Views: 0 Author: Site Editor Publish Time: 2026-04-08 Origin: Site
The quality and efficiency of drilling holes with rotary drilling machines are the core key to the success or failure of pile foundation construction, directly determining the overall project schedule, cost, and structural safety. The physical properties of different geological conditions (such as sand, clay, hard rock, pebble layers, etc.) vary greatly. If a universal drilling process is used, it is prone to problems such as low efficiency, hole wall collapse, and increased equipment wear and tear. Therefore, based on geological characteristics, optimizing drilling processes, matching exclusive drilling parameters and equipment configurations are the core paths to maximize drilling efficiency and ensure drilling quality under different geological conditions, and are also the inevitable requirements for fine management of rotary drilling rig construction.
The core of optimizing pore forming technology lies in "precise adaptation", and the prerequisite for precise adaptation is the accurate identification and classification of geological conditions in the construction area. In actual construction, common geological conditions include loose sand layers, cohesive soil layers, pebble (gravel) layers, hard rock layers, and composite layers (with multiple geological intersections). There are significant differences in particle size distribution, compactness, cohesion, and abrasiveness among each geological condition. For example, sand layers have high porosity and poor stability, making them prone to hole wall collapse during drilling; Hard rock formations have strong abrasiveness and high hardness, causing significant wear on drilling tools and low drilling efficiency; The properties of composite strata are diverse, requiring higher equipment control capabilities. Before construction, it is necessary to obtain a detailed understanding of key parameters such as soil distribution, moisture content, and rock compressive strength through geological survey reports, on-site drilling, and other methods, in order to provide scientific basis for subsequent process optimization and parameter matching, and avoid construction bottlenecks caused by the disconnection between process selection and geological characteristics.
Sand (especially silt and fine sand) and gravel layers are common difficulties in drilling holes with rotary drilling rigs, with the core challenge being unstable hole walls and high drilling resistance.
The core of optimizing the process for loose sand layers is "stabilizing pores". Static mud wall protection technology can be prioritized, and mud with different densities and viscosities (such as bentonite mud) can be configured according to the particle size of the sand layer to ensure that the mud forms a dense and strong mud skin on the hole wall, isolates moisture outside the hole, strengthens the hole wall, and prevents collapse. At the same time, a toothed sand scoop is selected to cut the sand layer and quickly scoop sand using the bucket teeth, reducing the dwell time of the drilling tool in the hole and minimizing the disturbance of the hole wall. For pebble layers, suitable drilling tools should be selected based on the particle size of the pebbles. For larger pebble layers, a double bottom toothed sand scoop should be used to enhance the material grabbing ability; For the mixed layer of hard rock and gravel, a cylindrical core drill bit is used, combined with high torque and low-speed drilling parameters, to first crush the gravel and then form a hole, avoiding drilling jamming and burying accidents. In addition, the operation mode of short stroke and frequent drilling can be combined to control the footage of each stroke within a reasonable range, timely discharge the debris in the hole, and reduce the impact of sediment in the hole on the efficiency of hole formation.
The pain points of pore formation in cohesive soil layers (clay, silty clay) are the sticking of drilling tools and the shrinkage of pore diameter, which can easily lead to poor discharge of debris and deformation of pore walls.
Optimizing the process requires focusing on solving the bonding problem, which can be achieved by using dry drilling+water flushing or low viscosity mud wall protection technology to reduce the bonding resistance between mud and clay. Equipped with a long spiral drill bit or a conical sand scoop, the cutting angle of the drill bit is used to quickly cut clay, and the slag is efficiently discharged through the bottom slag discharge port of the bucket to avoid clay accumulation inside the bucket. In terms of drilling parameters, a combination of medium high speed and medium torque is used to avoid clay adhesion caused by low speed, while controlling the drilling speed to prevent shrinkage of the hole wall due to overcutting. For high plasticity and high viscosity clay layers, appropriate amounts of bentonite or additives can be added during drilling to improve mud performance, enhance hole wall stability, balance hole formation efficiency and quality, and avoid difficulties in subsequent steel cage placement due to diameter reduction.
The core bottleneck of drilling in hard rock formations (such as granite, limestone, sandstone) is the difficulty of rock breaking, fast wear of drilling tools, and generally low efficiency.
The traditional single drilling mode is difficult to adapt to, and an integrated process optimization of "rock breaking+drilling" needs to be adopted. Firstly, select a dedicated rock breaking drilling tool based on the compressive strength of the rock: for medium hard rocks, use a toothed roller drill bit * * to cut and break the rock through the teeth; For hard and ultra hard rocks, roller cutters are used as drill bits to crush and crush the rock mass. The rock breaking efficiency is increased by more than 30% compared to the pick type. Secondly, optimize drilling parameters by adopting a low-speed, high torque drilling mode, combined with high pressure and short stroke, to ensure full contact between the drilling tool and the rock and efficient rock breaking. In addition, promoting the combination of roller drill bits and mud circulation technology, using mud to carry rock powder back out of the hole, while cooling the drilling tools, reducing the temperature inside the hole, and extending the service life of the drilling tools. For ultra deep hard rock holes, segmented drilling technology can be adopted, with conventional drilling tools used for the upper soil layer and specialized rock breaking drilling tools used for the lower hard rock, achieving efficient drilling of the entire hole section and avoiding efficiency losses caused by poor adaptability of a single drilling tool.
Composite strata (such as upper sandy soil+lower hard rock, upper clay+lower pebble layer) are complex working conditions for rotary drilling rig drilling, and a single process is difficult to cover the entire section's requirements.
The core of optimization lies in "segmented adaptation and dynamic switching". According to the geological stratification interface, the holes are accurately divided into sections, and drilling tools and parameters that match the geological characteristics of each section are used for each section. For example, the upper sandy soil section adopts mud wall protection and sand scoop for rapid drilling, while the lower hard rock section switches to roller cutter drill bit+low-speed high torque mode. At the same time, equipped with an intelligent working condition monitoring system * *, real-time perception of geological changes and drilling resistance inside the hole, dynamic adjustment of parameters such as speed, torque, and drilling speed, to avoid drilling jamming and collapse caused by geological changes. In addition, we will strengthen the optimization of drilling tool combinations, adopt multifunctional combination drilling tools, take into account the drilling needs of different geological conditions, reduce the number of tool replacements, improve construction continuity, and effectively shorten the drilling cycle of composite formations.
The optimization of drilling technology is not limited to the drilling process, but also requires comprehensive pre preparation and process control to ensure the effectiveness of the technology.
One is the refined selection of drilling tools, which is adapted to different geological reserves such as sand scoops, gear cutters, and roller cutters, to ensure that the drilling tools are highly matched with the geological conditions and reduce efficiency losses caused by non-compliance. The second is the dynamic optimization of mud performance. Different geological conditions have different requirements for mud density, viscosity, and sand content. It is necessary to detect mud indicators in real time and adjust the ratio. For example, in hard rock formations, the mud density needs to be increased to carry large particles of rock powder, and in sand formations, the mud viscosity needs to be increased to enhance the wall protection effect. The third is precise control of equipment status. Before starting up, a comprehensive inspection of the core components such as the power head, hydraulic system, and drill rod of the rotary drilling rig is carried out to ensure stable power output and no wear or jamming of the drilling tool, avoiding interruption of drilling due to equipment failure. The fourth is to improve the skills of construction personnel, strengthen the training of operators on the key points of different geological processes, standardize the operating procedures, avoid efficiency reduction due to improper operation, ensure that the optimization plan of drilling technology is truly implemented, and achieve the dual improvement of drilling efficiency and drilling quality of different geological rotary drilling rigs.
