The hottest rotary drilling rig is a common constr

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Rotary drilling rig is a commonly used construction technology

the construction process specification of rotary drilling machine has not been issued by the superior standard so far. Rotary drilling rig is a construction machine suitable for hole forming operation in building foundation engineering. It is widely used in municipal construction, highway bridge, high-rise building and other foundation construction projects. With different drilling tools, it is suitable for dry (short spiral), or wet (rotary bucket) and rock formation (core drill) hole forming operation, The rotary drilling rig has the characteristics of large installed power, large output torque, large axial pressure, flexibility, high construction efficiency and multi-function. The rotary drilling rig adapts to the soil geological conditions in most areas of China, and has a wide range of applications. It can basically meet the use of bridge construction, high-rise building foundation and other projects. At present, the rotary drilling rig has been widely promoted in various bored pile projects. Therefore, it is of great significance to discuss the construction preparation of rotary drilling rig and the common clean water construction technology

I. construction preparation

1. Data preparation

(1) before commencement, the site engineering geological data and necessary hydrogeological data, pile foundation engineering construction drawings and drawing review minutes should be available

(2) survey data of underground pipelines (pipelines, cables), underground structures, dangerous buildings, precision instrument workshops, etc. in the site and adjacent areas

(3) the technical performance data of the main construction machinery and its supporting equipment, the inspection and mix proportion test of the required materials, the physical property test of the required materials must be carried out, and the qualified laboratory must be entrusted to carry out the mix proportion test of concrete according to the raw materials used

(4) have effective construction organization design or construction scheme of pile foundation engineering, and test reference materials related to load and construction technology

joint review of drawings

make detailed safety technical disclosure, fully carry forward democracy before construction, mobilize the enthusiasm and creativity of employees, enable all employees involved in the construction to participate in the discussion of the construction scheme, improve the attention to the quality assurance of safety production, and evaluate all departments

2. Measuring instruments used for construction machinery and equipment, such as theodolite, level gauge, steel tape, rotary drilling machine, electric welding machine and other mechanical equipment, must have factory certificates. See Table 1 for the equipment recommendations required for construction:

3. Requirements for small and medium-sized machines and tools

(1) the mixer

has a solid and stable installation and a rain proof operation shed; All kinds of clutches, brakes, steel wire ropes and protective covers must be safe, reliable and effective; Operators should work with certificates; There must be good separate grounding

(2) hand held electric tools

must be separately installed with leakage protectors; The protective cover is safe and effective; The shell must be grounded or connected to neutral; The rubber cord shall not be damaged

(3) electric welding machine

has reliable rainproof measures; Have good grounding or neutral protection; 1、 The wiring of secondary line shall be equipped with complete protective cover; The secondary line should use the line nose; Wiring shall not be erected or pulled randomly, and the insulation of welding handle shall be good; Welders work with certificates

(4) gas cylinders

all kinds of gas cylinders have obvious color codes and shockproof rings, and are not allowed to be exposed in the open air; The distance between acetylene gas and oxygen cylinder shall be greater than 5m; Acetylene cylinders must be equipped with flashback preventers when in use; The leather tube shall be fastened with a collet; Operators must work with certificates

4. Installation of drilling tools

the drilling tools have a certain stiffness and do not move and shake during drilling or other operations. The installation of drilling tools should meet the standards of the manufacturer. Short auger bits, rotary buckets, core bits, core rotary bits and other bits with small amplitude can be used during construction. During construction, different drill bits of rotary drilling machine shall be selected according to different soil and geological conditions according to the following provisions: short auger, suitable for cohesive soil, silt and fill above the groundwater level, sandy soil above medium density, and weathered rock stratum. Spiral swivel head adopts slurry wall protection, which is suitable for cohesive soil, silt, sandy soil, fill, gravel soil and weathered rock above the groundwater level. Core auger bit, suitable for gravelly soil, medium hard rock and weathered rock. Core bit, suitable for weathered rock strata and cracked rocks. The specifications of drill bits are selected and matched by users according to the actual situation of the project

5. Common clean water construction technology

rotary drilling and hole forming technology of drilling machine: rotary drilling and hole forming first breaks rock and soil through the rotation of barrel drill bit with valve at the bottom, and directly loads it into the drill bit, and then the drill bit is lifted out of the hole by the lifting device of drilling machine and telescopic drill pipe to unload soil. In this way, soil is taken and unloaded continuously until it reaches the design depth. For rock and soil layers with good cohesiveness, dry or clean water drilling technology can be adopted without mud wall protection. For the loose and collapsible strata, or the distribution of groundwater, and the hole wall is unstable, the static mud wall protection drilling process must be adopted, and the wall protection mud or stable fluid must be put into the hole for wall protection. The following only discusses the construction technology of rotary excavation dry soil sampling and hole forming method

(1) hole forming process of clean water construction process:

in the hole forming process, mud is not required to protect the wall, but the self-made mud of the drill bit plays a certain role in stabilizing the hole wall in the process of slow rotary drilling. In the process of rotary drilling, the drill bit goes back and forth between the hole bottom and the surface, and the hole wall formed is relatively rough. The engagement between pile and soil of rotary drilling cast-in-place pile is strong, which can better reflect the interaction effect between concrete pile and loess and silty clay. See Figure 1 for the process flow

(2) site layout principle

reasonably arrange the construction site according to the design requirements, first level the site, remove sundries, replace soft soil, and compact it. After site leveling, organize qualified survey and setting out personnel to set out all pile positions, nail cross protection piles, conduct survey review, and record setting out data for filing; When planning the driving route, keep a certain distance between the access road and the drilling position; So as not to affect the stability of the hole wall; When the construction site is dry land and the groundwater level is below the original ground during construction, the site shall be leveled and compacted to remove debris; When the site is located in shallow water, the drilling machine is installed on the top surface after the island is built, and the top surface of the island is about 1.0m higher than the construction water level; The drilling machine chassis should not be placed directly on the unstable fill to avoid uneven settlement; The location of the drilling machine should consider the convenience of the excavation and transportation of the orifice during the drilling construction. (3) Setting out of pile position

setting out of pile position shall be carried out according to the principle of overall to local setting out of pile position. When setting out the elevation of drilling hole, the setting out elevation shall be rechecked in time. The total station is used to accurately set out the position of each pile point to make its error within the specification requirements

(4) drill in place

when the drill is in place, check whether the performance of the drill is in good condition in advance. Ensure that the drilling machine works normally

(5) embedding steel casings

(6) embedding casings on the premise of accurate setting out. The method and requirements of embedding casings should comply with the provisions of jtj041-89 (hereinafter referred to as the "specification"). If the drilling is carried out on land, the excavation method is generally adopted, which is relatively simple and easy

(7) the embedding of steel casing is the beginning of the construction of rotary drilling machine. The plane position and perpendicularity of steel casing should be accurate, and the surrounding of steel casing and the bottom of casing should be tight and impervious

(8) when embedding the steel casing, the location of the drill hole shall be marked at the bottom of the pit through the setting out of the positioned control pile. Then hoist the steel casing into the pit, find out the center position of the steel casing, use a crosshair on the top or bottom of the steel casing, and then move the steel casing to make the center of the steel casing coincide with the drilling center of the drilling machine. At the same time, check with a level ruler or a drop ball to make the steel casing firm and straight. After that, backfill the clay with the best water content symmetrically and evenly around the steel casing, and compact it in layers to achieve the best compactness. To ensure its perpendicularity and prevent mud loss, displacement and falling. If the soil layer at the bottom of the pile casing is not cohesive soil, it should be excavated or replaced. After backfilling and tamping 300-500mm thick clay at the bottom of the pit, the pile casing should be placed to avoid leakage and collapse at the bottom of the pile casing. During tamping, the deflection of the steel pile casing should be prevented. The upper opening of the pile casing shall be bound with timbers and hoisted symmetrically to prevent downward movement

(9) principle of making and embedding steel casings

for steel casings with a length of less than 4m, the physical and mechanical properties and harmful substance content of 46mm thick asphalt and asphalt mixture shall be tested; Waterproof coiled material, coating physical and mechanical properties, asphalt ductility tester, penetration tester, softening point tester, rotating film oven, flash point tester, wax content tester, Marshall tester, Marshall electric compaction tester, asphalt mixing mixer, constant temperature water bath box, balance, caliper, centrifugal extractor (4-flow extractor) or combustion furnace, rut sample forming machine, automatic rut tester, blast drying oven, 100kN press, vernier caliper The steel casing with a length of more than 4m is made of 6 ~ 8mm thick steel plate; When the steel casing is deeply embedded, multi section steel casing shall be used for connection, and the connection form shall be welding. During welding, the joint shall be round and smooth, and the requirements of stiffness, strength and leakage prevention shall be met at the same time; The inner diameter of the steel casing shall be greater than the diameter of the drill bit, and the specific size shall be selected according to the design requirements; The buried depth of steel casing shall meet the requirements of design and relevant specifications. If the pile hole is in the river, the steel casing should be buried to a depth of more than 0.5m in the hard and dense soil layer; The top of the steel casing is 1.5-2.0m higher than the construction water level or underground water level, and 0.3m higher than the construction ground; Before embedding the steel casing, measure and set out accurately to ensure that the position deviation of the top surface of the steel casing is not greater than 5cm, and ensure that the slope of the steel casing is not greater than 1% during embedding; Before embedding the steel casing, use a larger diameter drill bit to pre drill to the elevation of the bottom of the casing, then raise the drill bucket and press the steel casing into the predetermined position with the drill bucket. Use coarse-grained soil to backfill around the outside of the pile casing, and backfill tightly

(10) drilling construction

the hole forming process of the drilling machine is generally clear water construction process, without mud wall protection; If there is groundwater distribution and the hole wall is unstable, the wall protection mud or stabilizing fluid can be put into the hole for wall protection. The following are the basic operations of the rotary drilling rig drilling construction:

during the construction with clean water, turn the key switch to the power gear, the display of the rotary drilling rig displays the rotary drilling rig marking screen, and press any key to enter the working screen. Firstly, the drilling mast of the rotary drilling rig shall be erected and lowered, that is, first move the rotary drilling rig to the location of the drilling operation, and the display of the rotary drilling rig displays the working picture of the mast. The offset of x-axis and Y-axis of the mast can be observed in real time from the working screen of the mast. Operate the electric handle of the rotary drilling rig to lift the mast from the transportation state position to the working state position. In this process, the controller of the rotary drilling rig collects the signals of the electric handle and the inclination sensor, and outputs the signal to drive the proportional valve of the hydraulic cylinder through mathematical calculation to realize the closed-loop control of the mast. Realize the stable and synchronous rise of the mast. At the same time, the limit switch signal is collected to protect the left and right tilt angle of the drilling mast during the process of raising the mast. Before the drilling operation, the mast needs to be positioned and set. Generally, the straight hole operation is carried out, so the mast needs to be adjusted vertically. Sag adjustment can be divided into manual sag adjustment

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