I'm doing engineering in the instance.

The maintenance access road on the top of the dam extends to the right, about eighty meters away, where there is a small equipment room with the door open.

Xie Chengzhou and Engineer Li walked in that direction at the same time.

There are people in the equipment room.

He wasn't waiting for them; he was working—squatting in the corner, holding a thermos, his back to the door, shining a flashlight against the wall, looking at something.

Xie Chengzhou paused at the door.

He recognized that thermos. Not the style, not the color, but the way he held it—thumb on the lid, the other four fingers supporting the body—a habit only someone who had held that thermos for many years would develop.

He went inside and squatted down next to the man.

Old Zhao glanced at him sideways, then at Engineer Li who had followed him in, before turning his face back to continue examining the base of the wall. There was a thin crack at the base of the wall, with water stains inside, a darker color than ordinary seepage, tinged with a rusty hue.

"You've arrived," Old Zhao said, his tone as if to say, "You've come to the construction site today."

"When did you come in?"

"Earlier than you," Old Zhao said. "I came from that section of the dam over there." He pointed to the right with his chin. "I saw that crack over there too."

"What conclusion?"

"It was done by a person," Old Zhao said, his tone as flat as when he said, "The quality of these bricks is poor." "If the direction of the excavation is wrong, the cracks won't naturally follow that path. I've been working in the plumbing industry for thirty years, and I've seen plenty of excavation marks in concrete."

Engineer Li stood behind them without interrupting.

Xie Chengzhou took out the memo and added a line after "Third Crack - Confirmed": "Old Zhao (JG-0089) - Judgment: Manual cutting - Basis: The direction of excavation does not conform to the natural crack pattern - Confidence level: High."

Then he stood up, glanced at the rusty-colored seepage at the base of the wall, and then at the direction of the rhythmic sound coming from inside the dam.

"Where is the corridor?" he asked Engineer Li.

Engineer Li said, "That door on the right side of the equipment room."

Xie Chengzhou walked to the door, placed his hand on the edge of the door, and sensed the direction of the airflow.

Airflow is from the inside out.

He mentally reviewed the phenomenon: the higher air pressure inside the corridor indicated a buildup of closed water pressure or an accumulation of air inside. This relates to Rule 4's "one-way passage" principle—if there's a pressure difference between the inside and outside of the corridor, then "one-way" might not be spatial, but rather a pressure difference causing one-way passage—it's easy to go in, but the pressure difference will block the door when you come out.

The misleading aspect of fragment ③: "Channel · One-way" - refers to a time window, not a spatial one-way direction.

He found the manual pressure relief valve on the left side of the door frame; it was corroded by water seepage, but the valve stem was still intact.

"Help me." He placed his hand on the valve stem and looked at Old Zhao.

Old Zhao walked over, placed his hand on his, and the two of them pulled together. The valve stem turned, making a low metallic scraping sound, followed by the sound of water—the water pressure inside the corridor was being released outwards, thin but continuous.

Xie Chengzhou felt the change in vibration on the door panel. The vibration was decreasing.

He silently counted for about thirty seconds, then placed his hand again on the edge of the door to feel the direction of the airflow.

It's bidirectional, so you can hardly feel any directionality.

The pressure difference has been eliminated.

He pushed the door open.

The corridor was wider than he had expected. It was about 2.2 meters wide and 2.5 meters high, made of concrete, with the waterproofing layer partially peeling off. The ground was wet—not puddles, but a thin film of water seeping from the walls on both sides of the corridor, forming trickles on the ground and flowing deeper into the corridor.

The rhythmic sound came from deep within the corridor, occurring every two seconds with a fixed tone.

Xie Chengzhou mentally estimated the distance to the sound source—based on the echo delay, it was roughly forty to sixty meters ahead.

They walked about twenty meters further in, and the first anomaly appeared on the right side of the corridor.

It's not a crack, but a section of wall with the wrong color. It's about 1.5 meters wide and 2 meters high, and the color is half a shade darker than the surrounding area. It's not the darkness from water seepage, but the darkness of the concrete itself—it looks like it was poured with a different mix, or it was poured later.

Xie Chengzhou stopped in front of the wall, held the flashlight close, and shone the light at an angle upwards.

There are differences in texture. The aggregate distribution is arranged along an oblique axis, not randomly, but directionally formed after being compressed by some force.

He placed his palm against the wall and felt the temperature.

It was half a degree lower than the surrounding area. The low temperature indicates that there is a cavity behind this section of the wall, or that water is seeping through.

"Structural perspective" was triggered.

It's not actively triggered, but passively triggered—the palm touches the abnormal node in the structure, triggering automatically, just like when he walks across a foundation on a construction site, his feet tell him there's a problem with the soil layer, no need to think, his intuition comes first.

He saw the cracks. Not one, but two, parallel, about 8 centimeters apart, extending diagonally from the back of the wall at a 45-degree angle, from the lower left to the upper right.

Natural cracks in concrete gravity dams are controlled by the direction of the load and are usually vertical or nearly vertical, not a double crack at a 45-degree angle.

The 45-degree diagonal double seam is the direction of the cut.

His hand had already reached for the chisel in the tool bag.

It's instinct. The "structural perspective" assessment is: a high-priority structural risk node that needs immediate attention to eliminate hidden dangers and prevent further expansion. He's worked on construction sites for twelve years; this action requires no thought—his hands come first, his mind follows.

The chisel has been taken out.

"stop."

Old Zhao's voice.

It wasn't a loud voice, but the tone of a seasoned veteran who had heard it countless times—not a command, but a statement, as if saying, "You can't step on this."

Xie Chengzhou's hand froze in mid-air.

He looked at Old Zhao.

Old Zhao wasn't looking at him; he was looking at the wall with an expression Xie Chengzhou had seen on the faces of old construction workers—he had seen this kind of thing before, knew what it was, and knew what would happen if he touched it.

"This is for you to step on," Old Zhao said, "not for you to fix."

Xie Chengzhou put the chisel back into his tool bag.

He wrote the following line in his memo: "Right wall of the corridor - structural perspective - abnormal cracks - two parallel diagonal cracks - approximately 45 degrees - high priority node - decision: do not deal with it for now (Old Zhao's judgment: leave a weakness, one move will cause a chain reaction) - confidence level: high."

Then he paused after that line of text.

His "structural perspective" told him that immediate action was needed.

He put the chisel back.

This was the first time since he entered the realm that he had actively suppressed his engineering intuition.

He didn't know whether the decision was right or wrong.

He simply put the chisel away.

They continued walking in.

The corridor bends about 30 degrees to the right after about 20 meters. After the bend, there is a straight corridor ahead, about 40 meters long, with a door at the end, which is closed.

The rhythmic sound became clearer after the bend. Not because the volume increased, but because the direction changed—it used to come from deep within the corridor, but now it came from the right wall of the corridor, from the direction of that man-made crack.

The rhythm has changed.

It used to happen every two seconds, but now it happens every second.

It's twice as fast.

Xie Chengzhou paused at the bend and listened carefully.

"Turn off the lights," he said softly.

The three of them turned off their flashlights at the same time.

The corridor became completely dark.

He let his eyes adjust for about ten seconds, then slowly looked toward the right wall of the corridor.

bright.

It wasn't the light of a flashlight, but an extremely faint bluish-white light that shone through the seams in the wall, perfectly synchronized with the rhythmic sound—the light appeared when the sound appeared, and disappeared when the sound disappeared. But now the rhythm was once per second, and the light was flashing once per second, twice as fast as before, and also brighter.

It's inside the wall.

Directly behind that man-made crack.

Xie Chengzhou sensed something—when they entered the corridor, the manual pressure relief valve released the pressure inside the corridor, and this pressure change was sensed by the seepage entity, which was tracing the source of this pressure change.

It is moving towards the entrance of the corridor.

Move in their direction.

"Retreat," Xie Chengzhou said in a low voice.

They retreated behind the bend, their steps light, their feet landing on the edge of the left wall of the corridor—a dry patch about twenty centimeters wide, left by the wall preventing the seepage from spreading. Twenty centimeters, enough for one person to stand on, but not enough for two people to walk side by side.

As they backed up to the bend, the wall made a dull thud.

It wasn't a crackling sound, but a dull, muffled sound, like something forcefully pushing the inside of a wall.

Then came the sound of water.

A large amount of water seeped out from the crack, not seeped, but gushed out—pressurized, spraying from the crack joint and hitting the corridor floor. The water splashed up, rusty in color. Xie Chengzhou couldn't see the color in the darkness, but he could smell it—a strong smell of metal and corrosion, like a space that had been sealed off for many years had been opened up.

The blue-white light shone through the wall, no longer intermittent, but continuous, its brightness increasing and its outline becoming clearer—not a point, but a surface, about 1 meter wide and 2 meters high, with an irregular shape, like a space filled with water that was moving.

It emerged from that crack.

It didn't emerge through the wall, but rather seeped from a crack, like water being squeezed out of a fissure under pressure. Then it recombine in the corridor, forming that translucent, flowing shape. The recombination process lasted about two seconds, after which it was complete, standing in the corridor, facing their direction.

Xie Chengzhou did not move.

It advanced through the middle of the corridor, faster than he had anticipated—not flowing, but pushing. The water film on the ground was flattened as it moved forward, creating a wave that reached Xie Chengzhou's feet. He felt the coldness—not the coldness of water, but a deeper kind of cold, as if something was drawing heat away from his skin, penetrating his shoes, and spreading to his ankles.

He took a step back.

The water film wave then advanced one step.

It tracks changes in water pressure; the pressure generated by its foot pressing on the water film is its signal.

"Don't step in the water," he whispered.

He leaned against the left wall, stepping on the 20-centimeter-wide dry strip of ground, one foot on each side, his right foot dangling in the air.

Old Zhao was already next to him, also pressed against the left wall, his feet on the dry ground, the two of them squeezed together, shoulder to shoulder.

Li was about a meter ahead of them, also leaning against the left wall, but the dry area where he was leaning was only ten centimeters away, and one of his feet inevitably stepped on the edge of the water film.

Just once, at the edge of a foot.

The blue-white light paused for a moment, then split—the main body continued to move towards the corridor entrance, but a smaller part, about half a meter wide, turned towards Engineer Li's direction.

速度更快。

"Engineer Li," Xie Chengzhou said in a low voice, his tone flat but his tone firm, "to the right."

Li Gong moved a step to the right, but the right side was the center of the corridor, an area covered by a water film.

He stepped in.

The smaller split accelerated the moment Li stepped into the water film, as if the signal had suddenly strengthened. Its tip advanced nearly a meter in two seconds, reaching Li's position.

Xie Chengzhou heard Li Gong's voice—not a shout, but a short, suppressed sound, as if something had suddenly grabbed him and then forcibly held back.

He turned on his flashlight and shone it on Engineer Li.

On Li Gong's left wrist, there was a white mark about two fingers wide. The skin color disappeared into that mark, turning into a white that didn't belong to a living person, as if something had taken away the pigment and heat along with it. At the edge of the white mark, the skin color was shrinking inward at a visible speed, as if something was pulling the edge into the white.

The split is still progressing.

The front half of Li's wrist was already covered by it.

He didn't cry out, but his fingers were trembling—not a conscious tremor, but the kind of tremor that comes from muscles losing nerve signals, like an electrical circuit being cut off, but not completely.

Xie Chengzhou mentally reviewed the available options.

Time: Two seconds.

He looked at Old Zhao.

The thermos in Old Zhao's hand was held upside down with the lid facing down and the bottom facing up, and he had changed how he held it. No one knew when he had changed it.

Xie Chengzhou shone his flashlight toward the left side of the corridor—about eight meters away from them, there was a seepage point on the left wall of the corridor, with a larger seepage volume than other places, and a small water accumulation area on the ground, about half a meter in diameter, with a calm surface.

He held the flashlight beam over the flooded area for less than a second, then looked at Old Zhao.

Old Zhao saw it.

Without saying a word, he adjusted the thermos in his hand, and then, with an extremely flat and steady motion, threw the thermos towards the area of ​​water accumulation.

The thermos cup traced an arc in the air, landing first on the waterlogged area with a crisp impact. Water splashed up, and the water pressure in the waterlogged area experienced a noticeable peak disturbance at that moment.

The splitting process stopped.

one second.

Then it turned and moved towards the spot where the thermos had landed, faster than when it was tracking Mr. Li—the disturbance in that waterlogged area was more than an order of magnitude stronger than the signal generated by Mr. Li stepping on the water film, and its perception system prioritized the stronger signal.

Li's wrist was loosened.

The white mark was still there, but it had stopped spreading, and the edges had stopped shrinking inward.

"Let's go," Xie Chengzhou said in a low voice.

They moved deeper into the corridor, hugging the left wall, their footsteps landing on the dry ground, avoiding any areas of water. Xie Chengzhou was at the back, and as he walked, he felt something—a cold, damp sensation on the sole of his right shoe, left by the water ripples earlier; it was cold and had a slight tingling sensation.

He didn't stop, but he remembered that feeling.

That door ahead.

When they reached the door at the end of the corridor, the main blue-white light was still in the middle of the corridor, tracking the landing point of the thermos cup, but its direction of movement was slowly changing—it was rescanning the corridor, looking for new water pressure changes.

The time window is closing.

Xie Chengzhou placed his hand on the doorknob and felt the temperature and vibration of the door panel.

The temperature is normal, and there is no vibration.

He pushed the door open.

They rushed in, with Xie Chengzhou being the last to enter, closing the door behind him.

The moment the door closed, he felt a vibration on the door panel—not an impact, but when the blue-white light reached the crack in the door, its tip pressed against the crack. A chill seeped in from the crack, leaving a thin line about one centimeter wide on the back of Xie Chengzhou's hand. The line was three or four degrees cooler than the surrounding area, lasted for about two seconds, and then disappeared.

It paused outside the door for a moment, then retreated.

The corridor turned dark again.

The maintenance room is about six square meters. The floor is dry, with no water seepage or water film.

There is a plaque on the wall, and the words on the plaque are still legible: "Drainage Gallery · Second Dam Section · Maintenance Node · Number: P2-07".

Xie Chengzhou leaned against the wall, trying to calm his breathing.

Mr. Li sat on the ground, turned his left wrist over, and shone a flashlight on the white mark to look at it.

The mark was still there, about two fingers wide, and the skin color hadn't fully recovered. There was a pale purple ring around the white edge, as if the skin was trying to bring back the color, but hadn't quite succeeded. He moved the fingers of his left hand—except for his ring and little fingers, the other three fingers could move, but there was a sluggish feeling when he moved them, as if the signal transmission was half a beat slow.

"Can it be used?" Xie Chengzhou asked.

"Three of them are usable," said Engineer Li. "The other two will have to wait."

He neither said it hurt nor that it didn't hurt; he simply stated his current functional state.

Xie Chengzhou wrote the following in his memo: "Infiltrator: Physical contact; Engineer Li (hydraulic engineer); Left wrist; Contact duration: Approximately 3 seconds; Symptoms: Skin whitening; Pale purple edges; Delay in two fingers; Reduced sensation; Recovery time: To be observed."

Then he turned his gaze to Old Zhao.

Old Zhao was picking up the thermos. He had just thrown it out, and it rolled to the middle of the corridor. He picked it up as they retreated, and Xie Chengzhou didn't notice when he picked it up.

There is a new dent on the bottom of the thermos, left when it was hit in a waterlogged area, and the metallic luster is showing through the dent.

Old Zhao turned the cup over, glanced at the dent, and then put the cup back in his hand, his thumb gripping the lid and the other four fingers supporting the cup, still in the same position.

"Thank you," Xie Chengzhou said.

Old Zhao said, "This cup has been with me for twenty years."

He paused for a moment, then said, "If it's dented, it's dented."

Xie Chengzhou did not respond.

He mentally went over the events of the day.

They entered the corridor and discovered a man-made crack. His "structural perspective" prioritized it, and his hand had already touched the chisel. Old Zhao told him to stop, and he put the chisel away.

Later, the seepage victim emerged, leaving a white mark on Li's wrist.

He tried to find a cause-and-effect relationship in his mind—the seepage was caused by the pressure change when they released the pressure, and it had no direct relationship with the man-made crack. What would have happened if he hadn't put away his chisel and had disturbed the crack?

he does not know.

All he knew was that he put away the chisel, and then they survived, but Li Gong's wrist was left with that white mark.

He is currently unable to confirm the relationship between these two matters.

He wrote in his memo: "Key question: How would the behavior of the seepage victims change if the man-made cracks were dealt with? — This question cannot be answered at this time."

Then he paused for a long time after that line, and finally added a line:

"Structural Perspective Assessment: High Priority; Actual Decision: No Action Taken. First instance of actively suppressing engineering intuition. Result: Survival, but Engineer Li was injured. This doesn't prove intuition was wrong, it only proves that this time we didn't follow intuition; the result was survival, but the cost wasn't zero."

He closed the memo.

Engineer Li found a sign on the wall of the maintenance room and shone his flashlight on it: "The entrance to the expansion joint passage is here."

Xie Chengzhou raised his head.

There was a crack in the wall, about 60 centimeters wide, sealed with a metal plate. The edge of the metal plate had bolts, which were new, not the original old bolts, but were replaced later—someone had been here recently.

Xie Chengzhou mentally connected this detail with the man-made crack.

The same group of people.

Same purpose.

He added a final line to his memo: "Expansion joint access point · P2-07 · Metal sealing plate · Bolts are new · Inference: Someone recently entered or sealed this area · Same source as man-made crack · Priority: High."

The rhythmic sounds in the corridor disappeared.

The maintenance room was quiet, except for the sound of water seeping from the walls and dripping onto the floor, drop by drop, very evenly.

Xie Chengzhou felt the numbness in his right ankle.

Still.

Li Gong stood beside him and slowly bent the ring and little fingers of his left hand, stopping halfway before extending them again.

Bend again, stop again, stretch out again.

I'm practicing to regain the feeling in those two fingers.

Xie Chengzhou saw this action but remained silent.

He glanced at the water level.

The number on the wrist: 5.46 meters.

Distance from the warning line: 2.46 meters.

They wasted two fifteen-minute periods in the corridor.