Selection Guide for Four Typical Geological Rotary Drilling Rigs — Precise Matching to Improve Efficiency and Reduce Consumption

    The core of selecting a rotary drilling rig is to adapt to geological conditions. The four typical geological conditions of clay, sand, gravel, and hard rock have significant differences. Improper equipment selection can easily lead to low construction efficiency, increased equipment wear, and even affect project quality. Based on practical construction experience, provide precise machine allocation plans for different geological conditions, balancing efficient operations and cost control, and providing reference for construction selection.

    Clay geological adaptation: Clay soil has fine texture and strong viscosity, which can easily lead to problems such as drilling for clay and difficulty in unloading soil. The core of the machine is to prevent sticking and blockage, and improve the efficiency of soil lifting and unloading. Priority should be given to using small and medium-sized rotary drilling rigs, with friction type drill rods and double bottom open door drill buckets. Anti sticking coatings can be added to the inner walls of the drill buckets to reduce clay adhesion; If the clay has a high moisture content, a spiral drill bit can be used to assist in cleaning the hole, avoiding collapse of the hole wall, while controlling the drilling speed to balance efficiency and hole wall stability.

    Geological adaptation of sandy soil: Loose and highly permeable sandy soil is the core pain point during construction, which is the collapse and leakage of borehole walls. The focus of equipment allocation is on preventing collapse and strengthening wall protection. Choose medium to large rotary drilling rigs, with priority given to using machine lock drill rods to enhance stability and torsional resistance during drilling; The drill bit is equipped with a casing to follow the drilling bucket or a double-layer bottom drilling bucket, combined with mud wall protection technology to reduce sand loss; If the sand layer is thick and the particle size is uniform, a sand dredging drill bit can be used to assist in cleaning the hole, ensuring the quality of the hole formation while avoiding disturbance to the hole wall caused by high-speed drilling.

    geological adaptation: Pebble geological hardness is moderate, particle size is uneven, and it is prone to problems such as stuck drilling, buried drilling, and rapid wear of the drilling bucket. The core of the machine is impact resistance, wear resistance, and anti stuck drilling. Selecting high-power medium to large rotary drilling rigs with strong rigidity and high torque, coupled with machine lock drill rods, to enhance rock breaking and impact resistance capabilities; The drill bit is selected as a wear-resistant alloy tooth drill bucket or a roller drill bit to assist in crushing large-sized pebbles. The opening size of the drill bucket is adjusted according to the pebble particle size to avoid drilling jamming; At the same time, equipped with a clearing device to promptly handle debris in the hole and reduce equipment wear and tear.

    Adaptation to hard rock geology: Hard rock geology has high hardness and strong integrity. The core of construction is efficient rock breaking and reducing equipment loss. The key to equipment allocation is strong power and high wear resistance. Select a large high-power rotary drilling rig with a torque of not less than 300kN · m, paired with high-strength machine lock drill rods to ensure power transmission and stability during drilling; The drill bit is selected as a rolling cutter drill bit or a combination rock breaking drill bit, using a "slow drilling speed, strong torque" drilling method to gradually break down hard rocks; If the weathering degree of hard rock is high, a spiral drill bit can be used to drill into the surface weathered rock first, and then a rock breaking drill bit can be used to improve construction efficiency. At the same time, the wear of the drill bit should be checked regularly, and vulnerable parts should be replaced in a timely manner.

    Key selection supplement: In actual construction, there are often mixed geological conditions (such as clay mixed with sand, gravel mixed with hard rock), and it is necessary to flexibly adjust the machine selection plan based on the geological survey report to avoid insufficient adaptability of a single selection; At the same time, taking into account the requirements of engineering pile diameter and pile depth, reasonably matching equipment specifications, not only meeting construction requirements, but also avoiding equipment idle waste, achieving efficient, safe, and economical construction.