arranged on the connecting part, an anti-seepage panel is usually poured firstly, and the lower connecting part of the water stop sheet is inserted into the anti-seepage panel of the upper dam body before the anti-seepage panel is initially set, and the lower connecting part is fixed; the setting of draw-in groove can be in advance fixed the stagnant water piece on the indent template, when pouring the prevention of seepage panel, can pour the lower connecting portion of stagnant water piece in the prevention of seepage panel of last layer dam body simultaneously, and this process construction is laborsaving more, convenient, and is difficult for causing the damage of stagnant water piece. Due to the arrangement of the water stop sheets, the seepage prevention effect of the dam can be further improved.

Further, in the first step of S5, the water stop portion is U-shaped, located at the inter-layer construction joint, and the opening direction of the water stop portion is located at a side close to the upstream surface.

The beneficial effect of this scheme is: because the sealing part is U type, and the opening direction of sealing part is located and is close to the one side of upstream face, if water gets into in the prevention of seepage panel through the interlaminar construction joint, and the sealing part of U type can play the effect of buffering, can prevent the seepage of dam.

Because the water stopping part is U-shaped, in the process of pouring the next layer of dam body, the self-compacting concrete presses the water stopping part under the action of gravity to deform the water stopping part, after the water stopping part is deformed, folds are formed in the water stopping part, when water permeates into the water stopping part from the seepage-proofing panel, the water can erode the folds of the water stopping part, and the water stopping sheet is damaged, so that the service life of the water stopping sheet is shortened; and because the upper connecting part of the water stop sheet is clamped in the clamping groove, when the pressing groove template is disassembled, the pressing groove template is lifted upwards, and the pressing groove template can drive the water stop sheet to be lifted upwards, so that the water stop sheet is restored.

Further, in the second step of S5, self-compacting concrete is poured by pumping, and 1-3m of self-compacting concrete is required to be poured before pouring ³ And then self-compacting concrete is poured.

The beneficial effect of this scheme is: because self-compacting concrete is poured by adopting a pumping mode, 1-3m of self-compacting concrete is poured firstly ³ The self-compacting mortar plays a role in lubricating the pipeline, prevents the pipeline from being blocked when the self-compacting concrete is poured, and improves the controllability when the self-compacting concrete is poured.

Further, in the second step of S3, before the rock stacking is carried out, when the strength of the concrete cushion layer is larger than 5MPa, roughening treatment is carried out on the surface of the concrete cushion layer, then the rock stacking layer is stacked, and the rock blocks with different diameters are matched with each other for use.

The beneficial effect of this scheme is: through carrying out the roughening treatment to the concrete cushion, after pouring self-compaction concrete to the rock-fill layer, can improve the bonding strength of rock-fill layer self-compaction concrete and concrete cushion.

The stones with different diameters are matched with each other for use, so that the aim of avoiding overlarge dosage of self-compacting concrete due to low stone stacking rate caused by overlarge gaps among the stones is achieved; in the process of rock piling, the two relatively flat surfaces of different stones are prevented from contacting each other as much as possible, so that gaps among the stones are smaller, and self-compacting concrete cannot be filled compactly; if the two planes cannot be prevented from being contacted, small stone support pads are adopted, so that the compactness of the dam body after concrete pouring is finished is ensured.

Further, in the second step of S3, the exposed surface of the rock-fill layer contains less than 10 blocks/m of rocks having a particle size of less than 20cm ² 。

The beneficial effect of this scheme is: when the number of stones with the grain diameter smaller than 20cm contained on the exposed surface of the rock-fill layer is smaller than 10 pieces/m ² . The rock-fill layer can still keep proper natural gaps, thereby ensuring the filling effect of the self-compacting rock-fill concrete.

Further, in step S6, the self-compacting rockfill concrete is cured according to the change in air temperature.

The beneficial effect of this scheme is: by curing the self-compacting rock-fill concrete, the strength and other properties of the self-compacting rock-fill concrete can be fully developed to reach the optimal state, so that the impermeability and strength of the dam are improved.

Further, in S4, the self-compacting concrete is stirred by adopting a double horizontal shaft forced mixer, the self-compacting concrete is fed in sequence when being mixed, firstly, the weighed aggregate and the cementing material are respectively put into the mixer for dry mixing, then, water and an additive are added for continuous stirring for 60 seconds, and after the stirring is finished, the fluidity and the diffusivity of the concrete are tested.

The beneficial effect of this scheme is: the double horizontal shaft forced mixer can produce stirring material of partial powder, effectively raise the flowability of self-compacting concrete, and the aim of dry mixing aggregate and cementing material is to raise the crushing property and mixing uniformity, and then water and additive are added to raise flowability, and the control of the cementing material is mainly to maintain cementing effect.

Further, in S7, the steps of:

firstly, establishing a numerical simulation finite element model by adopting ABAQUS software;

secondly, automatically creating an initial analysis step by adopting ABAQUS software: determining the condition of the applied boundary, creating a load analysis step, and determining the load for application according to the concrete gravity dam design specification;

third, analyzing the result of data simulation: and respectively researching the displacement and stress distribution change rules of the gravity dam under different static load conditions under the normal water storage level working condition, the flood design working condition and the flood checking working condition, and analyzing the safety of normal operation of the gravity dam.

And fourthly, calculating the anti-skidding stable safety coefficient of the stepped gravity dam by a rigid body limit balance method.

The beneficial effect of this scheme is: the static force analysis is carried out on the gravity dam by utilizing finite element analysis software ABAQUS, the stress strain conditions of the gravity dam under three working conditions of normal water storage level, design flood level and check flood level are analyzed, the gravity dam accords with the stress distribution rule of a common gravity dam through analysis, the maximum value of the tensile stress and the compression stress of the dam body is not more than the allowable tensile stress of concrete, and the safety of the gravity dam is not damaged. And the deformation of the dam is small, and the maximum displacement positions of the dam body are all at the top of the dam. The stability of the dam foundation is verified by calculating the safety values of the stability coefficient of the dam foundation meeting the specification. Therefore, the stress distribution condition of the gravity dam is good, the stability coefficients meet the safety values specified by the specifications, and the design of the step gravity dam meets the requirements.

Drawings

FIG. 1 is a side cross-sectional view of the present application;

FIG. 2 is a side cross-sectional view of the lower dam of the present application mated with a form;

FIG. 3 is a schematic illustration of the process flow of the present application;

FIG. 4 is a graph showing the distribution of lifting force;

FIG. 5 (a) is a lateral displacement cloud of a stepped gravity dam under condition 1;

FIG. 5 (b) is a lateral displacement cloud of a stepped gravity dam under condition 2;

FIG. 5 (c) is a lateral displacement cloud of a stepped gravity dam under condition 3;

FIG. 6 (a) is a vertical displacement cloud of a stepped gravity dam under condition 1;

FIG. 6 (b) is a vertical displacement cloud of a stepped gravity dam under condition 2;

FIG. 6 (c) is a vertical displacement cloud of a stepped gravity dam under condition 3;

FIG. 7 (a) is a Mises stress cloud for a stepped gravity dam under condition 1;

FIG. 7 (b) is a Mises stress cloud for a stepped gravity dam under condition 2;

FIG. 7 (c) is a Mises stress cloud for a stepped gravity dam under condition 3;

FIG. 8 (a) is a vertical stress cloud for a stepped gravity dam under condition 1;

FIG. 8 (b) is a vertical stress cloud for a stepped gravity dam under condition 2;

fig. 8 (c) is a vertical stress cloud for a stepped gravity dam under condition 3.

Detailed Description

The following is a further detailed description of the embodiments:

reference numerals in the drawings of the specification include: the concrete pile comprises a stepped slope surface 1, an original slope surface 2, a concrete cushion layer 3, an interlayer construction joint 4, an anti-seepage panel 5, a water stop sheet 6, an upper connecting part 7, a water stop part 8, a lower connecting part 9, a water facing surface template 10, a water back surface template 11, a pressing groove template 12, a connecting part 13, a forming part 14, a clamping groove 15, a rock-fill layer 16 and a groove 17.

Examples

The rock-fill self-compacting concrete gravity dam adopts a construction mode of rock block layered stacking and self-compacting concrete layered filling, and in the embodiment, the left side of the dam body is defined as an upstream surface, and the right side is defined as a downstream surface.

As shown in fig. 1, a step slope 1 is adopted on the back surface of the rock-fill self-compacting concrete gravity dam, and the position of a step external corner connecting line is consistent with that of an original slope 2, namely, the step slope 1 is retracted towards the inside of the dam body relative to the original slope 2, the step size is 1.6mx2.0m, a concrete cushion layer 3 is poured at the bottom of the rock-fill self-compacting concrete gravity dam, an interlayer construction joint 4 is formed between each upper layer step and each lower layer step, an impermeable panel 5 is poured on the upstream surface of the rock-fill self-compacting concrete gravity dam, the thickness of the impermeable panel 5 is 50cm, a water stop piece 6 is arranged in each layer construction joint 4, the water stop piece 6 is positioned in the impermeable panel 5 and is close to one side of the back surface, the water stop piece 6 comprises an upper connecting part 7, a water stop part 8 and a lower connecting part 9 which are sequentially connected, the upper connecting part 7 of the water stop piece 6 is integrally poured with the impermeable panel 5 of the upper layer dam body, the interlayer construction joint 4 is formed with the interlayer construction joint 4, the water stop piece 8 is positioned at the position of the side close to the water stop part 8 in the water stop direction, and the water stop part is positioned at the position close to the water stop part 8 on the upstream surface side.

As shown in fig. 3, the method for rapidly constructing the self-compacting concrete gravity dam of the rock-fill comprises the following steps:

s1, treating a bedrock surface and preparing a cleaning field;

firstly, treating a bedrock surface, namely firstly cleaning loose rocks on the bedrock surface, cleaning pumice virtual slag, cleaning the fine slag by an air compressor or a high-pressure water gun, draining accumulated water in a bin, if underground water gushes, making drainage measures and methods, and finally pouring a concrete cushion layer 3 on the bedrock surface;

secondly, preparing a cleaning field, wherein a flushing field is arranged in the material field, the ground of the flushing field is hardened by adopting C20 concrete with the thickness of 20cm, the flushing field is provided with a water storage tank, a sedimentation tank and a drainage ditch, water in the river is pumped to the water storage tank by means of a high-pressure water pump and used for stone flushing, the flushed waste water flows into the sedimentation tank through the drainage ditch, after sedimentation, the waste water can be recycled for stone flushing, redundant water is discharged into the river after being monitored to meet the discharge requirement, and mud in the sedimentation tank is cleaned regularly.

S2, installing a template;

as shown in fig. 2, the templates include a water-facing surface template 10, a water-facing surface template 11 and a groove pressing template 12, the water-facing surface template 10 and the water-facing surface template 11 are built into the outer contour of the dam body, the water-facing surface template 10 is fixed by a mounting bracket, the fixation of the water-facing surface template 10 belongs to the prior art, and only the water-facing surface template 10 can be fixed, and the water-facing surface template 10 can be ensured not to deform or topple, which is not repeated here. The back surface adopts the ladder design, and the ladder size is 1.6mX2.0m, and back surface template 11 is the individual layer template, and the individual layer template adopts circulated use back frame to implant anchor ground reinforcing bar and bolt and consolidates. The indent template 12 passes through the bolt to be installed in the upper end of upstream face template, specifically, indent template 12 is including connecting portion 13 and the shaping portion 14 that connect gradually, connecting portion 13 and shaping portion 14 integrated into one piece processing, open the bottom of connecting portion 13 has draw-in groove 15, the last connecting portion 7 card of stagnant water piece 6 is in draw-in groove 15, shaping portion 14's width is 15 centimetres, shaping portion 14's lower extreme stretches into in the heap layer 16, in this embodiment, the template adopts the steel template, the material of steel template is Q235, thickness is 6mm.

S3, screening and warehousing of piled stones;

first, screening and cleaning the rock fill, and using 1m of stone blocks mined in a stock ground ³ When the excavator is used for loading, the stones are screened for one time, the stones with the grain size ranging from 30cm to 160cm are selected for loading and are transported to a flushing site, the stones are flushed by water in a reservoir by means of a high-pressure water gun, and then the flushed stones are transported to a storage yard for stacking; when stacking the block stones on the bin surface, 1m of the block stones is used ³ The excavator is loaded, at this time, stones are screened for the second time, and the stones are transported to the bin surface by using the dump truck.

Secondly, rock stacking is carried out in a warehouse: before rock stacking, when the strength of the concrete cushion layer is greater than 5MPa, roughening the surface of the concrete cushion layer, stacking the rock stacking layer 16, placing the rock stacking layer into the warehouse by adopting a reverse method, namely, arranging the warehouse from the upstream surface to the downstream surface, arranging a loader and an excavator to carry out flat warehouse, specifically, transporting the rock stacking layer into the warehouse by the excavator in a space which is 50cm away from the inside of the upstream surface template 10, stacking the rock stacking layer, wherein in the rock stacking construction, the rock blocks with different diameters are matched with each other, and the exposed surface of the rock stacking layer 16 containsThe number of stones with the particle size smaller than 20cm is smaller than 10 pieces/m ² And must not be concentrated.

S4, producing and transporting self-compacting concrete;

firstly, mixing self-compacting concrete on site, wherein the mixing proportion is the basis of mixing the self-compacting concrete, so that raw materials entering the site need to be comprehensively detected, the detection mainly comprises the detection of the water content and the mud content of coarse and fine aggregates, after the detection result is out, the theoretical mixing proportion of the self-compacting concrete is determined according to the detection result of the raw materials on site, trial mixing verification is carried out on a construction site, after the verification is carried out, the actual situation of a production system on the construction site is adjusted, and the self-compacting concrete is mixed according to the optimal construction mixing proportion;

secondly, mixing the self-compacting concrete by adopting a double horizontal shaft forced mixer, feeding the self-compacting concrete in sequence, respectively adding weighed aggregate and cementing material into the mixer for dry mixing, adding water and additive for continuous stirring for 60s, controlling the water-cement ratio variation range within-0.02-0.01, and testing the fluidity and diffusivity of the concrete after the mixing is completed.

Thirdly, transporting the self-compacting concrete by adopting a concrete mixer, cleaning other types of concrete remained in the mixer before loading, and draining accumulated water in the mixer; in the transportation process, water is strictly forbidden to be added to the concrete in the vehicle, the concrete transportation time is normally controlled within 30 minutes, and the maximum time can not exceed 60 minutes after discharging; before unloading, the concrete mixer truck rotates at a high speed for more than 1 min; when the expansion degree of the self-compacting concrete is adjusted, the concrete transportation tank truck is rotated for 3min at a high speed after the additive is added, so that the self-compacting concrete is ensured to be uniform and consistent, and the self-compacting concrete can be discharged after being detected to be qualified.

S5, pouring self-compacting concrete in a pumping mode, wherein 1-3m of self-compacting concrete needs to be poured before pouring ³ Self-compacting mortar of (2) and then pouring self-compacting concrete, wherein pouring points of the self-compacting concrete are uniformly distributed, the distance between adjacent pouring points is less than 3m, and the principle of unidirectional point-by-point pouring is followed in the pouring process, so that the self-compacting mortar is positioned on the upstream surfaceOne end starts pouring, is parallel to the dam axis and pours to the other end, carries out "S" shape route pouring, and every pouring point is poured and can be moved to next pouring point pouring after being full, and the pouring point is not used repeatedly, and the maximum free falling height when pouring is less than 2m, adopts the cylinder cloth machine to pour and replaces former pump pipe to pour directly, has so the operation not only reduced the input of pump pipe dismouting operating personnel, simultaneously, has shortened the distance that the concrete flows automatically, has reduced the concrete segregation risk to quarter of pouring time has been shortened.

Firstly, pouring an anti-seepage panel 5; pouring self-compacting concrete in a space between the upstream face template 10 and the rock-fill layer 16 to form an impermeable panel 5, and pouring a water stop sheet 6 between the impermeable panel 5 of the upper dam body and the impermeable panel 5 of the lower dam body and mutually perpendicular to the interlayer construction joint 4;

secondly, pouring the stacking layer 16 self-compacting concrete; pouring self-compacting concrete in a space between the impermeable panel 5 and the back surface template 11, wherein the self-compacting concrete surface of the rock-fill layer 16 is lower than the rock-fill surface by 5-15 cm and is not more than 1/3 of the height of a stone, and the pressing groove template 12 can form a groove 17 with the width of 15 cm and the depth of 10 cm on one side close to the impermeable panel 5; and (3) carrying out roughening treatment on the self-compacting concrete surface in the groove 17, the seepage-proofing panel 5 and the self-compacting concrete surface of the mound layer 16 to expose coarse aggregate, and casting the next layer of dam body when the strength of the self-compacting concrete reaches more than 2.5 MPa.

S6, curing the self-compacting rock-fill concrete;

after the self-compacting concrete is poured, curing according to the temperature change, and when the temperature is above 20-35 ℃, covering and watering and curing are started within 6-8 hours after the concrete is poured; when the air temperature is above 5-20 ℃, covering sprinkling and curing within 12-24 hours after concrete pouring is finished; and when the air temperature is low, the curing is performed in a covering and heat-preserving mode, the curing time is at least 7 days, and the curing time is properly prolonged at the position with special requirements.

S7, checking the safety performance of the stepped gravity dam body through a numerical simulation method and a rigid body limit balance method;

Step four, calculating the anti-slip stable safety coefficient of the stepped gravity dam by a rigid body limit balance method;

engineering instance analysis and verification

Selecting a typical gravity dam in Guizhou province, wherein the gravity dam is a C15 rock-fill self-compacting concrete gravity dam, the back surface of the gravity dam is stepped, the position of a step external corner connecting line is consistent with that of the original slope surface 2, namely, the step is retracted into the dam body relative to the original slope surface 2, the step size is 1.6mX2.0m, the dam height is 48.5m, the dam top width is 5m, the dam bottom width is 39.8m, the normal water storage level 1475.00m of a reservoir is corresponding to 138 ten thousand m ³ The dead water level is 1454.00m, the dead reservoir capacity is 14.6 ten thousand m ³ Designing a flood level 1476.50m, checking the flood level 1476.90m, and setting the corresponding total storage capacity to 158 ten thousand m ³ Xingliku capacity 123.4 ten thousand m ³ 。

The safety performance of the gravity dam body is checked by a numerical simulation method and a rigid body limit balance method: the method specifically comprises the following steps:

firstly, establishing a numerical simulation finite element model by adopting ABAQUS software, and establishing a model with the same size in a component of the ABAQUS software; the material model adopts an elastic model; the parameters are specific parameters of C15 concrete; and (3) meshing the gravity dam numerical model, wherein CPE4 is selected as a unit type, quadrilateral units are adopted as unit shapes, and 3024 units are generated.

Secondly, automatically creating an initial analysis step by adopting ABAQUS software: determining a condition for applying a boundary, wherein the upper side and the left side and the right side of the numerical model are free boundaries, and applying fixed constraint to the bottom of the numerical model; a load analysis step is established, wherein the load applied by the method is determined according to the design specification of the concrete gravity dam, and the applied load comprises dead weight load, upstream and downstream hydrostatic pressure, lifting pressure and silt pressure;

(1) And (3) determining dead weight load: only consider the dead weight of the dam body, and the dam body is built and applied at one time, and 2400kg/m of the dam body is taken by adopting the C15 concrete volume weight ³ Adopting a mass-free bedrock when carrying out finite element analysis and calculation;

(2) Determination of hydrostatic pressure: the hydrostatic pressure is vertically acted on the surfaces of the upstream and downstream dam bodies, the hydrostatic pressure load is calculated according to different water level conditions, the application of the hydrostatic load is started by correspondingly calculating the free surface pressure of the water level in contact with the atmosphere to be 0, and the load gradient is applied along the vertical direction of the upstream and downstream dam surfaces to be 9800N/m ³ ；

(3) Determination of silt pressure: the calculation formula of the silt pressure is:

wherein: p is p _sk -silt pressure standard value (KN/m); gamma ray _sb -floating capacity of sediment, taking 6KN/m; h is a _s 1450.45m of sediment accumulation depth; phi (phi) _s -silt internal friction angle, 12 °; tg-tangent function.

(4) And (3) determining the lifting force: the lifting pressure consists of seepage pressure and buoyancy. Because the design of drain holes and seepage-proof curtain grouting is considered in the design, according to the specification, the lifting force of the dam is reduced to a certain extent in calculation, and the distribution diagram of the lifting force is shown in figure 4;

third, analyzing the result of data simulation: under the following three working conditions, researching the displacement and stress distribution change rules of the gravity dam under different static load conditions, analyzing the safety of normal operation of the gravity dam, wherein specific parameters under the three working conditions are shown in table 1, fig. 5 is a horizontal displacement cloud chart of the stepped gravity dam under three different working conditions, fig. 6 is a vertical displacement cloud chart of the stepped gravity dam under three different working conditions, fig. 7 is a stress cloud chart of the stepped gravity dam under three different working conditions, and fig. 8 is a vertical stress cloud chart of the stepped gravity dam under three different working conditions;

TABLE 1

Working conditions of	Upstream water level (m)	Downstream water level (m)
			Working condition 1: normal water storage level condition	1475.00	1440.00
Working condition 2: design flood level conditions	1476.50	1440.60
			Working condition 3: checking flood level conditions	1476.90	1440.91

Step four, calculating the anti-slip stable safety coefficient of the stepped gravity dam by a rigid body limit balance method: the calculation formula of the anti-slip stable safety coefficient is as follows:

wherein K is ^, -an anti-slip stable safety factor; f-dam body and damThe shear friction coefficient on the base contact surface is f=0.6; Σw—the total load pair acting on the dam body calculates the normal component of the sliding surface, taking Σw=8.457 e7n; Σp—all load pairs acting on the dam body calculate the tangential component of the sliding surface, taking Σp=3.702 e7n; a-cross section area m of contact surface of dam body and bedrock ² Take a=39.8m ² The method comprises the steps of carrying out a first treatment on the surface of the The magnitude of the U-elevating force, taking u=132.6n; c ^, -shear-resistant cohesive force MPa of contact surface of concrete and rock matrix, taking c ^, ＝0.8MPa。

Conclusion analysis:

as can be seen from FIG. 5, the maximum lateral displacement value of the dam crest position in the displacement cloud chart is 1.3mm under the working condition 1, 1.51mm under the working condition 2 and 1.56mm under the working condition 3; from this, it can be seen that. Along with the increase of the depth of the water level, the lateral displacement of the dam body is gradually increased, so that different water levels have obvious influence on the lateral deformation of the dam body; as can be seen from fig. 6, the vertical displacement value of the stepped gravity dam under different working conditions is basically smaller than 0.5mm. The maximum vertical displacement value under the working condition 1 is 0.42mm, the maximum vertical displacement value under the working condition 2 is 0.49mm, and the maximum vertical displacement value under the working condition 3 is 0.51mm, so that the vertical displacement values of the stepped gravity dam under different working conditions are not large, the dam body cannot be deformed to a large extent, and the displacement distribution is reasonable. In addition, compared with the vertical displacement deformation and the horizontal displacement deformation, the horizontal displacement deformation of the dam body has obvious horizontal lamellar distribution, and the displacement deformation is larger as the horizontal displacement deformation is closer to the top of the dam body, and the deformation is smaller as the horizontal displacement deformation is closer to the bottom of the dam body.

As can be seen from fig. 7 and 8, the numerical simulation results show that the dam body is in a compressive stress state mostly under the dead weight load, stress concentration occurs at the upstream abutment position, compressive stress is generated at the abutment position, the maximum compressive stress value of the dam body is 1.43MPa, the compressive allowable value of concrete is 15MPa, and the allowable compressive stress of bedrock is 30MPa, so that the maximum compressive stress value of the dam body is smaller than the compressive allowable value of concrete and the allowable compressive stress of bedrock. Under the working condition 1, along with the application of upstream hydrostatic pressure, sediment pressure and dam foundation lifting pressure load, the dam body continues to take the compressive stress as the main part, and small-range compressive stress concentration occurs at the upstream dam heel position, so that the deformation characteristics of the dam body under the working condition 1 are met. Under the working condition 3, along with the continuous increase of the upstream hydrostatic pressure, the tensile stress of the dam body at the dam heel can be seen by the stress cloud chart, and the vertical stress is continuously increased to 0.9MPa from 0.79MPa under the working condition 3 and is far smaller than the tensile allowable value of 1.2MPa of the concrete. In summary, the dam body stress meets the allowable value of the concrete tensile strength specification.

The anti-slip stability safety coefficient of the stepped gravity dam is calculated by using the formula (2). Through calculation, the anti-slip stable safety coefficient K of the step gravity dam ^, The value is 3.52, and according to the design specification requirement, the anti-slip stable safety coefficient K of the gravity dam is all satisfied with the safety value specified by the specification, so the stepped gravity dam satisfies the anti-slip stable safety requirement.

In conclusion, static analysis is performed on the gravity dam through the ABAQUS software, stress strain conditions of the stepped gravity dam under three working conditions are analyzed, the overall stress distribution condition of the dam section is better according to the stress cloud chart, the stress distribution rule of a general gravity dam is met, the maximum value of the tensile stress and the compressive stress of the dam body is not more than the allowable tensile stress of concrete, and the safety of the gravity dam is not damaged. According to displacement cloud patterns under different working conditions, the dam is smaller in deformation, and the maximum displacement positions of the dam body are all at the top of the dam. The stability of the dam foundation is verified by calculating the safety values of the stability coefficient of the dam foundation meeting the specification.

Therefore, the stress distribution condition of the stepped gravity dam (the step size is 1.6mX2.0m) is good, the stability coefficients meet the safety values specified by the specifications, and the design of the stepped gravity dam meets the requirements. The step surface of the gravity dam is designed to be a step slope 1, so that the gravity dam has the following advantages: 1. the size of the dam body is reduced: the stepped slope 1 may reduce the size of the entire dam by increasing the number of steps compared to the ramped slope. Not only can the construction cost be saved and the excavation quantity of the earth and stone be reduced, but also the dead weight of the dam body can be reduced; 2. the construction is convenient: compared with the slope, the stepped slope 1 facilitates the leveling and construction of the dam surface, can realize leveling more easily, and is convenient for construction and maintenance; 3. the cost is saved: when the back surface template 11 is installed, a female die is not required to be supported, so that the investment of the female die is saved, a tower crane is not required to be used for hoisting the template, and the back surface template 11 is not required to be reinforced by internally pulling reinforcing steel bars, so that the use of the steel bars is reduced, the rock piling rate is improved, the consumption of concrete is reduced, the appearance quality repair cost of the reverse bevel construction concrete is reduced, and the cost is saved; 4. the construction period is shortened: according to the technical scheme, the cast-in-situ step surface is used as a reference to mount the back surface template 11, so that the height of the working surface is reduced, the working surface is enlarged, the reverse bevel construction is avoided, the influence of the reinforcing steel bars pulled inwards by the template is avoided, the rock piling efficiency is high, the construction efficiency is improved, and the construction period is shortened.

The foregoing is merely exemplary of the present application, and specific technical solutions and/or features that are well known in the art have not been described in detail herein. It should be noted that, for those skilled in the art, several variations and modifications can be made without departing from the technical solution of the present application, and these should also be regarded as the protection scope of the present application, which does not affect the effect of the implementation of the present application and the practical applicability of the patent. The protection scope of the present application is subject to the content of the claims, and the description of the specific embodiments and the like in the specification can be used for explaining the content of the claims.

Claims

1. The method for rapidly constructing the rock-fill self-compacting concrete gravity dam is characterized by comprising the following steps of: the method comprises the following steps:

s3, screening and warehousing of piled stones;

s5, pouring self-compacting concrete;

firstly, pouring an anti-seepage panel;

secondly, pouring self-compacting concrete of the rock-fill layer;

s6, curing the self-compacting rock-fill concrete;

2. The method for rapid construction of the self-compacting concrete gravity dam with rockfill according to claim 1, wherein the method comprises the following steps: in S2, the template still includes the indent template, and the indent template is the L type, and the indent template is including connecting portion and the shaping portion that connect gradually, and connecting portion installs in the upper end of upstream face template, and one side and the prevention of seepage panel contact of shaping portion, the width of shaping portion is 15 centimetres, and the lower extreme of shaping portion stretches into the rock-fill layer.

3. The method for rapid construction of the self-compacting concrete gravity dam with rockfill according to claim 2, wherein the method comprises the following steps: in the first step of S5, a water stop sheet is arranged at the downstream of the seepage-proofing panel, the water stop sheet comprises an upper connecting part, a water stop part and a lower connecting part which are sequentially connected, a clamping groove is formed in the bottom of the connecting part, the upper connecting part is clamped in the clamping groove, the lower connecting part and the seepage-proofing panel of the upper dam body are integrally poured, and the upper connecting part and the seepage-proofing panel of the lower dam body are integrally poured and are mutually perpendicular to an interlayer construction joint.

4. A method for rapid construction of a self-compacting concrete gravity dam of rockfill according to claim 3, wherein: in the first step of S5, the water stopping part is U-shaped and is positioned at the interlayer construction joint, and the opening direction of the water stopping part is positioned at one side close to the upstream surface.

5. The method for rapidly constructing the self-compacting concrete gravity dam with the rockfill according to claim 4, wherein the method comprises the following steps: in the second step of S5, self-compacting concrete is poured in a pumping mode, and 1-3m of self-compacting concrete needs to be poured before pouring ³ And then self-compacting concrete is poured.

6. The method for rapidly constructing the self-compacting concrete gravity dam with the rockfill according to claim 5, wherein the method comprises the following steps: in the second step of S3, before the piled stones are put into the warehouse, when the strength of the concrete cushion layer is larger than 5MPa, roughening treatment is carried out on the surface of the concrete cushion layer, and then the piled stones are piled, and the stones with different diameters are matched with each other for use.

7. The method for rapid construction of the self-compacting concrete gravity dam with rockfill according to claim 6, wherein the method comprises the following steps: in the second step S3, the exposed surface of the rock-fill layer contains less than 10 blocks/m of rocks with the particle size less than 20cm ² 。

8. The method for rapid construction of the self-compacting concrete gravity dam with rockfill according to claim 7, wherein the method comprises the following steps: in step S6, curing the self-compacting rockfill concrete, and curing the self-compacting rockfill concrete according to the temperature change condition.

9. The method for rapid construction of the rock-fill self-compacting concrete gravity dam according to claim 8, wherein the method comprises the following steps: and S4, mixing the self-compacting concrete by adopting a double horizontal shaft forced mixer, feeding the self-compacting concrete in sequence when mixing, respectively adding weighed aggregate and cementing material into the mixer for dry mixing, adding water and additive for continuous stirring for 60 seconds, and testing the fluidity and the diffusivity of the concrete after the mixing is finished.

10. The method for rapid construction of the self-compacting concrete gravity dam with rockfill according to claim 9, wherein the method comprises the following steps: in S7, the following steps are included: