When planning a well, well, or other hydrological structure on a site, a survey of the area for the occurrence of groundwater is mandatory. In the future, this allows you to more accurately formulate an action plan and object parameters. However, even upon successful completion of the examination, one should be prepared to detect quicksand. This is a type of soil with a high water, which can cause a lot of problems both in the course of land work, and during the operation of various kinds of structures on this site.
What is a quicksand?
According to the encyclopedic definition, quicksand should be understood as sand saturated with water. In a broader sense, it is a subterranean formation that can swell or spread. Also, in practice, you can meet loosely connected or incoherent sandy loam with similar characteristics. But in each case, it is assumed that quicksand is a certain volume of small colloidal particles with a diameter of up to 0.001 mm. The water saturation property is decisive for such soils, but sealing is also characteristic of quicksand. Typically, under natural environmental conditions, a layer of sludge saturated with water is closed and does not cause any inconvenience. On such a platform can stand a house or an engineering structure. The problems of exploitation of sections with quicksand arise in cases when it is necessary to carry out land work to the level of finding water-saturated soil.
Quicksand Features
The close interaction of soil with the aquatic environment of an experienced summer resident is not surprising. Equipping an individual water supply system due to an artesian well or well, one inevitably has to deal with the same groundwater. What is the fundamental difference between a quicksand and a water boat? A key feature is the specific ability of silty sand to accept certain properties of a liquid medium. Physically, this characteristic is expressed by hydrodynamic equilibrium, when the lower pressure is balanced by the mass of soil. This allows water to be retained in the sand structure. The quicksand maintains a pressure balance only in conditions of tightness. As already mentioned, it is enough to invade this layer during drilling or other earthwork, as the sand will move upward under the influence of lower pressure. The consequences of this behavior of the soil can be unpredictable and in any case depend on the volume of floating clusters.
True and false quicksand - how to distinguish?
Due to the difficulties in determining the characteristics of a particular quicksand and the similarity of its properties with the behavior of other clay loam when interacting with aqueous media, engineers separate true and false quicksand. In the first case, we mean sand and sandy loam with hydrophilic properties. As a rule, their structure is formed by very small colloidal and clay elements, which also perform the function of lubrication between larger particles. Under freezing conditions, such layers are characterized by strong heaving and low ability to filter, and after drying they become connected.
In turn, a false quicksand is the same sandy layer, but without colloidal particles, which determine the hydrodynamic qualities of the mass. A kind of imitation of the characteristics of a true quicksand is explained by the porosity of fine sand. However, from the point of view of practical measures of protection against such phenomena, there is no fundamental difference between these varieties of water-saturated ground masses. A false quicksand is also capable of opening sand under the influence of internal pressure upon opening, presenting similar threats.
The nuances of building on quicksand
Having stumbled upon a quicksand while carrying out land activities, one should expect an inevitable change in the structure of the soil in the area of work. A typical problem of this kind arises with the construction of the pit and the subsequent removal of sand into its niche. This will not only complicate further work as part of the operation, but also lead to soil deformations in areas of closely located buildings due to uneven settlement. Does this mean that digging in quicksand is basically impossible? There are various ways to circumvent them, but in principle it is far from always possible to predict quicksand and especially determine its size. In any case, one should take into account what may threaten direct contact with water-saturated formations during the implementation of land construction activities.
Dangers of Quicksand
The biggest threat relates to manual land activities, in which a well is excavated for subsequent laying of concrete rings. If a sealed layer of sand is under high pressure, then in the event of a breakthrough, along with the rings, the whole team of workers can be carried away. There are also cases of landslides, soil shifts and at least deformation of the wellbore. All such situations pose a threat to the life of diggers. On the other hand, quicksanding is not always a bad thing, since pressure balanced sand in a mine can act as a filtering barrier that naturally improves the quality of produced water.
Quicksand Workarounds
Using the experience of builders, surveyors, it is quite possible to solve the problem of water supply, even in the area with quicksand. To do this, use one of three methods to bypass a dangerous formation:
- Shock-rope technology. The method involves drilling a well with percussion equipment in a niche of the trunk of a metal pipe, which insures the structure from accident. The method is quite complex and technically demanding, but, from a security point of view, one of the best.
- The device of the Abyssinian well. If there is a question about how to pass quicksand while drilling small wells, then you can restrict yourself to the simplest means without special equipment. In particular, a metal tube 2.5 cm thick and a pump for pumping water are used. The pipe is driven to a depth of 15-20 m, and pumping equipment is installed on the surface.
- Tight installation of well rings. Fast and accurate laying of concrete rings eliminates the risk of collapses and flooding in the water. But only specialists can use this method with the help of powerful professional equipment.
General quick jump tips
Also, experts give several recommendations on the implementation of land work in hazardous areas with water-saturated soil of various types:
- Even with the successful passage of quicksand, one should not immediately take to the rapid pumping of water in large volumes. In this case, the formed emptiness will also be quickly filled with sandy loam, which will worsen the quality of the water.
- There are some nuances in doing this task with your own hands. How to get through quicksand manually with minimal cost and without the risk of an accident? You can use a small format drill while working with a partner. So perform small wells of small diameter. But it is precisely for the safety of the process that hydraulic balance must be monitored. To do this, it is necessary to fill the well with water, which compensates for the pressure that displaces the sand from the bottom of the well up.
- It is advisable to install additional filters on the water-bearing horizon.
- You can minimize the hydrodynamic activity of quicksand using special freezing solutions. They have a cementing effect on the sand, diverting water from it.
Conclusion
Mankind has long been familiar with quicksand, but so far there is no universal technology to deal with them. In each case, a specific method of quicksand drilling is selected taking into account the results of geodetic studies and the season. For example, many experts successfully practice the technique of passing a hazardous area in winter, when the soil is in a frozen state. The rest of the year there is also no reason to abandon land work, since the control of water-bearing soil can be done with casing pipes and special hydrodynamic equipment.