Looking at the thick mud and sand on the surface of the tunnel foundation on the screen, everyone was silent.

If it looks so thick with the naked eye, then it may be six or seven centimeters deep when measured?

The front immersion tube was installed so smoothly that there was no problem with the Section 14 immersion tube that was installed the day before yesterday, so that no one could believe the reality in front of him.

The sun is sunny this day, which is a rare and good weather.

Without heavy rain or ocean currents, why does this foundation trough have such thick accumulation of silt?

"What about yesterday's test results?" Chief Engineer Su lowered his eyes and dragged over a thick stack of information at his hand.

Chief Engineer Lin had a good memory and raised his hand to pull out a document: "This, yesterday's situation was very good. I had reported this morning that there was mud and sand in the base trough, but there was not much at that time, and it was not so thick within the controllable range."

Everyone knows that things are serious, and no one is idle, and they are all trying hard to calculate.

The divers quickly transferred the latest data. They carefully analyzed and verified it before submitting the latest report.

"The thickness of silt and silt has reached 6 cm to 8 cm in less than 24 hours, just exceeding the standard value!"

"According to the latest measurements, the thickest place of silt accumulation reached 8.6 cm."

"If we follow the previous standards... the standard volume of silt silt on the base bed surface of the immersed tube is 1.26 kg/cubic centimeter, and the silt thickness of the return silt shall not be greater than 4 cm..."

But that was the previous standard, and was formulated in accordance with international standards.

In fact, with Lu Zian's joining, their standards have long been raised to an astonishing level.

Lu Zian always has a way to achieve the most perfect accuracy.

But at present, they can't follow Lu Zi'an's standards, even according to international standards, the immersed tubes in this section are not installed in place.

Mr. Lin squeezed his palm and sweated, but in just a few minutes, a large area of ​​his back was soaked with cold sweat: "This..."

He exchanged glances with General Manager Su and saw the heaviness in each other's eyes.

The inquiry at the construction site also pierced into everyone's heart like a needle: "Then is this sinking tube still installed?"

On the screen, the sea water gently stroked the sinking tube.

The huge immersed tube is suspended above the foundation groove and has been staying for a long time.

The entire command room was in a state of anxiety.

If it is withdrawn from installation, it means that the construction of the undersea tunnel that is attracting attention in the world will be forced to be postponed...

But if it continues, even if Lu Zian is here, it will not be possible to erase the existence of these mud and sand.

Chief Engineer Su is still thinking about a solution, Chief Engineer Lin has made a decisive decision: "Notify everyone and hold a meeting."

The construction team was on standby, and the command center quickly gathered in the conference room.

After many days of running-in, these people led by Lu Zi'an have now been named the technical support team.

There are two teams in them.

Chief Engineer Su and Chief Engineer Lin sat down at the chief with a serious expression: "Okay, everyone can speak freely, and you can say anything you have."

The command center and each team are basically divided into three parties.

One party, represented by Lu Zi'an, insisted on quality first: "If the quality cannot keep up, what's the point of repairing this bridge?"

On the other hand, the construction period is higher: "The construction period is so fast, and the time I finally squeezed out is delayed because of the mere silt and sand?"

The remaining people will abstain.

They wanted quality and were reluctant to leave the construction period, so they were in a dilemma and simply abstained from it.

Is it necessary to have quality or construction period?

The two sides had a heated discussion.

"It's the standard of consultant Lu that is too high. In my opinion, many bridges and tunnels are implemented according to international standards, and no problems have occurred!"

"Since you can do your best, why should you settle it?"

"If we can do the best, who doesn't want to do it? The problem is that we can't do it now! Who knows whether this mud and sand return will be long-term or short-term? If this time is not installed, what should we do if there is more mud and sand pile next time? Every time we delay for a long day, huge amounts of funds are being exported!"

"If it is installed like this, there will be more mud and sand in the later stage, which will have a negative impact on the entire tunnel, do you want to have a later maintenance cost?"

Both sides have their own opinions and no one can convince anyone.

After they reached a certain level of quarrel, General Manager Su asked in a deep voice: "Consultant Lu, what do you think?"

Lu Zian, who was named, looked up at him and pointed his fingertips on the table: "I think it's better to turn the situation into control and then connect, so as not to try to be quick and leave a lot of worries."

This is really true.

Chief Engineer Lin pressed his eyebrows and looked at the time. They have been discussing for four hours since they discovered the problem.

"Okay." His voice was low, with a hint of hoarseness.

When they raised their eyes, everyone looked at him, as if they had become ten years older in an instant.

"Stop the sinking." Chief Engineer Lin's eyes were so painful that he made this decision that he had very painful but had to make: "Transfer the order and withdraw the sinking tube back into the dock!"

"General Engineer..." Someone looked at General Engineer Su and Lu Zi'an in surprise.

Is there really no other way?

Chief Executive Su waved his hand and interrupted their inquiry: "Go."

The news reached Beiyi and the whole country was concerned.

Under the coordination and guidance of the Ministry of Transport, the Fourth China Communications Communications Navigation Engineering Survey and Design Institute, the Tianjin Water Transport Engineering Science Research Institute of the Ministry of Transport, the Nanjing Water Conservancy Science Research Institute, and the Hekou Coastal Research Institute of Sun Yat-sen University all sent senior experts to urgently support...

25 top experts in China who have been studying the sediment and sand of the Pearl River Estuary for many years have established a "national team" for technical research.

The expert group held 36 special meetings, carried out more than 300 risk investigations in 9 major categories, and arranged 6 sets of fixed monitoring base stations and 24 sets of monitoring instruments in the 120 square kilometers of sea area around the construction site.

A geological sampling survey of 200 groups was completed and more than 30 density detections were conducted to analyze and study the causes of sediment production.

Formulate countermeasures and explore the possibility of establishing pre-jing and prediction mechanisms.

Everyone was nervous and frowning.

Lu Zian was also very anxious, but he was really powerless.

Marine silt recovery is a global engineering problem. As early as the design stage, engineers have considered the silt recovery recovery of the seabed of the Pearl River Estuary and formulated construction solutions.

Before, they had been following this plan and successfully completed the installation of the first fourteen immersive tubes.

However, as the tunnel extends, the hydrological conditions under the sea gradually change.

The foundation trough east of the "e15" sinking pipe is located at the end of the southern beach in Tonggu Shoal. Due to the direct influence of the diluted water of the estuary and the discharge of silt under the shallows, the silt at the tail of Tonggu Shoal moves southward, and the construction of the sinking pipe is in a hydrodynamic silt environment conducive to silt.

Especially in winter and spring, due to the effects of háo flow and eastward wind and waves, the silt in the copper drum shallows starts to spread again, directly affecting the base trough area east of the "e15" sinking tube, so the base trough silt becomes more and more serious.

The experts conducted countless fierce discussions and meticulous research based on a large amount of actual measured data on site, combined with dynamic landforms, satellite remote sensing inversion, mathematical model experiments and other related studies.

During this period, the only thing Lu Zian could provide was to make detailed model deductions on the content they proposed.

Surprisingly, as possible factors were eliminated, they finally found some problems from this model.

There are many sand mining ships in the nearby waters.

These surrounding sand mining activities seem ordinary, but in fact they have a great impact on the siltation of the immersed pipe foundation trough of the Hong Kong-Zhuhai-Macao Bridge Island Tunnel Project.

The main source of silt for abnormal silt in the foundation trough is caused by sand mining operations near Neilingding Island. The high-sand-bearing muddy water formed by sand mining enters the foundation trough by direct transfer and re-transport.

After the situation was discovered, the project department immediately made a detailed report to the superiors.

Based on the research team's extensive detailed and rigorous research results, the official announced the latest statement the next day: From now on, 7 sand mining points within a range of more than ten kilometers upstream of the sinking tube operation area will stop mining.

During the Spring Festival this year, everyone stayed in Zhuhai.

There were no strict regulations, but no one left.

Everyone is making detailed preparations for the re-domaination of the e15 immersed tube after the holiday.

After all sand mining activities stopped, the sea water gradually became clear, and the quicksand back silt on the seabed slowly entered the controllable range...

After three months, they did not delay any further. On the morning of the sixth day of the lunar month, the divers sent back the latest data and confirmed that the foundation trough had been cleaned up, the floating gondola dragged the e15 and slowly drove out of the dock again.

The wind on the sea was a bit harsh, but everyone's heart was warm.

The most troublesome problem has been properly solved, and the images on the seabed are now clearer, so there must be no problem this time!

When the immersed tube was halfway through, he had already seen the construction team's ships from afar. Before everyone could breathe a sigh of relief, the construction team urgently sent back the latest news: "Oh no, a large amount of silt suddenly appeared on the seabed. According to our estimates, the total meter of covering is about 2,000 cubic meters!"

Mr. Lin held his palms firmly on the table and said in a voice: "Repeat it, how much?"

"No less than two thousand cubic meters!"

Someone in the command room couldn't help but growl: "Why didn't you find out before? Why are you just saying it now!"

The ship has sailed out and the sinking tube has been out of the dock!

This drag is a waste of millions of funds!

"Report! It really didn't happen before, it happened suddenly!"

Originally, all of them were waiting anxiously for the arrival of the immersed tube, but the staff who had been staring at the sea found that the originally clear sea water suddenly became extremely turbid, and then they realized something was wrong and quickly reported it.

At the same time, everything on the seabed began to appear clearly on all screens.
To be continued...