A floating crane crashed into a support of the Crimean Bridge. Video

“The 256 support is back in the scaffolding, the frames are being knitted, concrete is being supplied. They write that it is cracked. All this is not without reason,” user Krymets said on Twitter.

Of the 595 bridge supports, 256, located almost in the middle of the Kerch Strait, cracked in two places, the cracks are clearly visible in the photo, reports Kuresh.info.

Currently, workers have reassembled the frame around the support to prevent further destruction and restore it. The support is located 8 kilometers from the shore. Experts argued that the supports would not even withstand the load of an empty railway line, not to mention the launch of trains. In this area, at the beginning of 2018, a subsidence of one meter of supports was already recorded.

On forums, pro-Russian Crimeans are confident in the success of the bridge construction:

Earlier it was reported that the builders of the Kerch Bridge were constructing metal spans of a road overpass in the sea on the Embankment - Fairway section in the area of ​​the Kerch Peninsula.

On February 14, information appeared that the supports of the bridge across the Kerch Strait, which should connect Russia with the occupied Crimean peninsula of Ukraine,

307 structures have been completed, which are now gradually taking over the spans - 160 thousand tons of metal structures. Information center "" reports this. “This is not just the completion of the installation of supports for the railway. All supports are ready Crimean bridge: both road and railway. A titanic work has been carried out. Thousands of piles for these supports are buried to great depths: in some areas - more than 100 meters. Difficult soil and frequent storms greatly complicated the work, but everything was done efficiently and on time,” said Arkady Rotenberg, Chairman of the Board of Directors of STROYGAZMONTAZH. The final one was railway support No. 254 in the Kerch Strait in the area between the fairway and the Crimean coast. It consists of a foundation on 16 tubular piles submerged under different angles to a depth of up to 70 meters, and bodies made of steel reinforcement and hydraulic concrete. “The support has been brought to the design level - 33 meters from the water level, almost 12 storeys high. The final stage was the concreting of its upper elements, onto which special devices - supporting parts - are subsequently installed. “Spans are installed on them,” said Alexey Dvoeglazov, project manager at the Crimean Bridge construction site. “The supporting parts, a kind of balancers, will provide the necessary angular and linear movements of the spans, invisible to the naked eye, in the event of thermal expansion of the metal or possible seismic vibrations.” Read: The main stage of construction of the railway part of the Crimean Bridge today is the installation of spans. This one is complicated technological process is carried out in all offshore and onshore construction sites. In total, more than 15 kilometers of the route have already been blocked by spans at 8 construction sites. “The builders have completed the construction of all the railway supports of the Crimean Bridge. There are 307 such supports in total, 85 of which are located in the waters of the Kerch Strait. The work was quite difficult and took place in difficult weather conditions. But, despite this, the builders coped with their task and completed all the railway supports with a slight advance. They are quite massive, they differ from automobile ones primarily in their dimensional characteristics, and the last support we completed was support 254 on the fairway section, its height is about 33 meters - this is about a 12-story building. The foundation of this support consists of 16 tubular piles, their immersion depth is about 70 meters. In general, if we talk about the foundations of the railway component of the transport crossing, the maximum immersion depth at the construction sites was more than 100 meters. Work is underway to assemble the spans and slide them. To date, about 130 thousand tons of metal structures have been assembled. The sliding is carried out in offshore areas. Both transverse and longitudinal. The work is progressing according to schedule. Also, as the scope of work becomes available, work is underway on laying the rail and sleeper grid,” said Leonid RYZHENKIN, Deputy General Director of the STROYGAZMONTAZH company. Read: The spans assembled on stands are placed on land supports using cranes, and on sea supports they are lifted using jacks in longitudinal and transverse ways. On the completed spans, the superstructure of the track is formed sequentially from the side of the Taman coast railway: More than 9 of the 38 km of rail and sleeper grating have now been laid.

All supports of the Crimean Bridge are ready. Video

At the end of October 2017, the bridge spans of the road part of the Crimean Bridge almost approached (were pushed) to the peak point of the transport crossing - the arched spans over the Kerch-Yenikalsky Canal.

The installation of column formwork began on support No. 256A -

Let me immediately draw your attention to the fact that the foundation grillage and support body were ready a long time ago. In the further analysis of the situation, we will assume that they are an unshakable stronghold. There were no problems with them and no problems arose when pouring the support columns. No piles under the support were sucked in anywhere, the grillage was not warped, and the body of the support was not cracked. Monolith! A reliable and heavy-duty monolith, which now carries a slightly larger load than originally planned.

Let me remind readers of this picture -

We are only interested in the support columns themselves.

In this photo you can clearly see that the bodies of the supports evenly change in height - they move like a ladder. This suggests that we are seeing a harmonious design solution that combines high reliability and elegance of designs. There were no diaphragm bridges between the support columns included in the project.

If anyone has not yet gotten their bearings, then time No. 256 is the third in a row from the channel support of the arched span (No. 253A). In the photo, there are cranes with yellow arrows standing next to her.

An important fact: the sliding to the arches came from both sides -

No one announced any social competition, but there were some exciting moments. On the wave of success, in euphoria, after the installation of the arched spans, each side wanted to quickly get to the cherished final point by the new year.

At the beginning of November, a press tour was organized for inspired bloggers -

Their reports are good and colorful. But no details. Everyone unanimously illuminated the erected arches; no one looked towards the usual supports.

The avant-back was already beginning to hang over support No. 256A -

Reference: Avant-bec (French avant-bec) is a temporary cantilever structure used when installing bridge spans using the longitudinal sliding method. The structure is attached from the front to the superstructure being moved up. The length and mass of the apron are set in such a way that the span along with it does not tip over until the apron reaches the first support of the bridge. The use of a foreback leads to a reduction in construction costs, as it allows the sliding of the span without the construction of intermediate supports. Great Russian Encyclopedia.

Kerch Bridge from the Kerch fortress on November 4, 2017.

Here the data differs somewhat: the filling could have been completed on the 5th. At least as of October 6, the columns were filled -

Let's take a close look at the spatial reinforcement frames of the columns -

As you can see: thick longitudinal reinforcement, and with frequent transverse piping.

I have already explained earlier: concrete works very well in compression and very poorly in tension. The strength differs by 10 - 15 times. Reinforcing bars are always placed in the expected tension zones of a reinforced concrete structure. That is, specifically in the support columns, the reinforcement does not bear a compressive load. It is needed to prevent bending of columns, with subsequent destruction.

Think about it... What loads can cause support columns to bend? Thus causing tension in some areas and compression in others. Did everyone bend plasticine bars as a child? Have you seen how one side cracks and the other wrinkles? Who later bent the pipes? What did you see on the walls of the pipes?

So, any pillars and piles are reinforced symmetrically to the center of their cross section. Columns can be reinforced symmetrically to an axis passing through their center. Pillars and piles are reinforced like this -

This is a very simple and clear example. The load on such a structure can act from any direction. For example: a windshield on a lamp post. That is why the horizontal sections of such structures almost always have the correct geometric shape - round or square.

The columns of the Crimean Bridge supports are oval in their cross section. Their cross section is somewhat elongated parallel to the longitudinal axis of the bridge, towards the spans. For better resistance to longitudinal loads from transport. The metal spans of the bridge rest on the crossbar, which, in turn, transfers the load to the columns. The spans are mounted on articulated movable and fixed supports. They are not pinched in the crossbars and do not cause any torques in the column bodies.

The columns of the bridge supports bear their own weight, the weight of the crossbar, partly the weight of the spans and the lateral load from vehicles. Under their influence, they compress and try to deviate from their vertical axis.

Let's not go into the wilds -

For those interested in more details - here .

Here it is -

Was it already possible to load the column?

Here is a graph of concrete strength gain -

What, you had to wait 28 days? No, of course not. On the third day, the concrete had already gained about 40% of its strength. Spatial weight reinforcement cage The crossbar no longer exerted any harmful excessive compression on the column.

Once again: the reinforced frame of the column close up -

I hope there is no need to voice the weight of the formwork. They can easily be ignored. The strength of concrete on the sixth day is 55-60%.

The strength of concrete columns is about 80%.

A day later, everything was ready for sliding the spans onto support No. 256A -

Now let's consider the following: which forces acted on the support columns during longitudinal sliding.

The most dangerous stresses occurred at the junction of the column with the support body (point A) -

From the force of the longitudinal slider, through friction, a moment of force arose at the base of the column. It will also arise from possible vibrations of the spans during an earthquake. At the same point "A". From the school physics course we know: the moment is equal to the force multiplied by the shoulder. The column is rigidly clamped in the body of the support. The column is tall. It could have cracked there. It shouldn’t crack so much that even the Maidans in Kyiv would see a crack the size of a fist. And very thin cracks. The presence of which became possible only after the formwork was removed, not even visually, but by ultrasonic testing.

The strength of the concrete structures of the Crimean Bridge is determined ultrasonic method .

Maybe there were no cracks at all, but the product simply did not pass the test for some other reason.

Good news -

You see: the slide on the Kerch side initially lagged behind. That is, there was some incentive to speed up the work.

If they were in a hurry to move things along at an accelerated pace and assembled the formwork on two crossbars at once, perhaps there was no time to dismantle the old formwork at that moment. And perhaps they knew about the slight tilt of the column that occurred during the slide. The slide is accompanied by constant geodetic control. Anything that deviates by a millimeter will be immediately noticed.

Please note: on the Tuzla side the formwork is on only one support. On the side of Kerch, the formwork contains columns of three entire supports: No. 254A, No. 255A and the one we are considering - No. 256A -

Personally, even then I had a reasonable suspicion: no matter how the columns had to be repaired. Everything went fine, but anything can happen. Precisely because very serious requirements are imposed on the structures of the Crimean Bridge, it is absolutely clear: any defective detail that is revealed by construction control will be corrected in the most serious manner.

Let's sketch out such a simple graph of the strength of the column, for clarity -

Vertical - the strength of the product in quiet conditions is 100%. Horizontal - earthquake magnitude on the Richter scale. The tendency of the structure to collapse with increasing seismic activity is shown in a simplified manner. At a magnitude of 0.0, everything is fine; if the magnitude of the earthquake exceeds 9.0, the structure is completely destroyed. The red round spot on the yellow field is the area in which the already solved problem of the column was located. It lay somewhere in the area of ​​a magnitude 7 earthquake. How and with what did its small defect threaten in our earthquake-free days? Nothing and no way.

All sorts of Ukrainian mead experts live at the negative levels of the horizontal scale. In the illusory delirium of which the bridge collapses on its own.

The Kerch side was almost the first to advance -

The unofficial unspoken competition was almost won.

And then ultrasonic inspectors came to the support columns...

As we already understand: no one initially intended to build any jumpers (diaphragms) between the support columns.

Oh! What are these boys doing at the base of the column?

Remember the diagram above, which is with the moment?

My December fears were justified: it was impossible to do without repairs. And it was already clear that he would be more thorough. In the photo above it’s just a small thing. Repairs were still to come.

An earthquake causes shear stress. In the longitudinal direction of the bridge axis, the column would not have fallen anywhere due to shaking. Its spans are held as if in a vice. But if it shook with a shift earth's crust, but across the axis of the transition, the spans swayed to the side, the column could have fallen.

Why is such a diaphragm needed there -

This is an increase in the rigidity of the support structure across the transition axis. So that the lateral seismic shock does not break the columns.

Asphalt was not yet delivered for the span then. Not because the columns would not have held up, there was simply no need for it yet. It was necessary to lower the span structures from the slides to the regular landing sites.

There was no talk of creating an additional jumper then -

The treatment process did not bring the support structure to the required safety margin. Subsequent monitoring showed this. The author's supervision responded professionally. Changes have been made to the project. That's why the diaphragm appeared.

Should the official information center of the Crimean Bridge have covered this epic with the support? Answer: NO! Consumers need a high-quality bridge - this is the main thing. And the bridge is being built very well. It's moments like these that speak to this. No one ignored the identified defects and began to decoratively cover up the beauty. It’s like this: let’s open it, and then we’ll see. They gouged it out as expected. Completely oblivious to the show. To reduce the stench from all sorts of “experts,” curtains were erected on the scaffolding.

Just think: the support stood in the forests until mid-April. While it was being repaired and strengthened there, a bunch of trucks carrying asphalt passed over it. Nothing settled anywhere, no column collapsed in the sea.

I already said: ironically, support No. 256A became the strongest of all. Which is great.

During the construction of the Crimean Bridge, its supports, contrary to all norms, were installed on semi-solid/semi-liquid clay of low density and on loose and porous silt.

Israeli blogger Eli Belenson wrote about this in his blog on OBOZREVATEL, who for a long time analyzed all documents on the progress of bridge construction. He also pointed out a certain fact: as soon as flagrant violations were announced online, previously available information immediately disappeared.

He emphasized that geology became the Achilles heel of the structure; it was precisely because of the inadequacy of the soil for the construction of the bridge that his project was rejected by Soviet experts.

“Usually, serious engineering structures, such as railway bridges, where serious loads are expected, are usually supported on solid soil foundations. To do this, special piles are drilled or driven, which rest on these very hard soils. If we support a massive structure on an insufficiently solid foundation, its individual parts or the entire structure may sag unevenly, become deformed and, ultimately, collapse,” the blogger wrote.

According to Eli Belenson, in the case of a railway bridge, unacceptable subsidence or deformation can lead after some time to disaster - we will be talking about huge economic losses and human casualties.

“Soviet and then Russian GOSTs forbade resting such structures on anything other than a solid rock foundation... Not even on sand. And not on clay. But, as we see from the above geosurveys, at the depth at which, according to the construction plans, the CM should support the piles (up to 58 meters deep), no rock foundation was found (see the bottom line of the table, highlighted in red). Moreover, not even sand was found there. But this is not enough - they didn’t even find clay there,” the expert pointed out.

According to him, the upper layers are silt - loose and porous, and then there are sands and sandy loams of varying degrees of density, several clay inclusions, and the lower layer, on which the bridge piles actually rest, is semi-solid clay.

“Now imagine that we are not just talking about an almost twenty-kilometer railway bridge, with huge loads and huge windage (storms, waves, side winds, trains), but we are also talking about a seismically dangerous zone, where tremors of varying strength regularly occur . The designers of the new bridge claim that it is enough to drive the piles 58 meters and everything will be fine, but is this semi-solid clay suitable as a base for the supports? – asked Eli Belenson.

According to him, previously the requirements to rest the piles on a rock foundation were prescribed in Building codes and rules, but later they strangely disappeared from the document on June 17, 2017.

He also pointed out another glaring nuance, according to which the geo-surveys before the start of construction were carried out poorly, and this turned out to be when the bridge was already being built in full swing.

“The Kerch/Crimean Bridge project seems to me potentially dangerous. I consider it immoral to assume this and remain silent. If I made a mistake somewhere, I will be glad to receive a professional and evidence-based refutation. It will be much worse if people die as a result of the operation of the bridge, and I will know that I understood that this could happen, but was silent,” concluded Eli Belenson.

Tags: Crimean bridge