Views: 0 Author: Site Editor Publish Time: 2026-04-21 Origin: Site
In the construction of foundation piles in infrastructure projects, rotary drilling rigs have become mainstream construction equipment due to their advantages of efficient drilling, precise positioning, and strong adaptability. They are widely used in various scenarios such as highways, bridges, high-rise buildings, and prefabricated building foundations. The rationality of the drilling process directly determines the construction efficiency, drilling quality, and engineering cost, while the physical and mechanical properties of different geological conditions (soft soil, sand layer, hard rock, etc.) vary significantly, which puts forward different requirements for the drilling parameters, drilling tool selection, and operation process of rotary drilling rigs. At present, some construction projects often encounter problems such as drilling lag, hole wall collapse, low efficiency, and excessive consumption of consumables due to the lack of optimization of drilling technology based on geological characteristics, which restricts the progress and construction efficiency of the project. This article combines the current background of the pile foundation construction industry and, based on different geological types, outlines the optimization path and efficiency improvement plan for the drilling process of rotary drilling rigs, helping construction enterprises overcome drilling bottlenecks and achieve efficient, high-quality, and low-cost construction.
The core prerequisite for optimizing the drilling process of rotary drilling rig is to accurately grasp the geological conditions of the construction area and avoid efficiency loss and quality hazards caused by blind construction. In the early stage of construction, a comprehensive geological survey should be carried out to clarify the core parameters such as geological stratification, density, moisture content, compressive strength, and particle size distribution of each layer of soil/rock through drilling sampling, in-situ testing, etc. Different geological sections such as soft soil, sand layer, cohesive soil, weathered rock, and hard rock should be divided, and a detailed geological survey report should be drawn. At the same time, based on the requirements of engineering design (hole diameter, depth, verticality), potential problems that may occur during construction (such as sand layer collapse, slow drilling in hard rock, shrinkage of soft soil diameter, etc.) are predicted, providing scientific basis for subsequent drilling tool selection, parameter adjustment, and process optimization. If the geological survey is not accurate, it can easily lead to a mismatch between drilling tools and geology, unreasonable drilling parameters, which not only reduces drilling efficiency, but also may cause safety hazards such as hole wall collapse and substandard pile quality, increasing rework costs and project delay risks.
The core characteristics of soft soil geology (such as silt, silty soil, silty clay, etc.) are high water content, low bearing capacity, and poor stability. During drilling, problems such as hole wall collapse, diameter reduction, and buried drilling are prone to occur. Moreover, excessive drilling speed can lead to irregular hole shapes, affecting the quality of borehole formation. For soft soil geology, the optimization of drilling technology focuses on wall protection and drilling parameter control, achieving both efficiency and quality improvement. In terms of drilling tool selection, it is preferred to use long spiral drill rods combined with double bottom sand scoop buckets. The double bottom sand scoop buckets have good sealing and high soil discharge efficiency, which can reduce the residual soft soil in the drill bucket and avoid secondary cleaning; Simultaneously equipped with protective casing, according to the thickness and burial depth of the soft soil, a follow-up casing is used to protect the wall and prevent the collapse of the hole wall. In terms of drilling parameters, the drilling speed should be controlled at 0.5-1m/min to avoid high-speed drilling disturbing the hole wall; Adjust the drilling rig speed to 60-80r/min and control the torque between 180-220kN · m to ensure smooth entry of the drilling bucket into the soil layer and reduce soil disturbance. In addition, during the drilling process, timely supplement the mud wall protection, control the mud density at 1.05-1.10, maintain the viscosity at 18-22s, form a stable hole wall protection film, and regularly clean the sediment in the hole to avoid excessive sediment affecting drilling efficiency and pile bottom bearing capacity.
The core difficulty of sand layer geology (medium sand, coarse sand, gravel sand, etc.) is the strong fluidity and high permeability of particles. During the drilling process, it is easy to cause hole wall collapse and sand loss, resulting in difficulty in forming holes, low drilling efficiency, and excessive sediment thickness. For sand layer geology, the optimization of drilling technology focuses on strengthening sand discharge capacity, stabilizing hole walls, optimizing drilling rhythm and wall protection measures. In terms of drilling tool selection, choose drill buckets with sand control devices (such as louvered sand scoop buckets) to increase the sealing and sand removal efficiency of the drill buckets, and reduce the loss of sand particles from the gaps in the drill buckets; For gravel sand layers, a toothed drill bucket can be used to improve the wear resistance and rock breaking ability of the drill bucket. In terms of wall protection measures, high-quality mud is used to protect the wall, with the mud density increased to 1.10-1.15 and viscosity controlled at 20-25s, enhancing the suspension capacity and wall protection effect of the mud. If necessary, casing is used to follow up with the wall protection, especially in areas with high groundwater levels in sand layers, which can effectively prevent the collapse of the hole wall. In terms of drilling operation, a "slow in, fast lift" rhythm is adopted, with a drilling speed controlled at 0.3-0.8m/min. After the drilling bucket is filled with sand particles, it is quickly lifted to reduce the retention time of sand particles in the hole; At the same time, every 1-2 meters of drilling, a hole cleaning operation is carried out using air lift reverse circulation to quickly remove sediment in the hole and avoid sediment accumulation affecting drilling efficiency.
The characteristics of cohesive soil (such as clay, silty clay, etc.) are strong plasticity and strong cohesion. During the drilling process, it is easy to encounter problems such as drilling bucket clay and difficulty in discharging soil, resulting in increased drilling resistance and decreased efficiency. In addition, the hole wall is prone to problems such as thick mud skin and reduced diameter. The key to optimizing the drilling process for cohesive soil is to reduce drilling resistance, prevent drilling bucket adhesion, and improve soil discharge efficiency. In terms of drilling tool optimization, choose drill buckets with spiral blades or tooth shaped drill buckets. Spiral blades can enhance soil discharge capacity, while tooth shaped drill buckets can reduce the contact area between clay and the inner wall of the drill bucket, thereby reducing the risk of bonding; At the same time, regularly clean the clay on the inner wall of the drill bucket and apply lubricating oil on the surface of the drill bucket to further reduce adhesion. In terms of adjusting drilling parameters, increase the drilling speed appropriately (80-100r/min) and reduce the drilling speed (0.8-1.2m/min) to allow the drilling bucket to fully cut the soil layer and reduce the compaction and bonding of clay inside the drilling bucket; The torque is controlled between 200-250kN · m to ensure smooth drilling of the drilling bucket and avoid overloading of the drilling rig due to excessive resistance. In addition, during the drilling process, clean water is regularly injected to dilute the mud in the hole, reduce the thickness of the mud skin, and accelerate the pace of soil discharge to avoid the accumulation of clay in the hole and improve overall drilling efficiency.
The characteristics of weathered rock geology (strongly weathered rock, moderately weathered rock, etc.) are moderate rock strength, loose structure, easy fragmentation but strong wear resistance. During drilling, problems such as rapid wear of drill teeth, slow drilling speed, and difficult slag discharge are prone to occur, which affect construction efficiency. For weathered rock geology, the optimization of drilling technology focuses on improving rock breaking ability, reducing drilling tool loss, optimizing drilling tool selection and drilling parameters. In terms of drilling tool selection, priority should be given to using toothed roller cutters or roller cutters. The toothed roller cutters have strong wear resistance, while the roller cutters can crush rocks by rotating and crushing, improving rock breaking efficiency; For moderately weathered rocks, impact drill bits can be used to assist in rock breaking and reduce drill tooth loss. In terms of drilling parameters, reduce the drilling speed (40-60r/min), increase the torque (300-400kN · m), and enhance the rock breaking ability of the drilling bucket; The drilling speed is controlled at 0.2-0.5m/min to ensure that the drill teeth fully break the rock and avoid further wear and tear caused by excessive speed. At the same time, during the drilling process, timely cleaning of rock debris in the hole is carried out, and mud circulation is used to discharge slag, reducing the accumulation of rock debris in the hole and lowering drilling resistance; Regularly check the wear of drill teeth and replace severely worn ones in a timely manner to avoid affecting drilling efficiency and hole quality due to drill tooth damage.
The core challenges of hard rock geology (such as slightly weathered rocks, fresh rocks, etc.) are high rock strength, good integrity, high drilling resistance, high difficulty in breaking rocks, extremely low efficiency of conventional drilling methods, and severe loss of drilling tools, which are the main bottlenecks of rotary drilling rig drilling technology. For hard rock geology, it is necessary to adopt composite drilling technology, combine multiple drilling methods, optimize drilling tools and parameters, and achieve a significant improvement in rock breaking efficiency. In terms of drilling tool selection, high-strength wear-resistant roller cone drill bucket or cutting tooth drill bucket should be selected, combined with high-power rotary drilling rig to enhance rock breaking power; At the same time, a composite drilling mode of "rotary drilling+impact" can be adopted. Firstly, the impact drill bit is used to break the surface of the rock, and then the rotary drilling bucket is used to clean the rock debris, alternating operations to reduce drilling resistance and improve rock breaking efficiency. In terms of drilling parameters, the drilling rig speed is controlled at 30-50r/min, and the torque is increased to above 400kN · m to ensure sufficient rock breaking power; The drilling speed should be controlled at 0.1-0.3m/min to avoid overloading of the drilling tool and damage to the drill teeth due to excessive speed. In addition, injecting cooling mud during the drilling process reduces the temperature of the drill teeth and minimizes wear; Regularly inspect the connection between the drill rod and the drill bucket to ensure a secure connection and avoid component damage caused by vibration, which may affect the construction progress.
In addition to specialized optimization for different geological conditions, ensuring proper operation and maintenance of rotary drilling equipment is a universal guarantee measure to improve drilling efficiency and reduce losses. In terms of equipment operation and maintenance, a comprehensive inspection of the core components such as the engine, hydraulic system, drill rod, and drill bucket of the drilling rig should be conducted before construction to ensure the normal operation of the equipment; Regularly lubricate and rust the drill rod, inspect the wear of the drill bucket and teeth, and replace vulnerable parts in a timely manner; Reasonably arrange equipment schedules to avoid equipment failures caused by long-term high-intensity operations and reduce project delays. In terms of operational standards, operators are required to undergo professional training, be familiar with drilling techniques and parameter settings for different geological conditions, and strictly follow the optimized process flow for construction; During the drilling process, closely observe the operation status of the drilling rig and the situation inside the hole, adjust the drilling parameters in a timely manner, and promptly deal with problems (such as hole wall collapse and buried drilling) to avoid the problem from expanding; At the same time, keep good construction records, detailing drilling parameters, drilling efficiency, consumables consumption, and other information for different geological sections, providing data support for subsequent process optimization.
By optimizing the drilling process for different geological conditions, the bottleneck of rotary drilling can be effectively overcome, achieving a dual improvement in construction efficiency and engineering benefits. Practical data shows that after optimization, the drilling efficiency of soft soil geology has increased by 20% -30%, sand layer geology by 15% -25%, weathered rock geology by 30% -40%, and hard rock geology by more than 40%; At the same time, the loss of drilling tools has been reduced by 15% -20%, the occurrence rate of quality problems such as hole wall collapse and diameter reduction has been reduced by more than 60%, and the rework cost has been reduced by about 30%. In addition, after process optimization, the quality of pore formation is easier to meet standards, the bearing capacity of the pile body is improved, effectively ensuring the safety of the engineering structure, shortening the construction period, reducing the comprehensive costs of labor, consumables, equipment operation and maintenance, and creating higher economic and social benefits for construction enterprises.
