SU1758141A1 - Method of erecting pressure dam on weak flooded foundation - Google Patents

Abstract

Usage: in the construction of underground pressure structures on the territory of the water dumps or sludge dumps. The gist of the invention: when building a dam being erected on a weak submerged foundation, first dumping of two parallel draining bridges is carried out. After that, in the interval between the bridges, the central low-permeable part of the dam is formed. 2 hp f-ly, 5 ill.

Description

The invention relates to hydraulic engineering construction, in particular, to the construction of ground pressure structures on the territory of hydraulic dumps, sludge storages, and can be used in other cases of the construction of pressure structures on a weak submerged base.

The purpose of the invention is to increase work efficiency by ensuring the watertightness of the dam,

Figure 1 shows the cross section of the pressure dam; in Figures 2, 3 and 4, the sequence of operations on the device of draining jumpers; figure 5 is a diagram of the closure of the upper slope of the pressure dam.

Figures 1-5 show parallel lintels 1 and 2, slopes 3, 4, the surface of a strong ground base 5, a layer of sludge or sludge 6, extrusion shafts 7, 13, 16, reservoir level 8, upper reach 9, upper part of the dam 10 , the bottom of lintel 11, the volume of sludge displaced from under the sole of lintel 12, zone 14 with elevated surface marks, direction 15 of slime overflow into the zone with lowered surface marks, undercut 17, shore 18, distribution pipe 19, slurry 20, low-permeable screening layer 21 .

The method is carried out as follows.

First, under the level of the reservoir 8, two parallel bridges 1 and 2 are drained from the draining soil, for example sand and gravel (figure 1). An excess of the ridge of jumpers above cut-edge 17 is assigned from the conditions for ensuring the safety of people and machinery.

When dumping drainage soil on a layer of sludge or sludge 6, it is pushed out to the surface of a solid soil base 5. The process of sludge (sludge) is displaced in the form of creeping slopes in the area of fresh dumping with the capture of a layer of a weak (sludge, silt) base. When this happens a significant improvement

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slope 3 compared with their initial laying 4 at an angle of repose a. At the same time, the sole of each web 11 acquires a curvilinear outline, its edges are located above the initial surface of the sludge (sludge),

The displaced volume of sludge (sludge) is placed in the form of shafts 7, 13 extrusions on both sides of the bridges and between them. With a limited space between the jumpers, the surface of the extrusion shaft 13 rises to elevations higher than those in the external extrusion shafts 7, and the sludge (sludge) in the process of extrusion and extrusion is compacted. Additional compaction of sludge (sludge) occurs under the influence of the weight of the upper part of the dam 10, poured or washed in the usual way from low-permeable, for example, clay soils. The process of compaction and consolidation of sludge (sludge) contributes to its placement in the gap between the two draining bridges.

Due to the described processes, in the central part of the pressure dam, a continuous (from the ridge to the ground base) is formed; a low-permeable zone (lock) is built up in the upper part by bulk or alluvial low-permeable (for example, clayey) soil, and in the lower part - by extruded compacted slime (silt ). Moreover, to form a lock, a natural, natural process of extruding a weak unconsolidated layer (sludge) from the bottom of drainage jumpers is used, and special expensive measures are not required to dry the base and dump the clay core or diaphragm dry.

To achieve the described effect, it is necessary that a certain distance be maintained between the draining bridges. Its minimum value is limited by the condition that there is a gap between the extreme nearest points of the foot of the bridges to form an extrusion shaft 13 between them. This condition is maintained when the ratio

,(one)

where a is the design distance between the axes of drainage bridges;

ai is the distance between the drainage bridges in the case of intersection of their internal slopes, formed at an angle of repose when dumping under the level of a reservoir, on the surface of a solid subgrade

ai 2hnctga + bn, (2)

where hn is the height of the lintel from its crest to the solid subgrade;

a - angle of repose when dumping rocks that make up the body of the lintel, the sublevel of the reservoir;

bn - ridge width of the jumper.

Figure 1 shows the case when a ai.

Another limiting condition is the correspondence of the planned distance between the draining bridges to the geometrical parameters of the upper (central) part of the dike, expressed by the following relation:

32 + bn and a2- bn, (3)

where 32 is the width of the profile of the central part of the dike on the ridge of the draining bridges,

32 (H - hn) (ctg en + ctg a2) + B, (4) where H is the full height of the dam from its crest to the solid subsoil base;

SP, and 2 - the slope of the slopes of the dam;

In - the width of the ridge of the dam.

The shielding effect of extruded sludge (sludge) can be enhanced if the dumping of the draining bridges is carried out sequentially. First, a drainage bridge, located on the downstream side of the pressure dam being constructed (Fig. 2), is poured, until the banks 18 are connected (Fig. 4). The extrusion shafts 7 are located approximately symmetrically on both its sides, and their power, due to the free conditions for spreading sludge (sludge), will be relatively small. Then, subject to conditions (1), (3), pour out the second drainage bridge 2 (FIG. 3). Since it is located above the extrusion shaft from the first web, the capacity of the sludge (sludge) under it will be greater than under the first. Most of the sludge (sludge) displaced from the bottom of the second bridge 12 is on the side of the first bridge, therefore the extrusion shaft in the gap between the two drainage bridges develops more intensively, its surface marks can significantly exceed the surface marks of the extrusion shaft 7 on the outside of the second bridge However, since the extruded sludge (sludge), despite its compaction, is still in a fluid or fluid-plastic state, it flows from zone 14 with elevated kami surface zone with lower marks in the directions indicated by the arrows 15 (Figure 4). The overflow occurs around the zone of fresh dumping of the second drainage bridge (figure 4). As a result, the extrusion shafts occupy positions 13, 16.

Due to the described process, the lower part of the slope of the second bulkhead, located on the side of the headwater 9, is loaded with a layer of sludge (sludge), which creates an additional shielding effect (Fig. 3).

To enhance the shielding effect on the pressure dam surface on the upstream side 9, a distribution pipeline 19 is laid (Fig. 5), from which the pulp 20, for example, clay slurry, is then dumped onto the upstream slope of the dam. The particles of the clay slurry, deposited on the surface of the slope, in particular the slope of the draining bridge, form a low-permeable screening layer 21.

Claims (3)

Claim 1. A method of constructing a pressure dam on a weak submerged base, mainly at a hydraulic heap or sludge dump, including dumping of dry draining rocks on a submerged base with the displacement of weak rocks to a solid subsoil base and the subsequent formation of the design profile of the dam, characterized in that the purpose of increasing the efficiency of work by ensuring the watertightness of the dam, dumping of the draining rocks is carried out in the form of two parallel draining bridges, after of bulk webs between them form a low permeable part of the central dam, the distance between the axes of draining webs selected from the relations: a ai, Э2 + bft and Э2 - bri, where a is the design distance between the axes drainage jumpers; ai is the distance between the drainage bridges in the case of intersection of their internal slopes formed at an angle of repose when dumping under the level of the reservoir, on the surface of a strong soil base; 32 - the width of the profile of the central part of the dam at the ridge level of the draining bridges; bn - the width of the ridge of the drainage lintel. 2. A method according to claim 1, characterized in that first of all the dumping of a drainage bridge located on the downstream side of the pressure head dam being constructed is made. 3. Method according to paragraphs. 1 and 2, characterized in that a distribution pipeline is laid on the surface of the pressure dam from the upstream side, from which the pulp, for example, clay slurry, is discharged onto the upper slope of the dam. Fig f sh l X W8S11 15