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Analysis of the construction case of the small KR125 drilling rig in Xuzhou Institute of Technology

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Analysis of the construction case of the small KR125 drilling rig in Xuzhou Institute of Technology

  • Categories:Case
  • Time of issue:2021-08-05 10:37

(Summary description)In April 2013, a KR125 series rotary drilling rig produced by Pinghan Heavy Industry was transferred to Xuzhou Institute of Technology and participated in the second phase of the construction of the college, including 12 teacher apartments and more than 1,500 cast-in-place pile foundations.

Analysis of the construction case of the small KR125 drilling rig in Xuzhou Institute of Technology

(Summary description)In April 2013, a KR125 series rotary drilling rig produced by Pinghan Heavy Industry was transferred to Xuzhou Institute of Technology and participated in the second phase of the construction of the college, including 12 teacher apartments and more than 1,500 cast-in-place pile foundations.

  • Categories:Case
  • Time of issue:2021-08-05 10:37
  • Views:
Information

In April 2013, a KR125 series rotary drilling rig produced by Pinghan Heavy Industry was transferred to Xuzhou Institute of Technology and participated in the second phase of the construction of the college, including 12 teacher apartments and more than 1,500 cast-in-place pile foundations.

There are also 5 other brand drilling rigs under construction on this site, models ranging from 100-220, reflecting the trend of subdivision of domestic drilling rigs. At the same time, KR125 is given to compete with multiple and various rotary drilling rigs. opportunity.

There are three types of pile depths for this construction, namely 24 meters, 27 meters, and 29 meters; the pile diameter is 600mm. The geological conditions are mainly sand and clay. From the ground down, about 1 meter is clay; 2-9 meters is fine sand layer; 10-15 meters is sand layer; 15-20 meters is silty clay; below 20 meters is clay layer.

In this kind of sand-based cast-in-place pile construction, the quality of the mud directly affects the hole-forming speed and the hole-forming quality, and the construction needs to be cautious.

The following points must be achieved in the construction of static slurry wall protection technology:

1) The buried protection tube is 3 meters long to protect the orifice;

2) The specific gravity of the mud is about 1.15;

3) The viscosity of the mud is controlled between 18-20;

These two data should be measured with professional measuring instruments. During the specific construction process, experience should not be taken for granted, which will affect the mud quality.

The mud raw materials include water, clay, and additives. The additives are mostly bentonite, carboxymethyl cellulose, soda ash, etc. The specific functions are as follows:

1) Bentonite: It has good water swelling properties, dispersing and suspending slurry making properties, low density, good viscosity, low sand content, low water loss, thin mud skin, strong stability, strong wall-fixing ability, etc. Advantages, for construction in the stratum containing sand, bentonite in the mud is an indispensable important ingredient. Bentonite is divided into sodium, calcium and lithium. The pulping effect is good for sodium, followed by calcium, and relatively poor for lithium. In actual use, calcium bentonite is widely used because of its low price and good slurry stability. The blending amount of bentonite is generally 8%, and the amount of poor bentonite should be increased to about 12%.

2) Carboxymethyl cellulose: increase the viscosity of the mud, can form high-viscosity colloids and solutions, and form a film on the surface of the soil layer, thereby preventing the pore wall from falling off, and has the effect of reducing water loss. In the actual construction, when encountering the stratum that is particularly prone to collapse, it is recommended to add carboxymethyl cellulose to the mud to enhance the wall protection effect of the mud and improve the quality of drilling. The blending amount should be controlled within 0.1%-0.3% of bentonite.

3. Soda ash: Soda ash is scientifically called sodium carbonate, which can increase the pH of the mud to about 10. If the pH value in the mud is too small (when it is acidic), the clay particles are difficult to decompose, the viscosity is reduced, the water loss is increased, the fluidity is relatively reduced, and the drilling tool will be corroded. If the PH value is too high, the mud will penetrate into the clay on the pore wall, soften the pore wall surface, weaken the cohesive force between the clay particles, and cause the cracking pore wall to collapse. The pH value is 8-10, which can increase the thickness of the hydration film, improve the colloid rate and stability of the mud, and reduce the water loss. The utilization rate in the construction site is relatively high. Generally, the blending amount is 0.3%-0.5% of bentonite.

The above 3 kinds of additives are common in the construction process. The dosages listed above are normal conditions and are for your reference only. The specific dosage of additives should be determined according to the specific conditions of the construction site.

 

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Photos of collapsed holes caused by poor mud

 

The hole collapse and diameter reduction occurred during the early construction of the KR125 rotary drilling rig. In order to eliminate this kind of phenomenon, it was decided to increase the proportion of mud, reduce the speed of piling, and reduce the time to wait for pouring after the hole is formed. Effectively reduce the occurrence of hole collapse and diameter reduction. Summarizing the sand piling experience, it is not difficult to see that in the construction with sand as the main stratum, the speed cannot be blindly pursued. The sand plow must comply with the principle of less footage and slow drilling, minimize disturbance to the hole wall, and rationally configure the mud , Ensure sufficient mud in the hole, excavate back to the slurry tank if necessary. And pay attention to check the amount of sediment at the bottom of the pile, drill a good pile hole to ensure the quality of the pile.

After the construction was stabilized, Pinghan Heavy Industries KR125 drilling rig was constructed at the Xuzhou site, with a daily pile output of about 8 pieces. The efficiency is higher than other types of drilling rigs. The total amount of construction holes is 40% higher than other drilling rigs. The reasons are summarized as follows:

The KR125 rotary drilling rig is an integral transport drilling rig. Construction will start within 2 hours after entering the site. There is no cumbersome installation process of the drilling rig, which saves time and effort;

The torque of the K125 rotary drilling rig is 125KN.m, which fully meets the needs of pile diameter and pile depth at the construction site. Although other models have large torque, they have no advantage;

The KR125 power head has a fast speed and a fast forward and reverse function, which is good for slagging;

A body-opening drill bucket with a diameter of 600 was selected, and the fast forward and reverse rotation was used to throw soil;

The pile diameter of this construction site is small, and the big power of the big drilling rig cannot be used;

The KR125 drilling rig is small in size, light in weight, and under the premise of meeting the stability requirements, the actions such as lowering, lifting, and turning are faster than other models, which is reflected in the sensitive action;

During the construction of this project, the power of the small drilling rig is small, and the fuel consumption for the same work is reduced by nearly half compared with the large model of the 22 model, saving tens of thousands of yuan a month.

Both the sounding display device and the rotary display device of the KR125 drilling rig are unique technologies, with high display accuracy and bottoming protection function. The machine hand knows the situation of the hole well and accurately judges;

The control system developed in cooperation with the Robotics Institute of Tianjin University has an intuitive and friendly display interface, simple operation, integrated information display, and all common operations are located at the first level of the program.

Pinghan Heavy Industry is committed to the professional manufacture of small and medium-sized rotary drilling rigs that are affordable, affordable and usable for the industrial and civil construction. Adhering to this concept, the Pinghan team started with the various details of the construction of the drilling rig, the various steps of the operator’s operation, and the various intelligent information required for the construction, and continued to improve the product, and improve the construction efficiency and reliability of the whole machine. Users can experience the advantages of drilling rigs in actual use. The various data indicators of this construction site have verified the effects and benefits of this concept after implementation from all aspects.

 

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Field operation for Australian customers

 

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KR125 construction site shows its glory

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