What is quicksand, its varieties. How to determine its presence in the well, what to do in this case. The most effective technologies and preventive measures. Quicksand is a viscous semi-liquid substance composed of sand, clay and water, which creates many problems in the construction of a creek bed. You can overcome it with the help of special technologies and a set of activities. We will talk about how to get through quicksand when digging a well in this article.
Description and types of quicksand in the well
Quicksands are loose and loose soils highly saturated with moisture, consisting of sand or sandy loam. The smallest particles are interconnected by water and form a jelly-like mass that can move in the water layer. In the well, the thick mixture clogs the veins and creates a host of other problems.
It is very difficult to overcome volumetric layers of viscous substance - the vacated space is immediately filled with wet sand. The depth of quicksand ranges from 1.5 to 10 m and depends on the structure of the soil and the size of the aquifer. The loose mass can be motionless for the time being, and then at the beginning of digging the well, quicksand begins to move under the action of a water vein.
There is a great danger of an unpleasant formation occurring if the shaft is dug into a layer of fine sand. The impetus for the onset of contamination of the well can be the movement of underground layers or mechanical impact, for example, this often happens during the construction of the foundation for a residential building.
For the passage of education, special technologies are used that do not allow sand to move into the mine. However, if the inflow of water from quicksand turns out to be very large, work will have to be stopped and another place for the well should be looked for.
There are two types of quicksands - true and false. The first option is the most dangerous. It is based on clay soils, which swell when freezing and can destroy the mine. It is very difficult to isolate water from a true quicksand, less than 0.5 m is pumped out per day3.
False formations consist only of fine sand and dust, glued together with water. In contrast to the first case, a lot of moisture is released from the false quicksand. In a well built on a similar mass, the liquid level reaches 1.5 m.
If you do not fight this phenomenon at the stage of well construction, the following problems will arise in the future:
- The water in the spring becomes cloudy. Krinitsa must be cleaned frequently.
- In winter there is intense heaving. As a result, the bottom rings of the shaft are displaced in the horizontal plane, which can lead to the appearance of gaps between them.
- Often, after a short period of operation, the krynitsa dries up.
- When using concrete rings, quicksand can completely absorb the lower elements and be carried away.
- After haphazard excavation from a well, sinkholes may appear near the mine.
There are several technologies for extracting water from a quicksand crust: passing through the formation and digging a mine to the next aquifer; strengthening the trunk with concrete rings; pumping out liquid with special devices capable of functioning in softened soil.
How to determine the presence of quicksand in a well
The presence of quicksand in the well is determined by the small water level in the mine, which cannot be increased in any way. A cloudy brown liquid collects at the bottom. Digging a hole is easy, but the volume of soil removed is many times greater than when working with ordinary soil.
This is due to the property of the semi-liquid mass to quickly move to the place of the removed soil, so the depth of the mine practically does not change. It is impossible to use the pump when digging a hole, a high speed of sand removal can lead to a distortion of the walls of the mine and its destruction. In addition, the composition of quicksand is heterogeneous, and large chunks of hard rock are often found in it, which can damage equipment. The rapid movement of large pieces deprives the wellbore of a solid support and destroys it.
The presence of quicksand in the area is determined with great accuracy only with the help of test drilling, but in some cases its presence can be predicted in advance.
There are the following signs of a close occurrence of a semi-liquid mass:
- At a shallow depth from the surface, there is a layer of very fine sand or dust.
- Groundwater is too close to the surface.
- The appearance of moisture in the well at a much shallower depth than the occurrence of the useful layer, determined by calculation.
- Quicksand occupies a fairly large area, so if the neighbors did not encounter such a problem, then you will not have it either.
- Education most often appears in places where ground displacement is possible. These include slopes, ravines, quarries, etc.
- There are sinkholes on the site.
If a suspicious formation appears in the well, it is necessary to make a decision on further actions. You can choose one of the following options:
- Move the krynitsa to another place;
- Refuse to deepen the source and use the small volume of water that is collected in the mine;
- Continue digging using a special technology for passing problem areas.
To make a choice, ask your neighbors if they have encountered a similar problem and how they solved it. Thus, you can take advantage of work experience that has led to a positive result. In the absence of information, order an engineering and technical expertise, but it is expensive and not all owners agree to spend money on it.
How to get through quicksand in a well
It will not work to go through a viscous education using the traditional methods with which wells are dug. To go 20-30 cm deeper, you need to remove 50-60 buckets of soil to the surface. To solve the problem, both old methods and the latest technologies are used.
How to get past quicksand with concrete rings
For work, you will need products with a diameter of 1-1.5 m, a height of 0.25-0.5 m and a thickness of at least 5 cm. The larger the rings, the easier it is to work inside, but the more weight. To get through the problem layer, a drop method is used. The sequence of work is as follows:
- Dig a shaft until signs of quicksand appear at the bottom of the well.
- Expand the diameter of the hole to accommodate the concrete rings.
- Place the cutting shoe on the bottom.
- Place the first ring on top of it. Check the verticality of the element wall.
- Remove soil from the inner cavity, first around the perimeter and then in the center. The mine will drop down under its own weight.
- Check the verticality of the wall. Level it if necessary by removing soil from one side.
- Place the second ring on the first. Be sure to seal the joint with deep penetrating crystallizing soil compounds and plasticized grout.
- Securely connect the elements to each other with metal plates that are bolted. The shackles create a monolithic structure and prevent quicksand from destroying the mine.
- Select the soil inside the pit until the rings drop to a new level.
- Perform the operation to install the next part and fasten the elements together. The appearance of a brown turbid liquid means the entry of the trunk into the thickness of quicksand.
- Repeat the procedure until education is completed. The depth of the well after passing the semi-liquid mass can increase by 10 meters.
Use of tongue-and-groove boards
This method has proven itself well in shallow water strata, as well as in the case of a low pressure of a semi-liquid mass. For work, you need a dried edged board 5 cm thick and 2 m long, one side of which is pointed.
Perform the following operations:
- Make sturdy lumber shields. Their dimensions should allow for the movement of products inside the shaft.
- Drive the shields into the bottom of the well along 400 mm rails using a cast iron woman or other pile driving device. As a result, a box should be formed, which separates the barrel from the moving mass and makes it possible to remove the viscous substance. When hammering, provide cushioning for the dowels.
- Remove the soil inside the structure up to the edge of the boards.
- Re-hammer the 40 cm dowel and repeat the operation until the quicksand has passed completely. If the well is deep, use oblique dowels, which are driven in sequence, with spacers. This design is able to withstand the pressure from a 2 m thick semi-fluid formation.
- After passing the problem area, make a wooden box with a height of at least 1.5 m and install it on the bottom of the well. In the bottom, make small holes through which water will flow.
- Pour a layer of medium-sized crushed stone with a thickness of 30 cm on the bottom, and then 20 cm of sand. This "cake" will not let sand and dirt into the barrel.
For the passage of massive quicksand, a tongue-and-groove in the form of a bulkhead 80 cm high with beveled edges is used. After removing the sand inside the structure from above, secure the second part of the product. Connect both parts together, and install spacers inside. Drive the product 40 cm into the bottom and remove the soil inside. Repeat the process until you reach solid ground.
Bottom filter
The device is installed in the mine when it was not possible to pass the semi-liquid mass and a solution to how to get rid of the quicksand in the well was not found. In this case, the krynitsa begin to operate in the state in which the construction was stopped. Its use is justified with a large inflow of water, when the quicksand is true. If the formation is false, the sand will quickly clog the filter holes and block the flow of moisture into the well. The product is made from waterproof wood species, for example, from aspen.
Perform the following operations:
- Knock down a shield from the boards, the size of which is 5 cm less than the size of the well. Make sure that there are no gaps between the boards.
- From the bottom, nail the bars that play the role of legs.
- Drill holes with a diameter of 5-6 mm in the shield.
- Lower the shield to the bottom and level it to the horizon along the water surface.
- To improve filtration, sprinkle at least 3 layers of stone on it. The cake should look like this: bottom layer - medium sized river pebbles; the second is small pebbles; the third is quartz sand; upper - shungite. The thickness of each layer is at least 15 cm, but the top layer can be poured thinner, within 50 mm. The total filter thickness can be up to 500 mm.
The bottom filter can be used for 5-6 years, after which it must be replaced. The structure is raised to the surface and a new one is installed in its place. If you do not install a wooden shield on the quicksand, you will have to clean the well every year.
Other ways to get past quicksand in a well
To do this, you can use shock-rope methodwhen the quicksand is punctured by the impact nozzle, which is moved into the casing. After passing through the formation, it is necessary to seal the bottom of the bottom, so that sand does not enter from below. To do this, you need a linen bag, the diameter of which in the filled state is equal to the diameter of the well. Fill it with sand and cement in a 1: 1 ratio and lower it to the bottom. After 24 hours, the mixture will harden and the water will immediately be cleaner.
Abyssinian well
is a structure of a thin metal pipe with a diameter of 1.5-2 inches, the lower part of which plays the role of a filter. With its help, liquid is extracted from a shallow depth, regardless of the composition of the water layer. The tube is driven into the ground to the required depth. The appearance of moisture in it is controlled using a special device. The disadvantages of such a well include a small volume of produced fluid and the use of a pump that is installed on the surface.
Bottom box
used for the passage of very liquid quicksand. The design is a box with a cutting knife at the bottom and a lid on the other. Place the product on the bottom of the well and press it into the ground as much as possible. Open the lid and remove the sand from the box. In this way, you can dig a hole no more than one meter deep.
Within the framework of gluing moving mass for the passage of quicksand, it is allowed to use special substances that, when interacting with water, increase their volume dozens of times. These include, for example, bentonite. Pour the product into the well and wait until it hardens. As a result, an excellent waterproofing composition is formed, which will allow you to easily pass this substance.
Preventive measures to prevent the appearance of quicksand
In order not to provoke the appearance of a viscous mass, you must adhere to the following rules:
- Do not pump out all the water from the pot. The lack of liquid contributes to the formation of quicksand.
- Do not try to increase the moisture level in the well; it can change throughout the year.
- Do not violate the integrity of the bottom filter, this will lead to irreversible consequences.
- The use of a bottom filter will reduce sand contamination of the mine.
- Do not take long breaks while passing quicksand in the well.
- After 5-6 years, clean the well and replace the wooden board.
What to do if there is quicksand in the well - watch the video:
A semi-liquid mass of sand, clay and water is a serious obstacle and often causes anxiety. To solve the problem, it is necessary to collect as much information as possible about the quicksand (flow rate, its power, size and depth of occurrence, etc.) and choose one of the options for dealing with it discussed above. However, the best solution is to move the well to another location, which will save money and energy for other work.
