CN108589697B - Replacement method of miscellaneous filling soil in the construction area of ground connection wall - Google Patents

Abstract

The embodiment of the invention provides a method for replacing miscellaneous fill in a diaphragm wall construction area, which comprises the following steps: measuring and setting out in a diaphragm wall construction area to determine a replacement area; excavating miscellaneous filling soil of the filling area to form a filling pit; and filling backfill soil in the filling and replacement pit to fill and replace the miscellaneous fill soil in the construction area. The method provided by the invention can improve the grooving effect of the diaphragm wall, protect the diaphragm wall reinforced concrete structure from being corroded, improve the diaphragm wall construction quality and provide safety guarantee for subsequent construction.

Description

Replacement method of miscellaneous filling soil in the construction area of ground connection wall

technical field

The invention relates to the field of municipal engineering construction, in particular to a method for replacing miscellaneous soil filling in a ground connecting wall construction area.

Background technique

The ground connecting wall is a foundation project using a grooving machine on the ground. Along the peripheral axis of the deep excavation project, under the condition of mud wall protection, a narrow and long deep groove is excavated. After the groove is cleared, the steel cage is suspended in the groove. , and then use the conduit method to pour underwater concrete to build a unit groove section, and so on section by section, a continuous reinforced concrete wall is built underground. The ground connection wall has the functions of intercepting water, preventing seepage, bearing load and retaining water. It is very important for the subsequent construction.

When the soil buried in the local connecting wall construction area is miscellaneous fill, since miscellaneous fill is mainly composed of soil and construction waste, domestic waste, humus and other wastes, the structure of miscellaneous fill is loose and the uniformity is poor. The thickness of the soil structure in the construction area of the ground connecting wall is different, and the ground connecting wall is easy to collapse when it is formed into a groove. At the same time, the miscellaneous fill contains a large amount of sulfate ions and carbonate ions. The crystals formed by the reaction of sulfate ions and carbonate ions with water or combined with cement hydrate will expand the volume of the concrete structure and cause cracks inside it. The surface softens, which affects the strength of the concrete, and the miscellaneous fill also contains chloride ions, which are corrosive to the steel bars, resulting in poor construction quality of the ground connection wall and a potential safety hazard for later construction.

SUMMARY OF THE INVENTION

In view of the technical problems in the prior art that the ground connecting wall construction is performed in the miscellaneous fill area, the effect of forming the ground connecting wall is poor, the reinforced concrete is easily corroded, and the construction quality of the ground connecting wall is poor. The invention provides a ground connecting wall construction The regional miscellaneous filling soil replacement method can improve the troughing effect of the ground connecting wall, protect the reinforced concrete structure of the ground connecting wall from corrosion, improve the construction quality of the ground connecting wall, and provide a safety guarantee for the subsequent construction.

In order to achieve the above purpose, the method for replacing miscellaneous soil in the construction area of the ground connecting wall provided by the present invention includes the following steps: measuring and setting out the line in the construction area of the ground connecting wall to determine the replacement area; Fill soil to form a replacement pit; fill the replacement pit with backfill to replace the miscellaneous soil in the construction area.

Preferably, the backfill is a mixture of cement soil, silty clay and nitrite.

Preferably, the volume ratio of the cement-soil, the silty clay and the nitrite is 99865:900000:135.

Preferably, the filling of the replacement pit with backfill to replace the miscellaneous soil in the construction area includes: dividing the replacement pit into multiple layers; Fill in the backfill separately.

Preferably, the method further comprises: after each layer is filled with the backfill, rolling the backfill.

Preferably, the method further comprises: after filling the backfill in the replacement pit, determining the water content of the backfill; determining the amount of water sprinkled according to the water content and current weather conditions; The amount of water sprinkles water on the backfill.

Through the technical solution provided by the present invention, the present invention has at least the following technical effects:

In the method for replacing miscellaneous fill in the ground connection wall construction area of the present invention, the miscellaneous fill in the ground connection wall construction area is excavated, the backfill soil is filled in the replacement pit, and the miscellaneous fill in the ground connection wall construction area is replaced. , which can improve the groove forming effect of the ground connecting wall, protect the reinforced concrete structure of the ground connecting wall from corrosion, improve the construction quality of the ground connecting wall, and provide a safety guarantee for the subsequent construction.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of drawings

FIG. 1 is a flow chart of a method for replacing miscellaneous soil in a ground connection wall construction area provided by the present invention.

Detailed ways

The specific implementations of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

In the present invention, unless otherwise stated, the directional words used such as "upper, lower, top, bottom" are usually for the direction shown in the drawings or for the vertical, vertical or gravity direction The words used to describe the mutual positional relationship of the components mentioned above.

The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

Please refer to FIG. 1 , an embodiment of the present invention provides a construction method for a shallow buried tunnel crossing a river. The method includes the following steps: S101 : measuring and laying out lines in a ground connecting wall construction area to determine a replacement area; S102 : excavating The miscellaneous soil in the replacement area is filled to form a replacement pit; S103 : backfill is filled in the replacement pit to replace the miscellaneous soil in the construction area.

In the embodiment of the present invention, firstly, according to the design drawings, the stakeout is measured at the construction site, the replacement area is determined, and the replacement area is excavated. During excavation, an excavator is used to excavate in a backward driving manner. Due to the presence of a large amount of corrosive minerals in the miscellaneous fill in the replacement area, the miscellaneous fill cannot be screened for secondary use, and it needs to be excavated at the same time. For side shipments, dump trucks are arranged on both sides of the excavator to transport earth. During excavation, excavate from top to bottom and in layers. The replacement pit is sloped at a slope of 1:0.75. After all the miscellaneous fill in the replacement pit is excavated, the backfill is filled into the replacement pit.

The method of the embodiment of the present invention can improve the groove-forming effect of the ground connecting wall, protect the reinforced concrete structure of the ground connecting wall from corrosion, improve the construction quality of the ground connecting wall, and provide a safety guarantee for the subsequent construction.

Preferably, the backfill is a mixture of cement soil, silty clay and nitrite.

Due to the influence of miscellaneous fill, the groundwater in the construction area of the ground connection wall contains carbonate ions, sulfate ions and chloride ions. It is very high and is corrosive to reinforced concrete structures, and if ordinary soil is used to fill the replacement pit, the soil of ordinary soil is easy to loosen, and it is easy to cause the problem of ground wall excavation and collapse. In the embodiment of the present invention, a mixture of cement-soil, silty clay and nitrite is used as the backfill. The backfill soil is a weakly permeable layer, which can effectively inhibit the diffusion of carbonate ions, sulfate ions and chloride ions, and reduce the concentrations of carbonate ions, sulfate ions and chloride ions near the ground wall. The ions react as follows:

1. Reaction of backfill with carbonate ions:

The main components of cement soil are tricalcium silicate, dicalcium silicate and tricalcium aluminate. After encountering water, a hydration reaction will occur to generate heat:

3CaO·SiO ₂ +H ₂ O→CaO·SiO ₂ ·YH ₂ O+Ca(OH) ₂

2CaO·SiO ₂ +H ₂ O→CaO·SiO ₂ ·YH ₂ O+Ca(OH) ₂

3CaO·Al ₂ O ₃ +6H ₂ O→3CaO·Al ₂ O ₃ ·6H ₂ O

Carbonate ions in groundwater will decompose when heated:

CO ₃ ^2- +2H ⁺ →CO ₂ +H ₂ O

Secondly, the cement soil contains calcium ions, which combine with carbonate ions to form calcium carbonate:

Ca ²⁺ +CO ₃ ^2- →CaCO ₃

Calcium carbonate is an insoluble substance, which can reduce the conductivity of the electrolyte environment and slow down the corrosion of reinforced concrete.

2. The reaction between backfill soil and sulfate ions:

Ca ²⁺ +SO ₄ ^2- →CaSO ₄

Cement soil contains calcium ions, which combine with sulfate ions to form calcium sulfate. Calcium sulfate is an insoluble substance. Backfill soil can neutralize sulfate ions in groundwater.

3. The reaction between backfill soil and iron ions:

2Fe ²⁺ +2OH ^- +2NO ^2- →2NO+γ-Fe ₂ O ₃ +H ₂ O

The backfill contains nitrite, which will react with the steel bar to form γ-Fe ₂ O ₃ , and the γ-Fe ₂ O ₃ adheres to the surface of the steel bar to form a passivation film, which isolates the chloride ions outside the passivation film and protects the steel bar. not eroded.

Through the method of the embodiment of the present invention, the corrosion of the reinforced concrete structure of the ground connecting wall caused by the carbonate ions, sulfate ions and chloride ions in the groundwater due to the miscellaneous filling can be effectively solved, and the collapse of the ground connecting wall into a groove can be ensured. Improve the appearance and internal quality of the ground wall, improve the construction quality of the ground wall, and provide safety guarantee for the subsequent construction.

Preferably, the volume ratio of the cement-soil, the silty clay and the nitrite is 99865:900000:135.

In the embodiment of the present invention, the volume ratio of cement-soil, the silty clay and the nitrite is 99865:900000:135. Using this ratio of backfill can ensure the strength of the backfill on the one hand, and can ensure the strength of the backfill on the other hand. Save cement and reduce construction costs.

Preferably, the filling of the replacement pit with backfill to replace the miscellaneous soil in the construction area includes: dividing the replacement pit into multiple layers; Fill in the backfill separately.

In the embodiment of the present invention, the construction method of backfilling while transporting materials is used for operation. Before backfilling, calculate the amount of engineering required according to the daily workload and length, and arrange transportation vehicles. The silty clay is transported by large dump trucks, and an excavator is used for backfilling. Divide the replacement pit into multiple layers. After the backfill is laid out according to the amount of soil in each layer, it is leveled and leveled by machinery to prevent the accumulation of rainwater, so as not to affect the quality of the fill.

Through the method of the embodiment of the present invention, a large amount of soil subsidence and cracking in the ground connecting wall construction area after backfilling can be avoided, the construction quality of the ground connecting wall can be improved, and the safety guarantee for the later construction can be provided.

Preferably, the method further comprises: after each layer is filled with the backfill, rolling the backfill.

In the embodiment of the present invention, for each layer, after each layer of backfill soil is filled, the backfill soil needs to be rolled by a road roller. The process of rolling the backfill soil by the road roller is as follows: first use the road roller to lightly press the backfill soil for 1-2 times, and then vibrate the rollers of the roller to roll the backfill soil. The two sides are pushed toward the middle, and the rolling road of each rolling overlaps with the rolling road of the last rolling by 1/3 of the wheel width. Each layer of backfill needs to be rolled 6-8 times by a road roller until there are no obvious wheel tracks. Vehicles are prohibited from driving on the uncompacted backfill soil to avoid uneven pits and grooves on the backfill surface.

By means of the method of the embodiment of the present invention, the soil strength of the ground connecting wall construction area can be ensured, the collapse of the ground connecting wall into grooves can be reduced, and the construction quality of the ground connecting wall can be improved.

Preferably, the method further comprises: after filling the backfill in the replacement pit, determining the water content of the backfill; determining the amount of water sprinkled according to the water content and current weather conditions; The amount of water sprinkles water on the backfill.

In the embodiment of the present invention, when backfilling and replacing the pit, the water content of the backfill soil should be controlled. If the water content of the backfill soil does not meet the design standard, and the weather on the day is relatively dry, the water content should be determined according to the water content of the backfill soil. Sprinkle Water Amount Sprinkle water on the backfill.

Through the method of the embodiment of the present invention, the strength of the backfill soil can reach the design strength, and the backfill soil can be better bonded to the original soil, which further provides safety guarantee for the ground connection wall and later construction.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, These simple modifications belong to the protection scope of the present invention.

In addition, it should be noted that the specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner unless they are inconsistent. In order to avoid unnecessary repetition, the present invention provides The combination method will not be specified otherwise.

In addition, the various embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the contents disclosed in the present invention.

Claims (4)

1. A method for replacing miscellaneous fill in a diaphragm wall construction area is characterized by comprising the following steps:

measuring and setting out in a diaphragm wall construction area to determine a replacement area;

excavating miscellaneous filling soil of the filling area to form a filling pit;

filling backfill in the backfill pit to perform backfill on the miscellaneous fill in the construction area, wherein the backfill is a mixture of cement soil, silty clay and nitrite, and the volume ratio of the cement soil to the silty clay to the nitrite is 99865: 900000: 135.

2. the method of claim 1, wherein the filling backfill in the backfill pit to backfill the miscellaneous fill in the construction area comprises:

dividing the replacement filled pits into a plurality of layers;

and filling the backfill soil according to the layering.

3. The method of claim 2, further comprising:

and after each layer is filled with the backfill soil, rolling the backfill soil.

4. The method according to any one of claims 1-3, further comprising:

determining the water content of the backfill soil after the backfill soil is filled in the backfill pit;

determining the water sprinkling amount according to the water content and the current weather condition;

and sprinkling water to the backfilled soil according to the sprinkling amount.

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