What is the tuition fee for the rotary drilling rig training base?

What is the tuition fee for the rotary drilling rig training base? At present, the advantages of rotary drilling rig, such as advanced selection, rapid and stable hole formation, have become the mainstream selection of drilling pile machinery. Due to the different engineering geological conditions, different engineering choices can not be completely consistent with the actual strata, and sometimes even quite different. Therefore, when geotechnical construction units undertake bored pile foundation engineering, the drilling of pile foundation is faced with uncertainty. Improper selection of some technical problems in the process of pile foundation drilling will not only cause huge economic losses, but also threaten the safety of engineering equipment and even personnel.

Combined with the practical experience of using rotary drilling rig to drill in different strata in recent years, the technical problems and solutions often encountered in drilling construction in some special strata are summarized. I hope it can be used for reference by peers who choose similar problems.

A, soft soil, such as the collapse of the formation using rotary drilling method.

1 and the selection of soft soil collapse stratum and the risk of using holes.

When using soil, if the groundwater level of newly accumulated backfill soil and deposited loose fine sandy soil layer is high, after using soil for rotary drilling rig, even if drilling is used under the condition of mud wall protection, the hole wall should be kept stable, with hole collapse or necking as the most extreme. Because this kind of stratum is mostly used for shallow surface, with the gradual increase of landslides, the ground around the borehole will collapse, which often leads to casing sinking. In severe cases, it will also threaten the choice of drilling equipment and operators. When this happens, especially when it is found that the orifice casing has been suspended or sunk during the selection process, we should not take any chances to continue drilling, but should backfill the borehole as soon as possible and re-fix the orifice casing before drilling.

2, rotary drilling rig construction method

Soil in use, recently backfilled soil, etc. The water layer can not be effectively utilized, and the most effective and preferred rotary drilling method is to choose long wall protection measures. According to the difficulty of drilling, each drilling rig selects about 3 liners and/kloc-0 vibrating hammers with enough lifting force. The length of steel lining can be selected to the bottom of soft layer, and the diameter of steel lining should be about 100mm (too much waste of concrete; It is easy to use and choose when the drill bit is too small. It is difficult to ensure smooth construction). When using and selecting retaining wall for rotary excavation, the following points should be selected:

(1) Large stones with a depth exceeding 100mm should be selected to determine the depth range of the liner; According to the diameter and lowering length of the used casing, choose the hammer with appropriate power.

(2) In the construction of small diameter, the outer diameter and selected diameter of drill pipe should be considered. The outer diameter of drill pipe is more than 200mm smaller than the selected diameter, so the difference should be selected for the convenience of construction.

(3) The verticality under the steel casing should be selected, especially the diameter bored pile.

(4) After pouring concrete, select and pull out the liners.

(5) The selection of sinking should be closely coordinated with the rotary excavation pile. After the steel casing is put into use, it should be able to choose to sink into the next borehole to be constructed. In this way, assembly line operation will be selected to improve construction efficiency.

Second, the selection of drilling methods for sand and silt

1, the choice of sandy silt land becomes a risk.

When drilling holes with sand or silt, if the groundwater level is high, mud should be used to make the wall protection useful. This kind of stratum is easy to choose because of its intermittent adhesion. Because the rotary drilling rig uses drilling holes to borrow soil, the use of drilling holes is lifted from the drill bucket to the ground. The drill bucket moves in the mud, and the water flow outside the drill bucket is high, which is easy to cause hole wall selection. The sand washed by the hole wall further reduces the wall protection effect of mud. It is more likely to cause neck protection or even hole collapse.

2, rotary drilling rig construction method

When using mud to protect the wall in the first selected sand or soil layer, the following selection measures should be considered:

(1) appropriately reduce the bit selection and pulling speed, reduce the mud selection between the drill bucket and the hole wall, and reduce the erosion.

(2) Appropriately increase the rake angle of drill teeth. Increase the distance between the selection and the side wall of the bucket.

(3) Appropriately increase the flow hole area of the drill bucket, reduce the negative pressure at the bottom and the selection of the drill bucket during traction, so as to reduce the flow of the selection hole.

(4) Prepare high-quality mud for wall protection, and timely use the sand content selected in drilling. Take effective measures when exceeding the standard.

(5) Check the tightness of the bottom cover of the drill bucket after it is closed. If distortion is selected to cause a large gap, renovation should be selected to avoid sand leakage.

Three, boulder, boulder formation rotary excavation method

1, characteristics of rocks and gullies and drilling risks; Common technical problems and solutions of rotary drilling rig in special formation drilling in Guangdong Rotary Drilling Rig School

In the pile foundation construction of Tiaohe Bridge in mountainous area, boulders are often encountered during drilling. Because the selected particles are large in diameter and embedded in each other, the conventional sand fishing bit can not be drilled; If forced drilling, it is very easy to break the drill teeth and even damage the drill pipe. In addition, we also chose a big choice, which will encounter almost the same aperture, or the probe stone is partly located in the hole and mostly buried in the stratum around the hole. If the boulder is not handled properly, the hole wall will collapse due to long-term vibration. If the stone exploration is not handled properly, it is easy to choose inclined holes, which will cause practical difficulties for the subsequent lowering of reinforcing cages; If the pile collapses after lowering the reinforcing cage, the quality of the pile will be seriously affected.

2, rotary drilling rig construction method

When rotary drilling encounters large boulder formation, if boulder formation is shallow, it is advisable to dig boulder to backfill clay first, and then run orifice casing to drill in boulder formation. If the selection is located at the service depth, and if the selected particle size is larger than the opening diameter of the sand hopper, it is impossible to drill normally, the cylindrical bit can be taken out and selected, and then the sand hopper is used to drill gradually.

When the bored pile meets the boulder, if all the boulder happens to be used to form a hole, it can be taken out directly with a cylindrical drill bucket; If most boulders are buried in the strata around the hole to form exploration stones, drilling should not be forced. However, after the selected stone and the cylindrical outer surface are slowly cut, normal drilling can be carried out.

Four, hard clay, mudstone formation rotary drilling method

1, selection of hard clay and mudstone strata and risk of using holes

The biggest problem that hard clay brings to the drilling process is the difficulty of drilling and unloading soil. Compared with the Quaternary sedimentary strata, mudstone has the characteristics of high strength, high viscosity and easy sliding when it meets water. Drilling rigs are generally chosen because the pressure is very low. When drilling in mudstone, the drill bit is difficult to cut with rock, and the drill bit slides on the mud surface, which makes the drilling efficiency extremely high. When using rotary drilling rig to drill mudstone, especially when the hole depth is large, it is easy to have low drilling efficiency or even no drilling if the drill bit is selected in the design.

2, rotary drilling rig construction method

When drilling holes, the form of drill bucket or the bottom side of drill bucket should be selected to improve soil utilization efficiency. Rotary bored piles in mudstone stratum can be selected from the following to improve construction efficiency.

(1) Machine drill pipe is the first choice for dry drilling. When drilling with friction drill pipe, consider increasing the selection of drill pipe bucket, so that the drill teeth can cut into mudstone, and establish pressure through selection.

(2) For the stratum with strong weathering and high selection degree, V 19 drill tooth drilling should be considered when distributing drill teeth. If necessary, the design can be selected by selecting the teeth, the height difference between the left and right teeth of the drill bucket, and appropriately increasing the angle of the rock. When using drill bucket teeth, alloy picks must be selected to improve wear resistance and selection ability.

(3) When the hole diameter of foundation pile is large, graded drilling should be selected. For the first stage drilling, the cylindrical drill bucket with relatively large length and diameter is directly used as the core; For secondary drilling, select the same aperture as that of external drilling.

(4) Avoid using too few teeth. Avoid the same selection trajectory of teeth on both sides of the drill bucket, repair the severely worn selection in time, and effectively avoid the drilling difficulty caused by excessive wear of drill teeth and bottom support.

Five, limestone cave formation rotary drilling method

1, the formation characteristics of limestone caves and the risk of using holes

Limestone caves are often used in buildings in southern mountainous areas. The bedrock surface of this kind of stratum fluctuates greatly due to uneven selection, and the size and shape of karst caves are various. When drilling and grouting are selected in stratum construction, inclined holes, sudden slurry leakage and hole collapse, use of damaged drill pipe and drilling tools during sticking, and large amount of grouting for concrete are often encountered.

2, rotary drilling rig construction method

In the construction of bored pile in limestone karst cave stratum, measures can be taken from several aspects to choose the use risk. When encountering the bedrock surface, slow down the drilling speed and avoid using holes.

(1) Carefully compare the drilling data. When selecting the top surface of karst cave for drilling, the drilling speed should be slowed down, and the mud and clay used for backfilling should be used as backup. When drilling through the top of the hole leads to the rapid decline of protective mud on the inner wall, backfill drilling should be chosen to avoid hole collapse.

(2) The straight and extended drill bucket with better guidance is preferred. If inclined holes are used and drilling rigs are used near the roof of the cave, rotary drilling rigs should be used. Choose the welding at the top of the drill bucket to choose the structure for guidance.

(3) When the karst cave is large, filled or unfilled, backfill clay should be selected and tamped reversely with a drill bucket. Avoid too much excess in the process of selecting concrete after using holes.

Six, granite and other rock layers rotary drilling method Guangdong rotary drilling rig school rotary drilling rig in special strata drilling construction often encountered technical problems and solutions.

Selection of rock strata such as 1, granite-silicon and the risk of using holes.

When designing the pile foundation of many super-large bridges, it is required that the pile should enter the moderately weathered hard rock to a certain depth. Most of the pile diameters selected in these pile foundation designs are above 1.5mm, even up to 2 m. In this way, the selection of drilling in hard rock stratum requires the selection of power and pressure, and generally requires the selection of equipment above 280 kn m. When drilling in this stratum, the selection of drilling teeth is very large.

2, rotary drilling rig construction

In the construction of hard materials such as granite and sandstone, measures should be taken from the following materials to improve the use efficiency of holes and reduce risks.

(1) The drilling construction with power of 280kN.m and above shall be selected. Be prepared in advance and use drill teeth with higher selectivity and better grindability. It is useless to add water to reduce the wear of drill teeth.

(2) Reasonable selection of drilling tools. When piles are widely used in this stratum, graded drilling should be adopted. In the first stage, an extended barrel drill with a diameter of 600mm~800mm is selected, and the free surface is made directly from the core; Or use a small-diameter auger to form a free surface.

(3) It is extremely difficult to use holes after inclined holes appear in hard rock stratum. Therefore, when selecting inclined rock surface, it is necessary to correct it before normal drilling.

Seven. conclusion

From the practice of drilling and grouting with rotary drilling rig in recent years, it can be applied to the selection of most strata; However, for a specific project, the selection and effective implementation of rotary drilling rig energy need to select the actual stratum, design aperture and hole depth, reasonably select the model, reasonably select drill pipes and drilling tools, and formulate and use practical and reliable concrete measures. To sum up, there are the following points:

(1) Take measures to protect the orifice wall. For drilling with retaining wall, mud retaining wall drilling is preferred. For those who can't guarantee the effect of mud wall protection, such as selected soil and new backfill, the wall protection with liner should be selected.

(2) Choose the appropriate option. When the drilling rig is flexible, quick selection of drilling rig is more suitable for construction with good stratum, small depth and small pile diameter. Large drilling rig has a large choice, which can drill hard strata and choose large diameter drilling. Using high-power drilling rig to drill simple formation is inefficient; If you choose to use drilling, you cannot drill through the rock.

(3) Reasonably allocate drilling tools and optimize the layout of drilling teeth according to the type selection. Before rig selection, rig configuration should be made according to geological exploration data; First, drill several exploration holes. After understanding the actual geological conditions, optimize the layout of drilling teeth in time according to the type selection.

(4) drill the key points carefully. In selected parts such as rock surface, rock exploration and the top of karst cave, the drilling speed should be slowed down and selection measures should be made in advance.