Views: 0 Author: Site Editor Publish Time: 2025-10-20 Origin: Site
The 'Secret Weapon' of High-Rise Building Foundations
In today's world where city skylines are constantly being reshaped, skyscrapers spring up like bamboo shoots after rain. From bustling commercial centers in urban hubs to residential neighborhoods brimming with daily life, these towering structures are not only a testament to human ingenuity but also a symbol of modern societal development. Behind these magnificent edifices lies a crucial yet often overlooked component—the foundation construction. If skyscrapers are likened to giants, then the foundation is the "roots" of these giants, the bedrock upon which they stand firm.
The rotary drilling rig, as the "secret weapon" in the foundation construction of high-rise buildings, plays an irreplaceable and pivotal role. With its powerful capabilities and efficient performance, it has become a favorite in the modern construction engineering field. From early foundation projects to today's complex and diverse architectural endeavors, the rotary drilling rig is ubiquitous. Amid the fervor of urban development, whether in cramped downtown plots or expansive new development zones, its busy figure can be seen, laying a solid foundation for the construction of high-rise buildings.
Under certain soft soil geologica
l conditions, traditional drilling methods may encounter challenges such as borehole wall collapse and low drilling efficiency. However, rotary drilling rigs can easily overcome these difficulties thanks to their unique design and advanced technology. With precise pressure control and efficient drilling techniques, they can complete drilling operations quickly and stably, significantly improving construction efficiency and providing strong support for subsequent pile foundation construction. At construction sites, the working scene of rotary drilling rigs is truly impressive. The massive machine stands firmly on the ground, while the long drill rod resembles a steel dragon, plunging straight into the earth. As the engine roars, the drill rod spins rapidly, and the drill bit continuously cuts through soil and rock, gradually bringing them to the surface. Each drilling and lifting operation feels like a contest of strength with the earth, showcasing the formidable power of rotary drilling rigs.
Next, let's delve into the key construction points and quality control measures of rotary drilling rigs in high-rise building foundation construction, unveiling the secrets behind their efficient and high-quality performance.
Venue and Equipment Preparation
Before the operation of a rotary drilling rig, site leveling is the top priority. The construction site must be solid and level to ensure the stable operation of the rotary drilling rig during the work process. If the site is a soft soil foundation, reinforcement measures must be taken, such as laying steel plates or crushed stone layers. For instance, when working in soft soil areas like wetlands or rice fields, a layer of crushed stone about 30 - 50 centimeters thick can be laid first, followed by the placement of steel plates to build a stable working platform for the drilling rig. Site leveling not only concerns the stability of the equipment but also enhances construction efficiency and reduces equipment wear and construction risks caused by uneven sites. Please provide the text you would like translated.
Surveying and setting out is a crucial step to ensure the accuracy of pile positions. Based on the design drawings, precise surveying and setting out of pile positions are carried out using total stations and other surveying instruments. Wooden stakes are driven into the center of each pile position, with small iron nails nailed on top as markers. At the same time, protective stakes are set up, usually no less than four and placed 1 to 2 meters away from the center of the pile positions, in a cross or square pattern. The function of the protective stakes is to facilitate the checking of pile position deviations during construction at any time, ensuring the accuracy of the pile positions and providing precise location references for subsequent drilling operations. Please provide the text you would like translated.
Equipment inspection and commissioning play a decisive role in the normal operation of rotary drilling rigs. A comprehensive inspection of the rotary drilling rig should be carried out, covering whether the mechanical components are firmly connected, whether the power system and hydraulic system are working normally, and the wear condition of the drill pipe and drill bit, etc. Commission the performance parameters of the drilling rig, such as rotational speed and torque, to ensure that the equipment can operate normally. During the inspection process, it is particularly important that the verticality adjustment device of the drill pipe is flexible and accurate, because the verticality of the drill pipe has a great impact on the quality of the pile. Only equipment that has undergone strict inspection and commissioning can perform at its best during construction and ensure the smooth progress of the project.
Material and Personnel Preparation
The preparation of materials such as mud, steel bars and concrete is an important task before construction. Mud is generally composed of bentonite, water and additives. When drilling in easily collapsing soil layers or areas rich in groundwater, mud plays a crucial role in protecting the hole wall. The ratio of bentonite to water can be adjusted according to geological conditions and construction requirements, usually around 1:6 - 1:8. The prepared mud is delivered to the hole through a mud pump, forming a mud skin on the hole wall to protect it. During the drilling process, the performance of the mud, such as specific gravity, viscosity and sand content, should be monitored at all times. The specific gravity of the mud is generally controlled between 1.1 - 1.3, the viscosity between 18 - 25 seconds (funnel viscosity), and the sand content should not exceed 4%. If the performance of the mud does not meet the requirements, it should be adjusted in time.
The quality and specifications of steel bars must comply with design requirements. During the manufacturing process at the construction site, they should be straightened, cut and bent into shape strictly in accordance with the design requirements. Main bars are generally connected by welding or mechanical connection, and stirrups are connected to the main bars by binding or spot welding. To ensure the rigidity of the steel cage, a reinforcing stirrup is set every 2 - 3 meters. The dimensions of the steel cage should comply with the design requirements, with allowable deviations generally being: main bar spacing ±10 mm, stirrup spacing ±20 mm, steel cage diameter ±10 mm, and steel cage length ±50 mm.
Concrete should have good workability and fluidity, with a slump generally controlled between 18 - 22 cm. Before pouring concrete, it is necessary to ensure the accuracy of the concrete mix ratio and the quality of raw materials.
Personnel training and qualification review are important factors in ensuring construction quality and safety. Operators must undergo professional training, be familiar with the performance and operation methods of rotary drilling rigs, and master construction techniques and quality standards. At the same time, the qualifications of operators should be strictly reviewed to ensure they have the corresponding operation qualifications. Only personnel with professional knowledge and skills can accurately operate the equipment and strictly follow the specifications during construction, thereby ensuring construction quality and safety. In some large-scale construction projects, construction units will regularly organize operators for training and assessment to continuously improve their professional level and operation skills, providing a strong guarantee for the smooth progress of the project.
The positioning of the drilling rig and the drilling process
The positioning of the drilling rig is a crucial initial step in the construction process of rotary drilling rigs. The operator needs to precisely move the rotary drilling rig above the pile position. By adjusting the outriggers and the chassis of the drilling rig, the center of the turntable should be perfectly aligned with the center of the pile position. During this process, a level is used to carefully adjust the chassis of the drilling rig to be level, ensuring that the drill pipe is in a vertical state. The deviation of the drill pipe's verticality must be strictly controlled within 1%. Just like in the calibration of precision instruments, every minor adjustment is related to the quality and accuracy of the subsequent construction. In some construction projects with extremely high requirements for verticality, construction personnel will use advanced laser measurement technology to monitor the verticality of the drill pipe in real time. Once any deviation is detected, immediate adjustments are made to ensure that the verticality of the drilled hole meets the design requirements. Please provide the text you would like translated.
Drilling techniques vary significantly under different geological conditions. When drilling in soil layers, since the soil is relatively soft, rotary bucket drill bits can be selected. After starting the drilling rig, slowly lower the drill bit to the ground and then start drilling. During the drilling process, flexibly control the drilling speed and pressure according to the hardness of the soil layer. In soft soil layers, the drilling speed can be appropriately increased to improve construction efficiency; while in hard soil layers, the speed should be slowed down and the drilling pressure increased to ensure that the drill bit can smoothly cut through the soil layer. When encountering sandy soil layers, due to the low cohesion between sand particles, there is a risk of hole collapse. At this time, the drilling speed should be appropriately reduced and the mud's wall protection effect enhanced to ensure the stability of the drill hole. Please provide the text you would like translated.
When drilling holes in rock strata, the situation becomes more complicated. It is necessary to select the appropriate drill bit based on the hardness and characteristics of the rock strata, such as cone bits or pick bits, etc. For harder rock strata, the drilling pressure and torque should be increased while the drilling speed should be slowed down to prevent excessive wear or damage to the drill bit. During the drilling process, closely monitor the working status of the drilling rig, such as the verticality of the drill pipe, the drilling speed, and the flow rate of the mud, etc. Once any abnormality is detected, immediately stop the drilling, analyze the cause and take corresponding measures. When drilling through weathered rock strata, due to the relatively high hardness of the rock strata, the drilling speed may significantly decrease. At this time, it is necessary to increase the torque of the drill bit and adjust the performance of the mud to enhance its ability to carry cuttings, ensuring the smooth progress of the drilling.
Slurry Walling and Hole Cleaning
Slurry walling plays a crucial role in rotary drilling machine construction, especially in formations prone to collapse, such as sandy or silty layers. Slurry walling is indispensable in such cases. The main function of slurry is to form a layer of mud on the hole wall, balancing the pressure inside and outside the hole wall and preventing hole wall collapse. At the same time, slurry also has the functions of carrying debris, cooling, and lubricating the drill bit, which helps improve drilling efficiency and protect the drill bit.
The preparation method of slurry is relatively crucial. Generally, it is prepared by mixing bentonite, water, and additives in a certain proportion. The ratio of bentonite to water is usually around 1:6 - 1:8, which can be adjusted according to geological conditions and construction requirements. The types and amounts of additives also need to be determined based on actual circumstances. Common additives include soda ash and cellulose, which can improve the performance of slurry, such as increasing the viscosity of slurry and reducing the loss of water. When preparing slurry, first add water to the mixing bucket, then gradually add bentonite, mix evenly, then add additives, and continue mixing until the slurry reaches the specified performance indicators. The prepared slurry is transported to the hole through a slurry pump, and during the drilling process, the performance of the slurry should be regularly tested, such as specific gravity, viscosity, and sand content, and the performance of the slurry should be adjusted according to the test results.
Hole cleaning is an important step in rotary drilling machine construction, divided into the first hole cleaning and the second hole cleaning (if necessary). After the hole reaches the designed depth, the first hole cleaning is required. Raise the drill bit to a certain distance from the bottom of the hole, generally 0.2 - 0.3 meters, and clean the hole using either the forward circulation or reverse circulation method. Forward circulation cleaning involves using the slurry pump to press the slurry from the center of the drill pipe into the bottom of the hole, carrying the sediment out from the hole mouth; reverse circulation cleaning involves using vacuum pumps and other equipment to extract the slurry and sediment from the bottom of the hole through the drill pipe, and the slurry is replenished from the hole mouth. During the hole cleaning process, the flow rate and flow velocity of the slurry should be strictly controlled to avoid disturbing the hole wall. During the first hole cleaning, the thickness of the sediment at the bottom of the hole and the performance of the slurry should meet the design requirements. For friction piles, the sediment thickness is generally no more than 30 centimeters; for end-bearing piles, the sediment thickness is generally no more than 5 centimeters. The specific gravity of the slurry is generally controlled between 1.1 - 1.3, and the viscosity is controlled between 18 - 25 seconds (funnel viscosity), with a sand content of no more than 4%.
After the reinforcement cage and conduit are installed, a second hole cleaning may be required. This is because during the installation of the reinforcement cage and conduit, new sediment may fall into the bottom of the hole. The second hole cleaning method is similar to the first one, and the main purpose is to ensure that the sediment thickness at the bottom of the hole meets the design requirements, creating favorable conditions for the subsequent concrete pouring. During the second hole cleaning, the sediment thickness and slurry performance at the bottom of the hole should be strictly tested, and only when all indicators meet the requirements can the concrete pouring be carried out.
Fabrication and Installation of Reinforcement Cage
The fabrication of steel cages is a meticulous task, as its craftsmanship and quality standards directly impact the load-bearing capacity of pile foundations. When manufacturing at the on-site processing area, the reinforcement bars must be strictly straightened, cut, and bent according to design specifications. The main bars are typically welded or mechanically connected to ensure joint strength. During welding, the welds must be fully formed without defects such as incomplete fusion, slag inclusion, or other flaws. For mechanical connections, appropriate connecting sleeves should be selected to ensure secure fastening. The stirrups and main bars are connected by binding or spot welding. Binding requires tightening the binding wire, while spot welding demands precise control of current and welding time to prevent burning the reinforcement bars.
To ensure the stiffness of the reinforcement cage, a reinforcing hoop is installed every 2 to 3 meters. The diameter and spacing of the reinforcing hoops must comply with the design requirements, as they enhance the overall stability of the cage and prevent deformation during transportation and installation. During the fabrication of the reinforcement cage, it is essential to control dimensional accuracy. The allowable deviations are ±10 mm for the spacing of main reinforcement bars, ±20 mm for the spacing of stirrups, ±10 mm for the diameter of the reinforcement cage, and ±50 mm for the length of the reinforcement cage. The completed reinforcement cage must undergo strict quality inspection to ensure all specifications meet the design requirements.
The installation of the reinforcement cage involves accurately placing the prefabricated cage into the borehole. Using a crane, the cage is lifted and slowly lowered into the hole. During this process, special attention must be paid to the vertical alignment of the cage to ensure it is lowered vertically and avoid contact with the borehole wall. Any collision between the cage and the wall could lead to wall collapse and compromise the quality of the pile foundation. For longer cages, a segmented fabrication and installation approach is employed, with sections connected inside the borehole. When splicing, the quality of the main reinforcement connections must be ensured, with no more than 50% of the total main bars having joints in the same cross-section, and these joints should be staggered to maintain the load-bearing performance of the cage. Additionally, positioning bars are installed at the top of the cage to align its center with the pile position, ensuring precise placement within the borehole.
Concrete pouring
Concrete pouring is the final critical step in the construction process of rotary drilling rigs, where the procedures and requirements directly impact the quality and load-bearing capacity of the pile foundation. Prior to pouring, the installation of the conduit is a crucial preparatory task. The conduit is typically made of steel pipe, with a diameter ranging from 20 to 30 centimeters. Before use, the conduit must undergo trial assembly and airtightness inspection to ensure secure connections and prevent leakage. The conduit is slowly lowered into the borehole, with its bottom positioned 0.3 to 0.5 meters above the hole floor. This distance ensures smooth concrete pouring while preventing the conduit's base from being clogged by sediment. The upper part of the conduit is connected to the concrete pouring equipment via a funnel, forming a complete pouring system.
The concrete should possess good workability and fluidity, with a slump generally controlled between 18 to 22 centimeters. This slump ensures smooth flow of concrete during pouring, filling all corners of the hole, and guaranteeing the compactness of the pile foundation. During pouring, fill the hopper with concrete first, then open the valve to allow the concrete to be discharged through the guide pipe into the hole bottom. This process must ensure continuous pouring without interruption, as any interruption may lead to defects such as segregation or slag inclusion in the concrete, affecting the quality of the pile foundation. As the concrete is poured, the guide pipe should be gradually raised, but the depth of the pipe embedded in the concrete should be maintained between 2 to 6 meters. If the pipe is embedded too deeply, it may become difficult to withdraw; if embedded too shallow, mud slurry may mix with the concrete, compromising its quality. Throughout the pouring process, close attention must be paid to the concrete's pouring height and the depth of the guide pipe. By measuring the rising height of the concrete surface, the lifting height of the guide pipe should be adjusted promptly to ensure smooth progress of the pouring process.
When pouring concrete to the top of the pile, an over-pour of 0.5 to 1 meter is required to ensure the quality of the pile top concrete. During the pouring process, the concrete at the pile top may be affected by impurities such as mud, leading to reduced strength. By over-pouring to a certain height, the floating slurry and low-strength concrete at the pile top can be chiseled off in subsequent construction, ensuring the pile top concrete meets the design strength requirements. After pouring, promptly clean the conduit, funnel, and other equipment to prepare for the next pouring.
The Importance of Quality Control
The significance of quality control for the stability of the foundation of high-rise buildings is self-evident. The foundation of a high-rise building is like the foundation of a person, and the construction quality of the rotary drilling rig is the key factor determining whether this foundation is stable. Once there are problems with the construction quality, the bearing capacity and stability of the foundation will be greatly reduced, thereby causing a series of serious consequences. For example, uneven settlement of the foundation may lead to cracking, tilting, or even collapse of the building walls, seriously threatening the safety of people's lives and property. In some areas with frequent earthquakes, substandard foundations are more likely to be damaged under the action of earthquakes, causing greater losses to high-rise buildings. Therefore, strictly controlling the construction quality of the rotary drilling rig is the basis for ensuring the safety and reliability of high-rise buildings, and is an important manifestation of being responsible to society and the people.
Quality control measures
Personnel training and management are the fundamental aspects of quality control. Operators must undergo strict professional training, familiarize themselves with the performance, operation methods, construction techniques, and quality standards of rotary drilling rigs. The construction unit should regularly organize skill training and assessment for operators to continuously improve their professional level. At the same time, strengthen the daily management of operators, establish a sound assessment system, reward personnel with standardized operation and strong quality awareness, and punish personnel who violate regulations or neglect quality, in order to motivate operators to improve construction quality. In some large-scale construction projects, construction units also invite experts for on-site guidance and training, providing opportunities for operators to learn and communicate, and continuously improving their professional competence.
Equipment maintenance and management are important guarantees for ensuring construction quality. Regularly conduct comprehensive inspections and maintenance of rotary drilling rigs, including lubrication and fastening of mechanical components, inspection and maintenance of power and hydraulic systems, as well as wear detection and replacement of drill rods and bits. During the construction process, monitor the operation status of the equipment in real time. If any abnormal situation is found, immediately stop the machine for inspection, troubleshoot, and then continue construction. Establish equipment maintenance records, detailing the maintenance status and fault repair records of the equipment, in order to timely understand the operation status of the equipment and provide a basis for equipment maintenance and updates. On some long-term use rotary drilling rigs, problems such as hydraulic system oil leakage and drill pipe bending are prone to occur. Through regular maintenance and inspection, these problems can be detected and solved in a timely manner to ensure the normal operation of the equipment.
Material quality control is a key factor in ensuring construction quality. Strictly inspect the quality of raw materials such as mud, steel bars, and concrete to ensure that they meet design requirements and relevant standards. The performance indicators of mud, such as specific gravity, viscosity, sand content, etc., must meet the construction requirements to ensure the effectiveness of mud wall protection. The material, specifications, and dimensions of the steel bars must meet the design requirements. During the processing and installation process, the welding quality and connection strength of the steel bars must be strictly controlled. The mix proportion of concrete should be accurate, and the quality of raw materials should be stable to ensure that the concrete has good workability, fluidity, and strength. At the construction site, specialized material inspection personnel should be set up to inspect each batch of incoming raw materials, and unqualified materials must not be used.
Construction process control is the core link to ensure construction quality. During the construction process of the rotary drilling rig, strict adherence to the construction process requirements is required, such as the accuracy of the drilling rig's positioning, the verticality of the borehole, the quality of the mud wall protection, the effectiveness of hole cleaning, the production and installation of steel cages, and the continuity of concrete pouring. Establish a sound construction process quality control system, strengthen quality inspection and acceptance of each process, and only proceed to the next process after the previous process is qualified. During the construction process, it is necessary to promptly record construction data and quality inspection results in order to trace and analyze the construction quality. Under some complex geological conditions, optimizing construction techniques such as adjusting drilling parameters and improving mud formulations can effectively improve construction quality and ensure the stability of pile foundations.
Common Quality Issues and Solutions
Sinkholes are one of the common quality problems encountered in rotary drilling machine construction. The main reasons include complex geological conditions, such as in sandy or silty layers where the soil's own stability is poor; poor mud performance, such as too low mud specific gravity and insufficient viscosity, which cannot effectively protect the hole wall; excessive drilling speed causing excessive disturbance to the hole wall; high groundwater level, which exerts a large water pressure on the hole wall, etc. To address sinkholes, the following solutions can be adopted: improve mud performance by appropriately increasing the mud specific gravity and viscosity to ensure effective hole wall protection; during drilling, control the drilling speed according to the geological conditions, slow down the speed in loose layers; if the groundwater level is too high, take measures such as setting well points for water drainage; for the parts that have already developed sinkholes, if the sinkhole is not severe, use high-quality mud to re-protect the hole wall and continue drilling; if the sinkhole is severe, backfill and drill a new hole.
Shrinkage is also a possible problem in rotary drilling machine construction. The main reasons include poor mud performance, excessive water loss, causing the plastic soil layer to absorb water and expand, or forming a loose, honeycomb-like thick layer of mud skin; improper spacing between adjacent piles during construction, and stress in the soil layer has not yet dissipated, causing the new hole wall to be soft soil flow; excessive wear of the drill bit diameter, etc. To solve the shrinkage problem, the following methods can be adopted: use high-quality mud, control the mud specific gravity and viscosity, and reduce water loss; reasonably arrange the sequence and spacing of adjacent pile construction to avoid stress concentration in the soil layer; regularly inspect and replace worn drill bits to ensure the drill bit diameter meets the design requirements; for parts that have already developed shrinkage, if the sinkhole is not severe, use a high-quality mud to re-protect the hole wall and continue drilling; if the sinkhole is severe, backfill and drill a new hole.
Rising of the steel cage is a possible problem during concrete pouring. The main reasons include short initial and final concrete setting times, early formation of concrete lumps in the hole, when the concrete surface from the pipe is lifted to the bottom of the steel cage, the continued pouring of concrete forms a lump that lifts the steel cage; during cleaning the hole, there are too many suspended sand particles in the hole mud, during concrete pouring, these sand particles sink to the surface of the concrete, forming a relatively dense sand layer, and as the hole mud surface gradually rises, when the sand layer contacts the bottom of the steel cage, it lifts the steel cage; when the concrete is poured to the bottom of the steel cage, the pouring speed is too fast, causing the steel cage to rise; the steel cage at the hole opening is not firmly fixed, etc. To prevent the steel cage from rising, the following measures can be taken: control the mix ratio and pouring speed of the concrete to ensure that the initial and final concrete setting times meet the requirements; thoroughly clean the hole to reduce the suspended sand particles in the hole mud; during concrete pouring to the bottom of the steel cage, slow down the pouring speed; fix the steel cage opening firmly, increase the stability of the steel cage; weld inverted spurs on the main steel bars of the steel cage or add counterweights to prevent the steel cage from rising. If the steel cage has already risen, immediately stop the pouring and accurately calculate the pipe burial depth and the height of the poured concrete, when removing the pipe, it must be removed before pouring, try to make the rising steel cage return to the original height; or within the maximum limit of pipe lifting, quickly lift and slowly lower, repeat several times to see if the rising steel cage can return to the original height. When dealing with the problem of rising steel cage, it is necessary to be timely and decisive to avoid the problem from further deteriorating and affecting the quality of the pile foundation.
Rotary drilling rigs play a crucial role in the construction of the foundations of high-rise buildings due to their unique advantages and efficient operation capabilities. From the meticulous preparation of the construction site, equipment, materials, and personnel before the project, to the strict control of each step including the positioning and drilling of the rig, the protection of the hole with mud, the fabrication and installation of the steel cage, and the pouring of concrete during the construction process, every step is closely related to the quality and safety of the foundation construction. Through comprehensive quality control of personnel, equipment, materials, and construction techniques, common problems such as hole collapse, reduced diameter, and floating of the steel cage can be effectively prevented and solved, ensuring the stability and bearing capacity of the foundation of high-rise buildings.
With the continuous advancement of technology and the continuous development of the construction industry, the application prospects of rotary drilling rigs in the construction of the foundations of high-rise buildings will be even broader. On one hand, the technology of rotary drilling rigs will continue to innovate and upgrade, moving towards the direction of intelligence, automation, and environmental protection. Intelligent control systems will enable rotary drilling rigs to automatically adjust drilling parameters according to geological conditions, improving construction efficiency and quality; automated operation methods will reduce manual intervention, lower labor intensity, and enhance construction safety; more environmentally friendly materials and production processes will reduce environmental impact and meet the requirements of sustainable development. On the other hand, with the acceleration of urbanization and the continuous advancement of infrastructure construction, the demand for high-rise buildings will continue to grow, providing more application opportunities for rotary drilling rigs. In future construction projects, rotary drilling rigs will continue to play an important role, providing solid foundation guarantees for the construction of high-rise buildings and helping urban construction reach new heights.
