阅读说明：本技术 严寒地区碾压混凝土坝越冬层面防止水平裂缝的处理方法 (Method for preventing horizontal cracks of overwintering layer of roller compacted concrete dam in severe cold area ) 是由 王立成 任鑫龙 马妹英 李佳隆 任智锋 贾静 李岳东 刘春锋 金鹏 金津丽 于 2019-09-24 设计创作，主要内容包括：本发明公开了一种严寒地区碾压混凝土坝越冬层面防止水平裂缝的处理方法,即将经历冬歇期的老混凝土浇筑时,上、下游侧内分别预埋钢筋网片A和钢筋网片B,预埋两道铜片止水,冬歇期过后,浇筑新混凝土前,钢筋网片内侧,在老混凝土表面分别剔槽,槽内埋设半圆形钢管,内填沥青油麻。然后在老混凝土表面上游端填压高压闭孔板；老混凝土下游端设置PVC管作为预裂孔,管内填充沥青油麻,后期兼做灌浆孔。本发明可应用于严寒地区混凝土坝越冬层面防止水平裂缝,可有效地防止和减少越冬层面出现水平裂缝,阻止裂缝进一步扩大,且预留有灌浆通道,可有效解决坝体渗漏问题,保障大坝沿越冬层面的抗滑稳定性,便于后期维护、更换,使用成本大幅度较低。(The invention discloses a method for preventing horizontal cracks on an overwintering layer of a roller compacted concrete dam in a severe cold area. Then, the upstream end of the surface of the old concrete is filled with a high-pressure closed pore plate; the downstream end of the old concrete is provided with a PVC pipe as a pre-crack hole, asphalt and hemp are filled in the PVC pipe, and the PVC pipe is also used as a grouting hole in the later period. The invention can be applied to the overwintering layer of the concrete dam in severe cold regions to prevent horizontal cracks, can effectively prevent and reduce the occurrence of horizontal cracks on the overwintering layer, prevents the cracks from further expanding, reserves a grouting channel, can effectively solve the problem of dam body leakage, ensures the anti-slip stability of the dam along the overwintering layer, is convenient for later maintenance and replacement, and has greatly lower use cost.)

1. A method for preventing horizontal cracks on the overwintering layer of a roller compacted concrete dam in a severe cold area is characterized by comprising the following steps:

the method comprises the following steps: when the old concrete which is going to undergo the winter rest period is poured, the reinforcing mesh sheets are respectively embedded in the upper stream side and the downstream side, half of the reinforcing mesh sheets are embedded in the old concrete, and half of the reinforcing mesh sheets are exposed; at the upstream end of the old concrete, two copper sheets are pre-buried for water stop, and half of the copper sheets are buried in the old concrete and half of the copper sheets are exposed;

step two: after the winter rest period, before pouring new concrete, respectively picking grooves on the surface of old concrete on the inner side of the reinforcing mesh, embedding semicircular steel pipes in the grooves, and filling asphalt and hemp;

step three: then, the upstream end of the surface of the old concrete is filled with a high-pressure closed pore plate; the downstream end of the old concrete is provided with a PVC pipe as a pre-crack hole, asphalt and hemp are filled in the PVC pipe, and the PVC pipe is also used as a grouting hole in the later period; paving cement paste on the overwintering surface; then, pouring upper layer new concrete;

step four: and after the pouring is finished, the upper surface and the lower surface of the dam body are respectively provided with a polyurea coating, wherein the polyurea coating is thickened at the wintering surface of the upstream polyurea coating.

2. The method for treating the overwintering surface of the roller compacted concrete dam in the severe cold region to prevent horizontal cracks according to claim 1, wherein the overwintering surface (3) is formed between the lower old concrete (1) undergoing the winter rest period and the upper new concrete (2) newly poured after the winter rest period, and the treatment method comprises the following steps:

the method comprises the following steps: when old concrete which is about to go through winter intermission is poured, an upstream side reinforcing steel mesh piece A (4) and a downstream side reinforcing steel mesh piece B (5) are respectively embedded in the old concrete (1) along the axial direction of a dam at a distance from the upstream side and the downstream side, half of the upstream side reinforcing steel mesh piece A (4) and half of the downstream side reinforcing steel mesh piece B (5) are embedded in the old concrete (1), and half of the upstream side reinforcing steel mesh piece A and half of the downstream side reinforcing steel mesh piece B are exposed;

step two: after the winter rest period, before pouring new concrete (2), respectively picking grooves on the surfaces of old concrete (1) on the downstream side of an upstream side reinforcing mesh A (4) and the upstream side of a downstream side reinforcing mesh B (5), embedding a semicircular steel pipe A (8) with an upstream opening surface in the upstream picking groove, embedding a semicircular steel pipe B (9) with a downstream opening surface in the downstream picking groove, respectively binding and fixing the semicircular steel pipe B with the upstream side reinforcing mesh A (4) and the downstream side reinforcing mesh B (5), filling asphalt and hemp (10) in the semicircular steel pipe, wherein the depth of the picking groove is the same as the radius of the steel pipe, and the shape of the picking groove is 1/4 circular;

step three: then filling a high-pressure closed pore plate (11) between the upstream end of the surface of the old concrete (1) and the first copper water stop, fixing the high-pressure closed pore plate on the surface of the old concrete (1) by adopting cement nails, and tightly adhering the downstream end of the high-pressure closed pore plate (11) to the first copper sheet water stop; the downstream end of the old concrete (1) is provided with a PVC pipe as a pre-crack hole (12), the PVC pipe is horizontally arranged and is vertical to the axis of the dam, asphalt and hemp (10) are filled in the PVC pipe, and the PVC pipe is also used as a grouting hole in the later period; paving cement paste (13) on the overwintering surface (3) between the first copper sheet water stop and the downstream side reinforcing mesh B (5), and then pouring upper layer new concrete (2);

step four: after pouring is finished, the upstream polyurea coating (14) and the downstream polyurea coating (15) are respectively arranged on the upstream surface and the downstream surface of the dam body, wherein the thickened polyurea coating (16) is sprayed on the overwintering surface (3) of the upstream polyurea coating (14) on the basis of the original design thickness.

3. The method for preventing the horizontal cracks on the overwintering layer surface of the roller compacted concrete dam in the severe cold region as claimed in claim 2, wherein the distance between the upstream side reinforcing mesh A (4) and the upstream end is 1.5m, the distance between the downstream side reinforcing mesh B (5) and the downstream end is 0.8m, the height between the upstream side reinforcing mesh A (4) and the downstream side reinforcing mesh B (5) is 1.5-1.8 m, and the distance between the upstream side reinforcing mesh A (4) and the downstream side reinforcing mesh B (5) is 150-180 mm by adopting reinforcing steel bars with the diameter of 20-28 mm.

4. The method for treating the overwintering layer surface of the roller compacted concrete dam in the severe cold region to prevent the horizontal cracks is characterized in that two pre-buried copper sheet water stops are arranged, the upstream side is provided with a copper sheet water stop A (6), the downstream side is provided with a copper sheet water stop B (7), the distance between the two water stops is 0.4m, and the distance between the copper sheet water stop A (6) and the upstream end of the old concrete (1) is 0.6 m.

5. The method for treating the overwintering layer surface of the roller compacted concrete dam in the severe cold region to prevent the horizontal cracks according to claim 2, wherein the diameter of the semicircular steel tube A (8) and the semicircular steel tube B (9) is not less than 150mm, and the wall thickness is not less than 3 mm.

6. The method for treating the overwintering layer surface of the roller compacted concrete dam in the severe cold region to prevent the horizontal cracks according to claim 2, wherein the PVC pipes are horizontally arranged at a pipe spacing of 1.5-2.0 m.

7. The method for treating the overwintering layer of the roller compacted concrete dam in the severe cold region to prevent the horizontal cracks is characterized in that the thickness of the paved cement slurry (13) is 15-20 mm.

8. The method for treating the overwintering layer of the roller compacted concrete dam in the severe cold region to prevent the horizontal cracks is characterized in that the bandwidth of the thickened polyurea coating (16) is 0.6-1.2 m, the upper part and the lower part of the layer are symmetrically distributed, and the spraying thickness is gradually changed according to the gradient of 1: 5-1: 10.

Technical Field

The invention relates to a method for treating horizontal cracks on an overwintering layer, in particular to a method for preventing horizontal cracks on the overwintering layer of a roller compacted concrete dam in a severe cold region.

Background

The concrete dam (including a gravity dam and an arch dam) is built in a severe cold area, the dam which is not poured needs to be shut down for 3-4 months in winter due to cold weather in winter, an overwintering surface is formed on the dam, and when the dam is reworked in the next year, the strength, the elastic modulus, the temperature and the like of concrete below the overwintering surface and newly poured concrete are greatly different. Although in actual engineering, before pouring the upper concrete, the strict bedding surface is brushed or even chiseled, and cement paste or cement mortar is paved for processing, the condition that the upper concrete and the lower concrete are combined is poor, horizontal cracks appear on the bedding surface, even the phenomenon of cracking occurs, and the engineering safety of the dam is seriously threatened.

Before 2001, roller compacted concrete gravity dams built in cold regions of China are mainly distributed in northeast regions, such as kwan-yin pavilion, pine moon, full Taicheng city, dragon, white stone and the like; after 2001, it was mainly distributed in northwest, especially in Xinjiang.

In the roller compacted concrete gravity dam built in China, horizontal cracks appear on the overwintering joint surfaces of a plurality of dams. For example, although strict temperature control measures are adopted in the construction process of the Liaoning Guanyin pavilion roller compacted concrete dam, horizontal cracks appear on three overwintering junction surfaces and the upper and lower 0.75m range of the three overwintering junction surfaces in 1991-1994. The length of the cracks is different, part of the cracks penetrate through the whole dam section, overwintering horizontal cracks with the height of 233m penetrate through 42 dam sections, the width of the cracks is 0.2-3 mm, and the maximum depth of the cracks reaches 6.0 m. The Yandes and Yandes reservoir is located in the Shangyang city in the western Liaoning and is located in the Daling river dry stream 25km above the Shangyang city. In 3 middle of 1998, horizontal cracks appear at the joint of new and old concrete on the upstream of the overwintering surface of the overflow dam section. The penetrating cracks from upstream to downstream appear on the overwintering level surface shortly after the loose-moon dam and the full terrace city dam are built, large-area seepage occurs on the slope surface behind the dam, and after the dam enters winter, the slope surface seepage forms large-area ice arcs. The maximum dam height of a roller compacted concrete gravity dam in Xinjiang is 51m, and the average temperature of the dam for many years is 8.8 ℃. Although strict temperature control measures are also adopted in the construction process, the overwintering horizontal plane of the dam still has a cracking phenomenon. A certain dam in Xinjiang is in a severe cold area, and the maximum dam height of the dam is 71 m. After the first winter after the dam is poured, it is found that cracks of the 6# to 9# four power generation diversion dam sections are opened over the winter horizontal plane, and the downstream surface has a water seepage phenomenon, so that the downstream slope surface is heavily iced in winter.

From a foreign engineering perspective: the Yuchuan roller compacted concrete dam located in autumn county in northern China of island of Japan is 100m high and built in 1987, and although strict temperature control measures are adopted during construction, the horizontal construction joint cracks at the overwintering level occur in consecutive years.

Therefore, when the roller compacted concrete gravity dam is built in a cold area, cracking of an overwintering joint surface is a common phenomenon, and once the overwintering joint surface has horizontal cracks, the integrity and the stability of a dam body can be influenced. If the crack penetrates through the upstream and the downstream, a water seepage phenomenon occurs, and a large amount of ice is formed on the downstream slope of the dam in winter, so that the safety and the durability of the dam body are influenced. Therefore, the anti-cracking problem of the overwintering junction surface of the roller compacted concrete gravity dam in cold regions must be deeply researched.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for preventing horizontal cracks on the overwintering layer of a roller compacted concrete dam in a severe cold area, which can effectively prevent and reduce horizontal cracks of a dam body caused by an overwintering joint surface, is easy to construct, convenient for later maintenance and replacement and greatly lower in use cost.

In order to solve the problems, the technical scheme adopted by the invention is as follows: a method for preventing horizontal cracks of an overwintering layer of a roller compacted concrete dam in a severe cold region comprises the following steps:

the method comprises the following steps: when the old concrete which is going to undergo the winter rest period is poured, the reinforcing mesh sheets are respectively embedded in the upper stream side and the downstream side, half of the reinforcing mesh sheets are embedded in the old concrete, and half of the reinforcing mesh sheets are exposed; at the upstream end of the old concrete, two copper sheets are pre-buried for water stop, and half of the copper sheets are buried in the old concrete and half of the copper sheets are exposed;

step two: after the winter rest period, before pouring new concrete, respectively picking grooves on the surface of old concrete on the inner side of the reinforcing mesh, embedding semicircular steel pipes in the grooves, and filling asphalt and hemp;

step three: then, the upstream end of the surface of the old concrete is filled with a high-pressure closed pore plate; the downstream end of the old concrete is provided with a PVC pipe as a pre-crack hole, asphalt and hemp are filled in the PVC pipe, and the PVC pipe is also used as a grouting hole in the later period; paving cement paste on the overwintering surface; then, pouring upper layer new concrete;

step four: and after the pouring is finished, the upper surface and the lower surface of the dam body are respectively provided with a polyurea coating, wherein the polyurea coating is thickened at the wintering surface of the upstream polyurea coating.

Specifically, the overwintering surface is formed between the lower old concrete which undergoes the winter-stopping period and the newly poured upper new concrete after the winter-stopping period, and the processing method comprises the following steps:

the method comprises the following steps: when old concrete which is about to go through a winter rest period is poured, an upstream side reinforcing steel mesh piece A and a downstream side reinforcing steel mesh piece B are respectively embedded in the old concrete along the axial direction of a dam at a distance from the upstream side and the downstream side, half of the upstream side reinforcing steel mesh piece A and half of the downstream side reinforcing steel mesh piece B are embedded in the old concrete, two copper sheet water stops are also embedded between the upstream end of the old concrete and the upstream side reinforcing steel mesh piece A, and half of the copper sheet water stops are embedded in the old concrete and half of the copper sheet water stops are exposed;

step two: after the winter rest period, before pouring new concrete, respectively removing grooves from the surfaces of old concrete on the downstream side of an upstream side reinforcing mesh A and the upstream side of a downstream side reinforcing mesh B, embedding a semicircular steel pipe A with an upstream opening in the upstream removing groove, embedding a semicircular steel pipe B with a downstream opening in the downstream removing groove, and respectively binding and fixing the semicircular steel pipe A and the downstream side reinforcing mesh B, wherein asphalt and hemp are filled in the semicircular steel pipe, the depth of the removing groove is the same as the radius of the steel pipe, and the shape of the removing groove is 1/4 circular;

step three: then filling a high-pressure closed pore plate between the upstream end of the surface of the old concrete and the first copper water stop, fixing the high-pressure closed pore plate on the surface of the old concrete by adopting cement nails, and tightly adhering the downstream end of the high-pressure closed pore plate to the first copper sheet water stop; arranging a PVC pipe as a pre-crack hole at the downstream end of the old concrete, horizontally placing the PVC pipe, enabling the PVC pipe to be vertical to the axis of the dam, filling asphalt and hemp in the PVC pipe, and using the PVC pipe as a grouting hole at the later stage; paving cement paste on the overwintering surface between the first copper sheet water stop and the downstream steel mesh B, and then pouring upper-layer new concrete;

step four: after pouring is finished, the upstream polyurea coating and the downstream polyurea coating are respectively arranged on the upstream surface and the downstream surface of the dam body, wherein the thickened polyurea coating is sprayed on the overwintering surface of the upstream polyurea coating on the basis of the original design thickness.

The upstream side reinforcing bar net piece A is apart from upstream end 1.5m department, and downstream side reinforcing bar net piece B is apart from downstream end 0.8m department, and upstream side reinforcing bar net piece A and downstream side reinforcing bar net piece B are 1.5 ~ 1.8m high, adopt 20 ~ 28mm diameter reinforcing bar, interval 150 ~ 180 mm.

The two pre-buried copper sheets are used for water stop, the upstream side is a copper sheet water stop A, the downstream side is a copper sheet water stop B, the distance between the two is 0.4m, and the distance between the copper sheet water stop A and the upstream end of old concrete is 0.6 m.

The diameter of the semicircular steel pipe A and the semicircular steel pipe B is not less than 150mm, and the wall thickness is not less than 3 mm.

The interval between the horizontally placed PVC pipes is 1.5-2.0 m.

The thickness of the paving cement paste is 15-20 mm.

The bandwidth of the thickened polyurea coating is 0.6-1.2 m, the upper part and the lower part of the layer surface are symmetrically distributed, and the spraying thickness is gradually changed according to the gradient of 1: 5-1: 10.

The invention has the beneficial effects that: the two copper sheets are additionally arranged on the upstream side of the water-stopping device, so that the problem of interlayer water leakage can be effectively solved; the downstream side reinforcing mesh plays a role in limiting cracks; the semi-circular steel pipe filled with the asphalt and the hemp can prevent the crack from developing and expanding; the pre-cracking holes (filled with asphalt and oil flax) can lead horizontal cracks to crack along the overwintering layer surface and develop into the semi-circular steel tube end; if chemical grouting is needed in the later period, the asphalt oil ramie can be directly pumped out and utilized for chemical grouting, so that the chemical grouting amount can be greatly reduced; the processing method effectively solves the problems of dam body leakage (along the overwintering layer) and anti-sliding stability (along the overwintering layer), and is convenient and quick to construct.

Drawings

FIG. 1 is a schematic perspective view of the present invention.

Fig. 2 is a partial detailed view of the upstream end of the present invention.

FIG. 3 is a detail view of a portion of the downstream end of the present invention.

Detailed Description

The invention is described in further detail below with reference to the following figures and detailed description:

as shown in fig. 1-3, the method for preventing horizontal cracks on the overwintering layer of the roller compacted concrete dam in the severe cold region comprises the following steps:

the method comprises the following steps: when the old concrete which is going to undergo the winter rest period is poured, the reinforcing mesh sheets are respectively embedded in the upper stream side and the downstream side, half of the reinforcing mesh sheets are embedded in the old concrete, and half of the reinforcing mesh sheets are exposed; at the upstream end of the old concrete, two copper sheets are pre-buried for water stop, and half of the copper sheets are buried in the old concrete and half of the copper sheets are exposed;

step two: after the winter rest period, before pouring new concrete, respectively picking grooves on the surface of old concrete on the inner side of the reinforcing mesh, embedding semicircular steel pipes in the grooves, and filling asphalt and hemp;

step three: then, the upstream end of the surface of the old concrete is filled with a high-pressure closed pore plate; the downstream end of the old concrete is provided with a PVC pipe as a pre-crack hole, asphalt and hemp are filled in the PVC pipe, and the PVC pipe is also used as a grouting hole in the later period; paving cement paste on the overwintering surface; then, pouring upper layer new concrete;

step four: and after the pouring is finished, the upper surface and the lower surface of the dam body are respectively provided with a polyurea coating, wherein the polyurea coating is thickened at the wintering surface of the upstream polyurea coating.

Specifically, the overwintering surface 3 is formed between the lower old concrete 1 undergoing the winter rest period and the upper new concrete 2 newly poured after the winter rest period, and the processing method comprises the following steps:

the method comprises the following steps: when the old concrete which is going to undergo the winter rest period is poured, an upstream side reinforcing steel mesh piece A4 and a downstream side reinforcing steel mesh piece B5 are respectively embedded in the old concrete 1 along the axial direction of the dam at a distance from the upstream side and the downstream side, half of the upstream side reinforcing steel mesh piece A4 and half of the downstream side reinforcing steel mesh piece B5 are embedded in the old concrete 1, and half of the upstream side reinforcing steel mesh piece A4 and half of the downstream side reinforcing steel mesh piece B5 are exposed;

step two: after the winter rest period, before pouring new concrete 2, respectively removing grooves from the surfaces of old concrete 1 on the downstream side of an upstream side reinforcing mesh A4 and the upstream side of a downstream side reinforcing mesh B5, embedding a semicircular steel pipe A8 with an upstream opening facing into the upstream groove removing groove, embedding a semicircular steel pipe B9 with a downstream opening facing into the downstream groove removing groove, and respectively binding and fixing the semicircular steel pipe with the upstream side reinforcing mesh A4 and the downstream side reinforcing mesh B5, filling asphalt ramie 10 into the semicircular steel pipe, wherein the groove removing depth is the same as the radius of the steel pipe, and the shape is 1/4 circular;

step three: then filling a high-pressure closed pore plate 11 between the upstream end of the surface of the old concrete 1 and the first copper water stop, fixing the high-pressure closed pore plate 11 on the surface of the old concrete 1 by adopting cement nails, and enabling the downstream end of the high-pressure closed pore plate 11 to be tightly attached to the first copper sheet for water stop; arranging a PVC pipe as a pre-crack hole 12 at the downstream end of the old concrete 1, horizontally placing the PVC pipe, being vertical to the axis of the dam, filling asphalt and hemp 10 in the PVC pipe, and serving as a grouting hole at the later stage; paving cement paste 13 on the overwintering surface 3 between the first copper sheet water stop and the downstream side reinforcing mesh B5, and then pouring upper layer new concrete 2;

step four: after pouring is finished, the upstream polyurea coating 14 and the downstream polyurea coating 15 are respectively arranged on the upstream surface and the downstream surface of the dam body, wherein the thickened polyurea coating 16 is sprayed on the wintering surface 3 of the upstream polyurea coating 14 on the basis of the original design thickness.

Preferably, the upstream side reinforcing steel mesh A4 is 1.5m away from the upstream end, the downstream side reinforcing steel mesh B5 is 0.8m away from the downstream end, the upstream side reinforcing steel mesh A4 and the downstream side reinforcing steel mesh B5 are 1.5-1.8 m high, reinforcing steel bars with the diameter of 20-28 mm are adopted, and the distance is 150-180 mm. The two pre-buried copper sheet water stops, the upstream side is copper sheet water stop A6, the downstream side is copper sheet water stop B7, the distance between the two is 0.4m, and the distance between the copper sheet water stop A6 and the upstream end of the old concrete 1 is 0.6 m. The diameter of the semicircular steel pipe A8 and the semicircular steel pipe B9 is not less than 150mm, and the wall thickness is not less than 3 mm. The interval between the horizontally placed PVC pipes is 1.5-2.0 m. The thickness of the paving cement paste 13 is 15-20 mm. The bandwidth of the thickened polyurea coating 16 is 0.6-1.2 m, the upper part and the lower part of the layer surface are symmetrically distributed, and the spraying thickness is gradually changed according to the gradient of 1: 5-1: 10.

The position 3 of the overwintering surface of the upstream polyurea coating 14 is sprayed with a thickened polyurea coating 16 on the basis of the original design thickness, the bandwidth of the thickened polyurea coating 16 is 0.6-1.2 m (no gradual change section), the upper part and the lower part of the layer surface are symmetrically distributed, and the spraying thickness is gradually changed according to the gradient of 1: 5-1: 10.

The above-mentioned embodiments are only for illustrating the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to carry out the same, and the present invention shall not be limited to the embodiments, i.e. the equivalent changes or modifications made within the spirit of the present invention shall fall within the scope of the present invention.