the common engineering accident prevention and treatment measures

⑴ "piping" Handling
"Piping" refers to the process B pile into the hole, because the A uncured concrete piles, still in the fluid state, A concrete pile is possible from A, B B pile into the pile hole intersection. Overcome the "piping" There are several methods:
① A pile of concrete slump should be relatively small, not more than 18cm, in order to reduce the flow of concrete;
② casing bottom nozzle should always be kept a certain distance ahead of the cutting face, in order to create a "bottleneck", to prevent the flow of concrete, if the drilling conditions permit, this distance the better, but at least not less than 2.5m;
③ necessary Gutta Percha Points (in case of underground obstacles ahead of the casing end can not) be within the casing into a certain amount of water through the water pressure to balance the pressure of concrete piles A, to stop "piping" occurs;
④ A pile into the hole process, should be observed adjacent to both sides of the top surface of the concrete pile B, B is found piles of concrete subsidence, should immediately stop A pile excavation and under the pressure side of the sleeve as far as possible, within the pile to the A side filling or water until it is completely stopped, "piping."
⑵ steel cage floating processing
Because the casing wall and the space between the outer edge of the reinforcement cage is small, in the pull casing when casing reinforcement cage may be floating along with. Preventive measures are:
① A pile of concrete aggregate size should be smaller, not larger than 20mm;
② In the bottom of the reinforcement cage welded steel cage on a slightly smaller diameter than the steel sheet to increase its anti-floating capability;
Positive reinforcement cage installation guide ③ device;
④ must follow the rules for the pouring of concrete.
⑶ drilling encountered stone processing method
If there are more venues there are rules rock band, and we will use the "two stages into a hole method" for processing: the first stage, whether A or B piles pile, first got into the rock face to the earth, and then Remove the hammer grab change from the casing with a hammer drill to punch pile design elevation, into the hole after filling the casing, unplug while filling the side casing, the first stage into a hole filled with soil full; second stage, according to the normal construction method Secant Pile Construction.
⑷ segmented construction joint approach
Often a rig construction progress of the project can not meet the need multi-rig construction segment, which exist prior construction segment joints problems. Using sand pile is a better approach in the construction segment and the segment ends to set up a sand pile (after the sand into the hole filled), subject to this section after the construction joints can be dredged sand filling the concrete.
⑸ pile handling accident
In Secant pile construction process, because B super-retarding concrete pile appeared early condensate phenomenon or mechanical equipment failures and other factors, not Secant pile construction requirements for the formation of normal accidents pile. Accidents pile handling mainly the following situations.
a pan pile unilateral occlusion
A pile into the hole construction, concrete piles B1 its side has solidified, the casing can not rig the normal requirements
 
Cutting bite B1, B2 piles. Approach is to shift the direction of the pile A pile B2 bit, make unilateral cuts B2 pile casing drilling, construction A pile (in addition to cutting the original pile guide wall, and strictly control the pile) and B1 piles and piles outside A Another increase in a rotating pile as water treatment.
b back pile reinforcement
A1 into the hole pile construction, pile it on both sides of B1, B2 are solidified concrete piles, processing methods as a waiver of A1 pile construction, pile adjustment sequence, continue to the next bite pile construction, pile outside later in the A1
 
Occlusal side increased three piles and two jet grouting pile as reinforcement.
c aside bite tongue and groove
Shown in Figure 5, the pile into the hole in the B1 A1 pile of concrete construction has been found in early coagulation tendency but not yet completely solidified, then continue as normal sequence in order to avoid accidents caused by construction piles, pile on the right timely construction of the A1 a sand pile to reserve bite tongue and groove, to be adjusted to complete before continuing behind the pile construction.