Types of shallow foundations. What should a beginner do if his car has a flat tire for the first time? Shallow side

Let’s agree that we will only talk about “tubeless” wheels - wheels that do not have a tube. Nowadays this is the main type of rubber, and for good reason.
I’ll list the main ones: a lighter wheel, improved traction (due to lower pressure and air distribution features), increased comfort, and what we’re talking about is that it’s much more difficult to break such a wheel. More precisely, catching a nail is just as easy, but... on tubeless, you have every chance to get to the installation.

Types of damage

1. Regular puncture.

It doesn’t matter what you caught on the road - a nail, a piece of wire or a sharp stone (I’ve seen that too). A puncture is a minor damage, which in most cases will allow you to get to the tire shop. Also, a puncture does not render the wheel unusable.

2. Cut.

Can be either lateral or on a treadmill. A cut on a treadmill is a rare occurrence, since the treadmill has a massive layer of rubber. But a side cut is easy: if you rub the wheel against something, or throw it into a hole with sharp edges, there is a cut. A shallow cut (when the cord is not damaged) is usually not noticeable and the tire does not go flat. A deep cut causes the tire to flatten immediately, and almost always leads to an irreparable defect, but we will return to this later.

3. Lateral swelling: “bump, hernia, whoever calls it what.”
Appears as a result of driving on a flat tire, or during a strong impact, not necessarily from the side. The bump occurs only on the side surface of the rubber. You fell into a hole at speed, or ran over something, and that’s what caused the bump. Unfortunately, such a defect cannot be eliminated (also a little later - when I mention tire fitting), and leads to the tire being unusable.

4. Disc deformation.

Not exactly damage to the tires, but also a problem associated with the quality of the roads, and sometimes, the inexperience of the driver - the front wheels entered the turn, the rear wheels went along the curb. As a rule, after straightening the disc, the problem is solved and the tires do not suffer.

Wheel replacement and repair

If trouble happens on the road, the first thing is to remove the car from the roadway.
1. Place a sign 30 meters away if you are outside the city and 15 meters in the city. If you can clearly see other cars on the road, this does not mean that they can see you well. You have to change a tire, and it is very uncomfortable to do it on the roadway. Don't be afraid - a few meters on a flat tire will not damage the tires, but you will work in comfort, and you will not impede movement.

2. Next - take out the spare tire, keys, jack - everything you need in advance. I’ve seen a picture: a car is standing on a jack, rocking, and a poor fellow is unloading bags from the trunk in order to get a spare tire - don’t repeat such nonsense, and yes - and kick out the passengers - let them stretch their legs.

3. Before lifting the car, be sure to remove - slightly unscrew - the wheel nuts or bolts..

4. Stop the car: handbrake, speed, if possible - pads on the opposite side of the car, ideally - diagonally. That is: the rear left tire was flat, the pads were under the front right one. There are no blocks - anything at hand will do - an ordinary stone.

5. When you start lifting, make sure that the jack is level and the car is not pulled towards you or pushed away from you - it is better to lower it and move the base of the jack.

— When removing/installing, do not put your head under the fender or your feet under the wheel.
- Under no circumstances hold the wheel from below - hold it on the sides, if anything happens - your hands will be intact.
— Do not completely tighten the wheel while hanging: it is necessary to tighten it while hanging so that the bolts/nuts sit in their seats (cones in the disk), and then, when lowered, tighten them completely.

Tire service

Eat simple rules that need to be remembered. A side bump means the wheel is unusable. No matter what they tell you that it’s no big deal, let’s vulcanize it - such a wheel can be used as a spare wheel, and only as a last resort. With such damage, there is a break in the cord - the threads that serve as the frame of the wheel - no one knows whether they will break further or not. But such a wheel can “shoot” (burst) - be careful. When a cut occurs on a treadmill, if the cut is shallow, you can use it; if it is deep, the wheel should be scrapped.

Regarding: fungus or vulcanization. Definitely vulcanization. Fungus is a temporary measure - vulcanize the puncture as soon as possible. Poor-quality fungus, or tourniquet, can harden over time and lead to air etching. Temporary ones also include various self-adhesive patches - a temporary measure. And don't forget to balance the wheel after repair.
I forgot to mention: there are special sealants that are poured into wheels. In principle, this is a good option, only if there is a small puncture from a thin object.

How to check at home what's wrong with the wheel

First of all, check the spool by wetting the wheel nipple - if there are bubbles, you can replace it - this can be done at home. Also, if you wish and you have found the cause of the puncture, you can use so-called tourniquets or inserts. You can buy them, there are instructions there - if you feel empowered, try them.
For any cuts, swelling, or damage to the disc, go straight to the tire shop.

If the reason is not found

Unfortunately, this also happens - a tire goes flat, but neither you nor the tire shop can find the cause. The following can help: first, let them pump the wheel 1 -1.5 atmospheres more during installation and lower it into the water. Exactly the entire wheel, and do not smear the outside with a brush. Any, even the slightest defect will be clearly visible in the bubbles. But the second thing: everything new is well forgotten old. If you can’t find an object that sticks out in the wheel, use the old-fashioned method: disassemble the tire, ideally remove it completely from the rim. Take a regular cloth and carefully move it inside the tire. Believe me, no matter what sticks out there, the rag will definitely catch, and the rest is a matter of technique.

These are some simple tips on what to do if you get a flat tire for the first time - no nail or rod for you!

When inspecting a flat tire, a car owner often discovers tire side cut. The consequences of this defect, as a rule, come down to short-term repairs and subsequent replacement of a set of tires. The cause of a side cut may be protruding reinforcement, or the sharp edge of a hole in the hard surface of the road. Side cut of tire with knife they do it out of hooligan intentions, or, for example, wanting to take revenge for an insult.

And sometimes swelling appears on the side surface of the tire, the so-called. "hernia". Fortunately, both her and by contacting a specialized service, that is, us 😉

However, here you need to think about whether it’s worth patching the wheel or whether it’s easier to buy a new one. To do this, compare several factors:

• Cost of new tires.
• Tread wear.
• Is the cord damaged?
• Size of damage.
• Repair price.

How to assess tire repairability

This should be done by professionals, since poor-quality repair of side cuts, in particular repair of the tire cord, is fraught with emergency situations on the road. To prevent this from happening, we are waiting for you in our auto studio!

However, something can be assessed “by eye” - the size of the cut and its direction, whether it is through or superficial. Look at the situation more broadly - if the tread is noticeably worn out, it is better to buy new tires. And if the wheels are still new, the side cut of the tire is small, and the wheels have a non-standard size, you can safely repair it.

Is tire cord repair safe?

To guarantee normal subsequent operation of the tires, longitudinal cuts up to 3.5 cm in length and transverse cuts up to 2.5 cm in length are accepted for repair. The distance from tread to tread must be at least 4 cm. A side cut of the tire without damaging the cord and not at all should cause concern.

If the cuts are larger, the repair will be a temporary solution, since the side surface will behave unstable and “play” on the road while the wheel rotates. After some time, even the best quality patch will begin to leak air, and eventually the rubber will have to be replaced.

If the cut occurs in truck, you need to be even more careful. It makes sense to “treat” such tires if no more than 10 cord cables are damaged.

Side cut repair technology

Cut, aka side puncture of a tubeless tire, glued only with reinforced patches. A rubber patch without reinforcement is useless. The cut is sealed on both sides - on the inside and on the outside. After the examination, the Center’s specialists will advise how many layers of patch to put on the incision. It is worth listening to their opinion and making a choice in favor of safety.

If the owner has certain skills and necessary equipment, shallow side cut of tire can be fixed in the garage.

The cut area on both sides is cleaned, degreased, and the edges are ground down a little, in the shape of a saucer. This cavity is filled with raw rubber, onto which a patch is applied.

Bonding of the patch can be cold or hot (“vulcanization”). The cold method is faster and maintains wheel geometry.

Vulcanization slightly deforms the rubber at the patching site, but only with this method can a multi-layer patch be applied to a large cut. Garage repairs will save money, but in artisanal conditions it is difficult to achieve the required quality.

An additional argument for contacting “Rim Repair” will be the need to fully check the tire for leaks. When a cut occurs, small cracks may form near the damage; they must be identified immediately. Therefore, the Center’s technicians are asked to bring the tire for repair along with the rim. Another difficulty is associated with balancing the assembled wheel after repair. The patch upsets the balance, and installing an additional 60-80 g of balancing weights is normal.

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In many areas of construction, shallow foundations on natural foundations are most often used. TO promising direction their improvement can be attributed to the use of intermediate preparation of variable stiffness in strip foundations. Another direction is the use of the working side surface of both strip and single foundations. Such shallow foundations in cohesive, low-moisture soils of natural composition include slotted, round, slotted, trench and single-slab foundations. The technology of their design eliminates backfilling of the side surface and thus allows the use of lateral friction along their walls, which cannot be achieved when constructing columnar or strip foundations.

The experience of using effective shallow foundation designs on real objects is quite wide. Improved technologies introduced into construction practice were previously tested both on models and on construction sites specific objects in full size. The calculation methodology is the result of research, completed foundation projects, and put into operation.

For increase economic efficiency strip foundation designs, it is necessary to reduce the area of ​​the supporting monolithic strip and reduce metal consumption when reinforcement works. This can be achieved by using variable hardness preparation (Fig. 1, A). The preparation is a continuous concrete layer 5-10 cm high, 20-40% wide of the width of the cushion (ribbon). A layer of loose sand of the same height is poured on both sides of the intermediate preparation. A cushion or monolithic tape is placed directly on the preparation after the concrete has gained strength.

This foundation design transfers the initial load to the foundation soil through the base of the concrete preparation. As the foundation is loaded, it shrinks with simultaneous compaction of the loose soil, and at a certain load value, the entire lower plane of the tape base comes into operation. The console parts of the pillow (belt) are unloaded. By increasing the calculated soil resistance, it becomes possible to reduce the width, that is, the area of ​​the cushion (tape). A multi-storey experimental 144-apartment four-section residential building was erected on a foundation with intermediate preparation in the city of Kostanay, which is in normal use. A detailed study and determination of the methodology will ensure widespread implementation of this foundation design in construction practice.

Slot foundations

Improved shallow foundations in cohesive, low-moisture soils of natural composition also include foundations with a working side surface. By excluding backfilling of the side surfaces from the technology, we use lateral friction along the walls, which cannot be achieved when installing columnar or strip foundations in open pits. Such foundations include slotted, round, slotted, trench and single-slab foundations.

Sufficient amount of research conducted slot foundations showed their effectiveness and ease of manufacture. They are one or two narrow concrete (reinforced concrete) plates in the ground, connected by a grillage to transfer the load from above-ground structures to the plates themselves. The technology of the device consists in cutting narrow cracks in the ground with a bar (chain or rotary cutter) 100 - 300 mm wide, 1 to 3 m deep, followed by filling concrete mixture. The parameters of slotted foundations are selected depending on the engineering geological conditions, the values ​​of the design loads, the type and design of the above-ground structure. The use of slot foundations instead of strip foundations on a natural foundation is advisable in the absence of basements.

The peculiarity of the operation of slotted foundations is as follows. Load on the base with a single-slot foundation (Fig. 1, b) In addition to the sole of the grillage, it is transmitted by the side planes and the end of the wall. In a double-slit foundation (Fig. 1, V) the soil mass enclosed between the plates is also included in the work, thereby the main load is transferred to the plane at the level of the lower ends of the walls. The optimal distance between the walls, corresponding to the maximum load-bearing capacity of the foundation, is 0.6 - 1.3 m. The soil core, plates and grillage enclosed between the walls can be considered as a concrete soil foundation on a natural foundation, equal in height to the height of the working walls. The single-slot foundations under consideration are intended for one- and two-story cottages, dachas, garages; double-slot foundations are intended for residential and public buildings up to 7 floors high, as evidenced by the practice of design and construction on such foundations.

Round foundations

Device technology round foundations depth up to 3 m, diameter 0.6 - 1.2 m, similar to device technology bored piles. However, they cannot be classified as piles, since they have a ratio of length (height) to diameter l / d ≤ 5 , which significantly exceeds the number 10, by which the structure is classified as piles. Round foundations are used under reinforced concrete columns (Fig. 1, G) and metal (Fig. 1, d) frames of light structures (fences, warehouses, workshops, garages, utility rooms). As an example, we can cite round foundations made for unheated prefabricated warehouses from profiled galvanized steel sheets.

One of the types of round ones are foundations for supports engineering communications as reinforced concrete racks embedded inboreholes to their full height. They differ favorably from driven pile supports in that they can be straightened in plan and height. This is achieved by drilling wells with a larger diameter than the diagonal cross-section of the supports (Fig. 1, e). If wells are re-drilled, a sand-gravel mixture is filled in and compacted to the design bottom level, resulting in the formation of a low-compressible cushion. The cavities between the walls of the wells and the edges of the supports (column posts) are filled to the full height with concrete and compacted with an in-depth vibrator. Thus, high precision in laying such communications as busbars, fuel pipelines, heating mains, cable routes, and compensating sections of pipelines is achieved.

Description of Figure 2: a– splined foundation for a three-hinged frame; b - the same under a reinforced concrete column; c - trenchI-shaped foundation; g - trench foundation for the lighting mast; d - single-slab underreinforced concrete column.

Splined foundations

Splined foundations they are arranged with a bucket in short trenches (slots) with an oval-shaped base up to 3 m long, 0.4 - 1.0 m wide, and laying depth up to 3 m. Excavators, including those with a narrowed bucket, are used to develop slots. Rod pressure grabs can also be used to construct buried structures and anti-seepage curtains using the “wall in soil” method. When using a grab, the dimensions of the slot in plan will correspond to its outer dimensions at maximum opening of the jaws. The sludge from the bottom of the spline is removed by a scraper device and compacted with the flat part of the bucket or a closed grab by creating maximum pressure on the face of the spline. The slot is concreted by surprise (without formwork) at the same time as the nest is made (Fig. 2, A) or glass (Fig. 2, b). Splined foundations are the most rational for significant inclined, moment and horizontal loads. Therefore, they are best used for agricultural buildings made of three-hinged frames, as well as for industrial auxiliary buildings of the frame type with a metal or reinforced concrete frame.

Trench foundations

Trench foundations concreted in trenches 0.3 - 1.2 m wide with vertical walls up to 3 m deep of various configurations in plan: cross, tee, I-beam (Fig. 2, V). The verticality of the walls of figured structures is ensured by framing the foundation in plan with narrow slots using a bar working body, especially in frozen and strong soils. The technology of the device is similar to the technology of spline foundations. For example (Fig. 2, G), under steel lighting towers 28 m high in frozen soils, trench foundations with plan dimensions of 5x4 m of a complex configuration with a trench width of 0.6 m and a depth of 2.0 m were used.

Single slab foundations

Improved design columnar foundations are naturally single slab foundations (Fig. 2, d). Their essence is to cut a rectangular or square pit, with cutouts or cuts with a depth equal to the height of the slab. The bottom is cleaned manually, after which the pit (slab) is reinforced and concreted. Cutouts and cuts in the slabs serve to reduce material consumption and weaken the stress concentration in the foundation soils. To ensure an arched effect in places of rectangular cutouts, their area should not exceed 15 - 20% of the slab area.

conclusions

The given foundation structures are still in normal use, which allows us to draw a conclusion about their reliability. The proven method for calculating the bearing capacity of the working side surface of shallow foundations can be recommended for use with further improvement. Its essence is as follows:

The load perceived by the side surfaces of the described foundation structures can be determined by the formula:

T = m Ʃm f u i f i l i ,

Where m - coefficient of work of the concrete surface of the foundation in the ground, taken equal to 0.9;

m f - coefficient of soil operating conditions along the lateral surface of the foundation, taken for loams and sandy loams to be equal to 0.7; for clays - 0.6 when constructing foundations in summer period 0.5 and, accordingly, 0.4 - in winter;

u i - perimeter of the cross section of the foundation or slot wall (trench) at depth h hm;

l i - thickness i th layer of soil in contact with the side surface of the foundation (walls, trenches), m;

f i - design resistance i th layer of soil along the side surface of the foundation, determined according to table. 1.

Table 1

Calculated soil resistance along the lateral surfacefoundation
Depth of the soil layer from the planning mark hi, m	Calculated soil resistance along the lateral concrete surface of the foundation fi, kPa, at soil fluidity index IL, equal

Driving on virgin soil is often described as a kind of “unearthly” feeling, and this is not surprising. Can the sensations that arise in those magical moments of half-flight, half-gliding be expressed in words?
Every year, hundreds and thousands of virgin land lovers travel and fly to Sheregesh and Krasnaya Polyana, climb the Aykuaivenchorr ridge in Kirovsk and go “to the far South” or “North” of Cheget after snowfalls. In the United States, virgin snow skiing is something of a national skiing specialty - there are popular places like the Alta resort in Utah, and special schools that teach virgin snow skiing. In our country, there are not many specialists in this type of skiing, and only a few of them are ready to teach someone: virgin soil is rare, and spending a rare day of luck on excavations and searching for a ski lost in the snow by a novice rider is not the most interesting pastime.

However, for several years now, the “freeride with guides” program has been running at the resorts of the Caucasus, and it makes sense for all skiers who want to learn how to ski on virgin soil to participate in this program, regardless of which region - Krasnaya Polyana, Dombay or the Elbrus region – you are planning to spend your vacation. Guides in any of the regions are experienced riders, participants and prize-winners of Russian competitions, who know the mountain slopes on which they work very well. All of them, as a rule, are instructors, and not only themselves know how and love to ski in difficult conditions (on wet heavy snow, on sastrugi or breaking crust) and in virgin snow, but can also correct the technique of other ski enthusiasts. The tips given here, shared by the guides, will help those who are just entering off-piste areas to quickly get used to unusual, but very attractive, snowy conditions.

Tip 1: Descend to the rhythm of the snow

Skiing in virgin snow is very difficult to divide into individual turns, because their execution requires an impulse, which in deep snow can only be the result of a rhythmic and smooth descent, without sudden movements. The depth and density of the snow, the steepness of the slope, the speed of descent, the width of the skis, the depth of the sidecut and even the weight of the skier are the conditions that determine the rhythm of turns.

Conditions Rhythm and pattern of turns

Shallow snow
Light snow Fast rhythm of turns possible
Steep slope Small turning radius acceptable
High speed Lots of movement options
Wide skis
Deep side cut

Conditions

deep snow
Heavy snow Slow turning rhythm required
Gentle slope Large turning radius required
Low speed Narrow range of permissible movements
Narrow skis
Shallow side cut

We must clearly understand that in virgin snow it is impossible to turn as quickly as on compacted snow. In addition, different conditions of deep snow require different speed, intensity and duration of movements.

The key to mastering a smooth and flowing rhythmic descent is... the feeling of the snow. What it is? It is necessary to master skis and snow so much that with your feet you can feel the resistance of the snow to the movements of the skis. The goal is to constantly keep the skis in a state of smooth, jerk-free gliding through the snow by varying the intensity and duration of the impact on the skis. Naturally, the feeling of snow does not come with the first or second descent. It is necessary to spend quite a lot of time on virgin snow, and preferably accompanied by an experienced instructor who can tell you which elements need to be given maximum attention. Of course, you need to experiment, but first you need to master some “basic” set of knowledge, learn to move in such a way that the descent is stable, and only then try to expand the boundaries of what is permitted under given conditions.

Tip 2: stick - go!

A classic technique used for deep snow skiing since the 1960s. The basis of this technique is a very early forward movement of the stick, accompanied by the extension of the new “outside” hand forward and, as a result, a twisting of the body into the next turn, used as the initiating movement. In other words, immediately after the injection is made with the stick down the slope, the movement of the other stick and the arm begins forward. Then, after the skis have crossed the fall line of the slope - at the completion of the turn - the skier holds the forward stick with the tip down the slope until the next injection.
The early movement of the pole and hand forward creates a torque of the body, which helps facilitate the transition of the skis simultaneously with their unloading when moving from turn to turn. In addition, this movement, since it is directed downhill - across the skis, helps to remain balanced over the feet.

Many people get lost in deep snow, which prevents them from controlling their skis using their usual movements and performing associated turns. A stick brought forward in advance and ready to prick, oddly enough, directs thoughts in a more familiar direction. The result of this is a smoother (and self-predictable) movement of the skier.

Keeping the pole pointing down the slope during the second half of the turn (after the skis have crossed the fall line of the slope) helps you stay in a mid-stance, above your feet. In addition, pointing the tip of the pole down the slope after the skis have crossed the slope line keeps the torso turned towards the new turn. And this position of the torso helps to effectively use the legs to control the skis and in order to feel the resistance of the snow to the movement of the skis and use it.

The main condition, a kind of key to the successful use of this technique, is the inner hand, stably held forward and the shoulder, which is, as it were, blocked with the forearm and follows it at the moment of performing the injection. Without this blocking of the arm and shoulder muscles and the resulting stopping of the rotational movement of the torso, the skier's body will twist into the turn. The result of such twisting is usually... searching for an unfastened ski in fluffy snow.
There are various variations of this technique. Quite a long time ago, when a rotational movement of the upper body was considered necessary to initiate a turn, skiers would move their arm and stick around their body, across the direction of the skis. Amateurs who consciously use this technique can still occasionally be found on the slopes.

Another option for performing this movement is to point the stick down the slope and keep the elbow of the leading hand quite close to the hip. This uses accentuated angulation of the hips combined with a downward rotation of the hips and upper body to create powerful rotation of the legs and a corresponding counter-rotation of the torso.
The technique of early moving the stick forward in its modern version is characterized by the position of the hands. The skier's arms are raised a little higher and slightly wider apart compared to their position when skiing on a prepared slope. This hand position is much more effective and allows you to precisely control the skis, especially modern models - wide and short, which turn much easier than their predecessors.

Mastering this technique, which is quite easy to use, often gives excellent results - the descent becomes rhythmic and smooth. At the same time, it is possible and even necessary to start mastering this technique on a rolled slope, since it is quite effective not only in virgin soil, but also on steep slopes, and even on hillocks (with appropriate shock absorption - swallowing the hillocks with intense bending). It must be said that mastering this technique, like any elements, is much easier under the supervision of an instructor who knows it. Without external control, it’s easy to “slide” from moving the pole forward to twisting your torso into a turn.