Disclosure of Invention
The invention aims to provide a construction method of a sand flowing layer with an overlarge area of a vertical shaft raise-shaft method pilot hole, which solves the problems in the prior art, ensures the normal construction of the pilot hole and shortens the construction period.
In order to achieve the purpose, the invention provides the following scheme: the invention provides a construction method of a sand flowing layer with an overlarge area of a vertical shaft raise method pilot hole, which comprises the following steps:
a. construction preparation, namely excavating a circulation pool, a sedimentation pool and a raise boring machine foundation pit, accurately lofting hole positions according to the central coordinates of a ventilation vertical shaft pit shaft, pouring a C20 concrete construction base, leveling the base, wherein the size of the base is 4m multiplied by 3m multiplied by 1m, reserving a ground anchor bolt groove at a fixed drilling machine on the base, and laying a special track and then hoisting the raise boring machine in place;
b. installing a raise boring machine, wherein the raise boring machine is installed at a well mouth, when the raise boring machine is installed in place, checking whether the drilling direction of the drilling machine meets the design requirement, lofting a drilling vertex angle by using a hanging line, pouring second-stage concrete after the drilling machine is accurately positioned, and debugging and running the raise boring machine after 3 days;
c. the pilot hole drilling construction is carried out, and the drill rod is supported by a rod supporter in a short drill rod, low axial pressure, low rotating speed and intermittent propelling mode during drilling; after the short drill rod is drilled, firstly connecting a stable drill rod, gradually increasing the axial pressure and the rotating speed to normal values when the stable drill rod completely enters the guide hole, and continuously propelling the stable drill rod; and (4) connecting a second stable drill rod 7-8 m away from the first stable drill rod, and then installing one stable drill rod every 6-7 drill rods.
Preferably, when the pilot hole in the step c encounters a fault or a crack to generate vibration or drill sticking, intermittent propulsion is adopted to slow down the drilling pressure; along with the increase of the drilling depth, the flushing and deslagging time before changing the drill rod is gradually increased, and rock slag near the orifice is removed in time; and starting to start the hydraulic pressure reduction drilling system when the drilling depth reaches 50 m.
Preferably, when the sand layer overflows in the drilling process of the pilot hole in the step c, the bit of the raise-boring machine needs to be adjusted, and a roller bit is used for the common construction of the pilot hole; when the pilot hole passes through the hard rock section, a spherical or columnar alloy block drill bit is adopted; and selecting a wedge-shaped alloy block drill bit when the pilot hole passes through a softer rock section.
Preferably, the slurry used for the slurry retaining wall when the pilot hole passes through the sand flowing interval is mixed slurry which is prepared from 50kg of bentonite and 1m of mud3Water, 25kg of wood chips and an additive of cohesive soil.
Preferably, after the mud retaining wall is finished, hole sealing and pressurizing deep hole grouting is carried out on the pilot hole, hole sweeping needs to be carried out on the pilot hole before hole sealing and pressurizing deep hole grouting, and the position of starting hole sweeping is six meters after the drill bit passes through the quicksand layer.
Preferably, when a hole collapse occurs in the drilling process of the pilot hole in the step c, finding the hole collapse position through measurement, judging the rock stratum condition of the hole collapse position, performing hole sweeping and hole washing by using an air compressor and well washing liquid, stopping hole sweeping after residual rock slag in the hole is completely blown, performing grouting, and drilling after the residual rock slag is solidified;
the grouting amount is calculated according to the following formula:
Q=π×R2×L×n×k
wherein: r is the slurry diffusion radius; l is the length of the grouting pipe; n is the porosity of the rock mass; k is a filling coefficient, the value range is 0.3-0.5, and the value is taken according to different geological conditions.
Preferably, when secondary hole collapse occurs in the drilling process of the pilot hole in the step c, an air compressor is used for sweeping the hole to blow out residual rock slag, grouting is conducted on a wellhead, grouting is stopped when the grouting height reaches a position 20 m above the hole collapse position, hole sweeping is conducted again after 12 hours until the hole collapse position is reached, and drilling is continued if the hole collapse does not occur.
Preferably, when the drill rod breaks and falls into the pilot hole in the pilot hole drilling process in the step c, the drill rod needs to be salvaged, and drilling is continued after the drill rod salvaging operation is completed.
The invention discloses the following technical effects:
(1) the form of the drill bit is optimized and adjusted, the disturbance of the drill bit to the side wall and the loss of sand in the drilling process are reduced, and the effects of saving cost and quickly constructing are achieved.
(2) The specific slurry is prepared by adopting bentonite, water, wood chips and a proper amount of clay admixture, wherein the wood chips fill cracks, the slurry loss is prevented, the wall protection effect is enhanced, and the hole wall collapse phenomenon is controlled.
(3) The high-pressure grouting is carried out on the local hole collapse position by adopting a grouting pump to connect the drill rod, the grouting is stable from the underground collapse position, the stabilizing effect is good, and the construction cost is low.
(4) The technology of salvaging broken drill rods and drill bits is researched and developed automatically, the treatment is convenient and quick, and the damage to construction appliances is small.
(5) The standardized management is advanced in depth, the safety quality is integrally controllable, the sample plate guiding effect is obvious, and the rapid and ordered construction and production are realized.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The invention provides a construction method of a sand flowing layer with an overlarge area of a vertical shaft raise method pilot hole, which comprises the following steps:
a. construction preparation, excavating about 8m3And a circulation tank and a sedimentation tank of about 6m3The raise boring machine foundation pit. Accurately lofting hole positions according to the central coordinates of a ventilation shaft, pouring a C20 concrete construction base, leveling the base, wherein the size of the base is 4m multiplied by 3m multiplied by 1m, reserving a ground anchor bolt groove at a fixed drilling machine on the base, and hoisting a raise boring machine in place after laying a special track;
b. and (4) installing a raise boring machine, wherein the raise boring machine is installed at a well head in a matched mode by using a 16T crane. When the drilling rig is installed in place, whether the drilling direction (drilling top angle) of the drilling rig meets the design requirement or not must be strictly checked, the drilling top angle is lofted by using a hanging line, second-stage concrete is poured after the drilling rig is accurately positioned, and the raise-boring rig is debugged and run in test after 3 days;
c. the pilot hole drilling construction is carried out, and a short drill rod, a low axial pressure, a low rotating speed and a discontinuous propulsion mode are adopted during hole opening, and a rod lifter is used for supporting the drill rod; after the short drill rod is drilled, the stable drill rod is connected firstly and plays a role in guiding, and when the stable drill rod completely enters the guide hole, the axial pressure and the rotating speed can be gradually increased to normal values, and continuous propulsion is adopted. And (4) switching in a second stable drill rod 7-8 m away from the first stable drill rod, and then installing one stable drill rod every 6-7 drill rods.
When the drill pipe is vibrated or stuck due to the contact with faults and cracks, intermittent propulsion can be adopted to reduce the drilling pressure. Along with the increase of the drilling depth, the time for flushing and deslagging before changing the drill rod is gradually increased, so that the rock slag in the hole is completely discharged and then the drill rod is changed, and the accident of slag return and drill burying caused in the process of changing the drill rod is avoided. Rock slag collected near the orifice is removed in time, and smooth slag discharge is guaranteed. And starting to start the hydraulic pressure reduction drilling system when the drilling depth reaches 50 m. As the depth of the drill increases, the reduced pressure is increased to maintain the axial pressure on the drill bit at a desired value. The table of the weight on bit, the rotational speed and the drilling rate when the pilot hole is drilled is shown in table 1:
TABLE 1 weight on bit, rotational speed and rate of penetration table for pilot hole drilling
Pilot hole drilling construction precautions:
(1) adjustment of drift sand layer drill bit
The common construction of the pilot hole uses a roller bit, and the roller bit is matched with a high-pressure air compressor to carry out high-pressure pulse impact on the drilling of the pilot hole, the working principle is that the grinding effect is generated between the bit and a rock body through the action of axial force and torque of a drill rod, and ground rock debris is taken out from the bottom of a hole through slurry circulating liquid. Different combinations of bits should be used for different formations. It is reasonable to use spherical or columnar alloy blocks on the hard rock drill bit, and wedge-shaped alloy blocks are suitable for softer rock.
Aiming at the characteristics that the flowing sand layer has extremely low plasticity or no plasticity, strong water permeability, low compressibility, quick compression process and close to a fluid state, the structural form of the lip surface alloy block of the drill bit is firstly modified, the original cylindrical alloy block is replaced by a wedge-shaped alloy block, and the grinding action principle in a rock stratum is changed into the cutting action with less disturbance in the sand layer. And secondly, adjusting the number, arrangement mode and cutting angle of the alloy blocks, increasing the number of wedge-shaped alloy blocks, and increasing the cutting area with the sand at the bottom of the hole by adopting a densely distributed arrangement mode to form the composite bit. The rock is crushed by adopting a continuous and stable cutting mode of pressing in and rotating. When the drill bit quickly passes through the quicksand layer, the disturbance of the drill bit on the quicksand layer caused by the extrusion effect of the drill bit is reduced, and the disturbance of the drill bit on the quicksand during the drilling, descending and pulling processes is also reduced.
(2) Adjustment of mud ratio in quicksand layer
Due to the development of rock mass cracks and the hydraulic action of a quicksand section, when the pilot hole passes through the quicksand section, the slurry loss phenomenon is serious, so that the injected slurry is continuously lost, the height of the slurry cannot reach a wellhead, and the slurry circulation requirement is not met. In order to realize that the mud meets the circulation requirement and enhances the wall protection effect, the sawdust is used as the mud mixture and used for filling the cracks to achieve the aim of preventing the mud from losing, and the mud is prepared according to the formula of' 50kg of bentonite +1m3The mixture of water, 25kg of wood chips and a proper amount of clay admixture (adopting the mud king on site) has good crack filling and wall protecting effects. After the sawdust-added slurry is injected, the loss condition of the slurry is improved, and the height of the slurry reaches the position of a well head again to meet the circulation requirement. And then, starting drilling, injecting the slurry for a plurality of times of repeated circulation, finding that the slurry protects the wall well and the well hole collapse phenomenon is obviously improved, and simultaneously suspending the rock drilling slag in the slurry to prevent the rock drilling slag from depositing and burying the drill rod so as to enable the drilling machine to drill through the collapsed bottom layer.
(3) Hole sealing pressurization deep hole grouting
As shown in FIG. 1, in order to check the grouting effect of the previous section and provide data for the next section, holes are swept along the original grouting holes. And (3) starting hole sweeping before high-pressure grouting, wherein the hole sweeping is consistent with the original hole position, and the hole sweeping is positioned about six meters behind a drill bit passing through a quicksand layer by adopting a light-pressure quick-rotation mode.
After the hole is swept, a section of rotten wood or a bag filled with filler with the same diameter as the inside of the hole is prepared on site, the rotten wood or the bag is connected with a rope with enough length, one end of the rope is connected to the derrick to be used as a lower support when the wellhead is plugged, a section of pvc pipe (which is longer than the length of the closed wellhead) with enough length is prepared, and the pvc pipe is positioned at the closed section

Filling a high-pressure grouting pipe into the high-pressure grouting pipe, filling a gap between the grouting pipe and the PVC pipe with diluted mortar to protect and stabilize the grouting pipe, lowering the grouting pipe into the well, mutually connecting rotten wood or bags filled with fillers prepared in advance, lowering the rotten wood or bags into corresponding positions in the well, grouting the closed section after all the bags are installed, and drilling after the strength meets the requirement after grouting is completed.
(4) Hole collapse construction operation
And judging whether the hole collapses or not according to the drilling slag of the drilling machine and the pulling condition of the drill rod.
If there is a hole collapse, first, as shown in fig. 2, measurement is performed to find the position of the hole collapse, and the rock formation state at the position of the hole collapse is determined by combining the geological map, the slag discharge texture, and the like. According to the field situation, a RAP-1000E air compressor and well washing liquid (sodium dodecyl sulfate solution) are used for hole sweeping and hole washing for a proper time, residual rock slag in the holes is blown out, hole sweeping is stopped when the rock slag in the holes is blown out and is not increased continuously, first grouting is carried out, and drilling is carried out after solidification. The grouting amount can be calculated as follows:
Q=π×R2×L×n×k
wherein: r is the slurry diffusion radius (m); l is the length of the grouting pipe; n is the porosity of the rock mass; k is a filling coefficient, the value range is 0.3-0.5, and the value is taken according to different geological conditions.
And if the rock is collapsed again, performing wellhead grouting treatment, performing hole washing treatment by using an air compressor, and blowing out residual rock slag. Stirring the C32.5 cement, adding a certain amount of accelerating agent, directly injecting from a wellhead, measuring while injecting, measuring when the grouting height reaches about 20 m above the hole collapse position, and stopping grouting. And (5) after 12 hours of solidification, performing secondary hole sweeping until the original collapse position is reached, and continuing drilling if the hole does not collapse.
If the wellhead grouting method cannot achieve the expected grouting effect, high-pressure grouting is adopted, a grouting pump is connected with a drill rod, cement slurry is conveyed to a collapse position from a center hole of the drill rod, and grouting is performed from the underground collapse position. Firstly, carrying out hole washing treatment by using an air compressor, removing residual rock slag, after the inside of a well hole is cleaned, injecting cement slurry provided by a mixing station from a ventilation hole in a drill rod by using a special drill bit welded by workers and a grouting pump with the rated pressure of 8 MPa (which can be adjusted according to actual conditions), reaching an underground collapse position, continuously injecting the slurry until the slurry reaches about 20 m above the collapse position, then injecting a certain amount of 32.5 cement added with a certain amount of accelerating agent from an orifice until the slurry height reaches about 50m away from the collapse position, and continuing drilling after 12 hours of solidification.
(5) Fishing for broken drill rod
When the sand-flowing layer collapses, the drill rod can break and fall into the pilot hole. A method for salvaging a drill rod comprises the steps of selecting a hollow steel pipe with the diameter larger than that of the drill rod, welding alloy particles with the length of about 1cm on the end of the hollow steel pipe, manufacturing an alloy drill bit, connecting the alloy drill bit to a pilot hole drilling machine, polishing downwards, polishing till the thread of the drill rod stops, lifting the alloy drill bit, replacing the alloy drill bit with a screw tap, screwing the screw tap into the drill rod easily due to the fact that the screw tap is in a threaded inverted cone shape and is fixed by concrete below, lifting the drill rod after screwing the screw tap, and completing the operation of salvaging the drill rod after lifting.
The invention has the advantages of conventional materials, low price, no need of additional purchased instruments, less professional equipment, simpler, more convenient and more flexible integral operation method, reduction of construction cost and equipment investment, great reduction of engineering cost, good economic benefit and effective guarantee of construction safety. The process has the advantages of high working efficiency, strong operability, safety, environmental protection, excellent quality, easy popularization and investment saving, adds a new option for the disposal method of the overflow sand layer of the pilot hole, promotes the development of the reverse well enlarging and digging technology and has huge potential social benefits. In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.