Composite support and construction method of pile-anchor deep foundation pit in water-rich sand layer

Abstract

The present invention relates to a pile-anchor composite support and construction method for a deep foundation pit in a water-rich sand layer, comprising the following steps: 1) construction preparation; 2) erection of an anchor drilling rig construction platform; 3) erection of a cantilevered operating platform; 4) positioning of a drill pipe; 5) installation of a water collecting trough; 6) drilling of a drilling rig; 7) installation of a steel casing; 8) construction of sand gushing prevention at the orifice; 9) construction of plugging the orifice to prevent backflow after grouting the final hole; 10) platform removal and cleaning. The beneficial effects of the present invention are: by setting a sliding track, a cantilevered operating platform, a lower discharge type protective cover and a water collecting trough, the construction speed of the drilling is greatly improved, waste water splashing is prevented, and the construction process is safe and environmentally friendly; the present invention installs a grouting pipe, a flange, a positioner and a limit fixing ear plate, so that the device is fixed and stable, and sand gushing at the orifice is effectively prevented; the present invention effectively ensures the tightness of the anti-backflow orifice plugging after grouting the final hole by setting a steel plate end cap, a separate ring plate and an expansion water-stopping sand bag, and the operation is simple and the construction effect is good.

Description

Technical Field

[0001] The invention relates to a pile-anchor composite support and construction method for a deep foundation pit in a water-rich sand layer, belongs to the field of foundation and basic engineering, and is suitable for a deep foundation pit support construction project in a water-rich sand layer. Background Art

[0002] In recent years, pile-anchor support technology has been widely used in construction engineering. On the one hand, it is the result of the development of science and technology, and on the other hand, there is no more convenient and effective alternative in construction technology. Foundation pit pile-anchor support is widely used due to its simple construction, economic rationality and good construction effect, especially in deep foundation pit projects. However, the construction of pile-anchor composite support for deep foundation pits in water-rich sand layers has always been a key research issue.

[0003] In view of this, in view of the shortcomings in the previous deep foundation pit pile-anchor support construction, a new deep foundation pit pile-anchor composite support and construction method in water-rich sand layer is urgently needed to improve construction efficiency, improve construction quality, and ensure the safety and reliability of the construction process. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a pile-anchor composite support and construction method for deep foundation pits in water-rich sand layers which can effectively improve the pile-anchor composite support effect and on-site construction efficiency and has the characteristics of environmental protection and energy saving, convenient construction, good sand gushing prevention effect, tight hole sealing, and simple assembly and disassembly.

[0005] This pile-anchor composite support for deep foundation pits in water-rich sand layers includes an environmentally friendly anchor drilling rig construction platform, a waist beam preset steel casing hole mouth anti-sand gushing device, and an anti-backflow hole mouth sealing structure after anchor cable final hole grouting;

[0006] The environmentally friendly anchor drilling rig construction platform includes a drilling rig casing, a platform stabilizing bracket, a platform main beam, a platform secondary beam, a sliding track, a cantilever support beam, an anti-skid steel plate, a cantilever operating platform, a lower row type protective cover and a water collecting tank. The platform stabilizing bracket is driven into the ground below, and its top is welded and fixed to the platform main beam. The platform main beam and the platform secondary beam are connected and fixed by standardized joint bolts. The anti-skid steel plate is laid on the platform main and secondary beams, and the sliding track is installed on the anti-skid steel plate. The non-crawler drilling machine moves on the sliding track. The cantilever support beam is connected and fixed to the platform main beam by standardized joint bolts. The cantilever operating platform is installed on the cantilever support beam. The lower row type protective cover is sleeved at the water outlet position of the non-crawler drilling machine. The water collecting tank is arranged at the bottom of the water outlet. The water collecting tank is fixed to the lower row type protective cover, and the drilling rig casing is driven into the retaining pile for a certain length.

[0007] The waist beam preset steel casing hole anti-sand gushing device comprises a steel casing, a flange, a positioner, a limit fixing ear plate, a positioning fixing ear plate and a steel surrounding purlin. The steel casing is driven between the surrounding piles; the flange is connected and fixed to the positioner and sleeved on the drill pipe; the steel surrounding purlin is fixed on the surrounding pile; the limit fixing ear plate and the positioning fixing ear plate are fixed on the steel surrounding purlin at the position of the steel casing;

[0008] The anti-backflow hole sealing structure after the anchor cable final hole grouting includes a steel plate end seal, a separate ring plate and an expansion water-stop sand bag. The separate ring plate is welded and fixed to the steel plate end seal at equal intervals. The expansion water-stop sand bag is placed between the separate ring plates and fixed to the steel plate end seal. The steel plate end seal is fixed to the waist beam.

[0009] As a preferred embodiment: the retaining piles and waist beams are both located in the foundation pit, the waist beam is connected to the retaining piles, the steel casing is installed at the drill rod construction position, and the drill rod is inside the steel casing.

[0010] As a preferred embodiment: the expandable water-stopping sandbag is wrapped with non-woven fabric and fixed on the steel plate end; the steel plate end is fixed on the waist beam by a full-length fixing screw.

[0011] As a preferred embodiment: the fixed end of the support frame is fixed to the cantilever operating platform by bolts, the bottom of the connecting and stabilizing steel pipe is welded to the fixed end of the support frame, the upper part of the connecting and stabilizing steel pipe is connected to the positioning sleeve, the positioning sleeve is fixed to the upper end of the connecting and stabilizing steel pipe by iron nails, and the positioning sleeve is fixed by fixing bolts.

[0012] As a preference: the anti-skid steel plate is welded and fixed to the primary and secondary beams of the platform at the corner position; the sliding track is mounted on the anti-skid steel plate and fixed by spot welding; the standardized joint bolt includes two screws, the two screws are connected by a circular nut, and the two screws are fixed to the connecting piece by a rotating nut.

[0013] Preferably: the lower row protective cover is mounted at the water outlet of the non-crawler drilling machine through a fixing ring, the water sump and the lower row protective cover are fixed through a fixing ring, the water sump support frame is fixed on the cantilevered operating platform, and the top of the water sump support frame is connected to the water sump and is used to fix the water sump.

[0014] As a preferred embodiment, when there is no waist beam, the grouting pipe is fixed to the steel casing by means of plastic tie and driven into between the retaining piles together.

[0015] Preferably, the flange and the positioner are fixed by fixing bolts through screw holes on the positioner; and the limiting fixing ear plate and the positioning fixing ear plate are fixed to the steel purlin by fixing bolts.

[0016] The construction method of the pile-anchor composite support for deep foundation pit in water-rich sand layer comprises the following steps:

[0017] Step 1: Construction preparation: prepare the sliding rails, shaped joint bolts, anti-slip steel plates, lower row protective covers, positioning sleeves, flanges, fixing bolts, positioning and fixing ear plates, non-woven fabrics and grouting pipes required for construction;

[0018] Step 2: Setting up the construction platform of the anchor drilling rig: The two screws of the standardized joint bolts are connected by round nuts, and fixed with the connecting pieces by rotating nuts. The platform stabilizing bracket is driven into the ground, and its top is welded and fixed to the platform main beam. The platform main beam and the platform secondary beam are connected and fixed by standardized joint bolts. The anti-skid steel plate is laid on the platform main and secondary beams, and welded and fixed at the corners. The sliding track is installed on the anti-skid steel plate and fixed by spot welding. The non-crawler drilling rig moves on the sliding track.

[0019] Step 3: erecting the cantilever operating platform: the cantilever support beam is fixed to the platform main beam through the standardized joint bolt connection, and the cantilever operating platform is installed on the cantilever support beam;

[0020] Step 4: Drill pipe positioning: The fixed end of the support frame is fixed to the cantilever operating platform with bolts, the bottom of the connecting and stabilizing steel pipe is welded to the fixed end of the support frame, the upper part of the connecting and stabilizing steel pipe is connected to the positioning sleeve, the positioning sleeve is fixed to the upper end of the connecting and stabilizing steel pipe with iron nails, the positioning sleeve is opened up and down, and the drill pipe is positioned and fixed with fixing bolts;

[0021] Step 5: Install the water collection tank: The lower row protective cover is placed at the water outlet of the drilling rig through a fixing ring. The water collection tank and the lower row protective cover are fixed together with a fixing ring. The water collection tank support frame is fixed on the cantilevered operating platform. The top of the water collection tank support frame is connected to the water collection tank to fix the water collection tank;

[0022] Step 6: Drilling with a drilling rig: After measuring and setting out the hole, the drilling rig is put in place, the drill rod is positioned through the positioning sleeve and the drilling rig casing, and the hole is drilled;

[0023] Step 7: Steel casing installation: After drilling, insert the steel casing;

[0024] Step 8. Construction of anti-sand gushing at the hole: When setting the steel purlin waist beam, the flange and the positioner are fixed with fixing bolts through the screw holes on the positioner and are sleeved on the drill rod. The steel purlin is fixed on the retaining piles. The limit fixing ear plate and the fixed positioning ear plate are fixed on the steel purlin at the position of the steel casing with fixing bolts; when there is no waist beam, the grouting pipe is tied and fixed to the steel casing by plastic tie, and driven into the retaining piles together, and grouting is sealed;

[0025] Step 9. After the final hole grouting, the hole opening is sealed: After the anchor cable final hole grouting, the hole opening is sealed, the separated ring plates are welded and fixed on the steel plate end at equal intervals, the expansion water-stop sandbags are placed between the separated ring plates, the non-woven fabric wraps the expansion water-stop sandbags and fixes them on the steel plate end, and the steel plate end is fixed to the waist beam through the full-length fixing screw;

[0026] Step 10: Platform dismantling and cleaning: After the construction is completed, dismantle the erected platform, recycle the reusable materials, and clean the site.

[0027] As a preferred embodiment: in step 2, when the drilling rig is a crawler self-propelled drilling rig, the sliding track is not installed.

[0028] The beneficial effects of the present invention are:

[0029] 1) The present invention greatly improves the construction speed of drilling by arranging a sliding track, a cantilevered operating platform, a lower discharge protective cover, and a water collection tank, prevents waste water from splashing, and ensures a safe and environmentally friendly construction process.

[0030] 2) The present invention makes the device fixed and stable by installing the grouting pipe, flange, positioner and limit fixing ear plate, thereby effectively preventing sand gushing from the hole mouth.

[0031] 3) The present invention effectively ensures the tightness of the anti-backflow hole after the final hole grouting by arranging steel plate end sealing, separate ring plate and expansion water-stopping sandbag, and has simple operation and good construction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0033] Figure 2 It is a schematic diagram of the construction platform of the environmentally friendly anchor drilling rig;

[0034] Figure 3 It is a schematic diagram of the standardized mobile platform of a non-crawler drilling machine;

[0035] Figure 4 It is a schematic diagram of the standardization mobile platform of the crawler drilling machine;

[0036] Figure 5 It is a schematic diagram of the structure of the standardized joint bolts;

[0037] Figure 6 is a schematic diagram of a wastewater collection device;

[0038] Figure 7 It is a schematic diagram of the limit support structure of the drill rod and casing rod;

[0039] Figure 8 It is a schematic diagram of the positioning sleeve structure;

[0040] Fig. 9 It is a schematic diagram of the structure of a steel casing anti-sand gushing device without a waist beam;

[0041] Fig.10 It is a schematic diagram of the structure of the sand gushing prevention device for the steel casing hole preset in the waist beam;

[0042] Fig.11 is a schematic diagram of the locator structure;

[0043] Fig.12 This is a schematic diagram of the anti-backflow hole plugging structure after the anchor cable final hole grouting;

[0044] Fig.13 It is a schematic diagram of the steel plate end sealing structure;

[0045] Description of the accompanying drawings: 1-foundation pit, 2-guard pile, 3-waist beam, 4-drilling casing, 5-steel casing, 6-platform stabilizing bracket, 7-platform main beam, 8-platform secondary beam, 9-non-crawler drilling machine, 10-sliding track, 11-shaped joint bolts, 12-cantilever support beam, 13-anti-slip steel plate, 14-cantilever operating platform, 15-water outlet, 16-lower row protective cover, 17-water collection tank, 18-water collection tank support frame, 19-fixing ring, 20-positioning sleeve, 21 -fixed end of the support frame, 22-connecting stabilizing steel pipe, 23-flange, 24-positioner, 25-round nut, 26-screw, 27-rotating nut, 28-fixing bolt, 29-drill rod, 30-limited fixing ear plate, 31-positioning fixing ear plate, 32-screw hole, 33-steel plate sealing end, 34-separate ring plate, 35-through-length fixing screw, 36-expansion water-stop sandbag, 37-non-woven fabric, 38-steel purlin, 39-plastic cable tie, 40-grouting pipe. DETAILED DESCRIPTION

[0046] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principles of the present invention, several improvements and modifications may be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0047] like Figures 1 to 13 As shown, the pile-anchor composite support for deep foundation pits in water-rich sand layers includes an environmentally friendly anchor drilling rig construction platform, a waist beam preset steel casing hole mouth anti-sand gushing device, and an anti-backflow hole mouth sealing structure after anchor cable final hole grouting.

[0048] The environmentally friendly anchor drilling rig construction platform includes a drilling rig casing 4, a platform stabilizing bracket 6, a platform main beam 7, a platform secondary beam 8, a sliding track 10, a cantilever support beam 12, an anti-skid steel plate 13, a cantilever operating platform 14, a lower row protective cover 16, a sump 17, a fixing ring 19, and a sump support frame 18. The platform stabilizing bracket 6 is driven into the ground below, and the top is welded and fixed to the platform main beam 7. The platform main beam 7 and the platform secondary beam 8 are connected and fixed by standardized joint bolts 11. The anti-skid steel plate 13 is laid on the platform main and secondary beams and welded and fixed at their corners. The sliding track 10 is installed on the anti-skid steel plate 13 and is fixed by spot welding. The non-crawler drilling machine 9 can move quickly on the sliding track 10. The standardized joint bolts 11 includes two screws 26, which are connected by circular nuts 25 and fixed to the connecting piece by rotating nuts 27. The cantilever support beam 12 is connected and fixed to the platform main beam 7 by standardized joint bolts 11. The cantilever operating platform 14 is installed on the cantilever support beam 12 to provide a platform for construction personnel to operate. The lower row protective cover 16 is sleeved on the water outlet 15 of the non-crawler drilling machine 9 through a fixing ring 19. The water collection tank 17 is at the bottom of the water outlet 15 and is fixed together with the lower row protective cover 16 by a fixing ring 19. The water collection tank support frame 18 is fixed on the cantilever operating platform 14, and the top is connected to the water collection tank 17 and is used to fix the water collection tank 17. The drilling rig casing 4 is driven into the retaining pile 2 for a certain length after drilling.

[0049] The waist beam preset steel casing hole anti-sand gushing device includes a steel casing 5, a flange 23, a positioner 24, a limit fixing ear plate 30, a positioning fixing ear plate 31, and a steel surrounding purlin 38. The steel casing 5 is driven between the retaining piles 2, and the flange 23 and the positioner 24 are fixed with fixing bolts 28 through the screw holes 32 on the positioner 24, and are sleeved on the drill rod 29. The steel surrounding purlin 38 is fixed on the retaining pile 2, and the limit fixing ear plate 30 and the positioning fixing ear plate 31 are fixed to the steel surrounding purlin 38 at the position of the steel casing 5 with fixing bolts 28.

[0050] The anti-backflow hole sealing structure after the anchor cable final hole grouting includes a steel plate end seal 33, a separate ring plate 34, an expandable water-stop sand bag 36, and a non-woven fabric 37. The separate ring plate 34 is welded and fixed to the steel plate end seal 33 at equal intervals. The expandable water-stop sand bag 36 is placed between the separate ring plates 34. The non-woven fabric 37 wraps the expandable water-stop sand bag 36 and is fixed to the steel plate end seal 33. The steel plate end seal 33 is fixed to the waist beam 3 by a through-length fixing screw 35.

[0051] As an improved specific implementation method, the anti-backflow hole sealing structure after the anchor cable final hole grouting also includes a foundation pit 1, retaining piles 2, a waist beam 3, and a steel casing 5. The retaining piles 2 and the waist beam 3 are both located in the foundation pit 1, and the steel casing 5 is installed at the construction position of the drill rod 29.

[0052] As an improved specific implementation method, the environmentally friendly anchor drilling rig construction platform also includes a positioning sleeve 20, a support frame fixed end 21, and a connecting and stabilizing steel pipe 22. The support frame fixed end 21 is fixed to the cantilever operating platform 14 with bolts. The bottom of the connecting and stabilizing steel pipe 22 is welded to the support frame fixed end 21, and the upper part is connected to the positioning sleeve 20. The positioning sleeve 20 is fixed to the upper end of the connecting and stabilizing steel pipe 22 with iron nails, and the positioning drill rod 29 is opened up and down and then fixed with fixing bolts 28.

[0053] As an improved specific implementation manner, when the drilling rig is a crawler self-propelled drilling rig, the sliding track 10 may not be installed.

[0054] As an improved specific implementation method, the sand gushing prevention device of the steel casing hole preset in the waist beam also includes a plastic tie 39 and a grouting pipe 40. When there is no waist beam 3, the grouting pipe 40 is fixed to the steel casing 5 by means of the plastic tie 39, and is driven into the space between the retaining piles 2 together with the steel casing 5, and sealed by grouting.

[0055] The construction method of the pile-anchor composite support for a deep foundation pit in a water-rich sand layer comprises the following steps:

[0056] Step 1, construction preparation: According to the construction requirements of pile-anchor composite support for deep foundation pits in water-rich sand layers, prepare the sliding rails 10, standardized joint bolts 11, anti-slip steel plates 13, lower row protective covers 16, positioning sleeves 20, flanges 23, fixing bolts 28, positioning fixing ear plates 31, non-woven fabrics 37, and grouting pipes 40 required for construction.

[0057] Step 2: Setting up the anchor drilling rig construction platform: the two screws 26 of the standardized joint bolts 11 are connected by the round nuts 25 and fixed to the connecting parts with the rotating nuts 27. The platform stabilizing bracket 6 is driven into the ground, and its top is welded and fixed to the platform main beam 7. The platform main beam 7 and the platform secondary beam 8 are connected and fixed by the standardized joint bolts 11. The anti-skid steel plate 13 is laid on the main and secondary beams of the platform and welded and fixed at the corners. The sliding track 10 is installed on the anti-skid steel plate 13 and fixed by spot welding. The non-crawler drilling machine 9 can move quickly on the sliding track 10; when the drilling rig is a crawler self-propelled drilling rig, the sliding track 10 may not be installed.

[0058] Step 3: Setting up the cantilever operating platform: The cantilever supporting beam 12 is connected and fixed to the platform main beam 7 by means of standardized joint bolts 11, and the cantilever operating platform 14 is installed on the cantilever supporting beam 12 to provide a platform for construction workers to operate.

[0059] Step 4, drill pipe positioning: the fixed end 21 of the support frame is fixed to the cantilever operating platform 14 with bolts, the bottom of the connecting and stabilizing steel pipe 22 is welded to the fixed end 21 of the support frame, and the upper part is connected to the positioning sleeve 20. The positioning sleeve 20 is fixed to the upper end of the connecting and stabilizing steel pipe 22 with iron nails. The positioning sleeve 20 is opened up and down and the drill rod 29 is positioned and then fixed with fixing bolts 28.

[0060] Step 5, water collection tank installation: the lower row protective cover 16 is put on the water outlet 15 of the drilling rig through the fixing ring 19, the water collection tank 17 is at the bottom of the water outlet 15, and is fixed together with the lower row protective cover 16 by the fixing ring 19, the water collection tank support frame 18 is fixed on the cantilevered operating platform 14, and the top is connected to the water collection tank 17 for fixing the water collection tank 17.

[0061] Step 6, drilling with a drilling rig: After measuring and setting out to determine the hole to be drilled, the drilling rig is put into position, the drill rod is positioned by means of the positioning sleeve 20 and the drilling rig casing 4, and the hole is drilled.

[0062] Step 7: Steel casing installation: After drilling, the drill rig drives in the steel casing 5.

[0063] Step 8, construction of anti-sand gushing at the hole mouth: when setting the steel purlin waist beam, the flange 23 and the positioner 24 are fixed with fixing bolts 28 through the screw holes 32 on the positioner 24, and are sleeved on the drill rod 29, the steel purlin 38 is fixed on the retaining pile 2, and the limiting fixing ear plate 30 and the positioning fixing ear plate 31 are fixed on the steel purlin 38 at the position of the steel casing 5 with fixing bolts 28; when there is no waist beam, the grouting pipe 40 is tied and fixed to the steel casing 5 by the plastic tie 39, and is driven into the retaining pile 2 together, and sealed by grouting.

[0064] Step nine, construction of anti-backflow hole opening plugging after final hole grouting: After the final hole grouting of the anchor cable, the hole opening is plugged, the separate ring plates 34 are welded and fixed to the steel plate end 33 at equal intervals, the expansion water-stop sand bags 36 are placed between the separate ring plates 34, the non-woven fabric 37 wraps the expansion water-stop sand bags 36 and is fixed to the steel plate end 33, and the steel plate end 33 is fixed to the waist beam 3 by a through-length fixing screw 35.

[0065] Step 10: Platform dismantling and cleaning: After the construction is completed, dismantle the erected platform, recycle the reusable materials, and clean the site.

Claims

1. A pile-anchor composite support for deep foundation pit in water-rich sand layer, characterized in that: It includes an environmentally friendly anchor drilling rig construction platform, a waist beam preset steel casing hole anti-sand gushing device, and an anti-backflow hole plugging structure after anchor cable final hole grouting; The environmentally friendly anchor drilling rig construction platform comprises a drilling rig casing (4), a platform stabilizing bracket (6), a platform main beam (7), a platform secondary beam (8), a sliding track (10), a cantilevered support beam (12), an anti-skid steel plate (13), a cantilevered operating platform (14), a lower row type protective cover (16) and a water collecting tank (17). The platform stabilizing bracket (6) is driven into the ground below, and its top is welded and fixed to the platform main beam (7). The platform main beam (7) and the platform secondary beam (8) are connected and fixed by standardized joint bolts (11). The anti-skid steel plate (13) is laid on the platform main and secondary beams. The sliding track (1 0) is installed on an anti-slip steel plate (13), the non-crawler drilling machine (9) moves on a sliding track (10), the cantilever support beam (12) is connected and fixed to the platform main beam (7) through a shaped joint bolt (11), the cantilever operating platform (14) is installed on the cantilever support beam (12), the lower row type protective cover (16) is sleeved at the water outlet (15) position of the non-crawler drilling machine (9), the water collecting trough (17) is arranged at the bottom of the water outlet (15), the water collecting trough (17) is fixed to the lower row type protective cover (16), and the drilling machine casing (4) is driven into a certain length of the retaining pile (2); The waist beam preset steel casing hole anti-sand gushing device comprises a steel casing (5), a flange (23), a positioner (24), a limit fixing ear plate (30), a positioning fixing ear plate (31) and a steel surrounding purlin (38); the steel casing (5) is driven between the surrounding piles (2); the flange (23) is connected and fixed to the positioner (24) and is sleeved on the drill rod (29); the steel surrounding purlin (38) is fixed on the surrounding pile (2); the limit fixing ear plate (30) and the positioning fixing ear plate (31) are fixed on the steel surrounding purlin (38) at the position of the steel casing (5); The anti-backflow hole plugging structure after the anchor cable final hole grouting comprises a steel plate end seal (33), a separate ring plate (34) and an expansion water-stop sand bag (36), wherein the separate ring plate (34) is welded and fixed to the steel plate end seal (33) at equal intervals, the expansion water-stop sand bag (36) is placed between the separate ring plates (34) and fixed to the steel plate end seal (33), and the steel plate end seal (33) is fixed to the waist beam (3); The fixed end (21) of the support frame is fixed to the cantilever operating platform (14) by bolts, the bottom of the connecting and stabilizing steel pipe (22) is welded to the fixed end (21) of the support frame, the upper part of the connecting and stabilizing steel pipe (22) is connected to the positioning sleeve (20), the positioning sleeve (20) is fixed to the upper end of the connecting and stabilizing steel pipe (22) by iron nails, and the positioning sleeve (20) is fixed by fixing bolts (28); The lower row type protective cover (16) is sleeved at the water outlet (15) of the non-crawler drilling machine (9) via a fixing ring (19); the water collecting trough (17) and the lower row type protective cover (16) are fixed via the fixing ring (19); the water collecting trough support frame (18) is fixed on the cantilevered operating platform (14); the top of the water collecting trough support frame (18) is connected to the water collecting trough (17) and is used to fix the water collecting trough (17).

2. The pile-anchor composite support for deep foundation pit in water-rich sand layer according to claim 1 is characterized in that: The retaining piles (2) and the waist beam (3) are both located in the foundation pit (1); the waist beam (3) is connected to the retaining piles (2); the steel casing (5) is installed at the construction position of the drill rod (29); and the drill rod (29) is inside the steel casing (5).

3. The pile-anchor composite support for deep foundation pit in water-rich sand layer according to claim 1 is characterized in that: The expansion water-stopping sandbag (36) is wrapped with a non-woven fabric (37) and fixed to the steel plate end seal (33); the steel plate end seal (33) is fixed to the waist beam (3) via a full-length fixing screw (35).

4. The pile-anchor composite support for deep foundation pit in water-rich sand layer according to claim 1 is characterized in that: The anti-skid steel plate (13) is welded and fixed to the primary and secondary beams of the platform at the corner position; the sliding track (10) is installed on the anti-skid steel plate (13) and fixed by spot welding; the shaped joint bolt (11) includes two screw rods (26), the two screw rods (26) are connected by a circular nut (25), and the two screw rods (26) are fixed to the connecting piece by a rotating nut (27).

5. The pile-anchor composite support for deep foundation pit in water-rich sand layer according to claim 1 is characterized in that: When there is no waist beam (3), the grouting pipe (40) is tied and fixed to the steel casing (5) by means of a plastic tie (39) and driven into between the retaining piles (2) together.

6. The pile-anchor composite support for deep foundation pit in water-rich sand layer according to claim 1 is characterized in that: The flange (23) and the positioner (24) are fixed by fixing bolts (28) through screw holes (32) on the positioner (24); the limiting fixing ear plate (30) and the positioning fixing ear plate (31) are fixed to the steel purlin (38) through fixing bolts (28).

7. A construction method for pile-anchor composite support for deep foundation pit in water-rich sand layer as claimed in claim 1, characterized in that: The following steps are involved: Step 1, construction preparation: prepare the sliding rail (10), the shaped joint bolts (11), the anti-skid steel plate (13), the lower row type protective cover (16), the positioning sleeve plate (20), the flange (23), the fixing bolts (28), the positioning fixing ear plate (31), the non-woven fabric (37) and the grouting pipe (40) required for the construction; Step 2: Setting up the anchor drilling rig construction platform: the two screw rods (26) of the shaped joint bolt (11) are connected by a circular nut (25), and fixed to the connecting piece by a rotating nut (27), the platform stabilizing bracket (6) is driven into the ground, and its top is welded and fixed to the platform main beam (7), the platform main beam (7) and the platform secondary beam (8) are connected and fixed by the shaped joint bolt (11), the anti-skid steel plate (13) is laid on the platform main and secondary beams, and is welded and fixed at the corner position, the sliding track (10) is installed on the anti-skid steel plate (13) and fixed by spot welding, and the non-crawler drilling machine (9) moves on the sliding track (10); Step 3: erecting the cantilever operating platform: the cantilever support beam (12) is connected and fixed to the platform main beam (7) by means of a standardized joint bolt (11), and the cantilever operating platform (14) is installed on the cantilever support beam (12); Step 4, positioning the drill pipe: the fixed end (21) of the support frame is fixed to the cantilever operating platform (14) with bolts, the bottom of the connecting and stabilizing steel pipe (22) is welded to the fixed end (21) of the support frame, the upper part of the connecting and stabilizing steel pipe (22) is connected to the positioning sleeve (20), the positioning sleeve (20) is fixed to the upper end of the connecting and stabilizing steel pipe (22) with iron nails, the positioning sleeve (20) is opened up and down and the drill pipe (29) is positioned and then fixed with fixing bolts (28); Step 5: Installing the water collecting trough: The lower row type protective cover (16) is placed on the water outlet (15) of the drilling rig through the fixing ring (19); the water collecting trough (17) and the lower row type protective cover (16) are fixed together with the fixing ring (19); the water collecting trough support frame (18) is fixed on the cantilevered operating platform (14); the top of the water collecting trough support frame (18) is connected to the water collecting trough (17) for fixing the water collecting trough (17); Step 6: Drilling with a drilling rig: After measuring and setting out the hole to be drilled, the drilling rig is put into position, the drill rod is positioned by means of a positioning sleeve (20) and a drilling rig casing (4), and the hole is drilled; Step 7: Install the steel casing: After drilling, drive the steel casing (5) into the hole. Step 8, construction of preventing sand from gushing out of the hole: when setting the steel purlin waist beam, the flange (23) and the positioner (24) are fixed by fixing bolts (28) through the screw holes (32) on the positioner (24), and are sleeved on the drill rod (29), the steel purlin (38) is fixed on the retaining pile (2), and the limiting fixing ear plate (30) and the positioning fixing ear plate (31) are fixed on the steel purlin (38) at the position of the steel casing (5) by fixing bolts (28); when there is no waist beam, the grouting pipe (40) is tied and fixed to the steel casing (5) by plastic tie (39), and is driven into between the retaining piles (2) together, and grouting is sealed; Step 9: Construction of anti-backflow hole opening plugging after final hole grouting: After the anchor cable final hole grouting, the hole opening is plugged, the separated ring plates (34) are welded and fixed to the steel plate end caps (33) at equal intervals, the expansion water-stop sandbags (36) are placed between the separated ring plates (34), the non-woven fabric (37) wraps the expansion water-stop sandbags (36) and is fixed to the steel plate end caps (33), and the steel plate end caps (33) are fixed to the waist beam (3) by a full-length fixing screw (35); Step 10: Platform dismantling and cleaning: After the construction is completed, dismantle the erected platform, recycle the reusable materials, and clean the site.

8. The construction method of pile-anchor composite support for deep foundation pit in water-rich sand layer according to claim 7 is characterized in that: In step 2, when the drilling rig is a crawler self-propelled drilling rig, the sliding track (10) is not installed.

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