A construction method for anchor cables passing through easily caving strata

Abstract

The present invention provides a construction method for anchor cables passing through easily caving strata. The present invention uses a casing to support the drilling, avoiding the problem that the drilling hole is blocked due to the collapse of round gravel, which in turn causes the anchor cable to be unable to be inserted.

Description

Technical Field

[0001] The present invention relates to the field of construction technology, and more particularly to a construction method for anchor cables passing through strata prone to hole collapse. Background Art

[0002] Sheet piles + anchor cables + steel support beams are common components of the foundation pit retaining system. Miscellaneous fill, silty clay with sand, gravel, strongly weathered argillaceous siltstone, and moderately weathered argillaceous siltstone are the conventional geological structures of the strata in the construction area. Thus, when the gravel layer has a situation of prone to hole collapse, it will cause difficulties in placing the anchor cables, affecting the construction efficiency of the project's anchor cables. The conventional construction process of the previous traditional anchor cables is: drilling the anchor rod, placing the anchor cable, grouting, secondary grouting, tensioning and locking, lacking consideration for preventing hole collapse. Therefore, how to solve the problem of hole collapse in the gravel soil layer has become a difficult problem often faced during the construction of anchor cables. Summary of the Invention

[0003] To solve the technical problems existing in the above background art, the present invention provides a construction method for anchor cables passing through strata prone to hole collapse.

[0004] A construction method for anchor cables passing through strata prone to hole collapse includes the following steps:

[0005] Lay the drill pipe inside the casing, and at least part of the drill head of the drill pipe extends out of the casing;

[0006] Drive the drill pipe to rotate and make the drill head act on the gravel layer and drive the drill head to advance for drilling, drive the casing and the drill pipe to advance synchronously, and keep the front end of the casing at an appropriate distance from the drill head;

[0007] After the drilling target is achieved, withdraw the drill pipe from the casing, place the anchor cable, and inject cement slurry into the drill hole to complete the construction of the anchor cable.

[0008] Optionally, the driving the drill pipe to rotate and make the drill head act on the gravel layer and drive the drill head to advance for drilling, driving the casing and the drill pipe to advance synchronously includes:

[0009] Use a first driver to drive the drill pipe to rotate and make the drill head act on the gravel layer and drive the drill head to advance for drilling, and use a second driver to drive the casing and the drill pipe to advance synchronously;

[0010] Wherein, the sub-tracks of the first driver and the second driver are arranged.

[0011] Optionally, the keeping the front end of the casing at an appropriate distance from the drill head includes:

[0012] During the process of the first driver driving the drill head forward for drilling, the driving resistance value is collected in real time and plotted into a first resistance curve;

[0013] During the process of the second driver driving the casing and the drill pipe forward synchronously, the driving resistance value is collected in real time and plotted into a second resistance curve;

[0014] When the first rising feature appears in the second resistance curve, it is judged whether the second rising feature appears in the first resistance curve. If not, the second driver is controlled to increase the driving force according to the first rising feature, so as to reduce the distance between the front end of the casing and the drill head.

[0015] Optionally, the controlling the second driver to increase the driving force according to the first rising feature includes:

[0016] Using a trained prediction model to process the first rising feature and the advancing speed of the drill pipe to obtain a first driving force, a driving duration, and a second driving force; wherein, the first driving force is greater than the second driving force;

[0017] During the driving duration, the second driver is controlled to output the first driving force to the casing, and after the driving duration, the second driver is controlled to output the second driving force to the casing.

[0018] Optionally, the determination amplitude of the second rising feature is higher than the determination amplitude of the first rising feature.

[0019] Optionally, the putting the anchor cable, injecting cement slurry into the drill hole, and completing the anchor cable construction includes:

[0020] Keeping the casing from withdrawing from the drill hole, putting the anchor cable into the casing, injecting cement slurry into the casing, and the cement slurry enters the gravel layer through the through holes provided on the casing wall to complete the anchor cable construction.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention uses a casing to support the drill hole, avoiding the problem that the drill hole is blocked due to the collapse of the gravel, resulting in the inability to put the anchor cable. Moreover, the present invention also designs an adjustment mechanism for the distance between the casing and the drill bit, solving the problem that the collapse of the gravel in the middle area between the front end of the casing and the drill bit affects the synchronous advancement of the casing and the drill bit. Description of the Drawings

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a schematic flow chart of a cable anchor construction method for crossing easily caving hole strata disclosed in an embodiment of the present invention;

[0025] Figure 2 It is a schematic construction scene diagram of a cable anchor construction method for crossing easily caving hole strata disclosed in an embodiment of the present invention;

[0026] Figure 3 It is a schematic diagram of the combined use of a casing and a drill pipe disclosed in an embodiment of the present invention. Detailed implementation manners

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0029] It should be noted that: similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0030] In the description of the present invention, it should be noted that if terms such as "upper", "lower", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0031] In addition, terms such as "first" and "second" are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0032] It should be noted that, without conflict, the features in the embodiments of the present invention can be combined with each other.

[0033] As Figures 1-3 shown, an anchor cable construction method for crossing easily caving strata according to an embodiment of the present invention includes the following steps:

[0034] Dispose the drill pipe inside the casing, and at least a part of the drill head of the drill pipe extends out of the casing;

[0035] Drive the drill pipe to rotate and make the drill head act on the gravel layer and drive the drill head to advance for drilling, drive the casing to advance synchronously with the drill pipe, and keep a suitable distance between the front end of the casing and the drill head;

[0036] After the drilling target is achieved, withdraw the drill pipe from the casing, put the anchor cable in, and inject cement slurry into the drill hole to complete the anchor cable construction.

[0037] To prevent the pile hole drilled in the gravel layer from being blocked due to the collapse of the gravel layer, the above construction method of the present invention uses a casing. Specifically, the drill pipe is disposed inside the casing. When the drill pipe drills the gravel layer, the casing can support the gravel around the drill hole to avoid the collapse of the gravel and blockage of the drill hole. When the drilling reaches the target depth, withdraw the drill pipe, put the anchor cable into the casing, and then inject cement slurry into the casing, thereby realizing the anchor cable construction. Repeating this scheme can realize the anchor cable construction at multiple points. Therefore, the present invention uses a casing to support the drill hole, avoiding the problem that the drill hole is blocked due to the collapse of the gravel, resulting in the inability to put the anchor cable.

[0038] Optionally, the driving the drill pipe to rotate and making the drill head act on the gravel layer and driving the drill head to advance for drilling, driving the casing to advance synchronously with the drill pipe, includes:

[0039] Use a first driver to drive the drill pipe to rotate and make the drill head act on the gravel layer and drive the drill head to advance for drilling, and use a second driver to drive the casing to advance synchronously with the drill pipe;

[0040] Wherein, the first driver and the second driver are arranged on separate tracks.

[0041] In the embodiment of the present invention, the present invention uses two drivers arranged on separate tracks to drive the drill pipe and the casing to advance synchronously respectively, so that the casing and the drill pipe can always be at a relatively reasonable distance, reducing the blockage of the newly drilled pile hole at the drill bit by the collapsed gravel and affecting the advancement of the casing.

[0042] Optionally, keeping the front end of the casing at an appropriate distance from the drill head includes:

[0043] During the process of the first driver driving the drill head forward for drilling, the driving resistance value is collected in real time and plotted into a first resistance curve;

[0044] During the process of the second driver driving the casing and the drill pipe forward synchronously, the driving resistance value is collected in real time and plotted into a second resistance curve;

[0045] When the first rising feature appears in the second resistance curve, it is judged whether the second rising feature appears in the first resistance curve. If not, the second driver is controlled to increase the driving force according to the first rising feature, so as to reduce the distance between the front end of the casing and the drill head.

[0046] In the embodiment of the present invention, during the process of the two drivers driving the drill pipe and the casing forward respectively, the driving resistance values of the drivers are collected in real time and plotted into resistance curves. When the first rising feature appears in the second resistance curve of the second driver, it indicates that the forward resistance of the casing increases abnormally. At this time, it may be that the gravel collapses in the middle area between the drill bit and the casing, which hinders the forward movement of the casing. However, the increase in resistance at this place may also be caused by factors such as too large, too hard, or too compact gravel in the drilling area, rather than necessarily the occurrence of gravel collapse. To avoid misjudgment, the present invention further judges whether the second rising feature also appears in the first resistance curve of the first driver driving the drill pipe. If so, it indicates that the gravel in the drilling area is too large, too hard, or too compact, etc., which increases the resistance to both the drill pipe and the casing; if not, it indicates that the gravel in the drilling area has not changed in terms of being too large, too hard, or too compact, etc., and it is still a gravel layer with the same characteristics. Therefore, it can be determined that the gravel has collapsed in the middle area between the drill bit and the casing, and the collapsed gravel has a greater resistance to the forward movement of the casing. At this time, the driving force of the second driver can be increased according to the first rising feature, so as to reduce the distance between the front end of the casing and the drill head, that is, make the casing closer to the drill bit (even partially wrap the drill bit in the casing), thereby reducing the probability of gravel collapse in the middle area or the influence on the forward movement of the casing, so that the front end of the casing and the drill head can be kept at an appropriate distance, which is beneficial to the synchronous forward movement of the drill pipe and the casing.

[0047] Optionally, controlling the second driver to increase the driving force according to the first rising feature includes:

[0048] Using a trained prediction model to process the first rising feature and the forward speed of the drill pipe to obtain a first driving force, a driving duration, and a second driving force; wherein, the first driving force is greater than the second driving force;

[0049] Control the second driver to output the first driving force to the casing within the driving duration, and after the driving duration, control the second driver to output the second driving force to the casing.

[0050] In the embodiment of the present invention, the first rising feature reflects the increase in the resistance encountered by the casing. Therefore, it is necessary to increase the driving force of the second driver to accelerate the forward movement of the casing, so as to reduce the distance between the casing and the drill bit and reduce the influence of the resistance exerted by the collapsed round gravel. At the same time, the speed of the drill bit also needs to be considered. The present invention specifically constructs and trains a prediction model, which can be implemented through various neural network algorithms and will not be elaborated here. The prediction model can input the first rising feature and the forward speed of the drill pipe, and then output the first driving force, driving duration, and second driving force. Among them, within the driving duration, control the second driver to increase the driving force to the first driving force and maintain it, so as to achieve the acceleration of the casing. At the end of the driving duration, the distance between the casing and the drill bit is generally reduced to the target distance, which is sufficient to ensure that the casing can enter in time after the drill bit drills successfully and support the surrounding round gravel to prevent it from collapsing and hindering the forward movement of the casing. After the driving duration, due to the disappearance or weakening of the abnormal resistance, control the second driver to decrease to the second driving force to achieve synchronous forward movement with the drill bit.

[0051] Optionally, the determination amplitude of the second rising feature is higher than the determination amplitude of the first rising feature.

[0052] In the embodiment of the present invention, the foregoing first rising feature and second rising feature refer to the rising amplitude of the resistance curve, which is referenced to the average value of the prior resistance data. When the rising amplitude is higher than their respective determination amplitudes, the rising feature can be determined. At the same time, due to the differences in the round gravel in the round gravel layer, the probability of the rising amplitude exceeding the determination amplitude is greater during the drilling process of the drill bit, while the round gravel in front of the casing has been drilled by the drill bit and is softer and finer, and the rising amplitude is relatively more stable. Therefore, the present invention sets the determination amplitude of the second rising feature to be higher than the determination amplitude of the first rising feature, which can reduce the misjudgment probability of the rising feature of the drill bit and thus improve the judgment accuracy of the round gravel collapse in the middle area between the drill bit and the casing.

[0053] It should be noted that one or two controllers can be arranged to control the first driver and the second driver. At the same time, sensors are evenly arranged on the first driver and the second driver, and the driving resistance can be calculated based on the driving force feedback, which will not be elaborated here.

[0054] Optionally, the steps of placing the anchor cable and injecting cement slurry into the borehole to complete the anchor cable construction include:

[0055] Keep the casing from withdrawing from the borehole, place the anchor cable into the casing, and inject cement slurry into the casing. The cement slurry enters the gravel layer through the through holes provided on the wall of the casing, completing the construction of the anchor cable.

[0056] In the embodiment of the present invention, after the borehole is completed, the drill pipe is withdrawn but the casing remains in the borehole, and the anchor cable is placed in the casing. At this time, cement slurry is injected into the casing. A plurality of through holes are pre-arranged on the peripheral wall of the casing in the present invention, and the injected cement slurry can enter the surrounding gravel layer through these through holes. After the cement slurry solidifies, the anchor cable can be fixed in the gravel layer, completing the construction of the anchor cable.

[0057] The above is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A construction method for anchor cables passing through easily caving strata, characterized in that, it includes the following steps: Dispose the drill pipe inside the casing, and at least part of the drill head of the drill pipe extends out of the casing; Drive the drill pipe to rotate and make the drill head act on the gravel layer and drive the drill head to advance for drilling. Drive the casing and the drill pipe to advance synchronously, and keep a suitable distance between the front end of the casing and the drill head; After the drilling target is achieved, withdraw the drill pipe from the casing, put in the anchor cable, and inject cement slurry into the drill hole to complete the construction of the anchor cable; The driving the drill pipe to rotate and making the drill head act on the gravel layer and driving the drill head to advance for drilling, driving the casing and the drill pipe to advance synchronously, includes: Use the first driver to drive the drill pipe to rotate and make the drill head act on the gravel layer and drive the drill head to advance for drilling, and use the second driver to drive the casing and the drill pipe to advance synchronously; Wherein, the first driver and the second driver are arranged on separate tracks; The keeping a suitable distance between the front end of the casing and the drill head includes: During the process of the first driver driving the drill head to advance for drilling, collect the driving resistance value in real time and plot it into a first resistance curve; During the process of the second driver driving the casing and the drill pipe to advance synchronously, collect the driving resistance value in real time and plot it into a second resistance curve; When the second resistance curve shows a first rising feature, judge whether the first resistance curve shows a second rising feature. If not, control the second driver to increase the driving force according to the first rising feature so that the distance between the front end of the casing and the drill head decreases.

2. A construction method for anchor cables passing through easily caving strata according to claim 1, characterized in that: The controlling the second driver to increase the driving force according to the first rising feature includes: Use a trained prediction model to process the first rising feature and the advancing speed of the drill pipe to obtain a first driving force, a driving duration, and a second driving force; wherein, the first driving force is greater than the second driving force; Control the second driver to output the first driving force to the casing within the driving duration, and after the driving duration, control the second driver to output the second driving force to the casing.

3. A construction method for anchor cables passing through easily caving strata according to claim 2, characterized in that: The determination amplitude of the second rising feature is higher than the determination amplitude of the first rising feature.

4. A construction method for anchor cables passing through easily caving strata according to any one of claims 1-3, characterized in that: The putting in the anchor cable, injecting cement slurry into the drill hole to complete the construction of the anchor cable includes: Keep the casing from withdrawing from the drill hole, put the anchor cable into the casing, inject cement slurry into the casing, and the cement slurry enters the gravel layer through the through holes provided on the casing wall to complete the construction of the anchor cable.

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