RU2419705C1 - Method to clear defects in dams of homogeneous soil - Google Patents

Abstract

FIELD: construction. ^ SUBSTANCE: method includes digging trenches with depth exceeding crack or filtration path height, filling trenches with a soil mixture from a soil cement with an additive, a layer-wise compaction, arrangement of a protective coating along the upper slope and ridge with the thickness of not less than the freezing depth. The additive used to increase strength and frost resistance is a mixture of ash and siftings in the amount accordingly of 4-6% and 20-35% of the soil mix weight. ^ EFFECT: improved efficiency of hydraulic insulation due to elimination of filtration water leakage through dams body, protection of a dam body in most dangerous areas against harmful effect of earth-moving animals, and a better heat insulation effect at lower thickness of a protective coating. ^ 7 dwg, 1 tbl

Description

The invention relates to the field of irrigation and drainage construction and is intended for the repair of protective and regulatory dams with a height of up to 10 m from a homogeneous low-permeable soil by filling cracks, filtration passages and burrows with soil materials.

A known method of sealing cracks, filtration passages and burrows of digging animals, including extracting trenches on the crest of a dam with exceeding depth above the height of a crack or passage, filling trenches with soil of the same composition as the dam body, layer-by-layer compaction (G. Achkasov, Ivanov ES Technology and organization of repair of reclamation hydraulic structures. - M .: Kolos, 1984. - S.49-52, Fig. 13). The disadvantage of this method is that due to the low water and frost resistance, the waterproofing properties of the soil used to seal cracks, filtration passages and burrows will be lost over time, and cracks, filtration passages and burrows will reappear. In addition, due to the insecurity of the uphill slope and ridge with a protective (frost protection) coating, free-permeable (loamy, heaving) soil of the slope and ridge will freeze, contributing to softening, loosening and sedimentation of the soil, the appearance of filtration passages and water leakage through the dam body.

There is also a method for eliminating defects in bulk dams from homogeneous poorly permeable soil with cement cement (Achkasov G.P., Ivanov E.S. Technology and organization of repair of reclamation hydraulic structures. - M .: Kolos, 1984. - P. 44-47, Fig. 12, and Ivanov ES, Achkasov GP Organization and technology of repair work on reclamation systems. - Kolos, 1997. - P.88). The disadvantage of this method is the low strength and low frost resistance of cement, which will adversely affect its waterproofing properties and will again contribute to the appearance of defects (cracks, passages). In addition, due to the insecurity of the upper slope and ridge crest, free-permeable soil of the slope and ridge will freeze, contributing to the appearance of filtration passages and seepage of water through the dam body.

Closest to the proposed is a method for eliminating defects in dams from a homogeneous heaving (loamy, poorly permeable) soil, including a protective (frost protection) coating on slopes and ridges and eliminating defects with cement cement with added sand (A.I. Murashko. Reclamation: Encyclopedic Handbook. - Minsk: Belorussian Soviet Encyclopedia, 1985. - P.147, Fig. “Cross profiles of dams”, е .; Ivanov BC, Achkasov GP Organization and technology of repair work on reclamation systems. - M .: Kolos, 1997. - S.162, 208) .

The disadvantage of this method is the implementation of a protective (frost protection) coating of the slopes and the crest of the sand layer, which although protects the slopes and crest from freezing, but does not protect (due to the fragility of the layer) them from the harmful effects of earth-moving animals - muskrats, moles, mice and etc., arranging holes (passages) in the surface of the upper slope, which often becomes focal points of erosion. The thickness of the protective coating of sand is also excessive, due to the relatively low (judging by the high coefficient of thermal conductivity, see the formula below) heat-insulating ability of sand. In addition, due to the relatively low strength and frost resistance, the waterproofing efficiency of soil cement used to seal cracks and passages with an additive (with sand) will be insufficient, and water leakage will resume again.

The technical result achieved by the present invention is to increase the effectiveness of waterproofing.

This technical result is achieved by the fact that the protective coating is made of soil mixtures in the form of soil cement with an additive, and the coating thickness is not less than the depth of freezing, and as an additive to increase strength and frost resistance, a mixture of ash and seed are used in amounts of 4-6% and 20, respectively -35% by weight of the soil mixture.

As one of the components of the additive, fly ash of a state district power station is used, which is a by-product of combustion in the furnaces of boiler units crushed to a dusty state of Donetsk anthracite. Fly ash is removed from the furnaces by flue gases and deposited on electrostatic precipitators. Ash is mainly represented by a fraction of 0.01-0.1 mm. Its average size varies slightly in the range of 0.03-0.07 mm. The specific surface of the ash is in the range of 2500-3000 cm ² / g.

Another component of the additive is seeding - waste of stone crushing of quartzite fractions up to 5 mm with a particle size modulus of 2.48, containing 18.4% of dusty and clay particles determined by elutriation.

Due to the high specific surface area of the ash, dust and clay particles contained in the additive, the contact surface of the components of the soil mixture increases significantly, which intensifies the forces of adsorption, molecular and capillary interaction and increases the degree of connectivity of the soil mixture. This, in turn, will accelerate the process of hydrolysis and hardening of cement and will provide a significant increase in the strength and frost resistance of cement with the proposed additive.

In order to assess the effect of ash and sowing on strength and frost resistance, laboratory tests were carried out.

As a soil, light, slightly permeable loam was used. The Novorossiysk Portland cement of grade 500 served as binders. The composition of the soil mixture also included ash and sowing. For comparison, soil mixtures were prepared from soil cement without additives and soil mixtures from soil cement with the addition of quartz river sand with a particle size modulus of 1.67, containing 2.7% of dusty and clay particles. The amount of water in each case was selected taking into account the optimal humidity and maximum density of soil mixtures. Samples of cylinders with a height and diameter of 50 mm were made from prepared soil mixtures in cylindrical forms with two inserts, which were subjected to strength tests: a) after 28 days of hardening and complete water saturation; b) after 50 cycles of freezing and thawing. The test results are presented in table 1. The data for accepted as an analogue of cement without additives and accepted as a prototype of cement with the addition of quartz river sand are also given for comparison.

Table 1 Gruntoc
the cop The proportion of cement,% by weight of soil
mixtures The amount of additive,% by weight of soil mixture Strength, MPa

Frost coefficient

sand ash seeding After 28 days and complete saturation, R ₂₈ After 50 cycles, freeze. - thawing, R _mor No additives (equivalent) 10 0 0 0 11.35 8.85 0.78 fourteen 0 0 0 11.72 9.49 0.81 With the addition of sand (prototype) 10 fifteen 0 0 11.6 9.40 0.81 10 40 0 0 12.35 10.37 0.84 fourteen fifteen 0 0 12.30 10.21 0.83 fourteen 40 0 0 12.52 10.89 0.87 With the addition of ash and sowing (offered) 6 0 8 fifteen 9.97 8.67 0.87 6 0 8 twenty 10.70 9.63 0.90 6 0 8 thirty 11.36 10.45 0.92 6 0 8 35 11.57 10.76 0.93 6 0 8 40 11.70 10.88 0.93 8 0 6 fifteen 12.12 11.27 0.93 8 0 6 twenty 13.97 13.27 0.95 8 0 6. thirty 15.12 14.52 0.96 8 0 6 35 15.25 14.80 0.97 8 0 6 40 14.97 14.52 0.97 10 0 four fifteen 14,4 13.39 0.93 10 0 four twenty 15,20 14.59 0.96 10 0 four thirty 16.03 15.39 0.96 10 0 four 35 16.05 15,57 0.97 10 0 four 40 16.01 15,53 0.97 fourteen 0 0 fifteen 14.9 14.01 0.94 fourteen 0 0 twenty 15.67 15.04 0.96 fourteen 0 0 thirty 16,42 15.93 0.97 fourteen 0 0 35 16.36 15.87 0.97 fourteen 0 0 40 16.1 15.62 0.97

As can be seen from the data in the table, the addition of ash and sowing to soil cement in an amount of 4-6% and 20-35% of the total mass of soil mixture components, respectively, provides an increase in strength by 25-30%, and frost resistance - by 10-15%. A decrease in the amount of ash below 4% (or an increase in the proportion of cement in excess of 10%) does not give a significant increase in strength and frost resistance, and an increase in its (ash) share in excess of 6% does not exceed the corresponding figures for the prototype. It does not provide advantages over the prototype and the decrease in the number of seeding below 20% (see, with the proportion of cement and ash, respectively, 8% and 6%).

Figure 1 shows the operation to eliminate a longitudinal crack in the dam; figure 2 is the same, transverse cracks; figure 3 - protective (frost protection) coating of the upper slope and ridge, the filtration course and made across the trench with a castle of soil cement with the addition of ash and sowing.

The method is as follows.

From the surface of the uphill slope 1 and ridge 2 of the dam 3 during the period of absence or minimum water level in the pool (or after the installation of the tongue and groove fence), the soil that has been softened after freezing in winter is removed. To eliminate the longitudinal crack 4 on the crest 2, a trench 5 is torn along it with an excess of depth above the height of the crack 4 and a length approximately 1 m greater on each side than the length of the crack. In the case of transverse cracks 6 (or filtration passages 8, burrows of digging animals), trench 7 is torn off and across them for locking the castle perpendicular to crack 6 (or pass 8). Then, for backfilling the trenches (eliminating cracks, passages, holes) and the protective coating device 9 of the uphill slope 1 and ridge 2 in a soil mixing machine, a soil mixture is prepared from soil cement with the addition of ash and sowing and laid in layers with subsequent compaction in trenches 5, 7, and also uphill and crest. The thickness of the protective coating 9 of the upper slope and the ridge is no less than the depth of freezing (h) of freezing (h _prom ), given under the conditions of thermal conductivity, to the thickness of the sandy frost-protective coating, according to the formula

,

,

where h _p - the thickness of the protective (frost protection) coating of sand, 50-70 cm;

λ _p - the coefficient of thermal conductivity of sand, 1.65 kcal / (m · h · deg);

λ _Hz - coefficient of thermal conductivity of soil cement with additive, 0.95 kcal / (m · h · deg).

With a gentle uphill slope 1, mixing of soil with sowing, ash and cement can be carried out at the place of laying - slope 1. For this, the soil on slope 1 is crushed, transported and evenly sowed along it with special batchers (such as fertilizer seeders for fertilizer distribution, for example) ) according to the accepted dosages make ash and cement, mix, moisten the mixture to optimal humidity and compact. With a shallow downhill slope, in the case of heavy rains or a "high" position of the depression curve, part of the downhill slope will be saturated with water, which will require a protective coating 9 and over it.

The use of the invention will allow to exclude filtering water seepage through the body of the protective and regulating dams, since cracks, filtration passages and holes formed during operation will be sealed with high-strength and frost-resistant soil material with a rigid structure, which, being also laid on the slope and comb, will reliably protect the body of the dam (in the most dangerous places - the uphill slope, ridge) from the harmful effects of earth-moving animals, arranging passages and burrows in the surface part of the uphill slope, which often becomes It causes the erosion of dams. In addition, the device of the proposed protective coating will provide a better heat-insulating effect compared to similar coatings made of sand materials, which allows not only to more effectively protect the low-permeable (heaving, loamy) soils of dams from freezing and the further occurrence of filtering passages, but also to reduce the thickness of the protective coating, and also to widely use local soils in the absence of sand materials in the area of ongoing work.

Claims (1)

A method for eliminating defects in dams from homogeneous soil, including tearing off trenches with excess depth above the height of the crack or filtering passage, filling trenches with a soil mixture of soil cement with an additive, layer-by-layer compaction, a protective coating device on the upper slope and ridge with a thickness not less than the freezing depth, characterized in that that the protective coating is made of soil mixtures in the form of soil cement with an additive, and as an additive to increase strength and frost resistance, a mixture of ash and sowing in quantity 4-6% and 20-35% of the weight of the soil mixture, respectively.

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