CN112195942A

CN112195942A - Building foundation slope stepped supporting method

Info

Publication number: CN112195942A
Application number: CN202011011222.5A
Authority: CN
Inventors: 姜坤; 刘璇; 万廷荣; 张思斌; 覃鹤; 卢华; 甘衡; 袁肖; 周雨婷; 施正阳; 赵红霞
Original assignee: No 1 Construction Engineering Co Ltd of Guizhou Construction and Engineering Group
Current assignee: No 1 Construction Engineering Co Ltd of Guizhou Construction and Engineering Group
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2021-01-08

Abstract

The invention provides a building foundation slope stepped supporting method, which comprises the following steps: digging to form a side slope with a plurality of steps; selecting a side slope surface corresponding to one step as a working slope surface, and drilling a plurality of anchor holes on the working slope surface; inserting an anchorage device in the anchor hole and pouring concrete to form the anti-slide pile; laying steel bars on the tops of the anti-slide piles and pouring concrete to form inter-pile plates, wherein the inter-pile plates and the anti-slide piles form a composite slope protection unit; and sequentially selecting the slope surfaces corresponding to the corresponding steps as working slope surfaces, and finishing construction after constructing and obtaining a plurality of composite slope protection units. By adopting the technical scheme of the invention, the disturbance to the side slope soil body or rock mass is reduced in the construction process, a foundation is laid for ensuring the stability and reliability of a ground building, the upper layer soil body and the lower layer rock mass are connected into a unified whole through the anti-slide piles and the inter-pile plates in the supporting process, the supporting strength is improved, the number of the anti-slide piles and the number of the anchor cables are timely reduced along the direction from top to bottom, and the cost is saved.

Description

Building foundation slope stepped supporting method

Technical Field

The invention relates to the technical field of building engineering, in particular to a method for supporting a building foundation side slope in a grading manner.

Background

With the development of economy, cities face various construction problems. The new urban area needs to be expanded urgently, and the old urban area needs to be transformed urgently. For cities under the karst landform geological condition, the engineering construction task of the urban area is very difficult and serious, only a few plains exist in the urban area, and most buildings exist on the side slope. Most of the slope bodies are rock-soil mixed substance temporary foundation pit side slopes formed by miscellaneous fill, plastic red clay and stroke dolomite, and some slope bodies even contain karst caves or underground rivers. Therefore, in urban development, the safety of the foundation pit side slope directly concerns the life and property safety of the majority of residents, and simultaneously, the foundation pit side slope also provides great challenges for the construction process of construction units.

In the supporting construction of the temporary foundation pit side slope made of rock-soil mixed substances, the safety of a building above a slope body is mainly considered, namely, the influence of vibration on the building is reduced in the construction period, the traditional drilling mode is relatively rough, the vibration is large, and the stability of the building and the normal life of residents are influenced. If the construction is carried out under the condition that the life of residents above the side slope is not influenced, the construction is particularly difficult, and a safer construction scheme needs to be explored.

Disclosure of Invention

In order to solve the technical problem, the invention provides a building foundation slope stepped supporting method.

The invention is realized by the following technical scheme.

The invention provides a building foundation slope stepped supporting method, which comprises the following steps:

the method comprises the following steps: excavating earth and stone on the edge of the building foundation, and forming a side slope with a plurality of steps on the edge of the building foundation;

step two: selecting a side slope surface corresponding to one of the steps as a working slope surface, providing a drilling machine, a soil body drill bit, a rock body drill bit and a combined protective pipe, wherein the combined protective pipe comprises an inner layer casing pipe and an outer layer casing pipe sleeved on the outer peripheral surface of the inner layer casing pipe; installing a rock mass drill bit on a drilling machine, starting the drilling machine to enable the rock mass drill bit to penetrate through the combined protective pipe and then drill into a lower rock mass composite slope protection unit of the working slope surface to obtain a rear section hole, and enabling the front section hole and the rear section hole to be communicated to form an anchor hole;

step three: repeating the second step, and drilling and tapping on the working slope surface to obtain a plurality of anchor holes;

step four: providing a plurality of anchorage devices, wherein each anchorage device comprises a plurality of anchor cables bundled together in parallel, inserting one end of each anchorage device into the anchor hole in the third step one by one, extending the other end of each anchorage device out of the working slope surface, pouring concrete into a gap between each anchorage device and the corresponding anchor hole, and forming an anti-slide pile with each anchorage device after the concrete is solidified;

step five: arranging a plurality of steel bars at the tops of the anti-slide piles in the fourth step, connecting all the anti-slide piles together, then pouring concrete to cover all the steel bars, forming an inter-pile plate with the steel bars after the concrete is solidified, and forming a composite slope protection unit by the inter-pile plate and the anti-slide piles;

step six: and repeating the second step to the fifth step, sequentially selecting the slope surfaces corresponding to the corresponding steps as working slope surfaces according to the sequence from top to bottom, and finishing construction after constructing and obtaining a plurality of composite slope protection units.

In the second step, the inclination angle of the central axis of the anchor hole relative to the horizontal plane is 20 degrees.

And in the second step, the aperture of the anchor hole is not less than 150 mm.

In the fourth step, the anchor cable is made of steel strands with nominal diameter of 15-20 mm.

The concrete strength grade is not lower than C30.

And fifthly, the nominal diameter of the steel bars in the inter-pile plate is not smaller than 14mm, and the steel bars are divided into two layers and arranged along at least two directions.

And fifthly, the thickness of the inter-pile plate is not less than 300 mm.

And in the second step, the depth of the rear section hole is 1.5-6 m.

Along the sequence from top to bottom, the quantity of the anti-slide piles constructed on the slope surface of the side slope corresponding to each step is gradually reduced.

And the number of the anchors contained in the anti-slide piles constructed on the slope surface of the side slope corresponding to each step is gradually reduced along the sequence from top to bottom.

The invention has the beneficial effects that: by adopting the technical scheme of the invention, the 300-type crawler geological drilling machine with smaller vibration amplitude in the drilling process is firstly adopted for construction, then the spring pad is clamped and plugged between the drilling machine and the slope surface of the side slope for absorbing vibration, the hole wall is protected by using the double-layer combined casing pipe in the drilling process, the soil body at the upper layer of the side slope and the rock body at the lower layer are treated differently, various measures are adopted for dealing with the situation, the phenomenon that the hole cannot be formed due to hole collapse and block falling in the drilling process is effectively prevented, the hole forming quality is ensured, the construction progress is ensured, the disturbance to the soil body or the rock body of the side slope is reduced, the foundation is laid for ensuring the stability and reliability of a ground building, in addition, the outer casing pipe of the combined pile casing is made of degradable engineering plastic materials, the pollution to the soil body is avoided, the outer casing pipe is made of metal materials, and the combined pile casing, the hole collapse phenomenon is avoided, then in the supporting process, the difference treatment and the difference construction are carried out on the soil body structure and the rock body structure below the building foundation, the upper soil body and the lower rock body are connected into a unified whole through the anti-slide piles and the inter-pile plates, the supporting strength of the building foundation is improved, the thickness of the upper soil body is gradually reduced along the direction from top to bottom, the number of the anti-slide piles and the number of the anchor cables in the corresponding anchor devices are timely reduced, the resource waste is reduced, and the cost is saved.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 is a schematic structural view of the present invention;

fig. 3 is a schematic view of the structure of the anchor eye of the present invention.

In the figure: 1-upper soil body, 2-lower rock body, 3-anchorage device, 4-slide-resistant pile, 5-inter-pile plate, 6-drainage ditch, 7-combined protective pipe, 8-front section hole and 9-rear section hole.

Detailed Description

The technical solution of the present invention is further described below, but the scope of the claimed invention is not limited to the described.

As shown in fig. 1, 2 and 3, the invention provides a method for supporting a building foundation side slope in a stepped manner, which comprises the following steps:

step two: selecting a side slope surface corresponding to one of the steps as a working slope surface, providing a drilling machine, a soil body drill bit, a rock body drill bit and a combined protective pipe 7, wherein the combined protective pipe 7 comprises an inner layer casing pipe and an outer layer casing pipe sleeved on the outer peripheral surface of the inner layer casing pipe, firstly installing the soil body drill bit on the drilling machine, starting the drilling machine to enable the soil body drill bit to drill through a composite slope protection unit of an upper layer soil body 1 of the working slope surface and obtain a front section hole 8, and then pressing the combined protective pipe 7 into the front section hole 8; installing a rock mass drill bit on a drilling machine, starting the drilling machine to enable the rock mass drill bit to penetrate through the combined protective pipe 7 and then drill into the lower rock mass 2 composite slope protection unit of the working slope surface to obtain a rear section hole 9, and enabling the front section hole 8 and the rear section hole 9 to be communicated to form an anchor hole; further, in the second step, the inclination angle of the central axis of the anchor hole relative to the horizontal plane is 20 degrees. And in the second step, the diameter of the anchor hole is not less than 150 mm. And in the second step, the depth of the rear section hole 9 is 1.5m to 6 m.

step four: providing a plurality of anchorage devices 3, wherein each anchorage device 3 comprises a plurality of anchor cables bundled together in parallel, inserting one end of each anchorage device 3 into an anchor hole in step three in a one-to-one correspondence manner, extending the other end of each anchorage device 3 out of a working slope surface, pouring concrete into a gap between each anchorage device 3 and the anchor hole, and forming an anti-slide pile 4 together with the anchorage device 3 after the concrete is solidified; further, the anchor cable in the fourth step is made of steel strands with nominal diameter of 15-20 mm. The concrete strength grade is not lower than C30.

Step five: arranging a plurality of steel bars on the tops of the anti-slide piles 4 in the fourth step, connecting all the anti-slide piles 4 together, then pouring concrete to cover all the steel bars, forming an inter-pile plate 5 with the steel bars after the concrete is solidified, and forming a composite slope protection unit by the inter-pile plate 5 and the anti-slide piles 4; and fifthly, the nominal diameter of the steel bars in the inter-pile plate 5 is not less than 14mm, and the steel bars are arranged in two layers along at least two directions. And fifthly, the thickness of the inter-pile plate 5 is not less than 300 mm.

In addition, the number of the slide piles 4 constructed on the slope surface of the side slope corresponding to each step is gradually decreased along the sequence from top to bottom. Along the sequence from top to bottom, the anchors 3 contained in the slide-resistant piles 4 constructed on the slope surface of the side slope corresponding to each step are gradually decreased in number, and the anchors 3 contained in the anchors 3 are gradually decreased in number.

In addition, the step-by-step supporting method of the building foundation side slope further comprises the following steps: and excavating earth and stone on each step to form a drainage ditch 6 while performing the step one. And in the second step, the outer sleeve is made of engineering plastics. The inner layer sleeve is made of seamless steel pipes made of alloy structural steel. The outer diameter of the inner layer casing is phi 168mmmm, and the wall thickness of the inner layer casing is 5-8 mm. The step-by-step supporting method of the building foundation side slope further comprises the following steps: before the earth drill bit is installed on the drilling machine, spring pads are clamped at the bottom of the drilling machine and on the slope surface of the side slope.

Furthermore, the soil body drill bit is made of alloy steel. The rock mass drill bit is a coreless drill bit. The nominal outer diameter of the rock mass drill bit is phi 135 mmmm. The drilling machine is a 300-type crawler geological drilling machine. The step-by-step supporting method of the building foundation side slope further comprises the following steps: when the soil body drill bit or the rock body drill bit encounters solution cavern, mud stone inclusion or fracture dense zone in the drilling process, the soil body drill bit or the rock body drill bit is taken out immediately, filling slurry is poured into the front section hole 8 or the rear section hole 9 for plugging, and then the soil body drill bit or the rock body drill bit is made to continue drilling.

By adopting the technical scheme of the invention, the 300-type crawler geological drilling machine with smaller vibration amplitude in the drilling process is firstly adopted for construction, then the spring pad is clamped and plugged between the drilling machine and the slope surface of the side slope for absorbing vibration, the hole wall is protected by using the double-layer combined casing pipe in the drilling process, the soil body at the upper layer of the side slope and the rock body at the lower layer are treated differently, various measures are adopted for dealing with the situation, the phenomenon that the hole cannot be formed due to hole collapse and block falling in the drilling process is effectively prevented, the hole forming quality is ensured, the construction progress is ensured, the disturbance to the soil body or the rock body of the side slope is reduced, the foundation is laid for ensuring the stability and reliability of a ground building, in addition, the outer casing pipe of the combined pile casing is made of degradable engineering plastic materials, the pollution to the soil body is avoided, the outer casing pipe is made of metal materials, and the combined pile casing, the hole collapse phenomenon is avoided, then in the supporting process, the difference treatment and the difference construction are carried out on the soil body structure and the rock body structure below the building foundation, the upper soil body and the lower rock body are connected into a unified whole through the anti-slide piles and the inter-pile plates, the supporting strength of the building foundation is improved, the thickness of the upper soil body is gradually reduced along the direction from top to bottom, the number of the anti-slide piles and the number of the anchor cables in the corresponding anchor devices are timely reduced, the resource waste is reduced, and the cost is saved.

Example 1:

as shown in fig. 2, the building foundation slope has a plurality of steps;

firstly, before construction, the influence of existing cracks and defects of the building on the safety of the main structure of the building is graded on the building on a slope. And predicting the subway tunnel to be built and the subway exit. And grading according to the evaluation result. And enter the building to check the cracks and damage conditions one by one. So as to facilitate a comprehensive assessment of the building. And determining whether the anchor cable hole forming process can influence the building. If the influence is generated and the life of residents is influenced during construction, a damping process needs to be established.

Secondly, in order to ensure the safety of ground buildings, a 300-type crawler geological drilling machine with small vibration amplitude is selected for construction, a soil layer part adopts a sleeve following mode to drill, a sleeve is a disposable sleeve, and a rock part adopts a coreless bit or a core bit mode to drill. Digging and leveling the field by adopting an excavator, installing a drilling machine, adjusting the horizontal position, the height, the direction and the inclination angle of an arm support of the drilling machine to ensure that a drill rod and a casing clamp are aligned with hole positions, and adjusting the direction and the inclination angle to ensure that the drill rod and the casing clamp meet the design requirements. Drilling with a phi 168mm follow pipe, wherein the follow pipe is an alloy structural steel seamless steel pipe, the wall thickness is 5-8mm, the length of a single sleeve is 1.5m, the drill bit is a 168mm alloy drill bit, the drilling length of each section is preferably 3-6m, and the actual operation can be adjusted according to actual conditions. Drilling from the casing by adopting a phi 135mm triangular drill bit, wherein the drill rod is a 75mm coreless drill rod. Clear water is adopted for slag return in the drilling process, the water pressure in the drilling process cannot be too high, and the slag return can be performed normally. After entering the rock, the casing pipe is not followed, and after entering the rock, a 150mm coreless drill bit or a 150mm coring drill bit is adopted to drill the hole to a final hole. The following casing pipe is not pulled out any more, so as to ensure the stability of the soil body structure and the quality of the formed hole.

And thirdly, the anchor cable is stably and quickly installed by adopting a manual cable penetrating method, construction is carried out in a segmented mode, and the design is checked, modified and supplemented as necessary according to information such as site geological conditions, protection or supporting structure deformation and the like in the construction process.

According to the sequence from top to bottom, the first step is constructed, and the slope surface of the side slope corresponding to the first step adopts a support form of 'slide-resistant piles + anchors + plates between piles'. The first step is 27.5-29.1 m high, and the slope is provided with a drain hole, and the drain hole uses a drain pipe to lead water into a building design drainage system. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden. Anchor cable design: and (3) 11 rows of prestressed anchor cables are arranged, the distance between the anchor cables in the uppermost row and the crown beam top is 1.m, the vertical distance between the anchor cables in each row is 2.5m, and the horizontal distance is the pile distance. Each row of anchor cables are 1860 type 7 multiplied by 15.24mm anchor cables, and the diameter of each anchor hole is 150 mm. The inclination angles of the anchor cables in each row are 20 degrees, the lengths of the anchoring sections are 5.0m, and the lengths of the anchoring sections should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, each row of anchor cables are 12 bundles, the vertical distance is 2.5m, and the horizontal distance is equal to the pile distance. Designing horizontal prestress: from top to bottom, the first and second rows are 640 kN; the third ranking is 800 kN; 880kN in the fourth to sixth rows; the seventh to eleventh rows are 800 kN.

M30 cement mortar is poured into the anchoring section, secondary grouting is adopted, the grouting pressure is preferably 0.6-3.0MPa, and the length of the sand setting section is 0.5M. The anchor cable body is provided with a positioning bracket every 1.5m, and each row of anchors is selected for the designed bundle number. The finished subway tunnel is arranged in the slope corresponding to the first step, the anchor cable is used for strictly controlling the drilling error according to the standard, and the drilling gradient and the hole depth are strictly monitored.

And (3) anti-slide pile: the pile top elevation 1078m, the diameter 2.0m, the interval is about 3.0m, and the embedding section is embedded into complete weathered rock and is not less than 10.0 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top is provided with 2.0 multiplied by 1.2m crown beams which are connected, the anchor cable position is provided with 0.4 multiplied by 0.3m tie beams which are connected, and the crown beams and the tie beams are both cast by C30 concrete. Arranging phi 28 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welding joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint. And (3) a pile-to-pile plate: the thickness is 300mm, C30 concrete is adopted, and double layers of bidirectional phi 14@200 steel bars are distributed in the concrete.

It should be noted that if the slope surface of the side slope corresponding to the step is close to important pipeline cables such as gas and water supply, the hole jumping excavation is needed during the construction of the slide-resistant pile, the hole should be poured in time after the hole forming, and the pouring is not forbidden for a long time. When constructing in soil layer, mud protecting wall or steel protecting cylinder should be used to prevent the hole wall from collapsing. The displacement of the important pipeline cable should be closely monitored in the construction process.

According to the sequence from top to bottom, the second step is 4.25m high and 8m wide, and the support form of 'slide-resistant pile + anchorage device + inter-pile plate' is adopted, so that the slide-resistant pile: the diameter is 1.5m, the distance is about 3.0m, and the embedding section is embedded into the complete weathered rock and is not less than 6.0 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top is provided with 1.5 multiplied by 1.0m crown beams which are connected, and the crown beams are cast by C30 concrete. Arranging phi 28 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welding joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint. The rock mass between piles is supported by using C25 fine-stone concrete sprayed by a hanging net, the thickness of the concrete is 80mm, a single-layer bidirectional phi 8@150 reinforcing mesh is matched, and horizontal reinforcing steel bars are anchored into the anti-slide piles.

According to the sequence from top to bottom, the third step adopts a support mode of 'slide-resistant piles + anchor cables + inter-pile plates', the third step is about 20.3m high, and a support scheme of 'slide-resistant piles + anchor cables' is adopted. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Anchor cable design: 8 rows of prestressed anchor cables are arranged, the distance between the anchor cables in the lowest row and a slope toe is 1.15m, the vertical distance between the anchor cables in each row is 2.5m, the horizontal distance is the pile distance, and the anchor is anchored on a main pile. The anchor cable adopts a 1860 type anchor cable with the diameter of 7 mm multiplied by 15.24mm, and the anchor hole diameter is 150 mm. The inclination angles of the anchor cables in each row are 20 degrees, the lengths of the anchoring sections are 5.0m, and the lengths of the anchoring sections should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, each row of anchor cables are 12 bundles, the vertical distance is 2.5m, and the horizontal distance is equal to the pile distance. Designing horizontal prestress: from top to bottom, the first row is 640 kN; the second row is 720 kN; the third row is 800 kN; the fourth row is 880 kN; the fifth row and the sixth row are 960 kN; the seventh and eighth rows are 880 kN. M30 cement mortar is poured into the anchoring section, secondary grouting is adopted, the grouting pressure is preferably 0.6-3.0MPa, and the length of the sand setting section is 0.5M. The anchor cable body is provided with a positioning bracket every 1.5m, and each row of anchors is selected for the designed bundle number. Note that: in the slope body of the side slope, a finished subway tunnel is arranged, the anchor cable is required to strictly control the drilling error according to the standard, and the drilling gradient and the hole depth are strictly monitored. If the size of the drilled hole does not meet the requirement of the anchor cable anchoring section, the design unit is required to be timely connected for processing.

And (3) anti-slide pile:

a. main piling: the diameter is 2.0m, the distance is 3.0m, and the embedding section is embedded into the complete weathered rock and is not less than 10.5 m. The diameter of the plain concrete pile is 1.5m, the distance is 3.0m, and the embedding and fixing section is embedded into the complete weathered rock and is not less than 2.0 m. The slide-resistant pile is cast by C30 concrete, if underwater casting is performed, the concrete needs to be improved by one grade, and the underwater concrete is used for casting. The pile top is provided with 2.0 multiplied by 1.2m crown beams which are connected, the anchor cable position is provided with 0.4 multiplied by 0.3m tie beams which are connected, and the crown beams and the tie beams are both cast by C30 concrete. Arranging phi 20 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welded joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint;

b. plain concrete pile: the diameter is 1.5m, the distance is 3.0m, and the embedding section is embedded into the complete weathered rock and is not less than 2.0 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top should be embedded into the crown beam.

Note that: important pipelines such as gas and water supply are arranged near the top of the slope, the anti-slide pile must jump to be excavated during construction, and pouring is required to be carried out in time after pore forming, and pouring is not forbidden for a long time. When constructing in soil layer, mud protecting wall or steel protecting cylinder should be used to prevent the hole wall from collapsing. The construction process should closely monitor the displacement of the important pipeline.

The fourth step is about 10.1m in height, and a supporting scheme of 'slide-resistant piles + anchor cables + inter-pile plates' is adopted. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Anchor cable design: 5 rows of prestressed anchor cables are arranged, the distance between the anchor cables at the lowest row and a slope toe is 1.0m, the vertical distance between the anchor cables at each row is 2.0m, and the horizontal distance is a pile distance. The anchor cable for the step slope adopts a 1860 type anchor cable with the diameter of 150mm and the diameter of 7 multiplied by 15.24 mm. The inclination angles of the anchor cables in each row are 20 degrees, the lengths of the anchoring sections are 5.0m, and the lengths of the anchoring sections should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, each anchor cable is 12 bundles. The design level prestress of the slope of this step: from top to bottom 240 kN.

M30 cement mortar is poured into the anchoring section, secondary grouting is adopted, the grouting pressure is preferably 0.6-3.0MPa, and the length of the sand setting section is 0.5M. The anchor cable body is provided with a positioning bracket every 1.5m, and each row of anchors is selected for the designed bundle number.

Note that: in the slope body of the side slope, a finished subway tunnel is arranged, the anchor cable is required to strictly control the drilling error according to the standard, and the drilling gradient and the hole depth are strictly monitored. If the size of the drilled hole does not meet the requirement of the anchor cable anchoring section, the design unit is required to be timely connected for processing.

And (3) anti-slide pile: the diameter is 2.0m, the distance is 3.0m, and the embedding section is embedded into the complete weathered rock to be not less than 6.0 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top is provided with 2.0 multiplied by 1.2m crown beams which are connected, the anchor cable position is provided with 0.4 multiplied by 0.3m tie beams which are connected, and the crown beams and the tie beams are both cast by C30 concrete. Arranging phi 20 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welding joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint.

And (3) a pile-to-pile plate: the thickness is 300mm, C30 concrete is adopted, and double layers of bidirectional phi 14@200 steel bars are distributed in the concrete.

And the fifth step adopts a supporting scheme of 'slide-resistant piles + anchor cables + inter-pile plates'. The slope surface and the slope toe are provided with drain holes, and the drain holes use drain pipes to introduce water into a building design drainage system. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Anchor cable design: 1-3 rows of prestressed anchor cables are arranged, the distance between the anchor cables in the uppermost row and the slope top is 1.9m, the vertical distance between the anchor cables in each row is 2.5m, and the horizontal distance is 3.0 m. The anchor cable for the step slope adopts a 1860 type anchor cable with the diameter of 150mm and the diameter of 7 multiplied by 15.24 mm. The inclination angles of the anchor cables in each row are 20 degrees, the lengths of the anchoring sections are 5.0m, and the lengths of the anchoring sections should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, 10 or 5 cables each). The design level prestress of the slope of this step: 560kN is arranged on the slide-resistant piles from top to bottom.

And (3) anti-slide pile: the diameter is 1.5m, the distance is 3.0m, and the embedding section is embedded into the complete weathered rock and is not less than 1.5 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top is provided with 2.0 multiplied by 1.2m crown beams which are connected, the anchor cable position is provided with 0.4 multiplied by 0.3m tie beams which are connected, and the crown beams and the tie beams are both cast by C30 concrete. Arranging phi 20 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welding joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint.

Note that: important pipelines such as gas and water supply are arranged near the top of the slope, and the lower part of the slope is adjacent to a concealed excavated No. 1 access escalator section, and construction is carried out by adopting manual hole digging piles. During construction, holes must be jumped and excavated, pouring is required in time after the holes are formed, and pouring is forbidden for a long time. The construction process should closely monitor the displacement of the important pipeline.

The sixth step adopts a supporting scheme of 'step-by-step slope releasing + net spraying + lattice anchor rod'. The slope surface and the slope toe are provided with drain holes, and the drain holes use drain pipes to introduce water into a building design drainage system. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Slope is divided into three steps: the height of the first step is 5.5m, and the slope ratio of the slope is 1: 2; the second-step height is 4m, and the slope ratio of slope releasing is 1: 1.75; the height of the third step is 20.2m, the slope ratio of the third step to the slope is 1:0.15, and a 2m wide berm platform is arranged at the step division position.

Hanging net and spraying concrete: the slope surface adopts a single-layer bidirectional reinforcing steel mesh, hangs phi 8@150 reinforcing steel bars, sprays C25 concrete and has the thickness of 100 mm; 30mm expansion joints are arranged every 20m, and asphalt hemp threads are filled in the expansion joints. The slope is provided with drain holes, the distance between the drain holes is 2 x 2m, the height of the drain hole at the lowest row from the slope toe is not more than 0.3m, and the drain holes are made of PVC drain pipes with the diameter of 110 mm.

The seventh step is supported by adopting a lattice, an anchor rod and a net spray:

lattice structure: the size of the cross section of the lattice is 400 multiplied by 400mm, and the horizontal and vertical spacing is 4 m; c30 concrete is used for pouring, and the lattice column base is embedded with weathered dolomite by 0.5 m.

Anchor rod: the horizontal and vertical spacing of the anchor rod is 2m, HRB400 grade phi 25 steel bar is adopted, and the length and arrangement of the anchor rod are detailed in the drawing. The length of the sand sediment section is 0.5 m. The diameter of the formed hole is 80mm, and the inclination angle is 20 degrees. Pouring M30 mortar, adopting secondary grouting, and controlling the grouting pressure to be 0.6-3.0 MPa; the anchor rods are provided with a positioning bracket every 1.5-2.0 m.

Hanging net and spraying concrete: the slope surface adopts double layers of bidirectional reinforcing steel meshes, hangs phi 8@150 reinforcing steel bars, sprays C25 concrete, and has the thickness of 120 mm; the reinforcing rib adopts a 1 phi 12 reinforcing steel bar and is welded with the anchor cable head. 30mm expansion joints are arranged every 20m, and asphalt hemp threads are filled in the expansion joints. The slope is provided with drain holes at the interval of 2 x 2m, the height of the drain hole at the lowest row from the slope toe is not more than 0.3m, the drain holes are made of PVC drain pipes with the diameter of 110mm, and the size is detailed in the drawing.

And the eighth step adopts a supporting scheme of 'occlusive slide-resistant piles + anchor cables'. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

And (3) anti-slide pile: a. main piling: the diameter is 2.5m, the distance is 3.5m, and the embedding section is embedded into the complete weathered rock and is not less than 9.0 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top is provided with 2.5 multiplied by 1.5m crown beams which are connected, and the crown beams are cast by C30 concrete. Arranging phi 28 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welding joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint.

b. Plain concrete pile: the diameter is 1.5m, the distance is 3.5m, and the embedding section is embedded into the complete weathered rock and is not less than 2.0 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top should be embedded into the crown beam.

Note that: the basement of No. 1 completed wind pavilion group is arranged in the slope body of the side slope, hole jumping and excavation are needed during construction of the anti-slide pile, pouring is needed in time after hole forming, and pouring is not forbidden for a long time. When constructing in soil layer, mud protecting wall or steel protecting cylinder should be used to prevent the hole wall from collapsing. The construction process should closely monitor No. 1 pavilion group basement displacement.

Anchor cable design: 8 rows of prestressed anchor cables are arranged, the distance between the anchor cables at the lowest row and a slope toe is 2.0m, the vertical distance between the anchor cables at each row is 2.5m, the horizontal distance between the anchor cables at each row is 3.5m, and the anchor cables are anchored on a main pile. The anchor cable adopts a 1860 type anchor cable with the diameter of 7 mm multiplied by 15.24mm, and the anchor hole diameter is 150 mm. Designing horizontal prestress: from top to bottom, the first to fourth rows are 480 kN; and 400kN in the fifth to eighth rows. . The number of anchor cables: from top to bottom, each row of anchor cables are 12 bundles, the inclination angle of the anchor cables is 30 degrees, the length of each anchoring section is 5.0m, and the length of each anchoring section should penetrate through the layer surface to be not less than 1.5 m. M30 cement mortar is poured into the anchoring section, secondary grouting is adopted, the grouting pressure is preferably 0.6-3.0MPa, and the length of the sand setting section is 0.5M. The anchor cable body is provided with a positioning bracket every 1.5m, and each row of anchors is selected for the designed bundle number.

Note that: an excavated No. 1 passageway escalator underground excavation tunnel is arranged in the slope body of the side slope, the anchor cable is required to strictly control the drilling error according to the standard, and the drilling gradient and the hole depth are strictly monitored. If the size of the drilled hole does not meet the requirement of the anchor cable anchoring section, the design unit is required to be timely connected for processing.

And the ninth step adopts a supporting scheme of 'occlusive slide-resistant piles + angle braces (15'). The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

And (3) anti-slide pile: a. main piling: the diameter is 2.5m, the distance is 3.5m, and the embedding section is embedded into the complete weathered rock and is not less than 20.0 m. The elevation of the anti-slide pile at the position of the ventilation shaft at the bottom of the ventilation shaft is 1034m, so that the anti-slide pile is embedded into the complete weathered rock at the position of not less than 20.0 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top is provided with 2.5 multiplied by 1.5m crown beams which are connected, and the crown beams are cast by C30 concrete. Arranging phi 28 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welding joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint.

And (3) corner bracing: the first concrete structure is arranged, and the lower three concrete structures are supported by section steel. The elevation of the first inclined strut is 1069.75 m; the elevation of the second inclined strut is 1063.3 m; the elevation of the third inclined strut is 1057.3 m; the elevation of the fourth inclined strut is 1051.3 m.

The vertical support of bracing adopts steel pipe concrete column, and steel pipe diameter 610mm, wall thickness 16mm, height 23.85m packs C30 concrete in the pipe. The concrete pouring process has the same requirements as those of the slide-resistant pile.

The concrete diagonal bracing is cast by C30 concrete, and the size of the concrete diagonal bracing is detailed in a big sample diagram;

the section steel support is a steel pipe support, the GC-1 adopts the combination of two phi 580 steel pipes, and the GC-2 adopts a single phi 610 steel pipe. The middle connecting rod adopts spliced double 22a channel steel. The waist rail is cast by C30 concrete, the section size is 0.8m high, 1.2m wide, the detailed drawing of reinforcement and plane setting. Gaps between the waist beam and the anti-slide piles and the waist beam are densely poured by C30 concrete.

The tenth step adopts a supporting scheme of 'step arrangement, anti-slide piles, anchor cables and inter-pile plates'. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

The tenth step is about 5.6m high, and a supporting scheme of 'slide-resistant piles + anchor cables + inter-pile plates' is adopted. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Anchor cable design: 2 rows of prestressed anchor cables are arranged, the distance between the anchor cables at the lowest row and a slope toe is 1.0m, the vertical distance between the anchor cables at each row is 3.0m, and the horizontal distance is a pile distance. The anchor cable adopts a 1860 type anchor cable with the diameter of 7 mm multiplied by 15.24mm, and the anchor hole diameter is 150 mm. The inclination angles of the anchor cables in each row are 30 degrees, the lengths of the anchor sections are 5.0m, and the anchor sections should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, each row of anchor cables are 6 bundles, the vertical distance is 3.0m, and the horizontal distance is equal to the pile distance. Designing horizontal prestress: the first row is 240kN from top to bottom; the second row is 320 kN.

And (3) anti-slide pile: the diameter is 1.5m, the distance is 3.0m, and the embedding section is embedded into the complete weathered rock and is not less than 3.0 m. The slide-resistant pile is cast by C30 concrete, if underwater casting is performed, the concrete needs to be improved by one grade, and the underwater concrete is used for casting. The pile top is provided with 1.5 multiplied by 1.0m crown beams which are connected, the anchor cable position is provided with 0.4 multiplied by 0.3m tie beams which are connected, and the crown beams and the tie beams are both cast by C30 concrete. Arranging phi 20 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welded joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint;

The height of the eleventh step is about 24.2m, and a supporting scheme of 'occlusive anti-slide piles and inclined struts' is adopted. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Anchor cable design: 8 rows of prestressed anchor cables are arranged, the distance between the lowest row of anchor cables and a slope toe is 0.5m, the vertical distance of each row of anchor cables is a detailed sectional view, the horizontal distance is the pile distance, and the anchor is anchored on a main pile. The anchor cable for the step slope adopts a 1860 type anchor cable with the diameter of 150mm and the diameter of 7 multiplied by 15.24 mm. The inclination angles of the anchor cables in each row are 30 degrees, the lengths of the anchor sections are 5.0m, and the anchor sections should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, each anchor cable is 12 bundles. Designing horizontal prestress: the first row is 200kN from top to bottom; the second row is 660 kN; the third row is 580 kN; the fourth row is 100 kN; the fifth row is 60 kN; the sixth row is 150 kN; 390kN in the seventh row; the eighth row is 480 kN.

Note that: the side slope of the section serves as the side slope opposite to the corner support of the D1-E section side slope, and one of the important functions of the anchor cable is to adjust the thrust on the corner support. The design value of the prestress of the side slope at the section is only a theoretical value calculated according to an investigation report, and the prestress tension value is controlled according to the displacement monitoring conditions arranged at two ends of each corner brace during actual construction and is dynamically adjusted according to the excavation process. The displacement of the corner brace at the side D1-E to the slope body is forbidden, and the displacement at the supporting point of the upright post is not more than 5 mm. The construction of the side slope anchor cable in the section has a special scheme, and detailed construction measures are provided for tensioning and supplementing the anchor cable.

And (3) anti-slide pile: a. main piling: the diameter is 2.2m, the distance is 3.0m, and the embedding section is embedded into the complete weathered rock and is not less than 10.0 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top is provided with 2.2 multiplied by 1.4m crown beams which are connected, and the crown beams are cast by C30 concrete. Arranging phi 28 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welding joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint.

The concrete diagonal bracing is cast by C30 concrete, the section steel bracing is supported by steel pipes, the GC-1 adopts the combination of two phi 580 steel pipes, and the GC-2 adopts a single phi 610 steel pipe. The middle connecting rod adopts spliced double 22a channel steel. The waist rail is cast by C30 concrete, the section size is 0.8m high, 1.2m wide, the detailed drawing of reinforcement and plane setting. Gaps between the waist beam and the anti-slide piles and the waist beam are densely poured by C30 concrete.

The twelfth step adopts a supporting scheme of 'slide-resistant piles, anchor cables and inter-pile plates'. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

The thirteenth step adopts a supporting scheme of 'slide-resistant piles + anchor cables + inter-pile plates'. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Anchor cable design: 9-12 rows of prestressed anchor cables are arranged, the distance between the lowest row of anchor cables and a slope toe is 1.0m, the vertical distance between each row of anchor cables is 2.5m, the horizontal distance is the pile distance, the diameter of an anchor hole is 150mm, and the angle of incidence of the anchor cables is 30 degrees. Each row of anchor cables are 1860 type 1 multiplied by 7 phi 15.2 anchor cables, the length of each anchoring section is 5.5m, and the length of each anchoring section should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, each row of anchor cables is 12 bundles. M30 cement mortar is poured into the anchoring section, secondary grouting is adopted, the grouting pressure is preferably 0.6-3.0MPa, and the length of the sand setting section is 0.5M. The anchor cable body is provided with a positioning bracket every 1.5m, and each row of anchors is selected for the designed bundle number.

And (3) anti-slide pile: the diameter is 2.0m, the distance is 3.0m, and the embedding section is embedded into the complete weathered rock to be not less than 7.5 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top is provided with 2.0 multiplied by 1.0m crown beams which are connected, the anchor cable position is provided with 0.4 multiplied by 0.3m tie beams which are connected, and the crown beams and the tie beams are both cast by C30 concrete. Arranging phi 28 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welding joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint. And (3) a pile-to-pile plate: the thickness is 300mm, C30 concrete is adopted, and double layers of bidirectional phi 14@200 steel bars are distributed in the concrete.

The fourteenth step adopts a supporting scheme of 'slide-resistant piles + anchor cables + inter-pile plates'. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Anchor cable design: 9 rows of prestressed anchor cables are arranged, the distance between the lowest row of anchor cables and a slope toe is 1.0m, the vertical distance between each row of anchor cables is 2.5m, the horizontal distance is the pile distance, the diameter of an anchor hole is 150mm, and the angle of incidence of the anchor cables is 30 degrees. Each row of anchor cables are 1860 type 1 multiplied by 7 phi 15.2 anchor cables, the length of the anchor anchoring section is 5.5m, and the length of the anchor anchoring section should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, each row of anchor cables is 13 bundles. M30 cement mortar is poured into the anchoring section, secondary grouting is adopted, the grouting pressure is preferably 0.6-3.0MPa, and the length of the sand setting section is 0.5M. The anchor cable body is provided with a positioning bracket every 1.5m, and each row of anchors is selected for the designed bundle number.

And the fifteenth step adopts a supporting scheme of 'slide-resistant piles + anchor cables + inter-pile plates'. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Anchor cable design: 9-11 rows of prestressed anchor cables are arranged, the distance between the lowest row of anchor cables and a slope toe is 1.0m, the vertical distance between each row of anchor cables is 2.5m, the horizontal distance is the pile distance, the diameter of an anchor hole is 150mm, and the angle of incidence of the anchor cables is 30 degrees. Each row of anchor cables are 1860 type 1 multiplied by 7 phi 15.2 anchor cables, the length of each anchoring section is 5.5m, and the length of each anchoring section should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, each row of anchor cables is 12 bundles. M30 cement mortar is poured into the anchoring section, secondary grouting is adopted, the grouting pressure is preferably 0.6-3.0MPa, and the length of the sand setting section is 0.5M. The anchor cable body is provided with a positioning bracket every 1.5m, and each row of anchors is selected for the designed bundle number.

The sixteenth step adopts a supporting scheme of 'slide-resistant piles + anchor cables + inter-pile plates'. The slope is provided with a water drainage hole, and the water drainage hole introduces water into a building design drainage system by using a drainage pipe. Drainage ditches are arranged at the toe and the top of the slope, slope engineering is constructed according to a reverse construction method, and over excavation is strictly forbidden.

Anchor cable design: 12 rows of prestressed anchor cables are arranged, the distance between the lowest row of anchor cables and a slope toe is 1.0m, the vertical distance between each row of anchor cables is 2.5m, the horizontal distance is the pile distance, the diameter of an anchor hole is 150mm, and the angle of incidence of the anchor cables is 30 degrees. Each row of anchor cables are 1860 type 1 multiplied by 7 phi 15.2 anchor cables, the length of each anchoring section is 5.5m, and the length of each anchoring section should penetrate through the layer surface to be not less than 1.5 m. The number of anchor cables: from top to bottom, each row of anchor cables are 12 bundles, and the axial pretensioning force is detailed in the drawing. M30 cement mortar is poured into the anchoring section, secondary grouting is adopted, the grouting pressure is preferably 0.6-3.0MPa, and the length of the sand setting section is 0.5M. The anchor cable body is provided with a positioning bracket every 1.5m, and each row of anchors is selected for the designed bundle number.

And (3) anti-slide pile: the diameter is 2.2m, the distance is 3.0m, and the embedding section is embedded into the complete weathered rock and is not less than 7.5 m. C30 concrete is poured, if underwater pouring is met, the concrete needs to be improved by one grade, and the underwater concrete is poured. The pile top is provided with 2.2 multiplied by 1.0m crown beams which are connected, the anchor cable position is provided with 0.4 multiplied by 0.3m tie beams which are connected, and the crown beams and the tie beams are both cast by C30 concrete. Arranging phi 28 reinforcing ribs at every 2m of the pile reinforcement cage, wherein the lapping length of the reinforcing ribs is 300mm, and welding one side of the reinforcing ribs; the longitudinal reinforced pile top is reserved and connected with the crown beam, the joint of the longitudinal stressed steel bar adopts a welding joint, and the area of the stressed steel bar with the joint is not more than 50% of the area of the steel bar with the section within the range of 35d of the joint. And (3) a pile-to-pile plate: the thickness is 300mm, C30 concrete is adopted, and double layers of bidirectional phi 14@200 steel bars are distributed in the concrete. During the anchoring process, the anchor cable accessories are protected, and the grouting pipe is smooth and intact after the anchor bundle body is pushed to a preset depth. If the grouting pipe is not communicated, the anchor cable body is pulled out, the anchor cable body is placed again after the anchor cable body is smoothly treated. And grouting at the anchoring section is performed by adopting one-time grouting. After the anchor cable is installed, the grouting is carried out by using SUB8.0A mortar pumps through a PVC grouting pipe which is bundled with the anchor cable and has the diameter of phi 20mm, and the grouting pressure is 0.25 MPa-0.8 MPa. In the grouting process, when the grouting is finished after the orifice grout returning specific gravity and the grouting slurry inlet specific gravity, the slurry inlet must be continuous.

Before tensioning, a tensioning jack and a pressure gauge which are to be put into use need to be calibrated in a matched mode, and a relation curve graph of oil gauge pressure and jack tension force is drawn. The calibration interval of the tensioning equipment and the instrument is controlled within 6 months, and the equipment and the instrument which exceed the calibration interval or are impacted strongly must be calibrated and then can be put into use. And (4) mounting an anchorage device and a jack, connecting a hydraulic system, carefully checking the operation condition of each system, and starting tensioning after no error is ensured. And cutting off the steel strand by using a grinding wheel cutting machine, and reserving 15cm outside the anchor device. And pouring a c20 concrete closed anchor head by using a butter protection anchor and an externally-reserved steel strand, wherein the concrete protection thickness is not less than 10 cm. An anchor cable anti-pulling test is required before the prestressed anchor cable construction. After the specific point selection and test device and related requirements are negotiated by design and supervision, the point selection and test device and the related requirements are executed according to related specifications.

Claims

1. A building foundation slope stepped supporting method is characterized in that: the method comprises the following steps:

step two: selecting a slope surface corresponding to one of the steps as a working slope surface, providing a drilling machine, a soil body drill bit, a rock body drill bit and a combined protective pipe (7), wherein the combined protective pipe (7) comprises an inner casing pipe and an outer casing pipe sleeved on the outer peripheral surface of the inner casing pipe, firstly installing the soil body drill bit on the drilling machine, starting the drilling machine to enable the soil body drill bit to drill through an upper soil body (1) of the working slope surface and obtain a front section hole (8), and then pressing the combined protective pipe (7) into the front section hole (8); then installing a rock mass drill bit on a drilling machine, starting the drilling machine to enable the rock mass drill bit to penetrate through the combined protective pipe (7) and then drill into a lower rock mass (2) of the working slope surface, obtaining a rear section hole (9), and enabling the front section hole (8) and the rear section hole (9) to be communicated to form an anchor hole;

step four: providing a plurality of anchorage devices (3), wherein each anchorage device (3) comprises a plurality of anchor cables bundled together in parallel, inserting one end of each anchorage device (3) into the anchor hole in the third step one by one, enabling the other end of each anchorage device (3) to extend out of the working slope surface, pouring concrete into a gap between each anchorage device (3) and the anchor hole, and forming an anti-slide pile (4) with the anchorage device (3) after the concrete is solidified;

step five: arranging a plurality of steel bars on the tops of the anti-slide piles (4) in the fourth step, connecting all the anti-slide piles (4) together, then pouring concrete to cover all the steel bars, forming an inter-pile plate (5) with the steel bars after the concrete is solidified, and forming a composite slope protection unit by the inter-pile plate (5) and the anti-slide piles (4);

2. The method for supporting a building foundation side slope in different steps according to claim 1, wherein: in the second step, the inclination angle of the central axis of the anchor hole relative to the horizontal plane is 20 degrees.

3. The method for supporting a building foundation side slope in different steps according to claim 1, wherein: and in the second step, the aperture of the anchor hole is not less than 150 mm.

4. The method for supporting a building foundation side slope in different steps according to claim 1, wherein: in the fourth step, the anchor cable is made of steel strands with nominal diameter of 15-20 mm.

5. The method for supporting a building foundation side slope in different steps according to claim 1, wherein: the concrete strength grade is not lower than C30.

6. The method for supporting a building foundation side slope in different steps according to claim 1, wherein: and fifthly, the nominal diameter of the steel bars in the inter-pile plate (5) is not less than 14mm, and the steel bars are arranged in two layers along at least two directions.

7. The method for supporting a building foundation side slope in different steps according to claim 1, wherein: and fifthly, the thickness of the inter-pile plate (5) is not less than 300 mm.

8. The method for supporting a building foundation side slope in different steps according to claim 1, wherein: in the second step, the depth of the rear section hole (9) is 1.5m to 6 m.

9. The method for supporting a building foundation side slope in different steps according to claim 1, wherein: along the sequence from top to bottom, the number of the anti-slide piles (4) constructed on the slope surface of the side slope corresponding to each step is gradually reduced.

10. The method for supporting a building foundation side slope in different steps according to claim 1, wherein: along the sequence from top to bottom, the number of the anchorage devices (3) contained in the anti-slide piles (4) constructed on the slope surface of the side slope corresponding to each step is gradually reduced.