CN106836035B - A kind of cofferdam dam filling construction being applicable in existing culvert under spoil embankment - Google Patents

Abstract

The invention discloses a cofferdam filling method suitable for existing culverts under gangue embankments. Firstly, an anti-seepage film is laid on the embankment slopes on both sides of the culvert, and then a cofferdam is arranged. The cofferdam consists of circular arc sections and connecting circular arcs. The anti-seepage membrane is pressed by the straight section of the cofferdam, so that water cannot penetrate into the embankment from the embankment with the section covered by the anti-seepage membrane, and can no longer enter the culvert through the settlement joint of the culvert body The inside of the culvert can be drained as quickly as possible, the drainage cost inside the culvert can be reduced, and the project cost can be reduced.

Description

A cofferdam filling method suitable for existing culverts under gangue embankments

technical field

The invention relates to a method for filling a culvert cofferdam under a permeable embankment, which is suitable for the maintenance and reinforcement project of the existing culvert under the permeable embankment, and can reduce drainage costs during the maintenance and reinforcement of the culvert and reduce the engineering cost.

Background technique

Permeable embankments are usually embankments with water permeability built with large stones, pebbles or other materials with high porosity and good water permeability. The gangue embankment widely used in the coal mining subsidence area is filled with gangue materials. Gangue itself is a granular material, combined with insufficient construction and rolling, the water permeability of the filler is often high. Therefore, gangue embankment can also be considered as permeable embankment. The culvert under the permeable embankment needs to be strengthened and repaired due to various reasons, such as disrepair for a long time, increase in the thickness of the filler over the culvert, etc. The traditional method is to fill cofferdams at both ends of the culvert to isolate the interior of the culvert from the outside water system, and then drain the accumulated water in the culvert to obtain construction work space. Since the embankment itself is a permeable material, water can pass through the embankment during the drainage process, and then enter the culvert through the settlement joints of the culvert body. Although water cannot enter the culvert due to the existence of the cofferdam at the entrance, the seepage path of the embankment-cave body allows water to continuously enter the culvert during the drainage process. In order to drain the accumulated water inside the culvert as soon as possible and create a good working space for the maintenance and reinforcement of the culvert, we can only increase the drainage capacity, resulting in a rapid increase in drainage costs. This kind of problem has been highlighted in several existing culvert maintenance projects in Huainan mining area. Some individual projects have drainage costs as high as millions, accounting for 20% of the total project investment.

Contents of the invention

Purpose of the invention: Aiming at the above-mentioned prior art, a cofferdam filling method suitable for the existing culvert under the gangue embankment is proposed, which can reduce the drainage cost inside the culvert.

Technical solution: an anti-seepage method suitable for existing culvert cofferdams under gangue embankments, including the following steps:

Step a: laying anti-seepage membrane on the embankment slope on both sides of the culvert;

Step b: setting a cofferdam, the cofferdam is composed of a circular arc segment and a straight line segment connecting two ends of the circular arc segment, and the anti-seepage membrane is pressed by the straight line segment of the cofferdam.

Further, the anti-seepage membrane is extended to 2-3m outside the toe line of the embankment.

Further, the length L of the anti-seepage membrane along the direction of the embankment is determined according to the permeability coefficient of the embankment filler and the water head difference inside and outside the cofferdam, and the specific calculation method is:

L=KΔ/v

In the formula, L is the length of the anti-seepage membrane, Δ is the head difference inside and outside the cofferdam, K is the permeability coefficient of the embankment, and v is the seepage velocity.

Further, the top of the anti-seepage membrane exposes the water level.

Further, the cofferdam is composed of wooden piles and clay filler.

Further, the extension length of the straight section of the cofferdam along the direction of the embankment is consistent with the length of the anti-seepage membrane.

Beneficial effects: the present invention is a cofferdam filling method suitable for existing culverts under gangue embankments. The applicable embankment is filled with coal gangue and has strong water permeability. Due to underground mining activities, the ground surface will subside. In order to maintain the same elevation of the top of the embankment, it is necessary to heighten the embankment, resulting in an increase in the thickness of the filling on the top of the culvert. Therefore, it is necessary to strengthen the culvert structure. The reinforcement methods usually include thickening the side wall and roof of the culvert, or setting a rectangular steel frame in the culvert, which is in close contact with the original structure to form a composite structure under common stress. Regardless of the reinforcement method, it is necessary to fill in cofferdams at the entrances of the two sections to form a closed area, and then drain the accumulated water in the area so that personnel and equipment can enter the area and carry out construction operations. The cofferdam of the present invention is composed of three sections, the arc section needs to surround the culvert opening, and the straight sections on both sides extend outward along the direction of the embankment. The anti-seepage membrane is laid on the side slope of the embankment, and the anti-seepage membrane needs to be suppressed by the cofferdam of the straight section, so that water cannot penetrate into the embankment from the embankment with the section covered by the anti-seepage membrane, and can no longer pass through the culvert body The settlement joints in the culvert enter the interior of the culvert, so that the accumulated water inside the culvert can be drained as soon as possible, the drainage cost inside the culvert can be reduced, and the project cost can be reduced.

Description of drawings

Fig. 1 is a cofferdam elevation view of the present invention;

Fig. 2 is a cofferdam plan view of the present invention;

Fig. 3 is an embankment cross-sectional view of the present invention;

In the accompanying drawings, 1 is a culvert, 2 is an embankment slope, 3 is an anti-seepage film, 4 is an embankment slope footline, 5 is a cofferdam, 6 is a shoulder line, and 7 is an embankment centerline.

Detailed ways

The present invention will be further explained below in conjunction with the accompanying drawings.

An anti-seepage method applicable to existing culvert cofferdams under gangue embankments, comprising the following steps:

Step a: Lay the anti-seepage membrane 3 on the embankment slope 2 on both sides of the culvert 1. The anti-seepage membrane 3 extends to 2-3m outside the foot line 4 of the embankment, and the top of the anti-seepage membrane 3 exposes the water level line, as shown in the figure 3 shown. The length L of one side of the anti-seepage membrane 3 along the direction of the embankment is determined according to the permeability coefficient of the embankment filler and the water head difference inside and outside the cofferdam 5, and the specific calculation method is:

L=KΔ/v

In the formula, L is the length of the anti-seepage membrane, m; Δ is the head difference inside and outside the cofferdam, m; K is the embankment permeability coefficient, m/s; v is the seepage velocity, m/s.

Step b: Set up the cofferdam 5. The cofferdam 5 is composed of a circular arc segment and a straight line connecting the two ends of the circular arc segment. The cofferdam 5 is composed of wooden piles and clay fillers, and extends to the outside of the embankment footline 4 and the embankment slope The anti-seepage membrane 3 on the 2 is pressed by the straight section of the cofferdam 5, and the extension length of the straight section of the cofferdam 5 along the direction of the embankment is consistent with the length of the anti-seepage membrane, as shown in Figure 2.

Theoretically, the amount of water infiltrated into the cofferdam within a unit time is Sv, and the internal drainage capacity of the cofferdam is Q within a unit time, if:

Q≥Sv

Then there will be no accumulated water inside the cofferdam; where, Q is the drainage capacity of the pump, m ³ /s; S is the cross-sectional area of the part of the embankment below the water level, m ² .

Claims (6)

1. the anti-seepage method in existing culvert cofferdam under a kind of embankment suitable for spoil, which is characterized in that include the following steps：

Step a：Antiseepage film is set on the embankment slope surface upper berth of culvert two sides；

Step b：Cofferdam is set, and the cofferdam is made of the straightway of arc section and connection arc section both ends, the antiseepage film It is pushed down by the straightway in cofferdam.

2. the anti-seepage method according to claim 1 suitable for existing culvert cofferdam under spoil embankment, which is characterized in that institute It states and is extended on the outside of embankment leg wire of slope at 2-3m outside antiseepage film.

3. the anti-seepage method according to claim 1 or 2 suitable for existing culvert cofferdam under spoil embankment, feature exist In length L of the antiseepage film along embankment direction is determined according to the head difference inside and outside embankment fill material infiltration coefficient and cofferdam, tool Body calculation method is：

L=KΔ/v

In formula, L is antiseepage film length, and Δ is head difference inside and outside cofferdam, and K is embankment fill material infiltration coefficient,vFor seepage velocity.

4. the anti-seepage method according to claim 3 suitable for existing culvert cofferdam under spoil embankment, which is characterized in that institute Expose water level line in the top for stating antiseepage film.

5. the anti-seepage method according to claim 4 suitable for existing culvert cofferdam under spoil embankment, which is characterized in that institute Cofferdam is stated to be made of timber and clay filler.

6. the anti-seepage method according to claim 4 suitable for existing culvert cofferdam under spoil embankment, which is characterized in that institute It is consistent with antiseepage film length along embankment direction extension to state cofferdam straightway.