CN113802582A

CN113802582A - Mountain supporting method for near special-shaped buildings in hilly areas

Info

Publication number: CN113802582A
Application number: CN202111246963.6A
Authority: CN
Inventors: 黎新锋; 寇卫卫; 张峰; 朱金平
Original assignee: China MCC17 Group Co Ltd
Current assignee: China MCC17 Group Co Ltd
Priority date: 2021-10-26
Filing date: 2021-10-26
Publication date: 2021-12-17

Abstract

The invention discloses a mountain supporting method for a hilly area adjacent to a special-shaped building, which relates to mountain supporting engineering adjacent to mountain buildings in the engineering field.

Description

Mountain supporting method for near special-shaped buildings in hilly areas

Technical Field

The invention relates to a mountain support project close to a mountain building in the field of engineering, in particular to a mountain support method close to a special-shaped building in a hilly land.

Background

With the continuous development and progress of the building industry, people tend to more freemize the design of the building appearance, and the requirement on the artistic aesthetic property of the building is higher and higher, so that a plurality of special-shaped buildings with high aesthetic and artistic values appear. At present, when a special-shaped building such as an inclined building is constructed in a valley area of a hilly land, because the building is close to a mountain body and even a part of the building is positioned on the mountain body, in order to ensure safety, geological disaster analysis and support construction of the mountain body are firstly required, and therefore, the mountain body support method for the special-shaped building close to the hilly land is particularly important.

Disclosure of Invention

The invention provides a mountain supporting method for a special-shaped building close to a hilly land, which aims to ensure the safety and reliability of the construction of the special-shaped building close to the mountain in the hilly land.

The technical scheme adopted by the invention for solving the technical problems is as follows: a mountain supporting method for a hilly land adjacent to a special-shaped building is characterized in that: building a fire-fighting evacuation channel on a hillside, adopting slope cutting and soil nail supporting in the area above the hillside evacuation channel according to the contour line of the hillside, the actual position of the building and the geological survey data, adopting rotary drilling cast-in-place piles and anchor rope supporting in the area of one side of the evacuation channel, which is far away from the hillside, and hanging nets and spraying concrete on the pile side.

Further, the mountain supporting method comprises the following steps in sequence: the method comprises the following steps of land exploration construction, mountain body contour line measurement, mountain body slope cutting, soil nail support construction, cast-in-place pile construction, crown beam construction, earthwork excavation to a first row of anchor cables, slope surface trimming, anchor cable and grouting construction, pile side reinforcing steel bar net piece binding and water drain pipe installation, concrete spraying, maintenance and excavation of the next layer of working face.

Furthermore, the geological survey construction comprises the steps of drilling a mountain geological structure, knowing rock stratum distribution conditions of the mountain geological structure and obtaining detailed geological survey data, wherein the arrangement of geological survey points covers the range of required support.

Furthermore, the mountain body contour line measurement is to perform GPS measurement on a mountain body to be supported, process data, generate a contour line and provide data support for combing the relationship between a building and the mountain body.

And further, carrying out mountain slope evacuation channel construction according to mountain contour lines, actual building positions and geological survey data, carrying out mountain slope cutting construction according to design drawings above the evacuation channel, and carrying out soil nail support construction on the slope surface to ensure the safety of the mountain.

Furthermore, at the edge of the side, far away from the mountain, of the hillside evacuation channel, construction of the rotary drilling cast-in-place pile is carried out according to a design drawing, the pile diameter is 800mm, and the pile distance is 1000 mm.

Further, a crown beam of 0.8m by 1.0m is made on the upper part of each cast-in-place pile to connect all the piles into a whole.

Further, earth excavation is carried out after the crown beam is poured, when the earth excavation is carried out to the position 1m below the first row of anchor cables in the design drawing, slope surface trimming is carried out, anchor cable drilling, installation and grouting construction are carried out, the anchor cables are made of phi 15.2 steel strands with high strength, low relaxation and tensile strength not less than 1220MPa, the hole depth of the anchor cables is 15m, the hole diameter is 180mm, the horizontal distance is 2m, the inclination angle is 15 degrees, and the prestress borne by the prestress anchor cables is 120 KN.

Further, after the construction of the anchor cable is completed, pile side hanging reinforcing mesh sheet binding, water drain pipe installation and concrete spraying construction are carried out, after the working procedure is completed and maintenance is carried out, the pile side is continuously excavated downwards to a building base in the same mode, and the pile side between the anchor cable and the base is supported in a net hanging concrete spraying mode.

The mountain supporting method for the hilly area adjacent special-shaped buildings has the advantages that through the geological exploration construction and the measurement of mountain contour lines, data support is provided for mountain supporting and combing the relation between the buildings and the mountain, a fire-fighting evacuation channel is built on a mountain slope, slope cutting and soil nail supporting are adopted in the area above the mountain slope evacuation channel, rotary drilling bored piles and anchor cables are adopted in the area, far away from the mountain, of the evacuation channel, and the situation that landslide of the mountain is influenced on the safety of the evacuation channel is avoided.

Drawings

FIG. 1 is a schematic diagram of a building and a mountain;

FIG. 2 is a schematic view of the present support method;

FIG. 3 is a schematic view of a soil nail holder arrangement;

FIG. 4 is a cross-sectional view of a soil nail holder arrangement;

FIG. 5 is a perspective view of the soil nail holder;

FIG. 6 is a schematic view of grouting and anchor sheet construction;

FIG. 7 is a perspective view of the steel bars of the cast-in-place pile;

FIG. 8 is a schematic representation of the rebar placement of the crown beam;

FIG. 9 is a perspective view of a concrete wale;

FIG. 10 is a schematic view of the cable bolt assembly;

FIG. 11 is a schematic view of a suspended net between piles in elevation;

FIG. 12 is a schematic top view of a net suspended between piles;

fig. 13 is a view showing a large size of the drain hole.

In the figure: 1. anchor cable, 2 supporting piles, 3 soil nails, 4 retaining walls, 5 evacuation channels, 6 independent foundations, 7 centering supports, 8 grouting pipes, 9 cement paste, 10 reinforcing mesh sheets, 11 reinforcing bars, 12 expansion screws, 13 concrete injection layers and 14 water drain pipes.

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. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs.

As shown in fig. 1-13, the mountain supporting method for a hilly area near a special-shaped building of the present invention, because the supporting relationship between the building and the mountain is complex, needs to construct a fire-fighting evacuation channel on a hillside, according to the contour line of the mountain, the actual position of the building and the ground survey data, the area above the evacuation channel on the hillside is supported by cutting slope and soil nails, the area of the evacuation channel far away from the mountain side is supported by a rotary drilling bored pile and an anchor cable, and the pile side is hung with net and sprayed with concrete, and the main supporting method flow is: the method comprises the steps of land exploration construction → mountain contour line measurement → mountain slope cutting → soil nailing and supporting construction → bored concrete pile construction → crown beam construction → earth excavation to the first row of anchor cables → slope surface trimming → anchor cables and grouting construction → pile side reinforcing mesh binding and water drain pipe installation → concrete spraying → maintenance → excavation of the next working face. The specific process is as follows:

1. construction of land exploration

In order to ensure the safety of the mountain support, the mountain geology must be drilled and the rock stratum distribution condition of the mountain geology is known so as to provide the mountain support with the geological survey data support, and the arrangement of the geological survey points should cover the range of the required support.

2. Mountain contour measurement

In order to sort the relationship between the building and the mountain, contour line measurement must be performed on the mountain to determine the slope of the excavation.

3. The relationship between the mountain and the building is combed, and the supporting form is determined

Because the supporting relation between the building and the mountain is complex, the design needs to construct a fire-fighting evacuation channel on the hillside, in order to ensure the safety of the evacuation channel, the slope is constructed from the top of the hill to the edge of the evacuation channel close to one side of the mountain, soil nail supporting is carried out on the slope, cast-in-situ bored pile construction supporting is carried out on the edge of the evacuation channel far away from one side of the mountain, so as to avoid landslide of the mountain and influence on the safety of the evacuation channel, and the overall supporting form is as shown in figure 2.

4. Mountain slope cutting and soil nailing wall support

4.1 mountain slope cutting

According to the contour lines of the mountain and the building position, determining that the slope of the mountain slope cutting above the evacuation channel is 1: and (3) cutting the slope between 0.5 and 1:1.5 by adopting a backhoe excavator to dig the soil, reserving 50-100 mm of manual slope repairing on the slope surface, setting the excavation depth to be 500mm below the soil nail hole site every time, and reserving the width of a hole forming working face to ensure that the width of the hole forming working face is more than 5m so as to ensure the working face for forming the hole by the soil nail. And (4) cutting slopes of the mountain, and performing layered and segmented excavation according to design rules and constructing in sequence.

4.2 side slope cleaning

The side slope of this engineering clearance adopts artifical clearance, for guaranteeing to spout the level and smooth of concrete surface course, this process must hang the line location, and good slope ratio and slope roughness are controlled strictly.

4.3 soil nailing hole forming

Adopt anchor rope rig to carry out the pore-forming, the aperture is 100mm, need the laying-out before the pore-forming to go out the pore-forming position, the hole site interval is 1.5m, measures the angle of drilling rod before creeping into to ensure that pore-forming angle and horizontal plane contained angle are 15, and the pore-forming degree of depth is 6 m.

4.4 soil nail making and pushing

The upper and lower rows of soil nails are staggered from each other and are in a quincunx shape, the rod body is reinforced with C22 deformed steel bars, the hole forming is carried out by an anchor cable drilling machine, the aperture A is 100mm, the hole is inclined by 15 degrees, the rod body is provided with a centering bracket every 1.5m, the head of the soil nail is L-shaped and is internally wrapped in an anchor plate.

And (3) straightening the reinforcing steel bars, cutting the lengths according to the design requirement, arranging a centering bracket every 1.5m, and manufacturing hooks. And pushing the soil nails into the hole to the designed position along the axis of the drill hole to prevent the hole wall from being damaged or inserted into the soil body of the hole wall. The support is apart from the soil nail bottom distance and is 500 ~ 1000mm, and the support is apart from the soil nail top distance and is 300mm, and the support adopts the diameter to make for C8's reinforcing bar. The centering rod arrangement is shown in fig. 3-5.

4.5 grouting and anchor slab construction

The grouting adopts a normal pressure pouring method, pure cement slurry (mixed with a small amount of additives) is adopted for the slurry, 32.5-grade ordinary portland cement is adopted for preparation, the consolidation strength of the slurry is M20 (the water cement ratio is 0.4-0.5), and the full slurry of an anchoring section in a hole is ensured in the construction process.

The grouting quality is the key for ensuring the drawing force of the soil nail, and a grouting mode of low-pressure slow grouting, intermittent grouting and gradual pressurization is adopted in the engineering.

The anchor plate adopts a 300X 200C 30 reinforced concrete slab, the main reinforcement adopts 9C14 steel bars, and the stirrup adopts C10@50 steel bars. The anchor sheet is shown in a larger view in FIG. 6.

5. Cast-in-place pile construction

5.1 measurement of payoff

And measuring the control points according to a design drawing, measuring and releasing pile positions of the piles, and assembling the pile frame in place. According to the preset measurement control network (point), the central point of each pile position is determined, advanced drilling is carried out firstly, then the central point of the pile position is measured and placed again, the steel casing is embedded and fixed after bidirectional control positioning, and the pile center is controlled by a bidirectional cross wire.

The hole forming must be checked to see if the center of the pile hammer coincides with the center of the pile position. During the construction process, the position of the drilling tool is required to be frequently detected to ensure the correctness of the hole position.

5.2 embedding of pile casing

After the pile foundation is released from the pile position, the pile casing can be embedded by finding out whether underground pipelines exist at the pile position, the inner diameter of the pile casing is 200 mm larger than the diameter of a drill bit, the center of a pile hammer is aligned with the pile position, then the pile casing is embedded according to the size of the pile casing, the pile casing is 30-50 cm higher than the ground, the slurry surface is 200 mm and the construction water level is 1.0-1.5 m, the thickness of the pile casing in the buried soil is not less than 1.5m, the length of the pile casing is more than the buried depth of the miscellaneous filling soil, and the pile casing is forced to weather for 0.2m so as to ensure that holes are not collapsed.

5.3 Forming the holes

The hole forming is a key process for controlling the quality and the construction period of the pile foundation, a rotary drilling form is adopted during hole forming, and the hole forming is realized by a dry operation hole forming method due to good geological conditions.

The perpendicularity is controlled in the hole forming process, and the measures are as follows:

firstly, the field must be leveled so that the rotary digging machine can be stably placed;

secondly, adopting corresponding pore-forming speeds for different stratums;

checking the inclination of the pile hole frequently. The hole forming construction is guided by geological data, various problems in the construction need to be correctly judged and timely processed, the perpendicularity deviation of the pile is not more than 1/100, the pile position deviation is not more than 50mm, and deviation and inclination towards the pit are avoided. After the hole is formed to the designed depth, the hole depth is checked, and the allowable deviation of the hole depth is 0 to +300 mm; the allowable deviation of the pile diameter is 0 to +30 mm.

The hole inspection is carried out once when the depth of 3m is drilled, the hole inspection is carried out at the place where the hole is easy to shrink, and when the pile construction enters the bedrock, the sampling is carried out once by sections when the hole is drilled by 100mm and 500 mm: wherein the height of the non-pile end supporting force layer section is 300-500 mm; the height of the pile end holding force layer is 100-300mm, and analysis sampling and final hole acceptance are prepared. The end of the designed pile is inserted into the weathered rock stratum not less than one time of the diameter of the pile and not less than 1.0 m.

The cast-in-place pile adopts a construction method of forming piles at intervals, and after the concrete strength of adjacent piles reaches 70% of the designed strength, hole forming construction can be carried out.

During drilling construction, the change of soil layers and rock debris is always noticed, slag samples are taken from the soil layers and the rock layers, the soil layers and the rock layers are judged and recorded in a record table, the record table is checked with a geological profile, a supervision is informed to carry out visa, and the rock samples are numbered, sealed and stored until the completion of the project is checked.

5.4 cleaning the hole

And drilling to the designed elevation and rock-entering consolidation to meet the requirements, and cleaning the hole after supervision and acceptance.

Hole cleaning requirements are as follows:

1) for sandy soil layers and sand-gravel layers with poor soil quality, the specific gravity of the hole bottom slurry after hole cleaning is 1.15-1.25 (g/cm)³)；

2) And (5) when the hole cleaning is finished, measuring the specific gravity, sand content and viscosity of the bottom mud. The sand content of the hole bottom slurry after hole cleaning is less than or equal to 8 percent, and the viscosity is less than or equal to 28 s;

3) the thickness of the sediment at the bottom of the hole after hole cleaning is not more than 50 mm. And (4) re-measuring the thickness of the sediments before pouring the underwater concrete, clearing the hole again when the sediments exceed the specification, and pouring the underwater concrete after the sediment is qualified.

5.5 fabrication and hoisting of Reinforcement cage

The steel reinforcement cage is manufactured on site, a large steel reinforcement sample of the cast-in-place pile is shown in figure 7, main reinforcements of the steel reinforcement cage are lapped and welded, longitudinal stressed steel reinforcements of the steel reinforcement cage are HRB 400-grade steel reinforcements, welding rods for welding are reasonably selected according to the material of a base material, and E55 type welding rods are recommended; the main bar is welded by a binding bar, the length of a single-side welding seam is not less than 10d (the length of the welding seam is more than 5d during double-side welding); the width of the welding seam should not be less than 0.8d, the thickness should not be less than 0.3d, and the clearance between the two main rib end faces should be 2-5 mm. The spiral stirrups and the transverse stiffening ribs are all HRB 400-grade steel bars, and the joints of the longitudinal and transverse steel bars are welded firmly. The main ribs and the stiffening hoops are firmly welded by 100 percent in a spot mode. The length of the main pile reinforcement anchored into the crown beam is not less than 800 mm.

After the reinforcement cage is manufactured, the reinforcement cage can be hung after being managed and accepted. If the steel reinforcement cage is small, the pile machine is used for placing the steel reinforcement cage, the steel reinforcement cage can be manufactured and hoisted in a segmented mode when the steel reinforcement cage is too long, main reinforcements of two sections of the steel reinforcement cage need to be in staggered lap joint and in welded butt joint, the number of joints on the same cross section is not larger than 50% of the total number of the main reinforcements, adjacent joints are staggered up and down, and the staggered distance is not smaller than 35 times of the diameter of the main reinforcements. Concrete cushion blocks need to be arranged on the outer side of the reinforcement cage or other effective measures need to be adopted to ensure the thickness of the reinforcement protection layer (the thickness of the reinforcement protection layer is 50 mm).

When the steel reinforcement cage is hoisted, the steel reinforcement cage is aligned to a hole position, and the crane is straight, stable and slowly sunk to avoid collision with the hole wall. When the reinforcement cage is lifted, proper measures are taken to prevent torsion and bending. And (4) immediately fixing the reinforcement cage after the reinforcement cage is sunk to the designed position. If the steel reinforcement cage is not over the bottom of the hole, in order to prevent the steel reinforcement cage from floating upwards when pouring concrete, a positioning measure that the steel reinforcement cage is connected with a protective cylinder by adding a hanging rib is adopted. In order to ensure the thickness of the protective layer of the steel bar, a positioning steel bar ring is arranged to ensure that the thickness of the protective layer of the steel bar is 50mm, and the allowable error is not more than 20 mm.

When the installation of the steel reinforcement cage is finished, a supervision engineer can carry out concealed project acceptance on the pile, and underwater concrete is timely poured after the pile is qualified.

5.6 Underwater concrete pouring

The pile body concrete adopts underwater concrete, and the key process of pile foundation construction is to pour the underwater concrete. The strength grade of the concrete of the support cast-in-place pile is underwater C30, and the materials and the mixture ratio of the underwater concrete are processed according to the current specification and regulations. Commercial concrete with production quality and passing through a quality system certification unit is selected as the concrete and is directly conveyed to each construction pile hole by a mixer truck. The filling coefficient of the concrete is 1.05-1.2, and is not more than 1.3.

The concrete is poured by a screw type connector guide pipe with the diameter of 250 mm. The catheters were tested for water tightness and pressure resistance before and after a period of use. The guide pipe is lowered to be about 30-50 cm away from the bottom of the hole. The method comprises the steps of checking the sediment condition at the bottom of a hole before pouring, performing secondary hole cleaning when a steel reinforcement cage is placed for too long time, hoisting a concrete prefabricated plug head in a guide pipe, shearing the plug only when a storage hopper needs enough concrete initial storage before opening the plug, ensuring that the guide pipe is buried in a management body for more than 1m after the first batch of concrete is poured, ensuring continuous supply of concrete in the pouring process, setting a specially-assigned person to measure hole depth record, accurately controlling the rising height of a concrete surface, strictly controlling the buried depth of the guide pipe to be within the range of 2-6 m, always burying the guide pipe in the concrete, strictly prohibiting the guide pipe from lifting the concrete surface, and strictly controlling the actual pouring amount of the concrete to be higher than the designed pile top by a certain length due to the fact that concrete at the pile top is mixed with slurry, the quality is influenced, and the actual pouring amount of the concrete should be higher than the designed pile top by a certain length, and the higher length should not be smaller than 500mm, and each pile should be made into a group of concrete test blocks.

6. Construction of crown beam

The top beam is constructed by adopting a subsection method, the supporting piles are poured in a partition mode, earthwork can be excavated to be used as the top beam when the pouring of the surrounding supporting piles in the area is finished, the top beam is paid off by technical personnel, residues, floating soil, accumulated water and the like on the top of the pile are cleaned according to the paying off, the top beam steel bars are bound, and the arrangement of the steel bars is specifically shown in figure 8.

7. Anchor cable and grouting construction

7.1 construction Process

Digging soil to a position 1000mm below the designed elevation of the anchor cable → paying off → forming a hole → placing an anchor cable body → secondary grouting → waist beam construction → tensioning and locking the anchor cable.

7.2 construction technology

(1) Paying off: and paying off by field measurement paying-off personnel according to design requirements, and making construction records after special inspection.

(2) Forming holes:

1) drilling an anchor cable by adopting a rotary drilling machine with a phi 180 drill bit to drill a hole with a drill pipe, and performing extra drilling for 500 mm;

2) the inclination angle of the formed hole is 15 degrees, after the hole is formed, the rod body is placed into the hole and is withdrawn out of the sleeve after being filled with cement mortar;

3) the allowable deviation of the pitch of the anchor holes in the horizontal and vertical directions is +/-50 mm, the allowable deviation of the drilling angle is +/-3 degrees, and the allowable deviation of the drilling bottom deviating from the axis is 3 percent of the length of the anchor cable;

4) and after the hole forming depth reaches the design requirement, immediately tripping the drill, and carrying out reaming operation after replacing the reaming drill. The hole can be enlarged by a mechanical hole enlarging drill bit or by a high-pressure jet grouting method.

5) After the hole is formed, the hole is washed in time until the specific gravity of the slurry flowing out of the hole opening is less than 1.10g/cm³Until the end;

6) and in the process of forming the hole, paying attention to control the verticality and the inclination angle of the anchor hole, checking and accepting the hole depth, the hole diameter and the inclination angle after forming the hole, and making construction records and hidden project checking records.

(3) Manufacturing a rod body:

1) the rod body is required to be processed on a flat mud-free ground, and the error of each stranded wire is less than 50 mm;

2) arranging a positioning bracket every 1.0-1.5 m along the axial direction of the rod body, and firmly binding the positioning bracket by using iron wires, wherein the protective layer of the rod body is not less than 20 mm;

3) the free section of the rod body should be coated with lubricating oil and wrapped with plastic cloth or plastic tubes, and the two ends should be tightly wrapped so as not to leak cement paste;

4) after the rod body is qualified in processing and inspection, the rod body can be put down. The stacking is neat, and the mark is clear;

5) proper manpower is needed to be allocated during the transportation of the rod body, so that muddy water is prevented from being polluted;

6) after the rod body is put into the hole, the stretching length is 1.2m (based on the outer skin of the waist rail).

(4) And (3) arranging an anchor cable: and (3) immediately putting an anchor rod after the drill is pulled out, and avoiding the twisting of the steel strand in the anchor rod placing process.

(5) Grouting for the first time:

1) primary grouting is carried out within 2 hours after the anchor cable is placed into the hole, and primary grouting is carried out immediately after hole cleaning is finished;

2) the first grouting material is M25 cement mortar, is prepared from 42.5R ordinary portland cement and fine sand, the admixture is FDN-Z, and the doping amount is 0.70 percent of the cement amount;

3) water and impurities poured into the drill hole in the first grouting are replaced out of the orifice, and the orifice can stop after cement mortar flows out of the orifice;

(6) waist rail construction

The wale is reinforced concrete wale, carries out the formwork after the pole setting installation, installation reinforcing bar, checks and accepts, concreting, and when the construction, the sleeve pipe of reservation stock should be paid attention to, and the concrete full-page view is shown in figure 9.

(7) Anchor cable tensioning and locking

1) The tensioning equipment needs to be calibrated by a metering department, and calibration parameters are used as the basis of field tensioning;

2) tensioning is carried out 28 days after grouting, single tensioning and integral tensioning are adopted, when single tensioning is carried out, the load is 8% of the designed prestress value, integral tensioning load is applied in five stages, the front four stages are respectively 25%, 50%, 75% and 100% of the designed strength, the next stage of tensioning is carried out after the front four stages are respectively stabilized for 5min, the last stage is 110% of the designed stress, the stabilizing time is 30min, and the temperature returns to 100%. And (3) within 48 hours after tensioning is finished, if the prestress loss is more than 10% of the designed prestress, compensating tensioning, wherein the designed stress is achieved by compensating tensioning once, grouting is performed on a free section after the compensation tensioning, and grease is filled between the outer side of the plug and the steel backing plate at the orifice. The grease should not corrode parts of the anchor cable. Then C30 concrete is adopted to close the anchor head so as to prevent the loss of locking stress caused by corrosion of exposed outside;

3) when the anchor cables are tensioned, the influence on the adjacent anchor cables is noticed, and a measure of tensioning by using anchor separation can be adopted;

4) an anchorage device meeting the technical requirements is adopted;

5) the anchor cable is preferably tensioned to 0.9 times of the design load and then locked according to the requirement of the design prestress value;

6) after the anchor cable is locked, if obvious prestress loss is found through monitoring, compensation tensioning is carried out;

7) the anchor cable tensioning and locking operations should be recorded in detail and completely.

7.3 notes

(1) The anchor cable is subjected to rust prevention and corrosion prevention treatment. The whole section of the anchor cable needs cleaning and rust removal. And coating grease on the free section of the anchor cable and coating a corrugated pipe with the diameter of phi 22mm outside the free section of the anchor cable for corrosion prevention.

(2) The prestressed anchor cable is made of phi 15.2 steel stranded wires with high strength, low relaxation and tensile strength not less than 1220MPa, and the steel stranded wires must meet the regulations of the existing national standard steel stranded wires for prestressed concrete (GB/T5224-. The anchorage device adopts OVM15 type.

(3) The anchor section of the anchor cable is made into a corrugated shape by adopting a series of bunch rings and isolating frames, and a date pit shape is formed after grouting. The wire binding rings of the anchoring sections and the isolation frames are arranged at intervals of 1m, the isolation frames are arranged at intervals of 2m of the free sections, and the specific outline is shown in figure 10.

(4) The front section of the anchoring section is provided with a guide cap so that the anchor rope can be smoothly anchored.

(5) The anchor section of the anchor cable needs to adopt a secondary grouting process to greatly improve the anchoring force. The grouting pipe is made of a phi 22 polyethylene pipe with the pressure resistance of more than 4MPa, the grouting material is M30 pure cement slurry, the pure cement slurry is poured for the first time, 42.5 common portland cement is adopted, the water cement ratio is 0.5-0.55, and the slurry is poured from the bottom of the hole until the orifice returns to the concentrated slurry. And (3) injecting pure cement slurry for the second time, wherein the water cement ratio is 0.5:1, the grouting is performed before final setting after initial setting of the first grouting, and high-pressure grouting is adopted for the second time, and the grouting pressure is 1.5-2 MPa. And tensioning when the strength of the grouting body reaches above 25 MPa.

(6) The position of the anchor cable must be determined strictly according to the design requirements, and the top surface of the anchor device base is ensured to be vertical to the axis of the drilling hole.

(7) In order to verify the design of the prestressed anchor cable, test the construction process of the prestressed anchor cable and guide safe construction, the prestressed anchor cable anti-pulling test is required to be carried out at the initial construction stage of the anchor cable engineering, the number of the anchoring tests is not less than 5 percent of that of the working anchor cable, the anchoring tests are not destructive, and the prestressed anchor cable anti-pulling test cannot be carried out in the range of the working anchor cable.

(8) And simultaneously pouring the anchor pier and the crown at the crown beam part to ensure that the bearing surface of the anchor pier is vertical to the axis of the anchor cable. And embedding a steel sleeve when the crown beam is poured, ensuring that the position and the direction of the anchor hole are consistent with the design, and if the position of the anchor hole conflicts with the position of the steel bar, taking the steel bar avoidance as a principle.

(9) Drilling: the position of the prestressed anchor cable is strictly determined by a measurer, and the drilling direction is strictly controlled by a drilling person during drilling. The drilling hole must meet the requirements of the aperture, depth, position and direction of a design drawing, the lithology and thickness of the anchoring section are closely known in the drilling process, and modes such as casing follow-up are adopted to avoid hole wall collapse or drill jamming. And cleaning the drilled hole after the drilling is finished.

(10) Manufacturing an anchor cable: the anchor cable is manufactured under the guidance of a skilled worker under the guidance of an experienced engineer, and firstly, the material of the anchor cable body is cut off according to the design requirement; performing rust-proof and corrosion-proof treatment according to design requirements; placing the processed anchor cable body material on a manufacturing bracket in a straight manner; manufacturing an anchor cable according to design requirements; after the inspection is qualified, numbering for standby.

(11) And (3) anchor cable installation: and after the depth of the anchor hole reaches the design requirement, immediately cleaning the hole, installing an anchor cable according to the requirement and grouting. Before the anchor cable is installed, the drilled hole is checked again, and hole collapse, block falling and the like are cleaned or treated; the anchor cable body is inspected in detail, and damaged protective layers, accessories and the like are repaired; when the anchor cable is pushed, the force is uniform and consistent, and the anchor cable body cannot be rotated; the anchor cable body is pushed to a preset position and the grouting pipe is enabled to be smooth. The centering bracket and the guide cap should be set when mounting.

(12) Grouting: and strictly executing grouting process requirements. The slip casting stopper can adopt the rubber buffer, needs effective fixed. The orifice outer grouting plug can be made of non-woven fabric and is in the shape of a ring bag sleeved on the PVC pipe, the outer grouting plug is fully injected with 0.2-0.4MPa pressure before grouting, and pressure grouting is carried out after the strength of the outer grouting plug reaches 20 MPa. The grouting pipe is fed into the bottom of the hole along with the anchor cable body, and is pulled out while grouting during grouting, so that a section of the grouting pipe is always embedded in the grouting liquid until the grouting liquid is full. When water is accumulated in the hole, the slurry is required to be completely discharged.

(13) Tensioning: when the cement slurry in the hole reaches 70% of the designed strength, tensioning can be carried out, and the extension and stress of the anchor cable need to be well recorded during tensioning. When the elongation or tension change is abnormal, the tension should be stopped immediately and the cause should be found and then the process should be repeated. When the anchor cable is tensioned, the anchor cable does not collide with a jack; it is strictly forbidden for a person to stay in the area behind the jack. When an anchor cable anchoring test is carried out on a working anchor cable, the counter force of the jack is strictly forbidden to act on the crown beam and the waist beam.

8. Construction of pile side concrete

8.1 design requirements:

the soil between piles of the foundation pit fender pile is supported by hanging C6@150 multiplied by 150 steel bar meshes and spraying concrete of 100mm, the steel bar meshes are fixed by adopting inter-pile dowel bars and pile body expansion screws, C16 steel bars of 1m length are used as dowel bars, the steel bar meshes are fixed, and the distance between the steel bar meshes is equal to the center distance of the row piles. The steel bar net piece is fixed and the sprayed concrete is constructed in time along with excavation of foundation pit earthwork, so that the exposure time of excessive foundation pit excavation of the earthwork is prevented from being too long, and the arrangement of the steel bar net piece is shown in a figure 11 and a figure 12.

8.2 the construction method comprises the following steps:

(1) installing and hanging a steel wire mesh:

after the excavation of the earthwork of the first layer is completed, C6@150 x 150 steel wire meshes are arranged on a soil slope, the steel wire meshes are fixed, 1C 16 fixed steel bars with the length of 1m are arranged between the piles, the vertical distance is 1m, the horizontal distance is 1.3m or 1.1m (the distance between the local piles is adjusted, and the distance between the local piles is the distance between the piles), expansion screws are arranged in the middle of the piles, and the steel wire meshes, the fixed steel bars and the expansion screws are firmly combined.

(2) The process flow of the sprayed concrete is as follows:

after the injection machine is installed and adjusted, water is injected and the air is ventilated, and impurities in the pipeline are removed. And the feeding ensures the continuity and the output ratio of the ingredients is corrected.

The operation sequence is as follows: when spraying, the admixture is firstly opened, then air is opened, and then the materials are fed, so that the adhesive is easy to adhere, the rebound quantity is small, and the surface is wet and glossy. The working wind pressure of the jet machine is strictly controlled within the range of 0.5 to 0.7Mpa, and the wind pressure is changed from high to low from top to bottom.

The thickness of the sprayed concrete is 100mm, and the sprayed concrete is sprayed in two layers.

(3) The technical points of the concrete spraying are as follows:

1) the earthwork is excavated to the position of 10cm away from the edge of the pit, the soil body between the piles is manually cleaned, and then the primary concrete spraying work is carried out to prevent the soil between the piles from falling off and causing damage to the personnel and machinery in the pit bottom construction. And before re-spraying, after finishing the installation work of the steel wire mesh sheet according to the design, immediately re-spraying the concrete to the designed thickness.

2) The laboratory is responsible for optimizing the mix proportion of the sprayed concrete and controlling the construction, and strictly forbids the backfill of other materials.

3) The sprayed concrete is maintained by spraying water by a specially-assigned person.

4) And installing a water outlet before spraying concrete, wherein the water outlet adopts an A50PVC pipe, the length is 500mm, the embedding angle is 5-15 degrees, a hole is drilled at the pipe end and a gauze is wrapped on the pipe end, and the water outlet needs to extend out of the concrete surface layer by 100 mm. The large pattern of the weep holes is shown in FIG. 13.

In summary, firstly, the work of collecting the geological survey data and collecting the contour line data is done, the schematic diagram of the position relationship between the building and the mountain is shown in fig. 1, the relationship between the building and the mountain is combed, the supporting form of fig. 2 is determined, earthwork excavation is carried out according to the slope of the designed slope, the mountain above the evacuation channel is supported by soil nails according to the patterns of fig. 3 to 6, then the construction of rotary drilling and pile filling is carried out at the position of the evacuation channel far away from the mountain, the big sample diagram is shown in fig. 7, then the pile head is processed, the crown beam is made according to fig. 8, the piles are all connected together, the earthwork is excavated to the position 1m below the first row of anchor cables in a layering way, the anchor cables are made, installed and grouted according to fig. 9 and 10, then the concrete hanging and spraying construction is carried out on the area below the crown beam and above the anchor cables, and the measures of draining water are made, the concrete measures are shown in fig. 11 to fig. 13, after the concrete spraying maintenance of the pile side is finished and the strength reaches 75 percent, and (4) continuously excavating the earthwork to the bottom of the foundation pit, continuously hanging net and spraying concrete on the pile side, and taking drainage measures to finish mountain support.

Claims

1. A mountain supporting method for a hilly land adjacent to a special-shaped building is characterized in that: building a fire-fighting evacuation channel on a hillside, adopting slope cutting and soil nail supporting in the area above the hillside evacuation channel according to the contour line of the hillside, the actual position of the building and the geological survey data, adopting rotary drilling cast-in-place piles and anchor rope supporting in the area of one side of the evacuation channel, which is far away from the hillside, and hanging nets and spraying concrete on the pile side.

2. The mountain supporting method for the adjacent special-shaped buildings in the hilly land according to claim 1, which is characterized in that: the mountain supporting method comprises the following steps in sequence: the method comprises the following steps of land exploration construction, mountain body contour line measurement, mountain body slope cutting, soil nail support construction, cast-in-place pile construction, crown beam construction, earthwork excavation to a first row of anchor cables, slope surface trimming, anchor cable and grouting construction, pile side reinforcing steel bar net piece binding and water drain pipe installation, concrete spraying, maintenance and excavation of the next layer of working face.

3. The mountain supporting method for the adjacent special-shaped buildings in the hilly land according to claim 2, which is characterized in that: the geological exploration construction comprises the steps of drilling a mountain geological structure, knowing rock stratum distribution conditions of the mountain geological structure and obtaining detailed geological exploration data, wherein the arrangement of geological exploration points covers the range of supporting.

4. The mountain supporting method for the adjacent special-shaped buildings in the hilly land according to claim 2, which is characterized in that: the mountain body contour line measurement is to carry out GPS measurement on a mountain body to be supported, process data, generate a contour line and provide data support for combing the relationship between a building and the mountain body.

5. The mountain supporting method for the adjacent special-shaped buildings in the hilly land according to claim 4, wherein the method comprises the following steps: and constructing the mountain slope evacuation channel according to the contour lines of the mountain, the actual position of the building and the geological survey data, performing mountain slope cutting construction according to design drawings above the evacuation channel, and performing soil nail support construction on the slope surface to ensure the safety of the mountain.

6. The mountain supporting method for the adjacent special-shaped buildings in the hilly land according to claim 5, wherein the method comprises the following steps: and (3) carrying out rotary drilling bored pile construction according to a design drawing at the edge of one side of the mountain slope evacuation channel, which is far away from the mountain body, wherein the pile diameter is 800mm, and the pile distance is 1000 mm.

7. The mountain supporting method for the adjacent special-shaped buildings in the hilly land according to claim 6, wherein the method comprises the following steps: and (3) manufacturing a crown beam of 0.8m by 1.0m at the upper part of each cast-in-place pile so as to connect all the piles into a whole.

8. The mountain supporting method for the adjacent special-shaped buildings in the hilly land according to claim 7, which is characterized in that: the method comprises the steps of performing earth excavation after a crown beam is poured, trimming slope surface when the earth excavation is performed to the position 1m below a first row of anchor cables in a design drawing, and then performing anchor cable drilling, installation and grouting construction, wherein the anchor cables are made of phi 15.2 steel strands with high strength and low relaxation and tensile strength not less than 1220MPa, the hole depth of each anchor cable is 15m, the hole diameter is 180mm, the horizontal interval is 2m, the inclination angle is 15 degrees, and the prestress applied to the prestressed anchor cables is 120 KN.

9. The mountain supporting method for the adjacent special-shaped buildings in the hilly area as claimed in claim 8, wherein the method comprises the following steps: after the construction of the anchor cable is finished, pile side hanging reinforcing mesh sheet binding, water drain pipe installation and concrete spraying construction are carried out, after the process is finished and maintained, the pile side is continuously excavated downwards to a building base in the same mode, and the pile side between the anchor cable and the base is supported in a net hanging concrete spraying mode.