In the construction of basic projects, in order to improve the effectiveness of the project quality, often take two or more construction machinery to cooperate with the construction. Nanchong Junhui Top Pile Foundation Project The use of rotary drilling rig and impact drill to carry out the construction of the cast-in-place pile has solved the problem of collapse of the silt stratum and the backlash of the stone, and the combination of the two processes has improved the construction efficiency and achieved good Economic benefits.

First, the project profile

Nanchong Junhui top grade project is a large-scale commercial housing development project, construction area of ​​600,000 m2, the main building of 33 layers, the company won the bid for the real estate 4 to 8 basic rotary excavation pile construction tasks. The engineering geological conditions are complex, the upper 15m deep within the backfill layer, the lower 15m ~ 30m deep range of strong weathering and breeze mudstone, the foundation bearing capacity is high, requiring the pile into the micro-weathered mudstone 3m above the design using rotary drilling Post-grouting process.

Second, the construction encountered in the digging machine is difficult to hole problem

Because the foundation of the project belongs to the backfill area of ​​the river, some of the silty strata contain the silt layer and the fluff layer in the original river channel. The hole of the rotary drilling rig has the phenomenon of shrinkage, the drilling is repeatedly collapsed and can not be formed. Very thick, backfill large pieces of stone size, overhead serious, rotary drilling rig construction leakage slurry, serious collapse and other difficulties, the construction of difficult. Backfill concrete re-hole construction cost is high, the progress is also greatly affected.

Third, the rotary drilling rig and the impact of drilling construction

In the work of rotary drilling rigs compared with the impact drill is easy to move, hole hole low slope, reaming coefficient is small, the construction speed, waste residue and other aspects of a little more, and more for bridge and real estate pile construction The But in the backfill block stone, dense overhead layer or mud layer, sand layer thick special formation conditions can not play its unique construction advantages.

In order to improve the efficiency, we use the impact drill on the different layers of the strong adaptability of the characteristics of the pile of its construction of the squeeze compaction, the impact of large rock crushing, silt and quicksand of the formation can also be effectively squeezed Dense, to prevent the occurrence of leakage slurry collapse phenomenon. In the special stratum of the supernatant project, we use the upper mud layer or the backlash block to impact the drilling hole, the lower strong weathering and the micro-weather mudstone rotary drilling rig construction method to ensure that the pile can successfully hole The

Fourth, the construction of technical aspects should pay attention to the problem

1, to prepare the work Notes

During the construction process in a rotary drilling rig and the impact of drilling with the time should be ahead of the construction site should be flat planning. Rotary drilling rig to advance to the impact of drilling a number of more embedded protection, to solve the impact of drilling bury the inconvenience, while avoiding the impact of drilling squeeze a pile after the hole on the next pile can not be timely construction and stop , But also to avoid the construction process of security incidents.

In the beginning of the impact drill before the construction of its flat car should be modified in the front of the flat car plus welding more than flat car plate to increase the carrying capacity to avoid the process of drilling in the base of the soft foundation of the conditions caused by drilling rigs, Bit, hole slope deviation of the impact of project quality. While avoiding the mechanical collapse of the safety accident occurred. In the drill in place after the construction of drilling before the construction of the pile hole to fill the loess for dynamic compaction.

2, construction process precautions

In the construction process to the hole of the strata to observe the understanding of the large stone frame in the specific situation, the high degree of overhead in the stratum we will add more loess extrusion, increasing the concentration of slurry to prevent the occurrence of slurry collapse. In the silt and quicksand of the lot will be diligent, more blocks of stone repeated squeeze compaction, to avoid the squeeze is not in place and the occurrence of rotary drilling rig occurred in the construction of the shrinkage caused by buried drill.

In the block of stone frame empty high and thick construction section, in advance to the pile of stone on the excavation of the loess to fill the loom to the excavator to create the conditions for the protection of the barrel, to avoid the stone can not be too large digging machine construction difficult. Construction should pay attention to strictly control the impact of drilling hole diameter and hole slope, to ensure that the rotary drilling machine for the lower part of the hole will not touch the hole.

For the impact of drilling squeeze dense pile hole must be tamped with a certain hardness of the formation before the acceptance of the delivery of rotary drilling rig construction. Finally, the hole will be completed by the rotary drive installed, the perfusion.

In this particular stratum construction, the mud is critical. The use of clay slurry in the impact of drilling holes, directly into the hole into the clay slurry, in the aerial layer of clay filled repeatedly. Rotary drilling rig construction, the use of better bentonite slurry, should ensure that the mud has a sufficient concentration.

5, on-site scheduling should pay attention to the problem

(A) staff with

1) the rational allocation of the division of labor. In the construction of the construction team to the work of a reasonable arrangements for deployment, to prevent the construction of a blank area. As the Nanchong project is a purely management project, each construction process is subcontracted to other teams, or internal contracting, which must be clear their respective construction tasks, from the contract to be clear, so that in the construction site to make all the construction tasks are Can be successfully completed. Otherwise, there are omissions in the construction process, re-arrange staff to add new tasks, not only is not conducive to the implementation of the construction task, because the outsourcing team may exist outside the contract content of the construction tasks conflict, and will produce high costs, increased claims And project costs.

2) According to the construction site plan layout order. Management staff to clear the construction of the order and progress, according to the construction site plan and the scheduled construction plan, do a good job in advance arrangements. Ready for the construction conditions, the rational allocation of existing resources, thereby enhancing the efficiency of construction, in the work of a ring of a ring, can not cause unreasonable arrangements for the work and delay the progress of work, so interlocking to promote the project Proceeded smoothly.

3) to strengthen communication and improve the enthusiasm of employees. In the construction decision-making process, require technicians, foreman to participate in, so as to enhance the acceptance of the construction program. In the actual management process can actively take the initiative to play a personal work ability, to play the initiative of managers, which is conducive to promoting the progress of construction.

(2) materials with

1) Reasonable stacking of material equipment. Due to the narrow construction site, it is necessary to do the safe stacking of containers, machinery and equipment, construction materials, determine the location and use of the system, strengthen the control, so as to free enough space to meet the construction needs in the narrow construction site to seek the most benefit The

2) reasonable scheduling equipment. To consider a good equipment to complete the task of its work done by the follow-up task, or is working on the work of another kind of equipment is affected, whether it can be carried out at the same time, to distinguish the priorities of the work, Reasonable arrangements for construction tasks, but also pay attention to cross-construction of the existence of security risks, put an end to the construction of the accident occurred,

3) the rational use of means of production. Production should be intensive use of existing materials to reduce the rigorous means of production and production of waste materials, increase the use of secondary opportunities to reduce costs to avoid waste of materials, good equipment maintenance and maintenance of old equipment, scrap iron accumulation and deal with.

Sixth, the security aspects should pay attention to the problem

1, equipment safety

Drilling machine should be in place before the rig must be filled with foundation, drilling rig in place according to the specified hole, drilling rig installed in place should be carefully adjusted to ensure that the construction does not occur tilt, shift. Drilling machine flat car with steel bedding, such as drilling before the phenomenon of collapse to be timely treatment, to avoid accidents. Lifting the rig when the first test hanging, hanging and then transferred in place to prevent the middle of uncontrollable accidents.

2, safe electricity

(1) pay attention to the main cable, start line and drill contact parts of the protection work, to avoid leakage phenomenon. By a special operator of the cable layout and wiring work.

(2) do the welding and distribution cabinet grounding work, by the electrician daily inspection and removal.

(3) on the three leakage switch to be checked at any time, electrical classes on each team to provide safe and responsible people, do this group of regional electricity safety.

(4) Shut down the maintenance of equipment, pay attention to turn off the power and suspend the marked.

Seven, concluding remarks

The advantage of the impact drill is the ability to squeeze the formation on the compaction, the large pieces of hard rock broken, but its cost is low efficiency. Rotary drilling rigs can be moved quickly and quickly, and the cost of forming holes is low. However, there are some drawbacks to the formation of soft and easy collapse. In the actual construction process, the two construction equipment can be reasonably Use to reduce costs and improve work progress.

As the implementation of the technology, increase the difficulty and intensity of scheduling, it must do other related supporting measures management, safety of electricity, machinery and equipment safety put forward higher requirements, construction management personnel must adapt and make a reasonable Arrangements and necessary supervision.