JP4101207B2 - Steel material replacement cycle setting method and replacement cycle management device - Google Patents

Description

  The present invention relates to a method for setting a replacement cycle of a steel material installed in an underground structure such as a submarine tunnel and where water (aqueous solution) containing a steel material deterioration promoting material such as seawater exists and the replacement cycle It belongs to the technical field of management devices.

Today, an underground structure such as a tunnel or a box culvert is frequently built at a position lower than the groundwater surface or the sea surface, and the steel material may be provided in such a state that the underground material is exposed. Among such steel materials, for example, there is water leakage that contains seawater in groundwater (hereinafter referred to as “seawater-containing water leakage”), and this continuously adheres. In such cases, the steel material contains water leakage. More specifically, the adhesion of seawater, which is an object, causes deterioration (corrosion) due to the adhesion of salt in the seawater. The electrochemical mechanism of corrosion when water such as seawater-containing water leakage adheres to the steel is considered as follows. First, in order for steel materials to corrode, it is premised on the presence of dissolved oxygen, which is an oxidizing agent, in the adhesion solution. Electrons are transported by the flowing water, and iron ions (iron (II) ions (Fe ²⁺ ), iron (III) ions (Fe ³⁺ )) are generated on the steel surface. Here, when a large amount of chloride ions are dissolved as in the case where the adhering water is seawater-containing leakage, the chloride ions coordinate with the generated iron ions to form an iron chlorocomplex. It interferes with the formation of iron hydroxide that is difficult to dissolve in water. Since the iron chlorocomplex is easily soluble in water and stable in water, the produced iron chlorocomplex is dissolved in the adhering water. As a result, the steel material is iron hydroxide. There is no surface covering and protection provided by objects, and fresh corroded surfaces will always be exposed to the corrosive environment. Under normal circumstances, there is sufficient dissolved oxygen in the seawater-containing leaks. As a result, the steel that continues to be exposed to the seawater-containing leaks has a continuous (continuous) chlorocomplex of the iron produced. Will be dissolved in the leaked water and corroded in a thin and thin state, and the deterioration will proceed.
By the way, when a steel material deteriorates due to vibration or thermal load, there is known an attempt to evaluate the degree of deterioration with ultrasonic waves (Patent Document 1). However, this is because the steel material is repeatedly subjected to vibration and thermal load. With this carbide layer precipitates at the grain boundaries inside the steel material, and the ultrasonic wave propagation speed is high in this carbide layer, this is used to evaluate the degree of deterioration and replace the steel material before failure occurs It will be.
And, as for the steel material that has deteriorated, it is the current situation that the inspection worker goes to the site and visually confirms the replacement before the failure occurs, so the method of setting the steel material replacement cycle is described There is no prior art document information to be used.
JP-A-7-260753

  As described above, the steel material to which seawater-containing leakage continues to adhere corrodes and deteriorates, leading to a decrease in strength. The steel material that has deteriorated is required to be subjected to a maintenance process such as replacement before it becomes less than the required strength. Conventionally, this replacement cycle has accelerated deterioration the earliest among the installed steel materials. The current situation is that the steel materials in all locations are changed according to things. For this reason, the deterioration has not progressed yet, and even those that can withstand sufficient use are replaced, which not only increases the replacement cost, but also the replacement work takes a long time and is inferior in workability. There is a problem to be solved by the present invention.

The present invention was created with the object of solving these problems in view of the above circumstances, and the invention of claim 1 is a water containing seawater that is a deterioration promoting substance for steel material deterioration. This is a method for setting the replacement cycle of long steel materials that are continuously installed from the entrance to the exit of a submarine tunnel where there is a seawater, and observes the degree of deterioration of steel materials at predetermined intervals. Then, the long steel material is divided into a plurality of sections based on the observed degree of deterioration, and the time from the installation of the steel materials to the earliest failure among the steel materials in each section is determined in each section. it is a method of setting the replacement period of the steel material, characterized in that so as to set each When it is replacement cycle of steel.
The invention of claim 2 is a replacement cycle of steel materials installed in a long place continuously installed from the entrance to the exit of a submarine tunnel where water containing seawater which is an accelerator for deterioration of steel materials exists. Each of the management devices, each observing the degree of deterioration of the steel materials at predetermined intervals , and dividing each of the long steel materials into a plurality of groups based on the observed degree of deterioration And the time until the first occurrence of a failure from the installation of the steel materials in each section is set as the steel replacement period in each section. is management device replacement cycle of steel, characterized means for registering the exchange period which is, to be configured with means for calculating the estimated replacement date of steel installation date and replacement cycle which is the registration

And this invention makes it possible to change the steel material by the division | segmentation divided into the finely divided part instead of the whole area by replacing the long steel material arrange | positioned continuously by making it like Claim 1. The replacement work of the steel material is facilitated and the replacement can be performed efficiently.
By making it like Claim 2, the management of replacement | exchange of the elongate steel materials arrange | positioned continuously can be performed, and the maintainability of steel materials further improves.

  As described above, the steel material to which the water containing the steel material degradation promoting substance adheres like seawater, for example, when the steel material degradation promoting substance is seawater, the corrosion progresses due to corrosion by chloride ions. The degree of deterioration is affected by the amount of iron chlorocomplex produced. This is related to the total amount of chloride ions adhering to the steel material from the time of installation of the steel material to the present, that is, the cumulative amount (which can also be expressed as an absolute amount, an integrated amount or a total passing amount), and the environment ( If the location is the same, it can be inferred that it will deteriorate in the same state.

  By the way, the amount of seawater leaked from the steel material installed in a long extension like a submarine tunnel differs between the entrance and exit of the tunnel and the center of the tunnel. In general, the amount of seawater increases toward the center of the tunnel. It is estimated that deterioration increases as there is more. As shown in FIG. 1, the submarine tunnel has a main mine 1 and a working mine 2, and the main mine 1 is provided with a tunnel entrance on land, and becomes deeper toward the middle of the tunnel. It is constructed with a substantially V-shaped inclined structure having a gradient change point 3. On the other hand, the work resistance 2 is constructed in a substantially inverted V shape that is inclined so as to reach the wellhead with the deepest position of the main shaft 1 as the gradient change point, and the vertical shaft 4 at the ground position on each wellhead side. Is built.

  Now, in a certain submarine tunnel like this, the degree of deterioration is observed at predetermined intervals (for example, 50 m intervals) for long steel materials continuously installed from the entrance to the exit of the main mine 1 did. FIG. 2 shows a graph of the degree of deterioration (mm) after 5 years from installation. According to this, when the change in the degree of deterioration from the position A which is the entrance to the position D which is the gradient change point 3 is observed, the change is slightly increased from the position A to the position B, and suddenly from the position B to the position C. It was a change that increased in an inclined manner, a change that increased in a parabolic manner from the C position to the D position, and it was confirmed that the D position was a maximum point.

  On the other hand, when observing a change in the degree of deterioration from the D position which is the gradient change point 3 to the H position which is the exit, the change is a parabolic decrease from the D position to the E position, and slightly decreases from the E position to the F position. It was confirmed that the change from the F position to the G position decreases steeply and the change from the G position to the H position has almost no change.

Therefore, from the A position to the B position, the first section, from the B position to the C position, the second section, from the C position to the F position, the third section, from the F position to the G position, the fourth section, from the G position. The section up to the H position is classified as the fifth section, and for the steel materials with the fastest deterioration in each section, the time (period) from installation to failure occurrence is set as the steel material replacement cycle, and this set replacement cycle In fact, by managing to replace half a year before this replacement cycle, it is no longer necessary to replace the steel material over the entire section as in the past, and the efficiency of the replacement can be improved. Therefore, useless replacement of steel materials can be avoided. In addition, there is an advantage that the steel material replacement can be scheduled in advance.
Such changes in the degree of deterioration are different depending on the individual submarine tunnels, but it is confirmed that the same submarine tunnels are changing in the same manner, and it is recognized that the present invention is reliable. .

  Next, the management apparatus for the exchange cycle will be described. This can be configured using a general-purpose computer, but the computer main body is provided with necessary means such as storage means (registration means) and calculation means in the control unit 6. It is registered, and the installation date and replacement period can be input (input using the keyboard 7 or the like) for each category. And the control part 6 will calculate an estimated replacement date based on this, and will display it on the display 8, if an installation date and a replacement period are input. Further, based on the clock function built in the control unit 6 itself, the number of days elapsed from the installation date to the present day and the remaining days until the replacement period expires are displayed. The control unit 6 further informs the administrator when, for example, six months before the expiration of the replacement cycle, by prompting replacement, for example, by displaying the description characters of the corresponding category in red, or by sound notification. It is set as follows.

  By managing the replacement of the steel material in this way, the replacement management for each divided section can be easily performed, and the maintenance of the steel material is facilitated.

It is a schematic sectional drawing of a submarine tunnel. It is a graph which shows the relationship between a deterioration degree and a tunnel position. It is a block circuit diagram of the management apparatus of an exchange period. It is a display screen figure of a management apparatus.

Explanation of symbols

    1 main pit

Claims (2)

A method of setting the replacement cycle of the elongated steel placed continuously up to the entrance of the undersea tunnel exists water containing seawater is accelerated deterioration of the steel deteriorates at the outlet, a preset predetermined Observe the degree of deterioration of the steel materials at the intervals , and divide the long steel material into a plurality of sections based on the observed degree of deterioration, and the steel material in each section is the most early setting of the replacement period of the steel material is characterized in that so as to respectively set the certain time to an exchange period of the steel in the respective division problems occur. It is a management device for the replacement cycle of steel materials installed in a long place continuously installed from the entrance to the exit of the submarine tunnel where water containing seawater that is an accelerator for steel deterioration exists, Means for observing the degree of deterioration of the steel materials at predetermined intervals , and registering each of the long steel materials divided into a plurality of groups based on the observed degree of deterioration; and The steel material installation date for each division and the time from the steel material installation to the earliest failure among the steel materials in each division are registered as the steel material replacement cycle for each division. And a means for calculating a scheduled replacement date from the registered steel material installation date and replacement period, and a steel material replacement period management device.

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