The anchor bolt of the equipment bears all the weight of the equipment and the dynamic load between operation and the wind, rain, snow and other loads in nature, as well as the unexpected load such as earthquake, which plays a very important role in the life and operation safety of the equipment.

With the rapid development of China's national economy, all kinds of large-scale new industrial equipment installation and large steel structure plant continue to increase, all kinds of foundation (especially equipment foundation) anchor bolts usually use embedded anchor bolts or reserved anchor bolt holes, the foundation of such buildings embedded bolts specifications, large number and high construction accuracy requirements. Once the large deviation of individual bolt embedment occurs, it will directly affect the normal installation and debugging of various equipment. The anchor bolt of the equipment bears all the weight of the equipment and the dynamic load between operation and the wind, rain, snow and other loads in nature, as well as the unexpected load such as earthquake, which plays a very important role in the life and operation safety of the equipment. The following is a combination of some engineering examples to describe the construction of large equipment foundation bolts and reserved holes.

Anchor bolt design:
Anchor bolts are generally made of Q235 steel. In order to facilitate processing and installation, anchor bolts should be standardized and customized as far as possible.
Anchor bolts are divided into dead bolts and live bolts:
There are three types of anchoring for dead bolts:
1) One-time embedding method: When pouring concrete, the bolt is buried.
2) Reserved hole method: When pouring foundation concrete, leave holes in advance, and then put bolts into the holes, and fix them with non-shrinkage fine stone concrete or fine stone concrete.
3) Drilling anchoring method: When the foundation concrete is poured and reaches a certain strength, check the bolt diameter, installation position, top elevation and other equipment, and then drill holes according to the bolt diameter and buried depth requirements, inject epoxy mortar or other cementing materials into the holes, and insert straight bolts, and install the equipment after a certain curing period.
Dead bolts have the following types: straight rod bolt Bent hook bolt Anchor plate bolt
The structure of the live bolt is that the screw passes through the casing buried in the foundation, and the lower end is fixed with a T-shaped head, a fixing plate or a nut. The upper end of the casing is covered with oil-impregnated hemp wire within 200mm.
The distance between the center line of the anchor bolt and the edge of the foundation is not less than 4d and not less than 100mm. For live bolts, the distance between the hole edge of the reserved hole and the edge of the foundation is not less than 100mm. If not, take reinforcement measures.
When the equipment foundation elevation requirements are accurate and the foundation is not allowed to have differential settlement, the screw thread length of the anchor bolt should be increased (that is, the top of the bolt elevation is increased). Generally, the soil foundation should be extended by 10 ~ 30mm. For soft soil foundation, in addition to increasing the screw thread length, the top of the foundation elevation should be increased according to the subsidence of the foundation, and the increase value can be determined by calculation or practical experience.
Anchor bolt construction:
Construction code GB50204-2002 Concrete structure engineering construction quality acceptance code stipulates that the equipment foundation embedded anchor bolt and embedded anchor bolt hole and embedded movable anchor bolt anchor plate allowable deviations are as follows, this construction method draws on the experience of mechanical and metallurgical industry in precision control, A high-precision special fixture is made to control the embedded anchor bolts of each group of equipment foundation. Because the construction of the anchor bolts of this construction method adopts the precise pre-embedding in place, and then pouring concrete. Compared with the chemical anchor, the cost is greatly reduced and the construction period is shortened. The construction method has the advantages of reliable technology, high construction precision, easy to understand, master and easy to operate.
1. Scope of application
This construction method applies to the design accuracy index range of anchor bolts:
"The center displacement between bolts in the same bolt group: ≤2mm, the top elevation deviation of bolts in the same bolt group: ≤2mm, the exposed length deviation of bolts: 0-2mm", and the embedded construction of anchor bolts with large specifications and a large number of bolts.
2. Process principle
The main technology of the construction method is according to the design drawings, according to the basic type of production of several sets of high-precision special fixture, high-precision special fixture according to the requirements of the design drawings, the use of 8# channel steel four sides welded into one, according to the different requirements of the bolt holes in the construction drawings on the channel steel holes.
The precision of the anchor bolts required by some equipment is also higher. Generally, in the construction of large-scale equipment foundation, the anchor bolt construction is controlled as a key process. In order to ensure the construction accuracy and complete the construction economically and quickly, we need to start from the following aspects.
The traditional installation method of the equipment is to set aside the position of the anchor bolts in advance when the foundation is poured, install the anchor bolts after the equipment is hoisted in place, perform secondary grouting of the concrete, maintain and solidified for 1 to 2 weeks according to different ambient temperatures, and verify the equipment level, install and tighten the anchor bolts when they reach the predetermined strength. Secondary grouting curing takes a long time. The new technology of Hilti's HAS chemical adhesive bolt and HVU chemical adhesive tube is adopted, which can be installed quickly, fast and firmly, without the need for secondary grouting of concrete, and effectively shorten the installation period of equipment.
The new equipment installation process is: First, lay the designed foundation without reserving anchor bolt positions, and directly install the device in place. According to the HAS anchor bolts of different specifications, select impact drill bits with different diameters (see Table 1 for specifications), adjust the depth limit of percussion drilling according to the drilling depth, and drill holes directly on the foundation where anchor bolts are installed. Then, the matching cleaning brush and high pressure air are used to clean the dust in the hole. After cleaning, the HVU chemical adhesion agent tube is placed in the hole, the HAS bolt is held on the drill chuck of the electric hand drill through the special chuck, and the HVU chemical adhesion agent tube is screwed into the predetermined depth. According to the ambient temperature, curing 20min~5h (see Table 2), the equipment can be adjusted horizontally.
Treatment method of anchor bolt deviation:
The embedment of anchor bolts directly affects the installation quality of equipment. Some equipment has strict requirements for the accuracy of elevation and position, especially linkage equipment with a high degree of automation, which requires more stringent requirements. Therefore, the anchor bolts must be inspected and corrected after they are buried and before the equipment is installed. When the deviation occurs, it should be handled according to the actual situation of the equipment, using different treatment methods, generally common treatment methods are as follows:
(1) Treatment of center deviation of anchor bolt
When the diameter of the anchor bolt is less than 30mm and the center line is offset within 30mm, the bolt can be roasted red with oxyacetylene, and then bent with a sledgehammer (or bent with a jack). After correction, the bolt should be soldered with a steel plate to prevent the bolt from recovering when tightened.
If the spacing of the bolts is not correct, it can be bent with a sledgehammer after the oxygen acetylene flame is roasted, and the steel plate is welded in the middle to strengthen it, and it is filled when the grout is later.
For large bolts (diameter of more than 30mm) when there is a large deviation, the bolt should be cut off and welded with a steel plate in the middle of the bolt. If the bolt strength is not enough, two reinforced steel plates can be welded on both sides of the bolt, and the length shall not be less than 3 to 4 times the diameter of the bolt.
(2) Treatment of elevation deviation of anchor bolts
1. When the bolt is too high, the higher part must be cut off and then threaded. When threading, it is necessary to prevent oil substances from dripping onto the concrete foundation and affecting the quality of the foundation.
2. When the bolt is low and the deviation value is not large (within 15mm), oxygen acetylene can be used to roast the bolt red, and then elongate it. The method of elongating is to use two stacks of cushion plates as supports, and then a steel plate with a hole in the middle is set on the anchor bolt on the top frame, and the nut is tightened on the top, and the bolt is stretched in the red with the help of the power of tightening the nut. Two to three steel plates must be welded to reinforce the diameter of the bolt. If the equipment has been placed on the foundation is inconvenient to move, in the case of sufficient strength of the base flange, you can directly tighten the nut on the base to lengthen the bolt. When screwed to the appropriate length, the nut must be loosened to avoid excessive tension after the bolt is cooled, and even fracturing the base flange.
If the bolt is too low (lower than its required height of 15mm), can not be stretched by heating method, can dig a deep hole around the bolt, about 100mm from the bottom of the pit to cut off the bolt, and weld a newly made bolt, elevation to meet the requirements, and then reinforced with round steel. The length of reinforced round steel is generally 4 to 5 times the diameter of the bolt.
(3) Treatment of loose anchor bolts in the foundation
When you tighten the anchor bolt, the bolt may be pulled out. In this case, adjust the bolt to the original position, shovel out enough foundation around the bolt, weld two horizontal and horizontal U-shaped steel bars on the bolt, and finally clean the pit with water and grouting, and tighten the nut after the concrete solidified to the designed strength.
(4) Handling of deviations of live anchor bolts
The treatment method of the deviation of the live anchor bolt is roughly the same as that of the dead anchor bolt, except that the anchor bolt can be pulled out for treatment. If the bolt is too long, a section can be cut off on the machine tool and then set the thread; If the bolt is too short, it can be extended by hot forging. If the position does not match, use bending method to correct.