Shanghai Jintai SZ80-35 multi-function drilling rig application is further expanded

The Shenzhen Industrial and Commercial Bank Building project undertaken by the China Construction Third Committee is located at Haide 3rd Road, Nanshan District, Shenzhen. It has a total construction area of ​​approximately 84,000m2, a building height of 180m, and a basement of 4 floors. The area of ​​the foundation pit is about 5010m2, the perimeter of the pit is 285m, and the excavation depth is about 20m.

The geological survey report reveals that the intrastratigraphic stratum mainly consists of lithified materials such as artificial backfill, organic clay, gravelly cohesive soil, and coarse-grained granite. The engineering foundation pit support adopts a new type of bite-in-place pile method, in which there are 289 occlusal piles with 1.2m diameter, 66 occlusal piles with 1m diameter, and 355 occlusal piles supported by foundation pits. (Specific pile type and distribution as shown below)

Shanghai Jintai SZ80-35 multi-function drilling rig application is further expanded

Segments I and II are 1.2m in diameter and 27.3 to 33.3m in length, and are constructed using the Jintai SZ80-35 full-casing drill. Segment III is a 1m occlusal pile with a pile length of no more than 13m and adopts a rotary bite hard bite technique.

During the visit to the construction site, it was learned that the mechanical option for the original foundation pit enclosure was a combination of boring machine + rotary drilling machine, not the SZ80-35 full casing drilling rig. At the time of the project review, it was generally believed that the use of the boring machine+rotary excavation combination under the working conditions of the project would have many adverse effects: First, each section of the pipe boring machine had a casing of 6 meters, which was added several times during the construction process. After the casing is applied, the verticality needs to be reviewed after each casing and the hole forming efficiency is low. Second, the cumbersome operation procedure may adversely affect the pile forming quality and bite degree of the supporting piles; The surface has been cramped and the casing of the sewer tube has occupied a large space, which will increase the difficulty of the construction layout.

Construction Site

The head department combined the design of the foundation pit support design and the ground investigation soil layer report. After repeated demonstration and several trial piles, the final decision was made to select a new type of pile foundation machinery with better construction performance under this working condition—SZ80-35 Multifunctional drilling rig. The final description of the construction plan describes this machine as follows:

1. SZ80-35 multi-function drilling rig is a new type of full-casing multi-functional drilling rig independently developed and manufactured by Shanghai Jintai Construction Machinery Co., Ltd. The main body is made of electro-hydraulic footing piles, low grounding ratio, and three-point supporting structure of the column. The stability of the whole machine is extremely strong. ;

2, dual power head configuration, two power heads drive the casing under the drilling / lifting and drill pipe drilling, bushing power head output torque of 650KN.m, drill rod power head torque of 360KN.m, powerful The driving force combined with the full casing process can adapt to all kinds of complicated geological conditions such as quicksand layer, pebble layer, karst stratum and rock layer to ensure construction efficiency.

3. Both the casing and the drill pipe are designed as a whole section. Auger drill pipe is drilled in the end, which greatly saves the manpower and time cost of casing and drill pipe.

4. The hole diameter and hole wall of the device are regular and the vertical precision of the pile hole is high. There is no need for slurry protection and no mud discharge during construction, which meets the requirements of green construction.

An engineer of the project department further introduced: “Drilling and filling bite piles” is a new type of building foundation pit supporting structure. The process is named after its piles and piles bite into each other and form a continuous wall. The Shenzhen Industrial and Commercial Bank Building project is adjacent to the Metro Line 11, and the No. 4 exit of Houhai Station is separated from the site by just one way. The foundation pit enclosure adopts the bite pile method in addition to meeting the requirements for the design and construction of the foundation pit. The safety of surrounding subway and site pile foundations must be greatly protected. At the same time, compared with the slotting process of underground continuous walls, the art of occlusal pile support has obvious advantages in terms of construction costs.

The skipping pile method of full-casing bite pile construction is not a simple “advance and retreat” progressive model. Instead, it adopts a continuous jump-piling method, so that the retardation time of prime can be reasonably used, while ensuring the quality of the pile, and at the same time, Can improve construction efficiency. Under normal circumstances, the construction sequence of full-casing drilling continuous jump piles is A1 → A2 → A3 → B1 → A4 → B2 → A5 → B3 → A6 → B4 (as shown in the following figure).

as the picture shows

Practice has proved that in the case of steel cage processing and timely supply of concrete, the SZ80-35 can ensure that the effective number of piles per day reaches seven. Under this premise, the number of consecutive hops can also be appropriately increased. The construction sequence can be adjusted to: A1 → A2 → A3 → A4 → B1 → A5 → B2 → A6 → B3.

Shenzhen Houhai completed bite pile foundation pit support efficiently

As of press time, 289 1.2m bite piles constructed by SZ80-35 have been completed as scheduled. According to feedback from the project department, the use of dual power head and full casing drilling process to efficiently complete bite pile construction is the first case in Shenzhen and even in Guangdong. The successful application of SZ80-35 in the landmark building of Houhai – Shenzhen Industrial and Commercial Bank Building has been very successful. A good demonstration effect will surely show greater achievements in the future construction of the Bay Area. (This article comes from Shanghai Jintai)