CN112323819A - Soft soil foundation pit bottom in-situ curing method and soft soil foundation pit bottom curing structure - Google Patents
Soft soil foundation pit bottom in-situ curing method and soft soil foundation pit bottom curing structure Download PDFInfo
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- CN112323819A CN112323819A CN202011405286.3A CN202011405286A CN112323819A CN 112323819 A CN112323819 A CN 112323819A CN 202011405286 A CN202011405286 A CN 202011405286A CN 112323819 A CN112323819 A CN 112323819A
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- 239000002689 soil Substances 0.000 title claims abstract description 97
- 238000001723 curing Methods 0.000 title claims abstract description 69
- 238000011065 in-situ storage Methods 0.000 title claims abstract description 36
- 238000010276 construction Methods 0.000 claims abstract description 67
- 238000009412 basement excavation Methods 0.000 claims abstract description 38
- 230000002787 reinforcement Effects 0.000 claims abstract description 10
- 238000002156 mixing Methods 0.000 claims description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- 239000004568 cement Substances 0.000 claims description 22
- 230000003014 reinforcing effect Effects 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 19
- 230000008569 process Effects 0.000 claims description 13
- 238000005553 drilling Methods 0.000 claims description 10
- 238000003756 stirring Methods 0.000 claims description 10
- 239000003795 chemical substances by application Substances 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 3
- 238000007711 solidification Methods 0.000 claims description 3
- 230000008023 solidification Effects 0.000 claims description 3
- 238000002203 pretreatment Methods 0.000 claims 1
- 230000006641 stabilisation Effects 0.000 claims 1
- 238000011105 stabilization Methods 0.000 claims 1
- 230000007613 environmental effect Effects 0.000 abstract description 4
- 239000010802 sludge Substances 0.000 abstract description 3
- 230000006872 improvement Effects 0.000 description 10
- 238000013461 design Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 3
- 230000000087 stabilizing effect Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000008239 natural water Substances 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
- E02D17/04—Bordering surfacing or stiffening the sides of foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
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Abstract
The invention discloses a soft soil foundation pit bottom in-situ curing method and a soft soil foundation pit bottom curing structure, belonging to the technical field of soft soil foundation reinforcement. The in-situ curing method for the soft soil foundation pit bottom has simple construction steps and simple and convenient operation, can obtain the soft soil foundation pit bottom curing structure with stable structure, provides a flat and stable foundation pit bottom surface for the entrance of subsequent construction machinery in the foundation pit, ensures the safety and reliability of related construction in the soft soil foundation pit, reduces the excavation amount and the abandonment amount of sludge, improves the economy and the environmental protection of the soft soil foundation pit construction, and has better popularization value and application prospect.
Description
Technical Field
The invention belongs to the technical field of soft soil foundation reinforcement, and particularly relates to a soft soil foundation pit bottom in-situ curing method and a soft soil foundation pit bottom curing structure.
Background
In foundation construction engineering, excavation and construction of foundation pits are common, and the foundation pits are the most basic parts in underground foundation engineering construction. In the process of foundation pit construction, the support design and the reinforcement design after the foundation pit structure is excavated are related to the safety and the reliability of the whole foundation pit construction.
According to different geological environments, the requirements for foundation pit construction often differ, and the difference is particularly obvious in certain specific construction environments. In coastal areas, soft soil layers in geological soil layers are widely distributed, the thickness of soft soil is large, the soft soil layers often have the characteristics of large natural pore ratio, natural water content larger than a liquid limit, low shearing strength, high compressibility, low water permeability, high rheological property and the like, the foundation pit bottom after deep foundation pit excavation is mostly a deep soft soil layer, the bearing capacity is low, pile foundation construction machinery often cannot enter, a leveling field cannot be provided for subsequent high-rise building pile foundation construction and basement construction, and the safety and the reliability of foundation pit engineering are influenced.
At present, the foundation reinforcement process at the bottom of a pit is usually required after excavation of a foundation pit for foundation pit construction under a soft soil geological environment. The common foundation pit bottom foundation reinforcing method is mainly a digging and filling method, namely, soft soil at the bottom of a pit is dug to a certain depth and then filled with materials with higher structural strength, such as construction waste soil, stone chips or gravel soil, and the treatment depth is generally 1-2 m. Although the method can meet the pit bottom reinforcement requirement in the soft soil foundation pit construction process to a certain extent; however, the construction waste soil is often difficult to ensure the flatness and bearing capacity of the foundation, while the gravel soil is generally difficult to source and expensive in construction cost, which results in extremely high construction cost. Moreover, the excavation and replacement mode inevitably leads to the increase of the excavation depth of the foundation pit, so that the active soil pressure borne by the supporting system is increased, the measures of the foundation pit supporting system need to be correspondingly enhanced, the design difficulty and the construction difficulty of foundation pit construction are undoubtedly increased, and the cost of foundation pit construction is increased.
Disclosure of Invention
Aiming at one or more of the defects or the improvement requirements in the prior art, the invention provides the soft soil foundation pit bottom in-situ curing method and the soft soil foundation pit bottom curing structure, which can realize the in-situ curing of the soft soil foundation pit bottom, provide guarantee for the entry of subsequent pile foundation construction machinery in a foundation pit, ensure the safety and reliability of the soft soil foundation pit construction, shorten the period of the foundation pit construction and reduce the cost of the foundation pit construction.
In order to achieve the above object, in one aspect of the present invention, there is provided a soft soil foundation pit bottom in-situ solidification method, including the following steps:
s101: determining a foundation pit excavation side line, and constructing a supporting system outside the foundation pit excavation side line;
s102: excavating in an area surrounded by the excavation sideline of the foundation pit to a designed depth to form the foundation pit;
s103: performing an in-situ curing process of a shallow layer of the soft soil foundation at the bottom of the foundation pit; mixing a curing agent into the soft soil at the bottom of the pit by using stirring equipment, and curing after stirring to form a hard shell layer positioned in the center of the bottom of the foundation pit and a passive reinforcing layer formed around the periphery of the hard shell layer; the outer side of the hard shell layer is connected with the inner side of the supporting system, and the inner side of the hard shell layer is connected with the hard shell layer.
As a further improvement of the invention, the construction of the supporting system comprises supporting pile construction and water stop pile construction, and the water stop pile is arranged on one side of the supporting pile, which is far away from the excavation sideline of the foundation pit.
As a further improvement of the invention, the construction process of the support pile comprises the following steps:
the foundation pit excavation sideline is outward along hoop interval drilling in proper order to make the bottom in each hole extend to below the stable ground layer surface respectively, pour respectively in each hole then, form a plurality of drilling bored concrete piles that set up along the hoop interval.
As a further improvement of the invention, the construction process of the water stop pile comprises the following steps:
sequentially drilling holes at intervals along the circumferential direction on the outer side of the support pile, which is away from the excavation side line of the foundation pit, so that the bottom of each hole extends to the position below the surface of the stable ground layer, and the axial distance between every two adjacent holes is not more than the inner diameter of each hole, namely, the two adjacent holes are overlapped with each other; and then, respectively pouring in each hole to form a circumferentially continuous closed water stop wall structure.
As a further improvement of the present invention, when the construction in step S103 is performed, the foundation pit bottom is first divided into a plurality of treatment area units, and then the curing operation is sequentially performed on each of the treatment area units.
As a further improvement of the invention, when the curing operation of two adjacent processing area units is carried out, the post-cured processing area unit is overlapped on the prior processing area unit, and the overlapping width is not less than 10 cm.
In another aspect of the invention, a soft soil foundation pit bottom curing structure is provided, which is arranged corresponding to a foundation pit excavated on a soft soil layer, and comprises a shallow soft soil curing layer arranged at the bottom of the foundation pit and a foundation pit supporting system arranged outside an excavation sideline of the foundation pit;
the shallow soft soil curing layer is obtained by mixing a curing agent into a soft soil layer and then stirring and curing the mixture, and comprises a hard shell layer arranged in the middle of the bottom of the foundation pit and a passive reinforcing layer arranged around the hard shell layer;
the foundation pit supporting system is arranged on the outer side of a foundation pit excavation sideline in the circumferential direction and comprises a plurality of supporting piles arranged at intervals in the circumferential direction and water stop walls continuously arranged on the outer sides of the supporting piles in the circumferential direction; the stagnant water wall is formed by a plurality of cement mixing stake interlock overlap joints that the hoop set gradually, just prop up the fender pile with cement mixing stake is respectively certainly soft soil layer surface extends to below the stable stratum.
As a further improvement of the invention, the setting thickness of the passive reinforcement layer in the soft soil layer is larger than that of the hard shell layer; and the setting thickness of the hard shell layer is 1-3 m, and the setting thickness of the passive reinforcing layer is 3-8 m.
As a further improvement of the invention, the length of the cement mixing pile extending into the surface of the stable ground layer is not less than 1 m; and/or the length of the support piles extending into the position below the surface of the stable ground layer is not less than 3 m.
As a further improvement of the invention, the meshing width between two adjacent cement mixing piles is not less than 10 cm.
The above-described improved technical features may be combined with each other as long as they do not conflict with each other.
Generally, compared with the prior art, the technical scheme conceived by the invention has the following beneficial effects:
(1) the in-situ curing method for the soft soil foundation pit bottom is simple in steps and easy and convenient to operate, and by adding the curing agent on the surface of the soft soil layer of the foundation pit bottom and carrying out corresponding stirring and forming, the surface curing layer consisting of the hard shell layer and the passive reinforcing layer can be formed on the foundation pit bottom, so that a flat and stable foundation pit bottom surface is provided for the entry of subsequent construction machinery in the foundation pit, the safety and reliability of the development of related construction engineering in the soft soil foundation pit are ensured, the excavation amount and the abandonment amount of sludge are reduced, and the economy and the environmental friendliness of the soft soil foundation pit construction are improved;
(2) according to the in-situ solidification method for the soft soil foundation pit bottom, the supporting system consisting of the supporting piles and the water stopping piles is arranged, so that the supporting system extends from the surface of the soft soil layer to the position below the surface of the stable ground layer, and the safety and the stability of the soft soil foundation pit construction are ensured; meanwhile, through the occlusion arrangement between the adjacent water stop piles, a plurality of water stop piles can form a continuous and closed water stop wall structure at the outer side of the soft soil foundation pit, so that the stability and the safety in the foundation pit construction process are ensured, the period of foundation pit construction is shortened, and the cost of foundation pit construction is reduced;
(3) the soft soil foundation pit bottom curing structure is simple in structure and convenient and fast to construct, can fully ensure the stability of the whole structure of the foundation pit and the stability of the bottom structure of the foundation pit after the soft soil foundation pit is excavated, provides guarantee for subsequent construction in the foundation pit, reduces the construction cost of the soft soil foundation pit, improves the economy and the environmental protection of the construction of the soft soil foundation pit, and has good popularization value and application prospect.
Drawings
FIG. 1 is a flowchart illustrating steps of an in-situ curing method for a soft soil foundation pit bottom in an embodiment of the invention;
FIG. 2 is a structural top view of a soft soil foundation pit bottom curing structure in an embodiment of the invention;
FIG. 3 is a structural sectional view of a soft soil foundation pit bottom curing structure in an embodiment of the invention;
in all the figures, the same reference numerals denote the same features, in particular: 1. stirring the piles with cement; 2. stabilizing the formation; 3. soft soil foundation; 4. side lines are excavated in the foundation pit; 5. a hard shell layer; 6. a passive reinforcement layer; 7. drilling a cast-in-place pile; 8. and (5) the bottom of the foundation pit.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
Example (b):
referring to fig. 1, the in-situ soft soil foundation pit bottom curing method in the preferred embodiment of the present invention is suitable for a foundation pit construction scene with a thick soft soil layer, and the construction method preferably includes the following steps:
and S101, constructing a supporting system by using a side line of the foundation pit excavation.
Firstly, marking a foundation pit excavation side line 4 in a foundation pit excavation area, and determining the excavation area of the foundation pit.
And secondly, constructing a foundation pit supporting pile and a water stop pile on the outer side of the foundation pit excavation sideline 4.
Specifically, as shown in fig. 2 and 3, the support pile in the preferred embodiment adopts a cast-in-situ bored pile 7, and the depth of the drilled hole extends from the surface of the soft soil foundation 3 to below the surface of the stable ground layer 2, and the depth of the drilled hole and other structural dimensions of the cast-in-situ bored pile 7 can be preferably designed according to actual construction needs. For example, in a preferred embodiment, the diameter of the cast-in-situ bored pile 7 is 0.5 to 1.5m, and more preferably 0.8 to 1.2 m; the pile spacing between two adjacent cast-in-situ bored piles 7 is 0.5 to 2m, and more preferably 1 to 1.5 m. Meanwhile, the depth of embedding of the bored pile 7 in the stable ground 2 in the preferred embodiment is preferably not less than 3 m.
Further, the water stopping pile in the preferred embodiment adopts the cement mixing pile 1, the cement mixing pile 1 is arranged on the outer side of the supporting pile, which is far away from the excavation area of the foundation pit, the pile diameter is preferably 0.4-1.5 m, more particularly preferably 0.6-1.0 m, and two adjacent mixing piles are mutually meshed, namely the distance between the two adjacent mixing piles is not less than the diameter of the mixing pile. Meanwhile, the bottom of the water stop pile is driven into the stable stratum 2, and the depth of the water stop pile entering the stable stratum is preferably not less than 1 m.
Through the sequential occlusion arrangement of the cement mixing piles 1, a continuous and peripherally-closed water stop wall structure is finally formed around the foundation pit excavation area at the outer side of the supporting pile, and the supporting and water stop effects are achieved. In addition, through the arrangement of the supporting structure, the curing agent or the slurry of the curing body can be effectively prevented from escaping in the curing process of the shallow layer at the bottom of the subsequent foundation pit, and the lateral slippage of the shallow layer curing body is effectively prevented.
And S102, excavating the foundation pit to a designed depth to form the foundation pit.
In this step, the excavation of the foundation pit is performed in a conventional excavation manner, which is not described herein.
And S103, carrying out an in-situ curing process of the shallow layer of the soft soil foundation at the bottom of the foundation pit.
Firstly, carrying out a shallow soft soil treatment process at the bottom of a foundation pit. In the concrete operation, materials such as curing agents are mixed into soft soil at the bottom of the pit by using stirring equipment (such as a slurry stirrer), and the mixture is cured after stirring to realize shallow in-situ curing treatment, so that a hard shell layer 5 and a passive reinforcing layer 6 are formed.
In actual construction, the crust layer 5 is formed at the bottom center of the pit, and the passive reinforcement layer 6 is annularly arranged around the periphery of the crust layer 5 upward, as shown in fig. 2. Simultaneously, during the actual setting, the vertical thickness of crust layer 5 is preferred 1 ~ 3m, and the vertical thickness of passive back up coat 6 is preferred 3 ~ 8 m. Through the arrangement of the hard shell layer 5 and the passive reinforcing layer 6 at the bottom of the foundation pit, a supporting system can be formed at the bottom of the foundation pit. Obviously, the bottom of both the crust layer 5 and the passive reinforcement layer 6 do not extend to the top surface of the stable formation 2, as shown in fig. 3.
Further, in a preferred embodiment, the curing agent for in-situ curing on the shallow layer of the soft soil foundation at the bottom of the pit is cement, fly ash, lime or gypsum, and the mixing amount percentage of the curing agent in the soft soil is 1% to 15%, and further preferably 2% to 12%. Meanwhile, when shallow in-situ curing operation is carried out, the foundation pit excavation area can be preferably divided into a plurality of processing area units for carrying out sequential curing operation; in a preferred embodiment, the treatment area units are square block-shaped areas of 3m × 3m to 6m × 6m, in-situ curing is carried out in a mode of curing while advancing, adjacent area units are connected in a lap joint mode, and the lap joint width is preferably not less than 10cm, so that the leakage of the whole foundation pit bottom surface curing construction is avoided.
Further preferably, during actual curing operation, the outer edge of the passive reinforcing layer 6 and each cast-in-situ bored pile 7 can be connected into a whole, so that stress on the passive reinforcing layer 6 can be transmitted to the stable stratum 2 through the cast-in-situ bored piles 7, and the stability of construction operation of the foundation pit bottom 8 is further ensured.
Through the in-situ curing method for the soft soil foundation pit bottom, the soft soil foundation pit bottom curing structure shown in the figures 2 and 3 can be obtained. Wherein, including the supporting construction who sets up in the regional periphery of foundation ditch excavation, this supporting construction includes a plurality of drilling bored concrete piles 7 that set up along the hoop interval, can equidistant setting between two adjacent drilling bored concrete piles 7, also can not interval setting as required (equidistant setting in preferred embodiment), and the interval between the drilling bored concrete pile 7 is 0.5 ~ 2 m. Meanwhile, each cast-in-situ bored pile 7 vertically extends from the surface of the soft soil foundation 3 to below the surface of the stable stratum 2, that is, the bottom of the cast-in-situ bored pile 7 extends into the stable stratum 2 to a depth of not less than 3m in the preferred embodiment. Obviously, the depth of the bored pile 7 is slightly less than 3m according to the design requirement, which is determined by the thickness of the soft soil layer, the depth of the foundation pit, the size of the foundation pit excavation and other factors in the actual operation.
Further, be provided with stagnant water structure along the hoop in supporting construction's the outside, it includes a plurality of cement mixing stake 1 that set gradually along the hoop in the soft soil foundation 3, and each cement mixing stake 1 is respectively from the surface vertical extension of soft soil foundation 3 to the subsurface of stabilizing ground layer 2, and the bottom of cement mixing stake 1 stretches into in stabilizing ground layer 2, and its degree of depth of stretching into is no less than 1m in preferred embodiment. Also, in actual installation, the depth of the above-mentioned protrusion may be slightly less than 1m depending on construction conditions.
Meanwhile, for two adjacent cement mixing piles 1, the two adjacent cement mixing piles are mutually meshed, namely the central distance between the two adjacent cement mixing piles 1 is not larger than the pile diameter of the cement mixing piles 1. Accordingly, the width of the mutual engagement of the two cement mixing piles 1 is not less than 10cm, and is usually 10 to 30cm, as shown in fig. 2. So, can fully guarantee the leakproofness of interlock between two adjacent cement mixing stake 1, avoid permeating water, the existence in infiltration gap.
Furthermore, a crust layer 5 and a passive reinforcing layer 6 are formed at the bottom 8 of the foundation pit within the excavation sideline 4 of the foundation pit. The passive reinforcing layer 6 is arranged on the periphery of the hard shell layer 5 along the annular direction, the periphery of the passive reinforcing layer is abutted to the cast-in-situ bored pile 7, and the inner periphery of the passive reinforcing layer is abutted to the peripheral wall surface of the hard shell layer 5. Meanwhile, the passive reinforcing layer 6 extends downwards at the bottom 8 of the foundation pit and is provided with 3-8 m, and an annular reinforcing layer on the bottom 8 of the foundation pit is formed. Correspondingly, the hard shell layer 5 is arranged in the area surrounded by the passive reinforcing layer 6, the outer peripheral wall surface of the hard shell layer is connected with the inner peripheral wall surface of the passive reinforcing layer 6, and the hard shell layer vertically extends for 1-3 m.
Through forming the top layer reinforced structure who comprises passive back up coat 6 and crust layer 5 on the foundation ditch pit bottom 8 of soft soil foundation ditch, can effectively guarantee the structural strength on foundation ditch surface after the soft soil foundation ditch excavation, provide the assurance for the approach of follow-up construction machinery, promote the efficiency, reliability and the security of soft soil foundation ditch construction.
The soft soil foundation pit bottom in-situ curing method and the soft soil foundation pit bottom curing system obtained by the method have the advantages of simple construction steps, convenience and quickness in construction, capability of effectively improving the efficiency and safety of soft soil foundation pit construction, reduction in the cost of soft soil foundation pit construction, guarantee for the entry of subsequent pile machine construction machinery in a foundation pit, guarantee of the safety and reliability of related engineering development in the soft soil foundation pit, reduction in the excavation amount and the abandonment amount of sludge, satisfaction of the economy and the environmental protection of engineering construction, and good popularization prospect and application value.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A soft soil foundation pit bottom in-situ curing method is characterized by comprising the following steps:
s101: determining a foundation pit excavation side line, and constructing a supporting system outside the foundation pit excavation side line;
s102: excavating in an area surrounded by the excavation sideline of the foundation pit to a designed depth to form the foundation pit;
s103: performing an in-situ curing process of a shallow layer of the soft soil foundation at the bottom of the foundation pit; mixing a curing agent into the soft soil at the bottom of the pit by using stirring equipment, and curing after stirring to form a hard shell layer positioned in the center of the bottom of the foundation pit and a passive reinforcing layer formed around the periphery of the hard shell layer; the outer side of the hard shell layer is connected with the inner side of the supporting system, and the inner side of the hard shell layer is connected with the hard shell layer.
2. The in-situ curing method for the bottom of the soft soil foundation pit according to claim 1, wherein the construction of the supporting system comprises supporting pile construction and water stop pile construction, and the water stop pile is arranged on one side of the supporting pile, which is far away from the excavation sideline of the foundation pit.
3. The in-situ curing method for the bottom of the soft soil foundation pit according to claim 2, wherein the construction process of the support pile comprises the following steps:
the foundation pit excavation sideline is outward along hoop interval drilling in proper order to make the bottom in each hole extend to below the stable ground layer surface respectively, pour respectively in each hole then, form a plurality of drilling bored concrete piles that set up along the hoop interval.
4. The in-situ curing method for the bottom of the soft soil foundation pit according to claim 3, wherein the water stop pile construction process comprises the following steps:
sequentially drilling holes at intervals along the circumferential direction on the outer side of the support pile, which is away from the excavation side line of the foundation pit, so that the bottom of each hole extends to the position below the surface of the stable ground layer, and the axial distance between every two adjacent holes is not more than the inner diameter of each hole, namely, the two adjacent holes are overlapped with each other; and then, respectively pouring in each hole to form a circumferentially continuous closed water stop wall structure.
5. The in-situ curing method for a soft soil foundation pit bottom according to claim 1, wherein during the construction in step S103, the foundation pit bottom is divided into a plurality of treatment area units, and then the curing operation is sequentially performed on each of the treatment area units.
6. The in-situ curing method for the bottom of the soft soil foundation pit according to claim 5, wherein when the curing operation of the two adjacent treatment area units is performed, the post-cured treatment area unit is overlapped on the pre-treatment area unit, and the overlapping width is not less than 10 cm.
7. A soft soil foundation pit bottom curing structure is arranged corresponding to a foundation pit excavated on a soft soil layer and is characterized by comprising a shallow soft soil curing layer arranged at the bottom of the foundation pit and a foundation pit supporting system arranged outside an excavation sideline of the foundation pit;
the shallow soft soil curing layer is obtained by mixing a curing agent into a soft soil layer and then stirring and curing the mixture, and comprises a hard shell layer arranged in the middle of the bottom of the foundation pit and a passive reinforcing layer arranged around the hard shell layer;
the foundation pit supporting system is arranged on the outer side of a foundation pit excavation sideline in the circumferential direction and comprises a plurality of supporting piles arranged at intervals in the circumferential direction and water stop walls continuously arranged on the outer sides of the supporting piles in the circumferential direction; the stagnant water wall is formed by a plurality of cement mixing stake interlock overlap joints that the hoop set gradually, just prop up the fender pile with cement mixing stake is respectively certainly soft soil layer surface extends to below the stable stratum.
8. The soft soil foundation pit bottom curing structure of claim 7, wherein the passive reinforcement layer is provided with a thickness in the soft soil layer that is greater than the thickness of the hard shell layer; and the setting thickness of the hard shell layer is 1-3 m, and the setting thickness of the passive reinforcing layer is 3-8 m.
9. The soft soil foundation pit bottom solidification structure of claim 7, wherein the length of the cement mixing pile extending below the surface of the stabilization ground layer is not less than 1 m; and/or the length of the support piles extending into the position below the surface of the stable ground layer is not less than 3 m.
10. The soft soil foundation pit bottom curing structure of any one of claims 7 to 9, wherein the meshing width between two adjacent cement mixing piles is not less than 10 cm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011405286.3A CN112323819A (en) | 2020-12-05 | 2020-12-05 | Soft soil foundation pit bottom in-situ curing method and soft soil foundation pit bottom curing structure |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011405286.3A CN112323819A (en) | 2020-12-05 | 2020-12-05 | Soft soil foundation pit bottom in-situ curing method and soft soil foundation pit bottom curing structure |
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| CN112323819A true CN112323819A (en) | 2021-02-05 |
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| CN113882418A (en) * | 2021-09-01 | 2022-01-04 | 武汉市政工程设计研究院有限责任公司 | Construction method of underground building pipe pile group foundation in deep soft soil area |
| CN113914321A (en) * | 2021-09-29 | 2022-01-11 | 温州市渣土利用开发股份有限公司 | Advanced integral curing method for ultra-soft site foundation pit |
| CN114086566A (en) * | 2021-11-10 | 2022-02-25 | 中铁第四勘察设计院集团有限公司 | Long and narrow soft soil foundation pit excavation support and soil transportation method |
| CN117431970A (en) * | 2023-12-22 | 2024-01-23 | 四川交通职业技术学院 | Intelligent supporting device and supporting method for roadbed pit |
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| CN114086566A (en) * | 2021-11-10 | 2022-02-25 | 中铁第四勘察设计院集团有限公司 | Long and narrow soft soil foundation pit excavation support and soil transportation method |
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