Soil nailing is an in-situ soil reinforcement technology. Drilling holes in the in-situ slope of the excavated soil to insert different material, and then grouting along the full length of the hole to form a slender rod anchored in the soil. This is called the soil nail wall.
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Relying on the frictional resistance between the soil nail and the soil mass, it is passively stressed when the soil mass is deformed, and mainly bears the action of tensile force. The reinforced concrete surface layer is sprayed on the surface of the slope body, so that the soil between the surface layer and the soil nails is reinforced to form an in-situ retaining wall with self-stabilizing ability, thereby maintaining the stability of the excavation surface.
Many materials can be used as soil nails, such as threaded steel bars, hot rolled ribbed steel bars, finishing rolled rebar, steel strand, self-drilling hollow rock bolts, etc. Different materials have different characters.
For threaded steel bars, it has been proven that using the threaded steel bar as soil nails is very economical. Also, the threaded steel bar can be designed in different ways. However, it is inevitable that we need to drill a hole first and then put the threaded steel bar in, which results in a longer construction cycle for every single bar.
Finishing Thread Steel BarsSimilarly, using the hot-rolled ribbed steel bar as soil nails is also very economical. This technique is relatively more feasible for most geological conditions and it has been applied to many projects. But, the hot-rolled ribbed steel bar requires a more spacious space and more workers to process.
The steel strand is different from the above two kinds of steel bars. It consists of several steel wires and every wire could provide an ultimate load of 94.3 to 530kN. Therefore, the ultimate load of the steel strand is much higher than other materials. The disadvantage of the steel strand is that it needs to be made on-site, which will extend the whole processing time and lower the constructing efficiency.
Steel StrandThe self-drilling hollow rock bolt system is a new technique to support unstable conditions, which is composed of a hollow anchor bar, coupler, nut, drill bit, plate, and centralizer. It can combine drilling, grouting, and anchoring in one process. It is safe, efficient, convenient, and technically feasible for broken rock, loose soil, and geological conditions where is difficult to drill holes. It helps to ensure the anchoring effect in complex ground conditions and achieve the best construction result.
Sinorock divides our products into R thread and T thread systems. The sizes of the self-drilling rock bolt include R25, R32, R38, R51, T30, T40, T52, T73, T76, T103, T111, T127, T130, T150, and T200.
Self Drilling Hollow Rock BoltWhen using the self-drilling hollow rock bolts as soil nails, we have a couple of advantages that list below.
1. Hollow bolts are drill pipes, grouting pipes, and bolts, no grouting pipes or exhaust pipes are required, and the construction equipment is simple;
2. The full-length bonding and anchoring are closely combined with the surrounding rock and soil, and the pulling force bearing capacity is larger;
3. The force value range of common bolts is 200kN-7940kN, and the selection range is wide;
4. The product can meet temporary or permanent support (galvanized);
5. There are many types of drill bits, which are suitable for a wide range of strata (sand soil-IV and V-level surrounding rocks);
6. Fewer personnel are required during construction, only three people are required, and the labor cost is low;
7. It can be used in special strata or strata with unknown geological conditions, and the effect of pore formation and force value is better than other bars;
8. The disturbance to the stratum during the construction process is small;
9. Grouting during drilling can properly expand the hole diameter and improve the bearing capacity of the drawing force;
10. The impact on the surrounding environment is small during drilling and construction, and almost no pollution is produced.
One way or another, there are various soil nails that we can choose according to the different conditions and demands.
In the construction industry and geological exploration, the drill rod is an essential drilling tool, and its performance and use effect directly affect work efficiency and operation quality. The thread type of the drill rod, as a critical link in the design and manufacturing of the drill rod, has a non-negligible impact on the performance of the drill rod.
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A thread is a kind of helical structure. It is an important mechanical element and industrial component, playing an important role in the development of modern science and technology. It can connect, fix, and transmit force and is widely used in machining, construction, transportation, electronic equipment, and other fields.
The application of threads on drill rods is mainly on threaded extension rods, which are hollow circular or hollow hexagonal rods with connecting threads at both ends or one end of the rod and are also the main part of the threaded connection drilling tool. As thread types play a critical role in various industrial applications, different thread types are suitable for different application scenarios and provide solid and reliable connections and fastening effects. This article will introduce several common drill rod thread types and discuss their characteristics and scope of application.
The process of applying threaded connection forms to rock drilling tools has gone through many evolutions. In the form of threaded connections, conical pipe threads, old-style trapezoidal threads, and serrated threads have been adopted successively. Extension rod rock drilling, often using the shoulder seat energy transmission serrated thread. Before 1940, shoulder-seated energy-transferring drill bits were used in tunnel boring to connect to drill rods with 25.4mm 4-button lamp-seated threads. These thread forms were all eliminated because of small pitch, small pressure-bearing contact area, the high tendency of stress concentration, fast wear, low service life, fast energy loss, processing, and loading and unloading difficulties.
After 1950, the wave thread of the 25.4mm 2 buckles appeared. As the cross-section of the drill rod becomes wider, the helix angle becomes smaller, the pressure on the thread surface increases, and the loading and unloading are laborious. Therefore, it is generally only used when the thread diameter is less than or equal to 32mm. However, in a tunnel or drifting, because the drilling rock hole is not deep, generally do not need to extend the drill rod and is also used for threads with a diameter of 38mm. With the emergence of high-frequency, high-power rock drills, the thread deepened, and the pitch increased. After 1960, there was a large-lead antialiasing thread- HL thread. This thread form is made of a combination of serrations and arcs and is also known as a composite thread. Later, due to the emergence of hydraulic rock drills, in 1970, the Swedish Secoroc and Sandvik companies simultaneously proposed a new FI-type thread, commonly known as trapezoidal or T-shaped thread, mainly used for threaded connections with a diameter of more than 38mm.
In recent years, the S thread has emerged. It is also known as the C thread, a kind of double-head trapezoidal thread. The S-thread tooth angle and T thread are the same, but their pitch is larger than the T thread. Compared with the T thread, this thread has smaller torque for tightening and dismounting and a larger pressure-bearing and wear-resistant area. It is a more suitable thread connection structure for large-section thread extension drilling tools.
Corrugated threads are the longest-used, more mature, and most widely adopted thread structure in threaded extension drilling tools. Its structure and geometric dimensions have been revised many times and formally incorporated into ISO international standards and national standards of various countries. At the same time, it is the main form of thread structure in the range of medium and small cross-section rock drilling tools, and it is the thread type with more varieties, specifications, and quantities in the rock drilling tools, adapted to a broader range of rock drilling machine models and drilling applications.
Characteristics are as follows:
A. After surface strengthening treatment such as carburizing, it has sufficient wear resistance.
B. The loss of energy transfer is small.
C. The loading and unloading are more convenient.
D. It can be processed by a special lathe, and the manufacturing cost is low.
Since its appearance in 1960, the composite thread has been widely used for quite a long time and has been adopted in many national and regional rock drilling tools and ISO standards. It synthesizes the advantages of corrugated thread and serrated thread. The disadvantage is that the friction at the corner of the thread is too high, and the processing is quite difficult. The thread type is applied to larger-diameter thread connections and is becoming replaced by T threads.
Characteristics are as follows:
A. Large pressure area, high energy transfer efficiency.
B. Slow wear, large allowable wear amount, long service life.
C. Convenient loading and unloading.
Due to its stable helix angle, low tightening and unclamping torque, large pressure-bearing contact surface, and volume available for wear, it has excellent application performance and long drilling life. Therefore, it has gradually become the main threaded connection structure on the matching drilling tools for medium and large cross-section threaded connections.
In engineering applications, selecting the proper drill rod thread type is critical. Different thread types can meet different connection needs, thus ensuring the performance and safety of the equipment. With the continuous development of technology, threaded connection technology is also constantly innovating, providing more reliable and efficient connection solutions for various industries.
Choosing the right drill rod thread type is critical to ensuring a smooth drilling operation. When choosing, you need to consider the following factors:
In addition, when selecting a drill rod, it is also necessary to pay attention to its material, size, and accuracy requirements. High-quality drill rod material can improve the strength and wear resistance of the drill rod. Appropriate size and accuracy can ensure a good match between the drill rod and the drill bit and improve drilling efficiency.
Selecting the appropriate thread type is crucial for ensuring the performance and stability of the drill rod. In practical applications, it is necessary to comprehensively consider factors such as the operating environment, working conditions, and drill rod size to select the most suitable thread type.
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