CN108035335B - Method for constructing shaft type underground parking garage by freezing method - Google Patents

Method for constructing shaft type underground parking garage by freezing method Download PDF

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Publication number
CN108035335B
CN108035335B CN201711370230.7A CN201711370230A CN108035335B CN 108035335 B CN108035335 B CN 108035335B CN 201711370230 A CN201711370230 A CN 201711370230A CN 108035335 B CN108035335 B CN 108035335B
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shaft
freezing
grouting
construction
monitoring
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CN201711370230.7A
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Chinese (zh)
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CN108035335A (en
Inventor
程志彬
袁兆宽
王鹏越
王申
张步俊
张坤
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中煤第五建设有限公司
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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D3/00Improving or preserving soil or rock, e.g. preserving permafrost soil
    • E02D3/11Improving or preserving soil or rock, e.g. preserving permafrost soil by thermal, electrical or electro-chemical means
    • E02D3/115Improving or preserving soil or rock, e.g. preserving permafrost soil by thermal, electrical or electro-chemical means by freezing
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D29/00Independent underground or underwater structures; Retaining walls
    • E02D29/04Making large underground spaces, e.g. for underground plants, e.g. stations of underground railways; Construction or layout thereof

Abstract

The invention discloses a construction method for constructing a shaft type underground garage by a freezing method. Before constructing a shaft, freezing a water-containing stratum around the shaft by using an artificial freezing method to form a frozen wall which has temporary bearing and water-resisting functions and meets the safety requirement of engineering construction, and then performing shaft digging and building operation under the protection of the frozen wall; the freezing wall is formed by mutually matching and complementing an inner ring freezing hole and an outer ring freezing hole; constructing a cap beam at the top of the shaft; then, carrying out digging construction on the outer wall of the shaft, pouring concrete on a bottom plate of the shaft and constructing the inner wall of the shaft in sequence; and after the shaft is stopped from freezing, filling and grouting after lining and formation melting and sinking compensation grouting.

Description

Method for constructing shaft type underground parking garage by freezing method

Technical Field

The invention relates to the technical field of shaft type underground parking garage construction, in particular to a method for constructing a shaft type underground parking garage by a freezing method.

Background

At present, at a position 1 of a shaft type underground garage which is built and operated in China, at positions 3-4 of the shaft type underground garage which is built, a city for building the shaft type underground garage comprises a plurality of cities such as Harbin, Beijing, Tianjin, Guangzhou and the like. The well shaft type underground garage which is built or built is constructed by adopting an open caisson method or an underground continuous wall method, no freezing method construction precedent exists, and the freezing method construction has certain application and popularization values.

The artificial stratum freezing method is suitable for not only loose and unstable flushing layers and water-bearing rock layers with developed cracks, but also silt, soft mudstone, saturated water-bearing strata and strata with particularly high water head, and has the main functions of sealing water and increasing the bearing capacity of the strata.

The freezing method is a construction method which freezes a water-bearing stratum around a structure by an artificial freezing method before the underground structure is constructed to form a frozen wall which has temporary bearing and water-resisting functions and meets the safety requirements of engineering construction, and then performs construction building operation under the protection of the frozen wall. The method has the characteristics of reliable technology, mature process and controllable construction, and is widely applied to engineering such as subway, deep foundation pit, mine construction and the like.

Freezing method construction process. Before shaft excavation, freezing holes are constructed downwards at equal intervals on a concentric circumference at a certain distance from the ground along the periphery of the shaft, the bottom of each hole penetrates into a waterproof layer, then a freezing pipe is sunk into each freezing hole, the freezing pipes are made of seamless steel pipes, and the lower ends of the freezing pipes are closed; a refrigerating station is installed on the ground, a Freon refrigerant is adopted to cool a refrigerant agent calcium chloride solution to-22 to-30 ℃, and then a circulating pump and a polyethylene liquid supply pipe inserted into the freezing pipe are adopted to send salt water into the freezing pipe. The heat of the stratum outside the pipe is continuously absorbed for a long time by low-temperature saline water, so that the surrounding stratum is frozen. The brine absorbs heat from the formation and rises in temperature, returns to the refrigeration equipment through a brine loop pipe, and is cooled again by contact with the refrigerant. The original liquid refrigerant absorbs the heat of brine when evaporating under the condition of decompression, and then is liquefied through compression and condensation, and the refrigeration cycle is continuously performed. The frozen soil cylinders are formed around each freezing pipe, and the cylinders are mutually connected into a dense and closed frozen soil curtain wall which can bear water and soil pressure and block underground water, and under the protection of the frozen soil curtain wall, the stratum is excavated and the lining is built.

The circulation system of the frozen salt water of the artificial frozen soil is shown in figure 1. Flow of a brine circulating system: liquid refrigerant in the refrigeration equipment is vaporized in an evaporator 1, heat of saline solution in a saline tank 2 is absorbed, cooled low-temperature saline water is subjected to saline circulation through a liquid distribution ring 4, saline water discharged by a saline pump 3 enters the liquid distribution ring 4, liquid is supplied to a freezing pipe 5 through the liquid distribution ring 4, the low-temperature saline water continuously absorbs heat of a peripheral stratum of the freezing pipe 5 for a long time, the stratum around a shaft is frozen, the circulating saline water enters the refrigeration equipment 1 through a liquid collection ring 6 for cooling, and the circulation is continuous.

When the freezing method is adopted for construction, the thickness of the frozen soil wall and the arrangement mode of the freezing holes are determined according to the stratum property, the stratum burial depth, the characteristics of a shaft, the digging construction progress, the strength required by the frozen soil wall and the like, freezing equipment is reasonably selected, and a frozen soil wall prediction and forecast regulation mechanism is implemented. And simultaneously, researching frost heaving during stratum freezing and thawing characteristics during thawing, and making a determination method and a measure.

The common open caisson method has the characteristics that: 1) the method is suitable for structures with shallow surface soil layers, and the sinking depth is limited. The surface soil layer depth is within 30m and the water pressure is not big. 2) There must be a stable formation at the bottom of the open caisson, otherwise the edge cannot be closed. 3) The soil layer penetrated by the open caisson does not contain large gravels, and the well wall is easy to block the well wall to slow down or stop sinking if meeting the large gravels in the pebble construction. 4) The pit shaft can produce great slope because of multiple reasons in the open caisson construction process, and the inhomogeneous crack phenomenon that easily produces of wall of a well atress if be used for promoting can influence the use.

The underground continuous wall method has the characteristics that: 1) under some special geological conditions (such as very soft mucky soil, alluvial deposit containing boulder, super-hard rock and the like), the construction difficulty is very high. 2) If the construction method is improper or the construction geological conditions are special, water leakage can be caused because the adjacent wall sections cannot be closed. 3) The underground diaphragm wall, if used as a temporary retaining structure, is more expensive than other methods.

Disclosure of Invention

The patent provides a method for constructing a shaft type underground garage by a freezing method, wherein a circular shaft is built underground by utilizing the freezing method and a modern mine well construction technology (a digging and building method and a wall back grouting method), and an elevator type intelligent tower type stereo garage system which is widely applied at home and abroad at present is installed in the shaft for operation.

The invention is realized by the following technical scheme: a freezing method construction shaft cylinder type underground parking garage method sequentially utilizes freezing method construction, digging construction, filling grouting and melting and sinking grouting, a round shaft is built underground, an elevator type intelligent tower type stereo garage system applied at home and abroad at present is installed in the shaft to operate, and shaft construction is as follows:

1) freezing method construction: before constructing a shaft, freezing a water-containing stratum around the shaft by using an artificial freezing method to form a frozen wall which has temporary bearing and water-resisting functions and meets the safety requirement of engineering construction, and then performing shaft digging and building operation under the protection of the frozen wall; the freezing wall is formed by mutually matching and complementing an inner ring freezing hole and an outer ring freezing hole;

2) digging and building operation: constructing a cap beam at the top of the shaft; then, carrying out digging construction on the outer wall of the shaft, pouring concrete on a shaft bottom plate and constructing the inner wall of the shaft in sequence;

3) filling grouting and melting and sinking grouting: and after the shaft is stopped from freezing, filling and grouting after lining and formation melting and sinking compensation grouting.

Preferably, the thickness of the freezing wall is 3-4 m, the inner ring freezing holes are used as reinforcing freezing holes, and the depth of the inner ring freezing holes penetrates through a shaft to be excavated by 3-5 m; the outer ring freezing hole falls on the impermeable clay layer or the bedrock with good water sealing performance, if the punching layer is deep, the depth of the outer ring freezing hole is 2 times of the shaft excavation depth and falls on the impermeable clay layer, if the upper part of the stratum is surface soil and the lower part of the stratum is bedrock, the depth of the outer ring freezing hole is more than 10m deep into the impermeable bedrock and more than 7m higher than the shaft excavation depth.

Preferably, the diameter of the freezing holes of the inner ring is controlled to be about 1.0m from the arrangement of the rings to the excavating and bricking rough diameter, and the hole opening distance of the freezing holes is 1.2-1.3 m; the distance between the holes of the outer ring freezing holes is 1.4-1.5 m.

Preferably, cap beam construction: after freezing and meeting the excavation condition, excavating the cap beam by adopting an island method, firstly excavating earthwork in 2 symmetrical regions on the periphery, clearing out a cast-in-place pile, then binding reinforcing steel bars and pouring concrete by using a vertical mold, reserving L-shaped reinforcing steel bars on the terrace of the cap beam, and pouring the cap beam and the outer wall of the shaft into a whole;

digging and building the outer wall of the shaft: the outer wall of the shaft is dug and built in a construction mode of layered and partitioned excavation and partitioned concrete pouring;

pouring concrete on the shaft bottom plate: after the outer wall of the shaft is dug to the bottom, bottom reinforced concrete is paved on the bottom plate;

construction of the inner wall of the shaft: the inner wall of the shaft is constructed by one-time wall sleeving from bottom to top by adopting a metal assembled template.

Preferably, filling and grouting after lining: filling grouting after lining is carried out within 3-7 days after freezing is stopped, and by using the pre-buried grouting pipe, the strength of lining concrete reaches more than 60% of the designed strength during grouting, and the method adopts the following steps of: 1-1: 1, injecting single-liquid cement paste, wherein before the cement paste is injected, clear water is injected, whether gaps among grouting holes are unblocked after lining is checked, the grouting is performed in a descending order, and when the grouting holes in the upper layer continuously return the grout, the grouting in the lower layer can be stopped until the grouting is finished at the top of a shaft;

stratum melting and sinking compensation grouting: performing thaw settlement grouting in a natural thawing mode, and after filling grouting is finished, performing thaw settlement compensation grouting when the ground settlement of the upper part of the shaft is more than 0.5mm or the accumulated ground settlement of the upper part of the shaft is more than 3mm in one day; grouting should be suspended when the ground at the upper part of the shaft rises for 3 mm.

Preferably, temperature measuring holes are uniformly distributed in four directions of the shaft, and a sensor is longitudinally arranged in each temperature measuring hole about 10 m; at least 1 hydrological hole is designed in the well bore.

Preferably, in the freezing method construction process, freezing hole monitoring, freezing system monitoring and surrounding environment influence monitoring are implemented,

the freezing hole monitoring comprises the steps of freezing hole opening position monitoring, hole forming deflection monitoring, freezing hole pressure resistance test monitoring, freezing hole length monitoring and liquid supply pipe lowering length monitoring;

the freezing system monitoring comprises de-loop brine temperature monitoring, freezer brine flow detection, temperature measuring hole temperature monitoring and brine tank liquid level monitoring;

the monitoring of the surrounding environment influence comprises the monitoring of the frost heaving and thawing sinking deformation of the surface of the earth and the monitoring of the vertical displacement of the deep soil body.

Compared with the existing open caisson method and underground continuous wall method, the invention has the advantages that:

1. the construction depth is not limited, the application range is wide, and the method is suitable for not only loose and unstable flushing layers and water-bearing rock layers with developed cracks, but also silt, quicksand, soft mudstone, saturated water-bearing strata and strata with particularly high water head.

2. The safety and reliability are good, underground water can be effectively isolated, and the construction quality of the shaft and the wall of the well is high.

3. The drilling construction slurry is less in use, and the waste slurry treatment is easier to treat compared with the underground continuous wall method.

4. Construction controllability is good, and the thickness and the strength of the frozen wall can be effectively controlled.

5. The construction period is guaranteed.

6. The frozen wall has high strength. The strength of the frozen wall is far greater than that of the melted soil, and the effect of a structural support wall is achieved.

7. The pollution is small. Has no pollution to the stratum, and belongs to a green construction method.

Drawings

FIG. 1 is a diagram of a frozen brine cycle for refrigerating artificial frozen soil;

FIG. 2 is a schematic plan view of a borehole;

FIG. 3 is a schematic view of a borehole cross-sectional arrangement;

FIG. 4 is a plan view of the wellbore excavation equipment;

FIG. 5 is a sequence diagram of excavation of a foundation pit;

FIG. 6 is a flow chart of a course zoning primary lining process;

1. the system comprises an evaporator, 2, a brine tank, 3, a brine pump, 4, a liquid distribution ring, 5, a freezing pipe, 6, a liquid collection ring, 7, a well barrel inner wall, 8, a well barrel outer wall, 9, an inner ring freezing hole, 10, an outer ring freezing hole, 11, a temperature measuring hole, 12, a hydrological hole, 13 and a well barrel bottom plate.

Detailed description of the invention

A method for constructing shaft-type underground garage by freezing method features that a circular shaft is built underground by freezing method and modern mine well-building technique (excavating and building method and grouting method), and the elevator-type intelligent tower-type stereo garage system widely used at home and abroad is installed in said shaft.

The method is characterized in that a reinforced concrete structure (500 mm of outer wall and 600mm of inner wall) is designed on the wall of the garage, the diameter of the structure is 17-20 m, the depth of the structure is 50-80 m, the height of each layer is 1.8m, and the bottom of a shaft is sealed by reinforced concrete.

One, freezing method construction

The freeze hole arrangement is shown in fig. 2 and 3. Designing and arranging a comprehensive construction scheme for co-operation of two circles of freezing holes. The two circles of freezing holes are mutually matched and supplemented to form a freezing wall group with high strength and high compactness. The outer ring freezing holes 10 are used as main freezing holes, so that the phenomena of bottom bulging, water inrush, sand gushing and the like during shaft excavation can be prevented; the inner ring freezing holes 9 are used as auxiliary freezing holes, so that the thickness and the strength of the frozen wall of the punching layer of the excavation section are ensured, the stability of the frozen wall is improved, and the rib spalling is prevented. The scheme can ensure that the thickness and the strength of the frozen wall formed within a preset time meet the design requirements, and ensure safe and continuous construction of a shaft.

1. Determination of freezing depth

The inner ring freezing holes are used as reinforcing freezing holes, and the depth of the inner ring freezing holes penetrates through a shaft to be excavated by 3-5 m.

The outer ring freezing hole falls in a water-tight clay layer (or bedrock with good water sealing property). And finally determining the depth of the outer ring freezing pipe through checking calculations such as overall stability, uplift resistance stability of soil at the bottom of the well, pressure-bearing water resistance stability, seepage resistance or piping resistance stability, overturning resistance stability and the like. If the erosion layer is deep, the freezing depth of the outer ring is generally 2 times of the excavation depth of the shaft and the outer ring falls on the impermeable clay layer; if the upper part of the stratum is surface soil and the lower part is bedrock, the freezing depth of the outer ring generally extends into the impervious bedrock by more than 10m and exceeds the excavation depth of the shaft by more than 7 m.

2. Basic design parameters of frozen wall

1) The lowest temperature of the saline water in the freezing period is-28 to-30 ℃;

2) taking the average freezing wall temperature T as-10 ℃;

3) permafrost strength of sandy soil layer: in the absence of frozen soilIn the case of data verification, its intensity (K)1) The instantaneous ultimate compressive strength (σ c) is divided by a safety factor (m 0). The instantaneous ultimate compressive strength refers to 'brief well construction engineering handbook', and when the average temperature of a frozen wall is-10 ℃, a sand layer is formed: 13.8 MPa; sand and soil: 12.5 MPa; clay: 5.4 MPa. The safety coefficient is 2.0-2.2 for the sandy soil layer m0 and 2.3-2.5 for the viscous soil layer.

4) And controlling the calculated earth pressure value of the stratum according to a fourth system.

3. Frozen wall thickness design

According to the thick-walled cylinder theory (the wall thickness/inner radius is more than or equal to 0.1), the frozen wall of the sandy soil layer is regarded as an infinitely long elastic thick-walled cylinder. And calculating the thickness of the frozen wall by adopting an infinite length thick-wall cylinder elastic theory Lamivian formula. The required thickness of the frozen wall is generally 3.0-4.0 m.

4. Safety driving section college nucleus

For the sake of construction safety, the control horizon at the lower part of the shaft is regarded as a clay soil layer, and the stability of the frozen wall is calculated according to the Villoff-Zalett-based finite long plastic thick-wall cylinder formula. The height of the safe tunneling section is within the range of 3.68-4.56 m, so that the tunneling section is safely controlled within 3.0 m.

5. Borehole layout design

The design of the drill hole arrangement fully considers the factors of the thickness of the frozen wall required by the control of the stratum, the development condition of the outer frozen wall, the radial deviation value of the drill hole and the like.

According to the development speed of frozen soil and the freezing time of a shaft with excavation conditions, the diameter from the arrangement of the inner ring hole to the excavation and bricking rough diameter is preferably controlled to be about 1.0 m. The hole opening distance of the freezing holes is 1.2-1.3 m; the distance between the holes of the outer ring freezing holes is 1.4-1.5 m.

In order to accurately master the development and change conditions of a freezing wall temperature field and strengthen informatization construction, temperature measuring holes 11 are distributed in four directions of a shaft, and a sensor is longitudinally arranged in each temperature measuring hole about 10 m.

At least 1 hydrological hole 12 is designed for accurately reporting the wall crossing condition of the fourth series of strata.

6. Shaft excavation conditions

1) The water level of the hydrological hole rises regularly and rises stably, or the water level overflows from the pipe orifice and the overflow quantity conforms to the frost heaving water release rule;

2) according to the analysis of temperature measurement data, the shallow part of the shaft is not provided with a rib, the thickness and the strength of the frozen walls of different depths and different soil layers meet the design regulations, and the requirement of continuous digging construction is met.

7. Construction monitoring

1) Freeze hole monitoring

In order to ensure the construction quality of the freezing hole, the freezing hole construction detection is required during drilling, and the freezing hole construction detection comprises the steps of freezing hole opening position monitoring, hole forming deflection monitoring, freezing hole pressure resistance test monitoring, freezing hole length monitoring and liquid supply pipe lowering length monitoring.

2) Freezing system monitoring

In order to ensure the freezing effect during the freezing period of refrigeration, the following detection should be made: the method comprises the following steps of loop-removing brine temperature monitoring, freezer brine flow detection, temperature monitoring of a temperature measuring hole, brine tank liquid level monitoring and the like.

3) Ambient impact monitoring

In order to protect the surrounding environment and pipelines below the ground, the following monitoring is required to be made in the freezing and reinforcing construction process and the final melting and sinking grouting process: monitoring the frost heaving and thaw collapse deformation of the earth surface and monitoring the vertical displacement of the deep soil body.

Monitoring frequency and planning: monitoring points are distributed 5 days before construction, the original values of the monitoring points are measured 3 days before construction, and the original data of each monitoring is submitted 1 day before construction. 1 time per day during drilling; freezing for 1 time every 3 days; 2 times a day during excavation; during the melting and depositing grouting period, the monitoring data can be properly adjusted according to the change condition of the monitoring data, and the monitoring is finished after the stratum is stabilized through tracking monitoring. And formally starting monitoring during the construction of the freezing hole, and stopping monitoring when various settlement values are stable after the completion of the melting, settling and grouting.

Second, construction scheme of bored pile

In order to fix the shaft outer wall template, a cast-in-situ bored pile is constructed before the construction of the freezing hole. The inner edge of the bored pile is located at the position of the rough diameter of digging and building, the diameter of the pile is 400mm, the length of the pile is determined according to the depth of surface soil, each template is fixed by using 2 bored piles, the bored pile is positively and circularly formed by adopting a rotary drilling machine, the wall is protected by high-quality slurry, the hole is cleaned by a high-quality slurry changing method, a reinforcing cage is arranged on the drilling machine or a grouting tower, and the grouting tower and a guide pipe are underwater poured with concrete to form the pile.

Third, digging and building construction

1. Sequence of construction

In order to prevent the outer wall of the shaft from sinking, a cap beam is firstly constructed at the top of the shaft; and then sequentially carrying out digging construction on the outer wall of the shaft, pouring concrete on a bottom plate of the shaft and constructing the inner wall of the shaft.

2. Cap beam construction

After the freezing condition is met, the cap beam earthwork is symmetrically excavated by 2 back-shovels.

The engineering quantity is 3m, the position of the upper opening plus 1.0m (relative elevation) of the cap beam, the elevation of the lower opening is minus 2.0m (relative elevation), and the width of the cap beam is 0.8 m. The excavation sequence of each area is determined according to the construction sequence of the high outer wall subsection of the area. The excavation is carried out by adopting an island method, earthwork in 2 symmetrical areas with the periphery of 6.18m multiplied by 4m multiplied by 3m (length multiplied by width multiplied by height) is excavated, cast-in-place piles are removed, and then steel bars are bound and concrete is poured by a vertical mold. The top beam is formed by casting a top-beam-shaped steel bar on the ground of the top beam and the outer wall of the shaft. Each template is an integral metal template with the arc length of 7.18m and the height of 3 m. During construction of each area, the metal formwork is fixed in a pull rod type connecting and fixing mode of anchor rods with the same strength of phi 25mm and cast-in-place piles. Commercial concrete is pumped into a mould through a concrete conveying pump, and is vibrated in layers by adopting a vibrating spear.

3. Shaft outer wall 8 digging construction

1) Construction scheme

The outer wall of the shaft is dug and built in a layered and partitioned mode of excavating and pouring concrete in a partitioned mode. And (3) symmetrically dividing the areas into 12 areas for soil excavation and concrete pouring, wherein each area is 3m high in a layered excavation section. During construction of each area, the metal formwork is fixed in a pull rod type connecting and fixing mode of anchor rods with the same strength of phi 25mm and cast-in-place piles. Each area is uniformly provided with 6 fixed points. And then concrete is poured.

2) Shaft excavation

In the shaft excavation process, a foundation pit dewatering measure is adopted, the free water level line in the pit after dewatering is lowered to 2m of the excavation surface of the foundation pit, and the excavation environment in each layer of foundation pit is kept relatively dry.

2 crawler cranes with lifting capacity of 100T are selected for lifting and are matched for 10m3The collecting hopper is used as an earthwork vertical delivery machine. And when the foundation pit is excavated, the distance between the edge of the crawler belt and the excavation edge of the foundation pit is controlled to be not less than 5 m. In addition, 1 QTZ40 tower crane is arranged around the foundation pit and 10m away from the edge of the foundation pit and is used as auxiliary materials such as reinforcing steel bars and templates and small-sized machines and tools to be put down. The plan position of the shaft excavation equipment is shown in figure 4.

2R 170LC-5 (bucket capacity 0.65m3) excavators are selected as 2 collecting buckets with the length of 10m3 to load soil and the middle part of the foundation pit is transferred to a soil grabbing area. 1R 80-7 (bucket capacity 0.28m3) excavator is used for brushing and leveling.

And after the construction of the cap beam of the foundation pit is finished, when the concrete reaches 70% of the design strength, excavating earthwork in the central island, carrying out second layered construction, and circulating the steps until the bottom plate of the foundation pit is reached, wherein the foundation pit is excavated from top to bottom according to the steps. The excavation sequence of the foundation pit is shown in figure 5.

The process flow of the layer partition primary lining is shown in figure 6.

Shaft excavation is strictly carried out according to design layering and partitioning, construction thickness of each layer is 3m, excavation is carried out in a partitioning mode on a plane of each layer, and earth excavation is carried out symmetrically through an excavator. The shaft excavation adopts the island formula method, and the slope excavation is put to make middle part region earthwork play the temporary ballast effect, guarantee shaft supporting construction atress safety.

Firstly, excavating the earthwork in the middle of the shaft, and when the earthwork in the middle of the shaft is excavated to the upper plane of the section of height, the excavation work is switched to the regional symmetrical excavation within the section of height. Brushing the upper after the soil layer of one digging and building section is basically dug. And excavating the frozen soil part by adopting a manual matching pneumatic pick, trimming to a designed excavation line, loading the soil to a lifting hopper by adopting an excavator, lifting the soil out of a pit, and leveling a bottom working surface.

3) Tie bar and vertical mould

After leveling and alignment by using a sideline and a level, carrying out blade foot positioning, steel bar binding and mold erecting. Firstly, various reinforcing steel bars are sequentially put into a place needing to be used in a foundation pit by a tower crane, and constructors strictly bind the reinforcing steel bars according to design and standard requirements. The vertical ribs are connected by straight threads, and the annular ribs are connected by lap joints.

Each area is provided with a set of template, an integral blade is arranged under the template, the blade is provided with a 30-degree slope, and the blade is favorable for the treatment of template erecting, concrete pouring, steel bar lapping and template connecting. The template and the blade foot vertical mold are carried out in a subarea mode, and after concrete is finally solidified, the mold is removed; and then moving to other areas, and repeatedly performing vertical mold pouring concrete. And (5) performing reciprocating circulation until the construction is finished.

The working surface of the vertical mould is firstly leveled before the vertical mould is erected, the height of the construction section is well controlled, and the construction blade foot is firstly leveled. And hoisting the template and the blade foot by using a tower crane and a crawler crane, and controlling the size of the template and fixing by using side line measurement. The template and the blade foot adopt a pull rod type connection and fixation mode of an anchor rod with the same strength of phi 25mm and the like and a cast-in-place pile, an upper layer pull rod, a middle layer pull rod and a lower layer pull rod are arranged at each section of the template and the blade foot, and 6 fixed points are uniformly arranged in each area.

4) Pouring concrete

12 excavation areas of the foundation pit are all provided with one time of ash sliding pipes, the ash sliding pipes are seamless steel pipes with the diameter of phi 159 multiplied by 6mm, and each time of the ash sliding pipes is provided with an anti-segregation device every 2 m. The ash sliding pipe is hung and fixed on the concrete on the outer wall of the foundation pit.

Concrete is provided by a commercial concrete station, the concrete is put down by a chute, passes through a phi 159 multiplied by 6mm ash chute and a buffer device, and enters a mould through a 8-inch steel wire spring rubber hose. Before pouring, the steel wire spring rubber hose must be in butt joint with the bent pipe on the template joint window.

The template is provided with an operation scaffold and a turnover extrusion type ash-bearing stubble-closing window, so that the close stubble is ensured to be tight and flat, and the concrete is symmetrically, uniformly, hierarchically poured and vibrated in a layered mode. The in-mold concrete is compacted by adopting an inserted electric vibrating rod to ensure the construction quality of the lining.

4. Shaft inner wall 7 construction scheme

1) Construction scheme

After the outer wall of the shaft is dug and laid to the bottom, the shaft bottom plate 13 is paved with bottom reinforced concrete, and then the inner wall construction is carried out. The inner wall adopts a 1.2m metal assembled template and a well ring back plate mode, and the well ring is processed by 20 channel steel, and the specification of a steel mould is 1200mm multiplied by 1000 mm. And putting the commercial concrete into a mould through an ash sliding pipe. And when pouring concrete, erecting a scaffold on the whole working surface from bottom to top as an operation platform.

2) Inner wall built

And the concrete of the bottom plate and the concrete of the inner wall of the shaft are provided with water stop steel plates, so that the waterproof performance of the foundation pit is ensured, and the sealing performance of the shaft is ensured.

After the bottom plate of the shaft is paved, a PVC waterproof plate with the thickness of delta 3mm is paved, outer-layer steel bars are bound from bottom to top, the vertical steel bars are connected by straight threads, and the annular steel bars are connected by steel bar lap joints; binding the steel bars by binding the vertical bars and then binding the ring bars; then binding the inner layer steel bar. The binding of the reinforcing steel bars should be horizontal, vertical and evenly distributed. And assembling the metal assembled template at a certain height by tying the ribs, correcting, pouring concrete, continuously tying the ribs upwards, assembling a second template on the first template for correcting, pouring the concrete, and the like. And reinforcing the assembled template by using a scaffold. The method comprises the steps of feeding by adopting an ash sliding pipe, pouring in layers and vibrating in layers, wherein the pouring height is about 300mm each time, and the mold-entering concrete is densely vibrated by adopting an inserted electric vibrating rod.

The characteristics of inner wall construction: the concrete is continuously built from bottom to top, no construction joint is realized, and the water-resisting performance of the inner wall is favorably improved. In order to ensure the quality of the inner wall concrete, the concrete mixing proportion, the slump and the mold-entering temperature must be strictly controlled when the inner wall is laid in a sleeving manner. If unexpected shutdown occurs, the construction joint is processed according to the requirements of construction specifications; and the well wall is protected by sprinkling water in time, so that the phenomenon of well wall cracks caused by temperature stress is prevented.

Fourth, filling grouting and melting and sinking grouting

1) Filling and grouting after lining;

and (5) after freezing is stopped, filling and grouting after lining is carried out within 3-7 days. By using the pre-embedded grouting pipe, the strength of the lining concrete during grouting can reach more than 60% of the designed strength. The following components were used: 1-1: 1 single-fluid cement slurry. Before the cement paste is injected, clear water is injected, and whether gaps among the grouting holes are smooth after lining is checked. The grouting is preferably carried out from bottom to top, and the next layer of grouting can be stopped after the grouting hole in the previous layer continuously returns to the top of the shaft until the grouting is finished.

2) Formation thaw-precipitation compensation grouting

The melting and depositing grouting pipe is pre-buried when the shaft structure is constructed. The pre-buried depth of the grouting pipe should penetrate through the primary support layer, and the hole distribution density is 2-4 m2A/one.

And after filling and grouting, performing freeze wall thaw collapse compensation grouting according to the stratum monitoring condition. And performing thaw settlement compensation grouting through a pre-buried grouting pipe, a ground vertical grouting hole and a freezing pipe. The construction method adopts a natural thawing mode to carry out the thaw collapse grouting.

The purpose of grouting is to control the ground settlement deformation. Therefore, during the defrosting process, ground deformation monitoring, frozen soil temperature monitoring and water and soil pressure monitoring after wall freezing are enhanced. In addition, in the grouting construction process, the pressure of grout can be reflected by installing pressure gauges on adjacent grouting holes. The comprehensive monitoring data is the basis for adjusting the grouting parameters.

After filling and grouting, performing thaw settlement compensation grouting when the ground settlement of the upper part of the shaft is more than 0.5mm or the accumulated ground settlement of the upper part of the shaft is more than 3mm in one day; grouting should be suspended when the ground at the upper part of the shaft rises for 3 mm. And particularly, the ground deformation monitoring condition is properly adjusted.

The completion of the melt-down grouting is based on the stability of ground settlement deformation. And if the frozen wall is completely melted and the stratum is actually measured to subside under the condition of no grouting, and the thickness is not more than 0.5mm every half month after one month, stopping the thawing and subsiding compensation grouting.

Claims (6)

1. A freezing method construction shaft cylinder type underground parking garage method is characterized in that: a circular shaft is built underground by sequentially utilizing freezing method construction, digging construction and filling grouting and melting grouting, the elevator type intelligent tower type stereo garage system applied at home and abroad at present is installed in the shaft to run, and the shaft construction is as follows:
freezing method construction: before constructing a shaft, freezing a water-containing stratum around the shaft by using an artificial freezing method to form a frozen wall which has temporary bearing and water-resisting functions and meets the safety requirement of engineering construction, and then performing shaft digging and building operation under the protection of the frozen wall; the freezing wall is formed by mutually matching and complementing an inner ring freezing hole and an outer ring freezing hole;
2) digging and building operation: constructing a cap beam at the top of the shaft; then, carrying out digging construction on the outer wall of the shaft, pouring concrete on a bottom plate of the shaft and constructing the inner wall of the shaft in sequence;
construction of a cap beam: after freezing and meeting the excavation condition, excavating the cap beam by adopting an island method, excavating earthwork in 2 symmetrical areas at the periphery, clearing out a cast-in-place pile, binding reinforcing steel bars, pouring concrete by using a vertical mold, reserving L-shaped reinforcing steel bars on the terrace of the cap beam, and pouring the cap beam and the outer wall of the shaft into a whole;
digging and building the outer wall of the shaft: the outer wall of the shaft is dug and built in a construction mode of layered and partitioned excavation and partitioned concrete pouring;
pouring concrete on the shaft bottom plate: after the outer wall of the shaft is dug to the bottom, bottom reinforced concrete is paved on the bottom plate;
construction of the inner wall of the shaft: the inner wall of the shaft is subjected to primary wall sleeving construction from bottom to top by adopting a metal assembly type template;
3) filling grouting and melting and sinking grouting: and after the shaft is stopped from freezing, filling and grouting after lining and formation melting and sinking compensation grouting.
2. The method for constructing the shaft-type underground parking garage by the freezing method according to claim 1, which comprises the following steps: the thickness of the frozen wall is 3-4 m, the frozen holes of the inner ring are used as reinforced frozen holes, and the depth of the frozen holes penetrates through a shaft to be excavated by 3-5 m; the outer ring freezing hole falls on the impermeable clay layer or the bedrock with good water sealing performance, if the punching layer is deep, the depth of the outer ring freezing hole is 2 times of the shaft excavation depth and falls on the impermeable clay layer, if the upper part of the stratum is surface soil and the lower part of the stratum is bedrock, the depth of the outer ring freezing hole is more than 10m deep into the impermeable bedrock and more than 7m higher than the shaft excavation depth.
3. The method for constructing the shaft-type underground parking garage by the freezing method according to claim 1, which comprises the following steps: arranging rings in the freezing holes of the inner ring until the diameter of the excavating and bricking waste is controlled to be 1.0m, and the distance between the holes of the freezing holes is 1.2-1.3 m; the distance between the holes of the outer ring freezing holes is 1.4-1.5 m.
4. The method for constructing the shaft-type underground parking garage by the freezing method according to claim 1, which comprises the following steps:
filling and grouting after lining: stopping filling grouting after lining in 3 ~ 7 days after freezing, utilizing pre-buried slip casting pipe, lining concrete intensity during slip casting to more than 60% of design intensity, adopt 0.8: 1-1: 1, single-liquid cement slurry is injected, clear water is injected before the cement slurry is injected, whether gaps among grouting holes are unblocked after lining is checked, grouting is performed from bottom to top, and the next layer of grouting can be stopped after the previous layer of grouting holes continuously return to the top of a shaft until the grouting is finished;
stratum melting and sinking compensation grouting: performing thaw collapse grouting in a natural thawing mode, and after filling grouting is finished, performing thaw collapse compensation grouting when the ground settlement of the upper part of the shaft is more than 0.5mm or the accumulated settlement of the ground of the upper part of the shaft is more than 3mm in one day; grouting should be suspended when the ground at the upper part of the shaft rises for 3 mm.
5. The method for constructing the shaft-type underground parking garage by the freezing method according to claim 1, which comprises the following steps: temperature measuring holes are uniformly distributed in four directions of a shaft, and a sensor is longitudinally arranged in each 10m of the temperature measuring holes; at least 1 hydrological hole is designed in the well bore.
6. The method for constructing the shaft-type underground parking garage by the freezing method according to claim 1, which comprises the following steps: in the freezing method construction process, freezing hole monitoring, freezing system monitoring and surrounding environment influence monitoring are implemented,
the freezing hole monitoring comprises the steps of freezing hole opening position monitoring, hole forming deflection monitoring, freezing hole pressure resistance test monitoring, freezing hole length monitoring and liquid supply pipe lowering length monitoring;
the freezing system monitoring comprises a de-loop brine temperature monitoring device, a freezer brine flow detection device, a temperature measuring hole temperature monitoring device and a brine tank liquid level monitoring device;
the monitoring of the surrounding environment influence comprises the monitoring of the frost heaving and thawing sinking deformation of the surface of the earth and the monitoring of the vertical displacement of the deep soil body.
CN201711370230.7A 2017-09-30 2017-12-19 Method for constructing shaft type underground parking garage by freezing method CN108035335B (en)

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CN108643625B (en) * 2018-05-28 2020-02-28 山东科技大学 Urban vertical circulation type underground parking garage building structure and construction method thereof
CN108678750B (en) * 2018-07-19 2019-06-25 淮矿西部煤矿投资管理有限公司 A kind of headframe pile foundation and freezing drill bore parallel construction system and parallel construction method
CN108952728B (en) * 2018-07-19 2019-06-25 淮矿西部煤矿投资管理有限公司 A kind of headframe main body construction and self well digging freeze parallel construction system and method
CN108843325B (en) * 2018-07-19 2019-08-13 淮矿西部煤矿投资管理有限公司 Cross parallel construction system and method are built in vertical headframe, pit shaft freezing, pick
CN109441453A (en) * 2018-11-28 2019-03-08 中煤邯郸特殊凿井有限公司 Partial freezing's construction method in inclines

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CN1614152A (en) * 2004-10-14 2005-05-11 上海隧道工程股份有限公司 Constructing method for in tunnel weak soil layer by freezing method horizontally
CN101463724A (en) * 2008-12-30 2009-06-24 上海隧道工程股份有限公司 Construction method for connection passage by double-row hole horizontal freezing method
CN103133004B (en) * 2013-01-25 2015-03-04 北京中煤矿山工程有限公司 Technological process of ground prefabrication and installation of inner shaft wall of freezing shaft
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