CN113982033B

CN113982033B - Method for repairing hydraulic retaining wall with inclination trend by using water in post-construction structure without damage to wall

Info

Publication number: CN113982033B
Application number: CN202111478990.6A
Authority: CN
Inventors: 郑旻文; 李佳超; 周继元; 郑铎
Original assignee: Jilin Xiangyu Constructional Engineering Co ltd Changchun Branch
Current assignee: Jilin Xiangyu Constructional Engineering Co ltd Changchun Branch
Priority date: 2021-12-06
Filing date: 2021-12-06
Publication date: 2023-06-06
Anticipated expiration: 2041-12-06
Also published as: CN113982033A

Abstract

The invention relates to a method for repairing a hydraulic retaining wall with inclination tendency of a post-construction structure without damage to the wall by water, belonging to the field of potential inclination damage of retaining walls by utilizing prestress nondestructive repair. The method comprises the steps of observing the retaining wall, determining the position of an anchor hole outside the wall, gradually increasing tensioning force for a plurality of times, tensioning and debugging an anchor rope at the tensioning end outside the retaining wall, and then anchoring and sealing the anchor. The method has the advantages that the method is suitable for retaining walls with inclination trend, no matter whether structures exist behind the walls or not, no water exists or water exists on soft foundation or rock foundation, the retaining walls with inclination trend of water workers can be quickly repaired or limited to continue to develop, after the retaining walls are processed, the retaining walls and the structures behind the walls can be kept stable, and hidden danger that the retaining walls continue to incline under the combined action of soil pressure and frost heaving pressure can be completely eliminated. The construction investment can be greatly reduced, the environment is not polluted in the repairing process, the construction progress is fast, and the construction operation is not influenced during the construction.

Description

Method for repairing hydraulic retaining wall with inclination trend by using water in post-construction structure without damage to wall

Technical Field

The invention belongs to a technology for repairing a retaining wall with potential inclination damage by utilizing prestress in a nondestructive way, which can realize construction after the wall is damaged and does not influence the normal operation of a hydraulic retaining wall.

Background

The hydraulic retaining wall with the height of 3 m-7 m is the most common structure of hydraulic engineering. After the engineering is built and put into operation, the retaining wall structure is subjected to the effects of water and soil pressure and a structure behind the wall for a long time, and frost heaving force is also superimposed in a seasonal frozen soil area, so that the wall body is displaced; sometimes, the wall structure bears excessive pressure, so that cracks are generated along the wall, and the wall is displaced. For soft foundations, the retaining wall is soaked in water for a long time, the water level in the water passing area is changed frequently, sometimes even without water, dry and wet changes are generated, the foundation consolidation degree is not in place, the softening condition of the toe point before the foundation is easy to occur, and the foundation deformation is also likely to occur. Because the retaining wall is positioned in the water body, cracks can be positioned in the water body, and the engineering safety is greatly threatened.

In general, the structural integrity of the retaining wall part generating deflection is better, the demolishing and reconstruction can cause great waste, a large amount of construction waste can be generated, the surrounding environment is influenced, and even the safety of a post-wall structure can be influenced. For hydraulic engineering, due to the existence of water, the dismantling reconstruction can seriously influence the normal operation of the engineering, and the dismantling construction has the possible problem of lowering the water level, can pollute the water, and has certain difficulty in the cleaning process. If a technology can be adopted to realize that the method of not reducing the water level or limiting the water level is adopted on the premise of not influencing the safety of the post-wall structure, the original structure is fully utilized, the retaining wall structure is recovered to normal use, and the post-wall structure is not influenced by potential safety hazards, the method can achieve the purposes of safety, investment saving and environment protection on the premise of not influencing the engineering operation.

Disclosure of Invention

The invention provides a method for repairing a hydraulic retaining wall with an inclined trend by using water without damaging a post-wall structure, which aims to realize that the original structure is fully utilized by adopting a method of not reducing the water level or limiting the water level on the premise of not influencing the safety of the post-wall structure, so that the retaining wall structure is recovered to be normally used, and the post-wall structure is not influenced by potential safety hazards.

The invention adopts the technical proposal that: comprises the following steps:

(1) Observing whether the retaining wall has a fracture part, repairing the broken retaining wall integrally, and performing an anchoring and grouting sealing bonding method, wherein the influences of water bodies on drilling, anchoring and bonding treatment are considered for the underwater or water-bearing condition, so that the retaining wall is integrated;

(2) The position of the anchor hole is determined outside the wall,

1) For the earth retaining wall which can be excavated after the wall, the earth retaining wall after the wall is cleaned, the earth after the wall is cleaned can be excavated, then the earth retaining wall is tensioned and reset by using an anchorage system, and then the earth is backfilled; for retaining walls with structures behind the walls or soil bodies behind the walls which cannot be excavated for other reasons, limited reset can be performed due to the action of passive soil pressure;

2) For the condition that the foundation of the structure is shallower, the anchor hole is lower than the bottom surface of the structure, the anchor hole is 0.3-3.0 m below the ground line, the drilling machine drills holes horizontally from the outside to the inside of the retaining wall or at an angle smaller than 30 degrees with the horizontal angle, the adjacent drilling holes are parallel to each other, and the distance between the adjacent drilling holes is 1.5-6 m;

For the retaining wall which is possibly reset completely, firstly cleaning the wall and then the soil body, and then arranging an anchorage system according to the condition after cleaning the soil body;

3) For retaining walls which have no structures behind the walls and mainly generate inclination trend due to frost heaving force action, the frost heaving force of the maximum section of the frost heaving gradient when the depth of the frost soil is 20-50 cm can be utilized to form internal anchoring action, and the anchor holes are positioned 0.3-0.5 m below the ground line, so that investment can be saved, the construction progress can be accelerated, and the retaining walls can be arranged according to the same anchor hole positions if the apparent consistency of the front ends of the retaining walls after construction is considered;

(3) For the condition that water exists in an anchor hole behind a wall and is a non-rock hole or a non-structure foundation, the drilling process is performed synchronously with the anchor rope penetrating, the sleeve adding or the grouting pipe as much as possible, otherwise, the hole collapse problem possibly occurs to influence the construction process;

(4) For a stone-built retaining wall, because the tensile property of the material is limited, and the action of passive soil pressure on the retaining wall can possibly cause the concentration action of tensioning prestress to generate a certain influence on the integrity of the retaining wall, when the stone-built retaining wall is restored, a pressure sharing structure is arranged at the prestress tensioning end of the retaining wall, and according to the concrete condition of the retaining wall, an X-shaped structure, a ten-shaped structure, a meter-shaped structure or a straight-shaped structure can be adopted, so that the structure can effectively distribute the concentration pressure generated on the wall in the tensioning and debugging process to ensure that the integrity of the wall is not damaged, and the debugging process of gradually increasing the tensioning force for a plurality of times is adopted to ensure that the stone-built retaining wall meets the design requirement;

(5) The anchor cable at the stretching end outside the retaining wall is stretched and debugged, then anchored and sealed, and the concrete sealing anchor can be directly poured into the grouted stone retaining wall structure with the concrete facing after the anchor cable is anchored; for a masonry retaining wall without concrete facing, the pressure sharing structure is of a steel structure, it is considered that after the structure is subjected to corrosion protection treatment, the structure is sealed with rust-resistant mortar or rust-resistant concrete, and if the pressure sharing structure is in water, the pressure sharing structure can be treated with underwater rust-resistant mortar.

In the step (1), the broken retaining wall is repaired in structural integrity, and the repairing can be finished by a method of anchoring first and then grouting bonding or a method of grouting first and then anchoring.

(1) The method is suitable for the situation that the broken part of the wall body is on water and the grouting pressure is not large, because the material of the anchoring slurry can be single, the grouting pipe is used for grouting the anchoring rib after the anchoring rib is inserted, the grouting pipe is pulled out after the slurry in the deep hole is full, and then sealing grouting is carried out, the grouting effect can be observed when the crack is sealed, grouting is completed after the grouting achieves the design effect, the vent hole is sealed by epoxy resin sealing cement, if the crack is smaller than 0.4mm, low-viscosity epoxy resin slurry is needed, for cracks larger than 0.4mm, cement-based grouting is needed, for cracks of a slurry stone structure, generally, the grouting slurry is larger than 0.4mm, and therefore, the method is suitable for low-cost cement slurry bonding slurry;

(2) Under the condition that water exists in the cracks, anchor holes are drilled first to seal the cracks, the cracks are sealed by grouting after the dowel bars are anchored, because the pressure grouting is adopted in the drainage process, the original cracks can be changed due to the action of the grouting slurry pressure, and the influence of the pressure on the wall body can be eliminated by grouting after anchoring. Generally, as long as the water depth is smaller than 40cm, the manual construction is not difficult, and as long as the possibility of the manual construction is ensured, the water depth has no influence on the construction effect basically;

(3) for the situation that the crack is positioned under water, grouting of the underwater closed crack can be completed by pressure grouting after a grouting pipe is buried or a grouting hole is drilled, and the grouting process needs to eject underwater bonding slurry out of water in the crack by using the grouting pressure, namely, the slurry is used for extruding water out of the crack, so that the underwater bonding slurry is left in the crack;

(4) embedding grouting pipe method: and (3) without grouting holes, drilling anchor holes, cleaning powder generated by drilling holes in the seams with pressurized water, inserting anchor ribs, sealing the seams, burying grouting needles and reserving observation holes in sequence according to set distances at the sealed seams, sequentially and slowly grouting in a circulating manner, and fully grouting to finish grouting, and evaluating grouting effect through the observation holes. If grouting is too fast, the water body can not be mostly discharged, and only the slurry is slowly and circularly pressed in for many times, so that most of the water body can be extruded out of the crack, for example, the observation hole is provided with a thicker slurry to flow out, and the grouting pump pressure is fast increased, so that grouting is full, and the grouting can be sealed by epoxy resin sealing cement. And if the slurry flows out and the pressure does not rise rapidly, the observation hole can be blocked, grouting is continued, and if the pressure rises rapidly, grouting is full.

(5) Drilling and grouting hole method: firstly drilling an anchoring hole, then cleaning powder generated by drilling holes in the seam by using pressurized water, sealing the slit, leaving a sequential drainage hole, then immediately inserting an anchoring rib after injecting underwater cement-based anchoring material slurry, drilling a grouting hole beside the anchoring hole after the anchoring slurry reaches the designed setting strength, grouting the grouting hole, and sealing the drainage hole when the grouting pump reaches the designed pressure and the grouting process is completed when the grouting hole is seen to have thicker slurry flowing out.

The underwater rapid hardening sealing mortar is prepared from the following raw materials in parts by weight:

20-40 parts of monoammonium phosphate, 2-30 parts of magnesium oxide, 0.2-2.5 parts of boric acid, 2-30 parts of cement, 0-38 parts of 120-200 mesh quartz sand, 0-50 parts of metakaolin, 0-50 parts of fly ash, 0-8 parts of calcium sulfate, 0-25 parts of calcium silicate, 2-80 parts of liquid sodium silicate, 1-80 parts of redispersible emulsion powder, 3-50 parts of polyacrylamide and 0-50 parts of cellulose;

the epoxy resin sealing cement is prepared from the following raw materials in parts by weight:

100 parts of E44 epoxy resin, 0-30 parts of phenolic amine, 2-30 parts of dibutyl phosphate, 2-30 parts of benzoate, 0-16 parts of styrene, 0-20 parts of acetone, 10-30 parts of egg white, 100 parts of flour and 0-100 parts of sulphoaluminate cement,

Mixing egg white, flour and sulphoaluminate cement, and then mixing with an epoxy resin material to form quick-setting cement with certain strength;

the low-viscosity epoxy resin is prepared from the following raw materials in parts by weight;

100 parts of epoxy resin E-44, 0-42 parts of polyvinyl butyral, 0-40 parts of polyamide, 0-30 parts of phenolic amine, 2-30 parts of dibutyl phosphate, 2-30 parts of benzoate, 0-30 parts of alumina powder, 5-25 parts of styrene and 0-25 parts of dimethylbenzene;

the cement-based bonding slurry is prepared from the following raw materials in parts by weight;

500 parts of cement, 0-100 parts of E-44 epoxy resin, 0-42 parts of polyvinyl butyral, 0-40 parts of furfural, 0-60 parts of acetone, 0-20 parts of diethylenetriamine, 0-25 parts of phenolic amine, 0-25 parts of cellulose, 0-25 parts of polycarboxylate water reducer and 0-100 parts of water;

the low-cost cement grouting bonding slurry material is prepared from the following raw materials in parts by weight;

1000 parts of cement, 0-500 parts of water, 0-1000 parts of fly ash, 0-1000 parts of heavy beads larger than 200 meshes, 0-500 parts of fine sand, 0-50 parts of polycarboxylate water reducer, 0-80 parts of redispersible emulsion powder, 0-50 parts of polyacrylamide, 0-50 parts of cellulose and 0-45 parts of triethanolamine.

In the step (5), in order to ensure that the retaining wall is not damaged under the action of concentrated external force generated by larger sudden tension, a pressure distribution structure can be arranged on the retaining wall at the tension end, and the structural type can be arranged according to the calculation of the self bearing capacity of the retaining wall structure, and an expansion type structure is generally adopted. The arrangement mode can be used for carrying out arrangement installation by adopting prefabricated ten-line, X-line, meter-line steel structures according to the bearing capacity of the wall body, tensioning and debugging are carried out after the pressure sharing structure is installed, gaps between channel steel and a retaining wall are filled in time by quick setting sealing mortar in the debugging process, rust-resistant mortar is adopted for sealing after the debugging is completed, and finally, the pressure distribution structure is protected by adopting rust-resistant concrete or mortar materials;

if the wall body is protected by a certain water depth, protecting the pressure distribution structure by adopting a rust-resistant underwater concrete or mortar material;

the construction sequence is that the water-based two-function phosphating rust remover is used for removing rust, about 1kg is used for every 5 square meters, the rust removal and limited-time rust prevention functions can be finished, and then the pressure distribution structure is installed after the rust removal is finished, in general, the phosphating layer cannot disappear within 40 days after the rust removal by the phosphating rust remover, namely, rust cannot be generated, so that the pressure distribution structure cannot rust in the effective construction period.

The rust-resistant underwater concrete or mortar material is prepared from the following raw materials in parts by weight;

1000 parts of cement, 0-500 parts of 5-10 cobbles, 0-3000 parts of sand, 0-500 parts of water, 0-1000 parts of fly ash, 0-250 parts of migration rust inhibitor, 10-100 parts of polycarboxylate water reducer, 0-80 parts of liquid sodium silicate, 0-80 parts of redispersible emulsion powder, 0-50 parts of polyacrylamide, 0-50 parts of phosphoric acid, 0-50 parts of hexamethylenetetramine, 0-50 parts of cellulose and 1kg/5m of difunctional phosphating rust remover ² 。

In the step (5), if a certain water depth exists in front of the wall body or water exists in the anchor hole, the underwater anchoring and grouting material for grouting is prepared from the following raw materials in parts by weight:

1000 parts of sulphoaluminate cement, 10-500 parts of water, 0-1000 parts of fly ash, 0-1000 parts of heavy beads larger than 200 meshes, 0-50 parts of polycarboxylate water reducer, 0-600 parts of quartz sand, 0-200 parts of asbestos fiber, 0-80 parts of cellulose, 0-50 parts of amide and 0-45 parts of triethanolamine.

The invention can repair wall cracks with water and apply prestressed anchor cables to reset the retaining wall or keep the retaining wall stable under the current situation according to the actual situation on site and the requirements of owners on the premise of keeping the original retaining wall structure and not affecting the operation safety of the post-wall structures and the retaining wall. Typically, the retaining wall height is less than 7 meters. The method not only can repair the retaining wall under the condition of no water, but also can repair the retaining wall with inclination trend under the condition of a certain water depth without damaging the post-wall structure. Of course, the term "certain water depth" is intended to be within the range in which both the labor and the equipment can be operated at the time of construction.

For the retaining wall without fracture, the anchor cable can be directly utilized to reset or protect the original retaining wall, so as to limit the continuous displacement of the retaining wall. The retaining wall with a processing space behind the wall can be cleaned firstly, then the soil body is cleaned, the passive soil pressure is eliminated, then the anchorage mode is determined, and the wall body is reset by stretching the anchor cable. For retaining walls without processing space behind the wall, limited repositioning can be achieved by means of pre-stressed anchor cables. This space contains two things: on the one hand, construction space and on the other hand construction capacity space.

The breaking conditions of the retaining wall are treated by water and water-free:

for the anhydrous case: the retaining wall without sliding can be restored by injecting cement-based bonding slurry into the cracks under pressure, and the retaining wall is prevented from expanding after the cracks are closed; for the retaining wall which has generated sliding, the retaining wall cannot be restored naturally, the retaining wall can be integrated by adopting the method that firstly, the basic reset of the wall is assisted, then, inclined holes are drilled, anchoring ribs are inserted into the holes, the positioning and splicing of the wall are completed by using quick setting cement-based anchoring materials, and then, cement-based bonding slurry is injected. A low viscosity epoxy paste may also be used for the microcracks.

For water conditions: the retaining wall without sliding can be pressurized and injected with underwater cement-based bonding slurry for repairing, so that cracks are not developed any more; for the retaining wall which has generated slippage, the retaining wall cannot be restored naturally, the retaining wall can be integrated by firstly assisting in basic restoration of the wall, drilling inclined holes and inserting anchoring ribs into the holes, completing positioning and splicing of the wall by using the underwater quick setting cement-based anchoring material, and then injecting the underwater cement-based bonding slurry. The low viscosity epoxy paste may also be used under water for microcracking.

If the post-wall land, mountain or underground water level is higher, the post-wall underground water level can be higher than the post-wall underground water level, the post-wall water body can flow to the drilling position after drilling, the construction problem of carrying water can occur during construction, and only constructors and equipment can operate, so that the invention can be implemented.

The invention has the advantages that the invention is applicable to retaining walls with inclination trend, no matter whether structures exist behind the walls or not, no water exists or water exists on soft foundation or rock foundation, the retaining walls with inclination trend of water engineering can be quickly repaired or limited to continue to develop, after the retaining walls are processed, the retaining walls and the structures behind the walls can be kept stable, and the hidden trouble that the retaining walls continue to incline under the combined action of soil pressure and frost heaving pressure can be completely eliminated. The construction investment can be greatly reduced, in addition, in the repairing process, the construction waste is basically not generated, the environment is not polluted, the construction progress is fast, and the construction operation is not influenced during the construction.

Drawings

FIG. 1 is a schematic view of a hydraulic retaining wall with a structure behind the wall and with a tendency to tilt;

FIG. 2 is a schematic view of an anchor drilling line of the structural style of the anchorage member;

FIG. 3 is a schematic illustration of the placement of anchorage plates and anchoring arrangements;

FIG. 4 is a schematic illustration of the deployment of anchorage plates and anchoring arrangements;

FIG. 5 is a schematic illustration of the anchoring and tieing structure within the structure;

FIG. 6 is a schematic illustration of the fabrication of an anchor end within a foundation body of a structure;

FIG. 7 is an illustration of drilling a hole through a structure foundation and then anchoring;

FIG. 8 is a schematic view of relay anchoring with a structure foundation;

FIG. 9 is an anchoring schematic of a soil anchor formed using reaming grouting;

FIG. 10 is a schematic view of the formation of an anchored end with a nearby structure foundation;

FIG. 11 is a schematic view of the formation of an anchored end with rock;

FIG. 12 is a schematic view of a pressure distribution structure made of channel steel;

fig. 13 is a schematic view of the hole locations for the borehole anchoring and grouting in the breaking area of the retaining wall.

Detailed Description

Comprises the following steps:

(2) Determining the position of an anchor hole outside the wall;

2) On the premise of not damaging the safety of the post-wall structure and ensuring the use function of the retaining wall, the anchor hole position is basically determined according to the structural form or the basic condition of the post-wall structure, under the premise of being capable of being constructed,

for the condition that the foundation of the structure is shallower, the position of the anchor hole is lower than the bottom surface of the structure, the anchor hole is positioned 0.3-3.0 m below the ground line, the drilling machine drills holes horizontally from the outside to the inside of the retaining wall or angles smaller than 30 degrees with the horizontal angle, the adjacent drilling holes are parallel to each other, the distance between the two drilling holes is 1.5-6 m, and the anchor holes can be arranged according to the coordination of the arrangement of the anchor holes on the premise of meeting the safety of the structure and the structure behind the wall for the sections with different structures behind the wall;

(5) And (3) stretching and debugging the anchor cable at the stretching end outside the retaining wall, and then anchoring and sealing the anchor cable. For the concrete masonry retaining wall structure with the concrete facing after the anchor is anchored, concrete sealing anchors can be directly poured; for a masonry retaining wall without concrete facing, the pressure sharing structure is of a steel structure, it is considered that after the structure is subjected to corrosion protection treatment, the structure is sealed with rust-resistant mortar or rust-resistant concrete, and if the pressure sharing structure is in water, the pressure sharing structure can be treated with underwater rust-resistant mortar.

the low-viscosity epoxy resin (the adjustment ratio can be used for underwater) is prepared from the following raw materials in parts by weight;

the cement-based bonding slurry (the ratio of which can be used for underwater) is prepared from the following raw materials in parts by weight;

The invention will be further described with reference to the drawings by taking a gravity retaining wall as an example.

1. Referring to fig. 1, according to the concrete situation behind the retaining wall, the anchoring mode of the technical scheme is determined according to the steps (1) - (5) of the invention. The wall body resetting capability is determined by calculating the combined pressure of the retaining wall, and the method comprises the steps of determining the anchoring force, the treatment of passive soil pressure behind the wall, drilling, the size of an anchor ingot plate, the form of an anchor rope, an anchoring method, a tensioning mode and an anchor sealing method. The drilling process and the anchor cable penetrating process are synchronously carried out, and whether the sleeve needs to be penetrated is determined according to the convenience of construction or not. The sleeve is configured according to the anchoring mode, and for grouting type anchoring, an anchor cable sleeve or a special grouting pipe is required to be penetrated.

2. And according to the result of the step, an anchorage distance is calculated outside the structure behind the wall, an anchorage member layout pit is dug out, the pit depth corresponds to the drilling height outside the wall, and the anchorage pier plate is generally arranged in a similar plate type mode, and only the anchorage plate type is used for describing, and the arrangement of the anchorage plate structure type drilling line and the anchorage member is shown in figure 2.

3. The drilling and anchoring process according to step (2) is generally described in the following.

(1) For the condition that the foundation of the structure behind the wall is shallower and has a certain water depth, the horizontal drill can be used for drilling holes in front of the retaining wall as shown in fig. 2, because the water depth is high, the construction bent frame is difficult to manufacture, ships can be used, the drilling hole depth reaches the anchor ingot plate layout pit, and the arrangement mode of the drilling holes and anchor ropes is shown in fig. 3.

a. If the water level is high in the mountain or the mountain after the wall, the groundwater flows to the drilling position, as shown in figure 3, the construction problem of flowing water outwards in the hole can occur during construction, and the anchoring construction is performed according to the steps (3), (4) and (5) of the invention.

b. For retaining walls with no structures behind the wall and inclined trend, the soil body behind the excavated wall can be directly adopted to eliminate the passive soil pressure, and after the anchor rope anchoring end is anchored, the step (4) is carried out on the stretch-draw end according to the invention, as shown in fig. 4. After the restoration is basically satisfied, locking the tensioning end, completing anchoring constraint, backfilling soil after the wall, and realizing the limitation of the displacement of the retaining wall by using the anchor cable. Note that: the retaining wall is required to be circularly stressed and stretched on a section of wall, the single-point sudden stress is too large, the retaining wall is easy to generate local cracking under the action of stretching force, and serious damage is possible.

(2) For structures with deeper foundations behind the wall, the step (4) is performed according to the invention.

a. If the structure has enough strength and width, the gravity of the structure can bear the wall tension on the premise of keeping the stability of the structure after the load effect of the structure is considered, and the foundation is a complete solid structure. The method of anchoring within a structure may be implemented. Because the anchor holes are located in a rigid closed structure, as shown in fig. 5, in order to ensure the anchoring effect, the grouting pipe should be used for grouting and anchoring no matter whether water exists in the pipe holes, and the situation that the water in the holes cannot be discharged to cause the anchoring to be ineffective may occur when the grouting pipe is not used for anchoring.

b. If the structure has enough strength and width, the self gravity of the structure can bear the wall tension on the premise of keeping the self stability after the load effect of the structure is considered. If the structure has a certain space in the foundation, the depth of the drilled hole can be within the structure, and anchoring can be performed in the middle of the structure.

The anchoring is carried out by arranging the anchor plates in the structure according to the steps (2) and (4) of the invention, and the anchor plates can be anchored by adopting an anchor plate type and an anchor plate type after the reinforcement of a foundation structure, as shown in figure 6.

c. In the construction according to the steps (2) and (4), if the structure is deeper in the foundation, but if the wall body is displaced and cannot be kept stable, the wall body and the wall body are anchored together and cannot bear the load acting force of the wall body together, and if the foundation is higher in strength and better in integrity, drilling holes can be adopted to penetrate through the foundation of the structure for anchoring, as shown in fig. 7.

In the construction according to the steps (2) and (4), if the integrity of the foundation of the structure is good and the strength is enough, the retaining wall can be repaired by adopting a double-head anchor mode relay anchoring by utilizing the foundation structure. This is usually the case to ensure the safety of the behind-the-wall structure and the wall, and to take into account the load effect of the structure when calculating the anchoring force.

(3) In the construction according to step (3) of the present invention, if the structure is wide, the foundation does not affect the drilling position, but the drilling may be long, and the arrangement of the anchorage plate increases a large investment. In this case, a method of boring a soil anchor, that is, a method of boring a hole with a certain length at the root part in the foundation of the structure is adopted, according to the calculation result, boring is carried out within the length range required by the calculation result to make the bore thick enough, and then pressure grouting is adopted to form the friction soil anchor, as shown in fig. 9. For the condition of water in the anchor hole, the retaining wall is easy to fail and destroy under the action of water seepage sometimes, the sleeve is required to be put down along with the drill rod, otherwise, the anchor hole can have a hole collapse condition, and the construction is negatively influenced. At this time, the sleeve pipe can use the flower pipe, the grouting pipe is used for grouting from inside to outside, the slurry adopts an underwater grouting material, the slurry can be effectively extruded out of the pipe water body from inside to outside through the flower pipe hole under the action of pressure when in grouting under the action of pressure, the slurry under the action of pressure enters into the soil body to form the wolf tooth stick type anchoring body, and the anchoring force can be greatly increased. Along with the slow extrusion of the water body under the grouting pressure, the water body outside the pipe is extruded into the soil body, and the sleeve and the soil body form a whole.

(4) In the construction according to step (2) of the present invention, if there is a structure behind the wall, but the structure is not wide, there are other structures behind the structure, and the anchoring length is insufficient by using the anchor plate therebetween, the anchoring end can be formed on a firm basis anchored to the nearby structure, as shown in fig. 10.

(5) In the construction according to step (2) of the present invention, if a structure is behind the wall, and a stronger rock is behind the structure, an anchor end may be formed on the rock, as shown in fig. 11. Of course, when anchoring to rock, the anchoring length should be determined according to the rock properties, and the grouting pipe is used to inject the anchoring slurry.

If the anchor hole is water or underwater during construction, an underwater anchoring construction method is adopted, and the slurry adopts an underwater cement-based anchoring material. For the structure of the anchor cable anchored in the rock mass, the situation that the anchor holes permeate outwards in the rock mass can be encountered during anchoring due to the fact that crack water exists in the mountain body. If rock mass cracks exist and the mountain water level is high, water seepage water quantity is large, and water flow can be formed, at the moment, a common anchoring method is difficult to apply, and an underwater cement-based anchoring material must be combined by a device (patent number: ZL 200820072081.6) for facilitating the anchoring of the prestressed anchor cable.

4. Retaining wall side stretching end pressure distribution structure and anchor sealing treatment

In the step (5), in order to ensure that the retaining wall is not damaged under the action of concentrated external force generated by larger sudden tension, a pressure distribution structure can be arranged on the retaining wall at the tension end, and the structural type can be arranged according to the calculation of the self bearing capacity of the retaining wall structure, and an expansion type structure is generally adopted. The arrangement mode can be arranged and installed by adopting prefabricated ten-shaped, X-shaped, meter-shaped or straight-shaped steel structures according to the bearing capacity of the wall body, and the arrangement mode is only illustrated by an asymmetric cross-shaped channel steel structure arranged at the stretching end, as shown in fig. 12. The steel seat plate is used for bearing the pressure transmitted by the prestress disc during tensioning, so that the steel seat plate is welded with the cross-shaped channel steel to form an integral structure. In general, in the case of convenient placement, the longer the channel length is, the more advantageous the wall is. Of course, this is only an illustration, and arrangements with non-stiff rebars are also possible. And after the pressure sharing structure is installed, tensioning and debugging are carried out, the gap between the channel steel and the retaining wall is filled in time by quick setting sealing mortar in the debugging process, and the gap is sealed by adopting rust-resistant mortar after the debugging is completed. If the structure is aesthetically pleasing, time allows, the overall safety is not affected when the structure is partially chiseled, and the pressure distribution structure can be arranged by chiseling pits in the retaining wall. And finally, adopting a rust-resistant concrete or mortar material to protect the pressure distribution structure.

The method has simple structure and convenient and quick construction, the steel structure arranged on the retaining wall carries out integral constraint on the wall surface, the wall body is good in protectiveness, and after the tensioning, debugging and sealing of the anchor and the protection of the pressure distribution structure are completed, the front wall repair of the anchor point is also completed simultaneously. The structure can be used for both a grouted stone retaining wall and a concrete retaining wall. Of course, if funds permit, the protection may be with a reinforced concrete facing.

If the wall body is protected by a certain depth of water, the pressure distribution structure is protected by adopting a rust-resistant underwater concrete or mortar material.

In the step (5), the constraint force of the anchor cable is tensioned and debugged, so that the damage to the retaining wall is not generated under the assistance of a pressure distribution structure arranged at a tensioning end, the uniform distribution of concentrated pressure to the retaining wall is ensured, and particularly, the restoration of the original position of the grouted stone retaining wall is ensured, and the integral restoration of the wall is ensured, wherein the local displacement is not generated under the pressure of frozen soil in winter. Therefore, the initial stress should be smaller, and the bearing effect of the pressure distribution structure is observed, if the local bearing structure is separated from the wall, the local displacement is possibly generated, and the fit between the bearing structure and the wall is adjusted. And then gradually and circularly increasing the anchoring force according to the debugging calculation result. The method comprises the steps of performing compound calculation according to displacement generated by applying prestress each time according to the displacement condition after trial adjustment, and then adjusting the tensile force of each bundle of anchor cable to gradually adjust the anchoring force in place.

In the step (5), if a certain water depth exists in front of the wall body or water exists in the anchor hole, grouting is carried out by using underwater anchoring and grouting materials.

5. Fracture treatment of broken retaining wall

In the step (1) of the present invention, it is necessary to repair the structural integrity of the broken retaining wall. The repairing can be finished by a method of anchoring and grouting bonding or a method of grouting and anchoring.

(1) The method is suitable for the situation that the broken part of the wall body is on water and the grouting pressure is not large, because the material of the anchoring slurry can be single, the grouting pipe is used for grouting the anchoring rib after the anchoring rib is inserted, the grouting pipe is pulled out after the slurry in the deep hole is full, and then sealing and grouting are carried out, so that the grouting effect can be observed when the crack is sealed, the grouting is completed after the grouting reaches the design effect, and the exhaust hole is sealed by the epoxy resin sealing cement. If the crack is less than 0.4mm, an epoxy slurry should be used. For cracks greater than 0.4mm, cement-based slurries are available. For cracks in masonry structures, typically greater than 0.4mm, low cost cement slurries are suitable.

(2) For the condition that water exists in the cracks, anchor holes are drilled first to seal the cracks, the inserted bars are anchored and then the cracks are grouted to seal the cracks, because the pressure grouting is adopted in the drainage process, the original cracks can be changed due to the action of the grouting body pressure, and the influence of the pressure on the wall body can be eliminated by grouting after anchoring. Generally, as long as the water depth is less than 40cm, the manual construction is not difficult. Of course, as long as the possibility of manual construction is ensured, the depth of water has no influence on the construction effect basically.

(3) The grouting of the underwater closed crack under the condition that the crack is positioned under water can be completed by pressure grouting after a grouting pipe is buried or a grouting hole is drilled, and the grouting process needs to eject underwater bonding slurry out of water in the crack by using the grouting pressure, namely, the slurry is used for extruding water out of the crack, so that the underwater bonding slurry is left in the crack.

(4) Embedding grouting pipe method: no grouting holes are needed as in fig. 13. Firstly, drilling an anchoring hole, then cleaning powder generated by drilling holes in the seam by using pressurized water, then inserting an anchoring rib, sealing the seam, simultaneously burying grouting needles at the sealed seam sequentially according to a set distance, leaving observation holes, sequentially and slowly grouting in a circulating manner, and fully completing grouting, and evaluating grouting effect through the observation holes. If grouting is too fast, the body of water is generally not largely expelled, and only slow, multiple, cyclical pressing into the slurry may force a substantial portion of the body of water out of the fracture. If the observation hole has thicker slurry flowing out and the grouting pump pressure rises rapidly, the grouting is full, and the grouting can be sealed by epoxy sealing cement. And if the slurry flows out and the pressure does not rise rapidly, the observation hole can be blocked, grouting is continued, and if the pressure rises rapidly, grouting is full.

(5) Drilling and grouting hole method: as shown in fig. 13, the anchoring holes are first drilled, then the powder produced by the drilling in the slit is washed with pressurized water, and then the slit is closed and the sequential drainage holes are left. Then the anchoring ribs are inserted immediately after the underwater cement-based anchoring slurry is injected. And drilling grouting holes beside the anchor hole positions after the anchoring slurry reaches the designed setting strength. When the grouting holes are used for grouting, the drainage holes are closed when the drainage holes are seen to have thicker slurry flowing out, and when the grouting pump reaches the design pressure, the grouting is basically full, and the grouting process is completed.

The anchoring and breaking belt pouring connection breaking area must be bonded by using adhesive slurry with good pouring property, and the underwater breaking area must be filled with underwater slurry. The bonding slurry is directly drilled and poured in the fracture area, and the bonding slurry material can be determined according to whether the construction requires quick bonding and specified strength.

Materials for the above applications:

the anchor cable comprises:

the steel bar, the unbonded prestressed steel strand and the prestressed steel strand are subjected to corrosion prevention treatment. The anticorrosion can adopt a coating asphalt material antirust method, a coating rust-resistant material coating method and the like according to the convenience degree of anchor cable penetration, and the simplest is to use an unbonded steel strand as the anchor cable, but the PE protective layer of the anchor cable is not damaged in the construction process.

The cement-based bonding slurry (the mixing ratio is adjusted to be used underwater) is prepared from the following raw materials in parts by weight;

a: 500 parts of cement;

b: 500 parts of cement, 50 parts of E-44 epoxy resin, 21 parts of polyvinyl butyral, 20 parts of furfural, 30 parts of acetone, 10 parts of diethylenetriamine, 12 parts of phenolic amine, 12 parts of cellulose, 12 parts of polycarboxylate water reducer and 50 parts of water;

c: 500 parts of cement, 100 parts of E-44 epoxy resin, 42 parts of polyvinyl butyral, 40 parts of furfural, 60 parts of acetone, 20 parts of diethylenetriamine, 25 parts of phenolic amine, 25 parts of cellulose, 25 parts of polycarboxylate water reducer and 100 parts of water;

a: 1000 parts of cement:

b: 1000 parts of cement, 250 parts of water, 500 parts of fly ash, 500 parts of beads larger than 200 meshes, 250 parts of fine sand, 25 parts of polycarboxylate water reducer, 40 parts of redispersible emulsion powder, 25 parts of polyacrylamide, 25 parts of cellulose and 23 parts of triethanolamine;

c: 1000 parts of cement, 500 parts of water, 1000 parts of fly ash, 0-1000 parts of beads with the particle size larger than 200 meshes, 500 parts of fine sand, 50 parts of polycarboxylate water reducer, 80 parts of redispersible emulsion powder, 50 parts of polyacrylamide, 50 parts of cellulose and 45 parts of triethanolamine;

The underwater anchoring and grouting material is prepared from the following raw materials in parts by weight:

a: 1000 parts of sulphoaluminate cement and 10 parts of water:

b: 1000 parts of sulphoaluminate cement, 255 parts of water, 500 parts of fly ash, 500 parts of beads with the particle size larger than 200 meshes, 25 parts of polycarboxylate water reducer, 300 parts of quartz sand, 100 parts of asbestos fiber, 40 parts of cellulose, 25 parts of amide and 23 parts of triethanolamine:

c: 1000 parts of sulphoaluminate cement, 500 parts of water, 1000 parts of fly ash, 1000 parts of beads with the particle size larger than 200 meshes, 50 parts of polycarboxylate water reducer, 600 parts of quartz sand, 200 parts of asbestos fiber, 80 parts of cellulose, 50 parts of amide and 45 parts of triethanolamine:

and fifthly, the underwater rapid hardening sealing mortar is prepared from the following raw materials in parts by weight:

a: 20 parts of monoammonium phosphate, 2 parts of magnesium oxide, 0.2 part of boric acid, 2 parts of cement, 2 parts of liquid sodium silicate, 1 part of redispersible emulsion powder and 3 parts of polyacrylamide;

b: 30 parts of monoammonium phosphate, 16 parts of magnesium oxide, 1.3 parts of boric acid, 16 parts of cement, 19 parts of 120-200 mesh quartz sand, 25 parts of metakaolin, 25 parts of fly ash, 4 parts of calcium sulfate, 12 parts of calcium silicate, 41 parts of liquid sodium silicate, 40 parts of redispersible emulsion powder, 26 parts of polyacrylamide and 25 parts of cellulose;

c: 40 parts of monoammonium phosphate, 30 parts of magnesium oxide, 2.5 parts of boric acid, 30 parts of cement, 38 parts of 120-200 mesh quartz sand, 50 parts of metakaolin, 50 parts of fly ash, 8 parts of calcium sulfate, 25 parts of calcium silicate, 80 parts of liquid sodium silicate, 80 parts of redispersible emulsion powder, 50 parts of polyacrylamide and 50 parts of cellulose;

a: 1000 parts of cement, 10 parts of polycarboxylate water reducer and 1kg/5m of difunctional phosphating rust remover ² ；

b: 1000 parts of cement, 250 parts of 5-10 cobbles, 1500 parts of sand, 250 parts of water, 500 parts of fly ash, 125 parts of migration rust inhibitor, 55 parts of polycarboxylate water reducer, 40 parts of liquid sodium silicate, 40 parts of redispersible emulsion powder, 25 parts of polyacrylamide, 25 parts of phosphoric acid, 25 parts of hexamethylenetetramine, 25 parts of cellulose and 1kg/5m of difunctional phosphating rust remover ² ；

c: 1000 parts of cement, 500 parts of 5-10 stones, 3000 parts of sand, 500 parts of water, 1000 parts of fly ash, 250 parts of migration rust inhibitor, 100 parts of polycarboxylate water reducer, 80 parts of liquid sodium silicate, 80 parts of redispersible emulsion powder,50 parts of polyacrylamide, 50 parts of phosphoric acid, 50 parts of hexamethylenetetramine, 50 parts of cellulose and 1kg/5m of difunctional phosphating rust remover ² 。

a: 100 parts of E44 epoxy resin, 2 parts of dibutyl phosphate, 2 parts of benzoate, 10 parts of egg white and 100 parts of flour;

b: 100 parts of E44 epoxy resin, 15 parts of phenolic amine, 16 parts of dibutyl phosphate, 16 parts of benzoate, 8 parts of styrene, 10 parts of acetone, 20 parts of egg white, 100 parts of flour and 50 parts of sulphoaluminate cement,

c: 100 parts of E44 epoxy resin, 30 parts of phenolic amine, 30 parts of dibutyl phosphate, 30 parts of benzoate, 16 parts of styrene, 20 parts of acetone, 30 parts of egg white, 100 parts of flour and 100 parts of sulphoaluminate cement,

the low-viscosity epoxy resin (the adjusting ratio can be used for underwater) is prepared from the following raw materials in parts by weight;

a: 100 parts of epoxy resin E-44, 2 parts of dibutyl phosphate, 2 parts of benzoate and 5 parts of styrene;

b: 100 parts of epoxy resin E-44, 21 parts of polyvinyl butyral, 20 parts of polyamide, 15 parts of phenolic amine, 16 parts of dibutyl phosphate, 16 parts of benzoate, 15 parts of alumina powder, 15 parts of styrene and 12 parts of xylene;

c: 100 parts of epoxy resin E-44, 42 parts of polyvinyl butyral, 40 parts of polyamide, 30 parts of phenolic amine, 30 parts of dibutyl phosphate, 30 parts of benzoate, 30 parts of alumina powder, 25 parts of styrene and 25 parts of xylene.

Claims

1. A method for repairing a hydraulic retaining wall with a tilting tendency on a post-wall structure without damage by water, which is characterized by comprising the following steps:

(1) Observing whether the retaining wall has a fracture, repairing the broken retaining wall integrally by adopting a method of anchoring and grouting sealing and bonding, and considering the influence of water on drilling, anchoring and bonding treatment on underwater or water conditions to ensure that the retaining wall forms a whole, wherein the concrete steps of repairing the integrity are as follows:

(1) the method comprises the steps of firstly drilling grouting holes, sealing the crack by using underwater quick setting sealing mortar, grouting to seal the crack, then performing dowel bar anchoring, and finishing anchoring by using the grouting holes, wherein the method is suitable for the condition that the broken part of a wall body is on water and grouting pressure is not large, because the material of the anchoring slurry is single, grouting the anchoring bar by using a grouting pipe after the grouting bar is inserted, pulling out the grouting pipe after the grouting body in a deep hole is full, sealing the crack for grouting, and observing grouting effect when the crack is sealed, completing grouting after the grouting achieves the design effect, sealing the vent by using epoxy resin sealing cement, and using low-viscosity epoxy resin slurry if the crack is smaller than 0.4 mm;

(2) Under the condition that water exists in the cracks, anchor holes are drilled first, the cracks are closed, the inserted bars are anchored, then the cracks are grouted and closed, because the pressure grouting is adopted in the drainage process, the original cracks are changed due to the pressure effect of grouting slurry, and the influence of the pressure on the wall body can be eliminated by grouting after anchoring;

(3) for the situation that the crack is positioned under water, grouting of the underwater closed crack is completed by embedding a grouting pipe or drilling a grouting hole and then performing pressure grouting, wherein the grouting process needs to eject underwater bonding slurry out of water in the crack by using grouting pressure, namely, the slurry is used for extruding water out of the crack, and the underwater bonding slurry is left in the crack;

(4) embedding grouting pipe method: the grouting method comprises the steps of firstly drilling an anchoring hole, then cleaning powder generated by drilling holes in a seam by using pressurized water, then inserting an anchoring rib, sealing a crack opening, simultaneously burying grouting needles at preset distances in sequence at the crack opening, leaving observation holes, sequentially and slowly and circularly grouting in sequence, fully grouting, and finishing grouting, wherein the grouting effect is evaluated through the observation holes, if grouting is too fast, water cannot be mostly discharged, most of water can be extruded out of the crack only by slowly, repeatedly and circularly pressing into the slurry, if the observation holes are filled with thicker slurry and the grouting pump pressure is fast increased, the grouting is fully described, sealing by using epoxy sealing cement, only the slurry is discharged, the observation holes can be sealed, grouting is continued, and the grouting is fully represented if the pressure is fast increased;

(5) Drilling and grouting hole method: firstly drilling an anchoring hole, then cleaning powder generated by drilling holes in a seam by using pressurized water, closing a slit opening, leaving a sequential drainage hole, then immediately inserting an anchoring rib after injecting underwater cement-based anchoring material slurry, drilling a grouting hole beside the anchoring hole after the anchoring slurry reaches the designed setting strength, grouting the grouting hole, and closing the drainage hole when the grouting pump reaches the designed pressure and the grouting process is completed when the grouting hole is seen to have thicker slurry flowing out;

(2) Determining the position of an anchor hole outside the wall and anchoring;

(1) for a retaining wall which can be excavated behind the wall and can clear up soil behind the wall, excavating the soil behind the wall, then tensioning and resetting the retaining wall by using an anchorage system, and then backfilling the soil; for retaining walls which have structures behind the walls or cannot be excavated for other reasons and cannot clear soil behind the walls, limited reset can be performed due to the action of passive soil pressure;

(2) for the condition that the foundation of the structure is shallower, the anchor hole is lower than the bottom surface of the structure, the anchor hole is 0.3-3.0 m below the ground line, the drilling machine drills holes horizontally from the outside to the inside of the retaining wall or at an angle smaller than 30 degrees with the horizontal angle, the adjacent drilling holes are parallel to each other, and the distance between the adjacent drilling holes is 1.5-6 m;

For the retaining wall capable of being completely reset, firstly cleaning the wall and then the soil body, and then arranging an anchorage system according to the condition after the soil body is cleaned;

(3) for a retaining wall which has no structure behind the wall and mainly generates an inclination trend due to the frost heaving force effect, the frost heaving force of the maximum section of the frost heaving gradient when the depth of the frost soil is 20-50 cm is utilized to form an internal anchoring effect, and an anchor hole is positioned 0.3-0.5 m below a ground line, so that the investment is saved and the construction progress is accelerated;

(3) For the condition that water exists in an anchor hole behind a wall and is a non-rock hole or a non-structure foundation, the drilling process is synchronous with the process of drilling an anchor rope, sleeving or grouting pipe, otherwise, the problem of hole collapse can occur to influence the construction process;

(4) For a grouted stone retaining wall, due to limited tensile property of the material and the action of passive soil pressure on the retaining wall, the concentrated action of tensioning prestress has a certain influence on the integrity of the retaining wall, when the retaining wall is restored, a pressure sharing structure is arranged at the prestress tensioning end of the retaining wall, and according to the concrete condition of the retaining wall, an X-shaped, ten-meter-shaped or straight-shaped pressure sharing structure is adopted, so that the pressure sharing structure can effectively share the concentrated pressure generated on the wall in the tensioning and debugging process to ensure that the integrity of the wall is not damaged, and the debugging process of gradually increasing the tensioning force for a plurality of times is adopted to enable the pressure sharing structure to meet the design requirement;

(5) Anchoring and sealing the anchor cable at the stretching end outside the retaining wall after stretching and debugging, and directly pouring concrete for sealing the anchor cable with the grouted stone retaining wall structure with the concrete protecting surface after anchoring; for a masonry retaining wall without concrete facing, the pressure sharing structure is of a steel structure, the corrosion prevention treatment of the pressure sharing structure is considered, then the rust-resistant mortar or the rust-resistant concrete is used for sealing anchors, and if the pressure sharing structure is in water, the underwater rust-resistant mortar is used for treatment;

20-40 parts of monoammonium phosphate, 2-30 parts of magnesium oxide, 0.2-2.5 parts of boric acid, 2-30 parts of cement, 0-38 parts of 120-200 meshes of quartz sand, 0-50 parts of metakaolin, 0-50 parts of fly ash, 0-8 parts of calcium sulfate, 0-25 parts of calcium silicate, 2-80 parts of liquid sodium silicate, 1-80 parts of redispersible emulsion powder, 3-50 parts of polyacrylamide and 0-50 parts of cellulose;

100 parts of E44 epoxy resin, 0-30 parts of phenolic amine, 2-30 parts of dibutyl phosphate, 2-30 parts of benzoate, 0-16 parts of styrene, 0-20 parts of acetone, 10-30 parts of egg white, 100 parts of flour and 0-100 parts of sulphoaluminate cement, and mixing the egg white, the flour and the sulphoaluminate cement with an epoxy resin material to form quick-setting cement with certain strength;

100 parts of epoxy resin E-44, 0-42 parts of polyvinyl butyral, 0-40 parts of polyamide, 0-30 parts of phenolic amine, 2-30 parts of dibutyl phosphate, 2-30 parts of benzoate, 0-30 parts of alumina powder, 5-25 parts of styrene and 0-25 parts of dimethylbenzene.

2. The method for repairing a hydraulic retaining wall with a tendency to tilt for a post-construction non-destructive wall according to claim 1, wherein: in the step (5), in order to ensure that the retaining wall is not damaged under the action of concentrated external force generated by large sudden tensioning, a pressure sharing structure is arranged at a tensioning end of the retaining wall, the pressure sharing structure type is arranged according to the calculation of the self bearing capacity of the retaining wall structure, an expanding type structure is adopted, the arrangement mode is arranged and installed according to the wall bearing capacity by adopting a prefabricated X, ten and meter type or a straight pressure sharing structure, tensioning and debugging are carried out after the pressure sharing structure is installed, gaps between channel steel and the retaining wall are filled in time by quick setting sealing mortar in the debugging process, the sealing is carried out by adopting rust blocking mortar after the debugging is completed, and finally, the pressure sharing structure is protected by adopting rust blocking concrete or mortar materials;

If the wall body is protected by a certain water depth, protecting the pressure sharing structure by adopting a rust-resistant underwater concrete or mortar material;

the construction sequence is that firstly, the water-based difunctional phosphating rust remover is used for removing rust, 1kg of material is used for every 5 square meters, the rust removal and limited time rust prevention functions can be finished, the pressure sharing structure is installed after the rust removal is finished, and the phosphating layer cannot disappear, namely cannot rust within 40 days after the rust removal by the phosphating rust remover, so that the pressure sharing structure cannot rust in the effective construction period.