CN116240899B - Foundation pit excavation deformation control process based on inverted arch reinforcement - Google Patents
Foundation pit excavation deformation control process based on inverted arch reinforcement Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
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- E02D17/00—Excavations; Bordering of excavations; Making embankments
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
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- E—FIXED CONSTRUCTIONS
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- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
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Abstract
The invention discloses a foundation pit excavation deformation control process based on inverted bottom arch reinforcement, which belongs to the technical field of foundation pit excavation deformation control and comprises the following steps: determining the collapse-bulge damage range of the periphery of the foundation pit according to the width and the depth of the foundation pit to be excavated; determining an upper arch axis boundary and a lower arch axis boundary of a range of a required reverse bottom arch reinforcement area of a foundation pit bottom plate according to the width and the depth of a foundation pit periphery sinking-bulging damage range; uniformly distributing reinforcing holes at intervals along the ground surface according to the range of the reinforcing area of the reverse bottom arch, and determining the reinforcing depth range of the reinforcing holes; performing reverse bottom arch reinforcement on the peripheral stratum along the range of the foundation pit to be excavated, and forming a reverse bottom arch reinforcement area inside the stratum; and excavating the foundation pit to be excavated along the surface in a layered and block mode until the foundation pit is excavated. The method can be used for reinforcing the reverse bottom arch, so that the deformation resistance of the foundation pit bottom plate can be effectively improved, the groundwater seepage path can be effectively changed, and the damage phenomena of water and sand gushing of the foundation pit bottom plate can be avoided.
Description
Technical Field
The invention belongs to the technical field of foundation pit excavation deformation control, and particularly relates to a foundation pit excavation deformation control process based on inverted arch reinforcement.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
In recent years, with the acceleration of the urban process, the construction of urban high-rise buildings and the scale of subway mileage are continuously enlarged, and high-rise building foundation pits and urban subway station foundation pits are developed in larger and deeper directions. In the deep foundation pit excavation process, the stress environment of stratum around the foundation pit is changed under the influence of excavation unloading effect, and the destruction phenomena such as surface subsidence, pit bottom bulge deformation and the like are more serious along with the increase of the excavation depth of the foundation pit. Particularly, when the foundation pit is excavated and positioned in a weaker stratum, the foundation pit side soil is extremely easy to generate sinking deformation in a certain range and the deformation degree is generally larger due to the lower strength of the stratum soil or the influence of strong groundwater factors, and a soil damage surface continuing from the foundation pit side to the position below the pit bottom is easily formed, so that the foundation pit bottom plate is damaged due to the larger range of bulge deformation, the stratum deformation stability control difficulty is higher, and the urgent need for ensuring the safety and the reliability of the foundation pit is solved. At present, foundation ditch bottom plate uplift deformation destruction control measure mainly includes: the pile comprises an anti-floating anchor rod, an anti-floating pile, an anti-pulling pile, a bottom plate soil body replacement and filling, grouting reinforcement, cement soil stirring pile reinforcement, high-pressure jet grouting pile reinforcement and the like. It should be noted, however, that the following problems remain to be solved in the above control measures:
1. when the foundation pit bottom plate uplift damage and peripheral subsidence control are designed, firstly, quantitatively determining the foundation pit peripheral stratum subsidence and bottom plate uplift damage range according to the foundation pit excavation size, and then providing a targeted basis for deformation control design, but the existing method for determining the foundation pit bottom plate uplift damage range is not provided with an effective theoretical basis, so that foundation pit uplift damage control measures are mainly based on a semi-empirical semi-theoretical method, and the problem of certain empirical design exists, and the quantitative design basis needs to be further optimized and provided;
2. at present, the modes of anti-floating anchor rods, anti-floating piles, anti-pulling piles, bottom soil body replacement and filling and the like commonly used in foundation pit bottom plate uplift damage control are all implemented after foundation pit excavation, at the moment, the foundation pit bottom plate is subjected to unloading by excavation unloading to generate unloading damage, and certain hysteresis exists in the implementation of the measures, so that the uplift damage effect of the foundation pit bottom plate rock-soil body is difficult to be effectively and timely controlled;
3. when reinforcing the stratum soil around the foundation pit by means of grouting reinforcement, cement-soil mixing pile reinforcement or high-pressure jet grouting pile reinforcement and the like, the stratum is usually reinforced in advance in a horizontal range at a certain depth position of the stratum around the foundation pit to form a horizontal reinforcing area with a certain thickness; however, it should be noted that, in this manner, due to the influence of the excavation unloading of the foundation pit, the maximum principal stress direction inside the bottom plate soil body is upward (the bottom plate soil body mainly deforms vertically upward) and the stress of the corresponding horizontal reinforcing region is maximum at the center of the bottom plate, so that the bending deformation is also maximum. Therefore, the traditional horizontal area reinforcement mode is not matched with the actual stress state in the foundation pit bottom plate, the maximum bearing performance of the reinforcement area is difficult to be fully exerted, and the control effect on the uplift deformation of the bottom plate is not optimal; in the traditional horizontal area reinforcing mode, because the stress is unreasonable, in order to obtain a better control effect, the thickness of the horizontal area reinforcing area can only be passively increased, and the control cost is correspondingly increased, so that the reinforcing mode about the traditional horizontal area needs to be further optimized.
4. In the current grouting reinforcement, cement-soil mixing pile reinforcement or high-pressure jet grouting pile reinforcement mode design, reinforcement parameters, such as the thickness of a reinforcement area, the reinforcement range, the positions and the number of reinforcement holes and the like, are often dependent on experience analogy, and lack of quantitative design basis; moreover, due to the influence of engineering geological conditions, when the foundation pit stratum is reinforced, the reinforcement parameters are often greatly influenced by the stratum, in loose and weak stratum, the reinforcement grout can effectively fill soil body pores, but in some dense stratum, the reinforcement grout is difficult to effectively fill the soil body pores, so that the reinforcement quality is difficult to effectively guarantee, and the reinforcement quality is difficult to guarantee.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a foundation pit excavation deformation control process based on reverse bottom arch reinforcement, which provides a quantitative parameter determination method for the collapse-bulge damage range of the stratum around the foundation pit, and provides a quantitative design flow of a reverse bottom arch reinforcement area by combining grouting reinforcement, high-pressure jet grouting piles, cement soil stirring piles and other modes; the arch structure is transferred to the underground for construction, so that the vertical soil pressure in the stratum can be converted into the horizontal soil pressure, the sinking resistance and the rising deformation resistance of the excavated foundation pit are enhanced, the deformation and the damage of the excavated foundation pit can be effectively controlled, and the overall stability of the foundation pit is improved; the anti-seepage capability of the foundation pit bottom plate can be effectively improved by the anti-bottom arch reinforcement area, and the damage phenomena such as water and sand gushing of the foundation pit bottom plate can be avoided by changing the groundwater seepage path.
In order to achieve the above object, the present invention is realized by the following technical scheme:
in a first aspect, the invention provides a foundation pit excavation deformation control process based on inverted arch reinforcement, which comprises the following steps:
determining the collapse-bulge damage range of the periphery of the foundation pit according to the width D and the depth H of the foundation pit to be excavated;
determining an upper arch axis boundary and a lower arch axis boundary of a range of a required reverse bottom arch reinforcement area of a foundation pit bottom plate according to the width and the depth of a foundation pit periphery sinking-bulging damage range;
uniformly distributing reinforcing holes at intervals along the ground surface according to the range of the reinforcing area of the reverse bottom arch, and determining the reinforcing depth range of the reinforcing holes;
performing reverse bottom arch reinforcement on the peripheral stratum along the range of the foundation pit to be excavated, and forming a reverse bottom arch reinforcement area inside the stratum;
and excavating the foundation pit to be excavated along the surface in a layered and block mode until the foundation pit is excavated.
As a further technical scheme, the foundation pit periphery sinking-uplift damage range consists of two pit side sinking damage areas above the horizontal plane of the foundation pit bottom plate and an uplift damage area below the horizontal plane of the foundation pit bottom plate; the foundation pit periphery subsidence-uplift damage range is a symmetric region along the vertical midline of the foundation pit floor.
As a further technical scheme, the uplift damage area is positioned from soil in a range below the bottom of the pit side to soil in a range below the bottom of the pit and sequentially comprises a vertical force transmission area, a shearing rotation area and a passive lifting area.
As a further technical scheme, the sinking damage area is a rectangular area with a set width, and the height of the rectangular area is equal to the excavation depth of the foundation pit.
As a further technical proposal, the vertical force transmission area is positioned below the sinking damage areas at the two pit sides of the foundation pit, is positioned below the horizontal plane of the foundation pit bottom plate, is an inverted isosceles triangle area which is vertically symmetrical, the length of the top edge is equal to the width of the sinking damage area, and the included angle between the waist edge and the top edge is thatWherein->Is the internal friction angle of the soil body of the foundation pit bottom plate to be excavated; the vertical force transfer area coincides with the corner point of the foundation pit bottom corner at the position of the top corner close to one side in the foundation pit; the passive lifting area is positioned below the horizontal plane of the bottom plate in the foundation pit and is an inverted isosceles triangle area which is vertically symmetrical, and the included angle between the waist edge and the horizontal plane of the bottom plate is。
As a further technical scheme, the shearing rotation area is a sector-like area positioned between the vertical force transmission area and the passive lifting area, and sector corner points of the sector-like area are respectively corresponding to two bottom corner points of the foundation pit; wherein the arc boundary of the sector-like region is a logarithmic spiral lineThe equation of the line isWherein->The waist edge length of the vertical force transmission area is +.>The start and stop points of the logarithmic spiral are respectively corresponding to the base angle point of the vertical force transmission area and the base angle point of the passive lifting area, and the included angle between the radius of the sector-like area corresponding to any point on the logarithmic spiral and the top edge of the vertical force transmission area is +.>。
As a further technical proposal, the reverse bottom arch reinforcement area is an inverted arch area, the two arch feet at the top are respectively supported at the bottoms of the two pit side sinking damage areas, and the curve equation of the upper arch axis boundary of the reverse bottom arch reinforcement area is thatThe curve equation of the lower arch axis boundary of the inverted bottom arch reinforcement region is +.>The boundary curve is in the shape of a circular arc arch or a parabolic arch or a catenary arch;
when the arch is formed by an arc arch, the circle centers of the upper arch axis and the lower arch axis are the same circle center, the boundary of the upper arch axis passes through the two base angle points of the foundation pit, and the connecting line of the circle center and the two base angle points of the foundation pit is the radius of the upper arch axisThe method comprises the steps of carrying out a first treatment on the surface of the The boundary of the lower arch axis passes through two widest position control points of the bulge breaking area, the intersection point of the two vertical force transfer areas of the foundation pit bottom plate, which are far away from the waist edge at one side in the pit, is the center of the lower arch axis, and the connecting line of the center and the two widest position control points is the radius of the lower arch axis>；
When the arch is a parabolic arch, the boundary of the lower arch axis is determined by two widest position control points of a bulge breaking area below the horizontal plane of the foundation pit bottom plate and bottom angle position control points of two vertical force transfer areas, and the boundary of the lower arch axis passes through the widest position control points of the bulge breaking area and the bottom angle position control points of the vertical force transfer areas; the boundary of the upper arch axis passes through the corner points of the two bottom corners of the foundation pit, and the included angle between the tangent line of the parabola corresponding to the upper arch axis at the bottom corners of the two foundation pits and the horizontal plane of the bottom plate is；
When the arch is a catenary arch, the upper arch axis boundary is determined by the two base angle points of the foundation pit and the base angle position control points of the passive lifting area, and passes through the two base angle points of the foundation pit, and the corresponding sagittal height of the upper arch axis boundary at the central position is as followsThe method comprises the steps of carrying out a first treatment on the surface of the The lower arch axis boundary passes through two widest position control points of the bulge breaking zone, and the corresponding sagittal height of the lower arch axis boundary at the central position is +.>，/>For the included angle between the extension line of the connecting line of the widest position control point of the bulge breaking zone and the deepest position control point of the shearing rotation zone and the top edge of the vertical force transmission zone, the arch axis coefficient of the lower arch axisThe ratio of the height of the vertical force transfer areas at the two sides of the bottom of the foundation pit to the sagittal height of the boundary of the lower arch axis is determined; upper arch axis coefficient->With the arch axis coefficient of the lower arch>Take the same value.
As a further technical scheme, the reinforcing holes are vertically and downwards drilled from the ground surface, the reinforcing holes are drilled to the boundary of the lower arch axis, the area, which is to be excavated, of the foundation pit inner range reinforcing holes between the boundary of the upper arch axis and the boundary of the lower arch axis is the reinforcing depth range of the reinforcing holes, and the area, which is to be excavated, of the foundation pit side range reinforcing holes between the bottom boundary of the sinking damage area and the boundary of the lower arch axis is the reinforcing depth range of the reinforcing holes.
As a further technical scheme, the reverse bottom arch reinforcement area is reinforced by grouting reinforcement or high-pressure jet grouting pile reinforcement or cement-soil mixing piles; the reinforcement depth range of the single reinforcement hole is determined by the thickness of the corresponding reverse bottom arch reinforcement area of the reinforcement hole, and the distance between the reinforcement holes is less than or equal to twice the reinforcement radius of the single grouting pipe or the high-pressure jet grouting pile or the cement mixing pile.
The beneficial effects of the invention are as follows:
according to the foundation pit excavation deformation control process, a quantitative determination method of the foundation pit peripheral subsidence-uplift damage range is provided according to the excavation width and depth of the foundation pit, the damage range is formed by extending from pit side subsidence to pit bottom through pit angle rotation, the foundation pit excavation deformation control process accords with foundation pit excavation deformation characteristics, scientific and effective theoretical basis is provided for the control technical design of foundation pit side subsidence damage range, bottom plate uplift damage range prediction and control measures, and the defect that the effective theoretical basis is lacking at present can be effectively overcome.
According to the foundation pit excavation deformation control process, an arch structure is innovatively introduced into reinforcement for the foundation pit peripheral stratum and the bottom plate bulge damage, compared with the conventional stratum horizontal reinforcement range, the arch structure is more in line with the stress state and deformation characteristics that the pit bottom soil body is deformed vertically upwards after the foundation pit is excavated, the vertical soil pressure of the lower stratum soil body is effectively transferred to the arch foot parts at the two pit sides of the horizontal foundation pit, meanwhile, the pressure transferred from the bottom plate can be effectively transferred by means of the arch foot parts, so that the sinking of the soil body at the two pit sides is resisted, the sinking resistance and the bulge damage resistance of the foundation pit peripheral stratum are improved, the foundation pit peripheral stratum has higher bearing capacity, and the problems of foundation pit side sinking damage and bottom plate bulge damage can be effectively solved; meanwhile, the mode optimizes the implementation mode and the bearing performance of the reinforcement area, so that better economy can be obtained when the foundation pit deformation control is carried out.
According to the foundation pit excavation deformation control process, the treatment method of the reverse bottom arch reinforcement area is implemented by drilling the stratum before the foundation pit is excavated, and soil and reinforcement materials can form an effective whole through the reverse bottom arch reinforcement area, so that deformation and damage of a foundation pit bottom plate are prevented; meanwhile, the method is applied before the foundation pit is excavated, so that the method has advancement and initiative for stratum deformation control, belongs to an actively advanced reinforcement method, and can effectively prevent stratum sinking and bottom plate uplift damage of the foundation pit.
The foundation pit excavation deformation control process provides a specific determination method of the reverse bottom arch reinforcement area, specific forms of different types of arch axes, a reinforcement parameter determination method and specific implementation modes, is flexible and practical, can effectively overcome the defects and shortcomings of semi-empirical semi-theoretical design in the modes of traditional high-pressure jet grouting piles, cement soil mixing piles, grouting reinforcement and the like, and provides quantitative design theory and method support for foundation pit excavation deformation damage control.
According to the foundation pit excavation deformation control process, the reverse bottom arch reinforcement area is formed by means of high-pressure jet grouting piles, cement soil stirring piles, grouting reinforcement and the like, so that the foundation pit bottom plate has certain waterproof and waterproof performances in the range; especially in the stratum with strong water-rich and strong permeability or the stratum affected by the pressure of the lower pressure-bearing water, the reverse bottom arch reinforcing area can effectively change the seepage path of the underground water, and effectively solve engineering problems such as water gushing of the foundation pit bottom plate.
According to the foundation pit excavation deformation control process, the integral stability of the foundation is improved by applying the reverse bottom arch reinforcement area, so that the foundation is not influenced by foundation instability in the process of sectionalized layered excavation, the deformation, uplift and damage of the foundation pit bottom plate in the process of foundation pit excavation can be greatly reduced, and the construction safety is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 is a flow chart of a foundation pit excavation deformation control process based on inverted bottom arch reinforcement of the present invention;
FIG. 2 is a schematic diagram of the composition of the collapse range of the peripheral subsidence-uplift of the foundation pit to be excavated according to the present invention;
FIG. 3 is a schematic diagram of the determination of the foundation pit floor anti-bottom arch reinforcement area to be excavated according to the present invention;
FIG. 4 is a schematic diagram of the placement of reinforcement holes required for a foundation pit floor inverted arch reinforcement zone to be excavated in accordance with the present invention;
FIG. 5 is a schematic view of an arc-shaped inverted bottom arch reinforcement area of a foundation pit floor to be excavated according to the present invention;
FIG. 6 is a schematic illustration of a parabolic inverted arch reinforcement zone of a foundation pit floor to be excavated in accordance with the present invention;
FIG. 7 is a schematic illustration of a catenary inverted arch reinforcement of a foundation pit floor to be excavated in accordance with the present invention;
in the figure: the mutual spacing or size is exaggerated for showing the positions of all parts, and the schematic drawings are used only for illustration;
wherein, 1-a vertical force transmission area; 2-shearing a rotating area; 3-a passive lifting zone; 4-a foundation pit bottom plate; 5-sinking the damaged area; 6-excavation boundary of the foundation pit; 7-a vertical center line of the foundation pit bottom plate; 8-the earth surface; 9-a reverse bottom arch reinforcement zone; 10-lower arch axis boundary; 11-upper arch axis boundary; 12-reinforcing holes;
a1 A2-two widest point of control of the bump destruction zone; c1 C2-a bottom angle position control point of the vertical force transmission area; o1 and O2 are the bottom corner points of the foundation pit; e1 E2, cutting a deepest position control point of the rotating area; g, a bottom angle position control point of the passive lifting area;a curve equation for the upper arch axis boundary; />A curvilinear equation bordering the lower arch axis.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
In an exemplary embodiment of the present invention, as shown in fig. 1, a foundation pit excavation deformation control process based on inverted arch reinforcement is provided, which includes the following steps:
step 1, predicting and determining a foundation pit periphery sinking-uplift damage range according to the width D and the depth H of a foundation pit to be excavated; the excavation boundary 6 of the foundation pit is shown in fig. 2;
step 2, determining an upper arch axis boundary 11 and a lower arch axis boundary 10 of the foundation pit bottom plate 4 in the range of the required anti-bottom arch reinforcement region 9 according to the width and the depth of the foundation pit periphery sinking-bulging damage range determined in the step 1, as shown in fig. 3;
step 3, uniformly and alternately arranging reinforcement holes 12 on the ground surface 8 at the front edge of the excavation of the foundation pit to be excavated according to the range of the reinforced area 9 of the reverse bottom arch determined in the step 2, and determining the reinforcement depth range of the reinforcement holes 12;
step 4, performing reverse bottom arch reinforcement on the peripheral stratum along the foundation pit to be excavated according to the reinforcement parameters such as the positions of the reinforcement holes 12, the reinforcement depth range and the like determined in the step 3, and forming a reverse bottom arch reinforcement area 9 in the stratum;
and 5, excavating the foundation pit to be excavated along the earth surface 8 in a layered and block mode until the foundation pit is excavated.
In the step 1, the foundation pit periphery sinking-uplift damage range is positioned in a certain depth range of the pit side and the pit bottom of the foundation pit to be excavated, sinking soil bodies in a certain width range from the two pit sides, and uplift soil bodies extending to a certain depth range in the pit bottom.
Specifically, the foundation pit periphery subsidence-uplift damage range is composed of two pit side subsidence damage areas 5 positioned above the bottom plate horizontal plane and an uplift damage area positioned below the bottom plate horizontal plane.
The uplift damage area is positioned from soil in a range below the bottom of the pit side to soil in a range below the bottom of the pit and sequentially comprises a vertical force transmission area 1, a shearing rotation area 2 and a passive lifting area 3;
the collapse-bulge damage range of the periphery of the foundation pit is a symmetrical area along the vertical center line 7 of the foundation pit bottom plate; the pit side sinking damage area 5, a vertical force transmission area 1, a shearing rotation area 2 and a passive lifting area 3 in the uplift damage area jointly form a soil body sliding damage area corresponding to the foundation pit periphery when the pit side is sunk to the bottom for uplift damage; stratum soil outside the collapse-bulge damage range of the periphery of the foundation pit is stable soil.
In step 1, the subsidence breaking areas 5 at two pit sides of the foundation pit are rectangular areas with certain width, and the height of the rectangular areas is equal to the excavation depth of the foundation pit.
In step 1, the vertical force transfer area 1 in the bulge breaking area is positioned below the sinking breaking areas 5 at two pit sides of the foundation pit, is positioned below the horizontal plane of the foundation pit bottom plate 4, and is respectively an inverted isosceles triangle area which is vertically symmetrical, the length of the top edge is equal to the width of the sinking breaking areas 5, and the included angle between the waist edge and the top edge isWherein->Is the internal friction angle of the soil body of the foundation pit bottom plate 4 to be excavated; the vertex angle positions of the vertical force transfer area 1, which are close to one side in the foundation pit, are respectively overlapped with the bottom angle point positions of the foundation pit; the passive lifting area 3 is positioned below the horizontal plane of the bottom plate in the foundation pit and is an inverted isosceles triangle area which is vertically symmetrical, and the included angle between the waist edge and the horizontal plane of the bottom plate is +.>。
The shearing rotation area 2 is two fan-like areas positioned between the vertical force transmission area 1 and the passive lifting area 3, and the fan-like angular points of the two fan-like areas are respectively corresponding to two base angular points of the foundation pit; wherein the arc boundary of the sector-like region is a logarithmic spiral, and the equation of the logarithmic spiral isWherein->For the length of the waist edge of the vertical force transmission area 1, the starting and stopping points of the logarithmic spiral line are respectively corresponding to the base angle point of the vertical force transmission area 1 and the base angle point of the passive lifting area 3, and the included angle between the radius of the fan-like area corresponding to any point on the logarithmic spiral line and the top edge of the vertical force transmission area 1 is->The method comprises the steps of carrying out a first treatment on the surface of the According to the geometrical relationship in FIG. 2, when +.>When the sector-like area is in use, the ending radius of the sector-like area corresponds to the waist edge of the passive lifting area 3, and the length of the sector-like area is as followsThe method comprises the steps of carrying out a first treatment on the surface of the Accordingly, the equivalent +.>When in use, the initial radius of the sector-like area corresponds to the waist edge of the vertical force transmission area 1, and the length of the sector-like area is +.>。
According to the waist edge length of the vertical force transmission area 1It is possible to obtain a top edge length of the vertical force transfer area 1 of +.>The height of the vertical force transfer area 1 is +.>The method comprises the steps of carrying out a first treatment on the surface of the According to the waist edge length of the passive lifting area 3The height of the passive lifting area 3 can be obtained as +.>The method comprises the steps of carrying out a first treatment on the surface of the The length of the top edge of the passive lifting area 3 is the excavation width D of the foundation pit.
In step 2, the bottom-arch-resisting reinforcement region 9 is an inverted arch region, the two upper arch legs are respectively supported at the bottoms of the pit-side sinking damage regions 5, and the curve equation of the upper arch axis boundary 11 of the bottom-resisting reinforcement region 9 isThe lower arch axis boundary 10 of the inverted base arch reinforcement region 9 has a curve equation of +.>The boundary curve shape can be circular arc arch, parabolic arch and catenary arch.
(1) When the curve shape of the upper arch axis boundary 11 and the lower arch axis boundary 10 is a circular arch, as shown in fig. 5, the lower arch axis boundary 10 is determined by two widest position control points of a bulge breaking area below the horizontal plane of the foundation pit bottom plate 4 and two bottom angle position control points of the vertical force transmission area 1 together, and the lower arch axis boundary 10 passes through the two widest position control points of the bulge breaking area; the intersection point of the vertical bisectors of the two vertical force transfer areas 1 of the foundation pit bottom plate 4 far away from one side waist edge in the pit is the center of the lower arch axis, and the connecting line of the center and the two widest position control points is the radius of the lower arch axisThe method comprises the steps of carrying out a first treatment on the surface of the The circle centers of the upper arch axis and the lower arch axis are the same circle center, the boundary 11 of the upper arch axis passes through the two base angle points of the foundation pit, and the connecting line of the circle center and the two base angle points of the foundation pit is the radius of the upper arch axis +.>；
(2) When the curve shapes of the upper arch axis boundary 11 and the lower arch axis boundary 10 are parabolic arches, as shown in fig. 6, the lower arch axis boundary 10 is determined by two widest position control points of the bulge breaking area below the horizontal plane of the foundation pit bottom plate 4 and bottom angle position control points of the two vertical force transmission areas 1 together, and the lower arch axis boundary 10 passes through the widest position control points and the bottom angle position control points; the upper arch axis boundary 11 passesThe included angle between the tangent line of the parabola corresponding to the upper arch axis at the bottom angle of the two foundation pits and the horizontal plane of the bottom plate is that；
(3) When the curve shape of the upper arch axis boundary 11 and the lower arch axis boundary 10 is a catenary arch, as shown in fig. 7, the lower arch axis boundary 10 is determined by the widest position control point of the bulge breaking area below the horizontal plane of the foundation pit bottom plate 4, the bottom angle position control point of the vertical force transmission area 1 and the deepest position control point of the shearing rotation area 2, the lower arch axis boundary 10 passes through the two widest position control points of the bulge breaking area, the corresponding sagittal height of the lower arch axis boundary 10 at the center position is determined by the height distance from the intersection point of the connecting extension lines of the widest position control points on two sides of the bulge breaking area and the deepest position control points of the shearing rotation area 2 to the horizontal plane of the foundation pit bottom plate 4, and the sagittal height is，/>For the included angle between the connecting line extension line of the widest position control point of the bulge breaking zone and the deepest position control point of the shearing rotation zone 2 and the top edge of the vertical force transmission zone 1, the arch axis coefficient of the lower arch axis is +>The ratio of the height of the vertical force transfer areas 1 at the two sides of the bottom of the foundation pit to the rise of the lower arch axis boundary 10 is determined; the upper arch axis boundary 11 is determined by the two base angle points of the foundation pit and the base angle position control points of the passive lifting area 3, and passes through the two base angle points of the foundation pit, the corresponding rise of the upper arch axis boundary 11 at the central position is determined by the height distance of the passive lifting area 3, and the rise is as followsUpper arch axis coefficient->With the arch axis coefficient of the lower arch>Take the same value.
In step 3, as shown in fig. 4, reinforcing holes 12 are uniformly spaced at certain intervals and vertically and downwardly punched from the earth surface 8, the reinforcing holes 12 are punched to the lower arch axis boundary 10, the area of the foundation pit to be excavated, in which the reinforcing holes 12 are located between the upper arch axis boundary 11 and the lower arch axis boundary 10, is the reinforcing depth range of the reinforcing holes 12, and the area of the foundation pit to be excavated, in which the reinforcing holes 12 are located between the bottom boundary of the subsidence failure zone 5 and the lower arch axis boundary 10, is the reinforcing depth range of the reinforcing holes 12.
In the step 4, the anti-bottom arch reinforcement area 9 can be reinforced by grouting reinforcement, high-pressure jet grouting pile reinforcement, cement mixing piles and other modes.
(1) When reinforcing by grouting, the in-pit range reinforcing holes 12 are taken as an example, and the grouting depth range of the grouting pipe in each reinforcing hole 12Determined by the thickness of the reinforcing region 9 of the inverted bottom arch corresponding to the reinforcing holes 12, i.eWherein->A horizontal position coordinate corresponding to the reinforcing hole 12 at the position; the reinforcement holes 12 are spaced apart from one another>Slurry diffusion radius from single grouting pipe +.>Confirm, and guarantee->；
(2) When the high-pressure jet grouting pile is reinforced in a reinforcing mode, taking the reinforcing hole 12 in the pit range as an example, the slurry high-pressure jet grouting depth of the high-pressure jet grouting pile in the single reinforcing hole 12RangeIs determined by the thickness of the reinforcing region 9 of the counter bottom arch corresponding to the reinforcing hole 12, i.e. +.>Wherein->A horizontal position coordinate corresponding to the reinforcing hole 12 at the position; the reinforcement holes 12 are spaced apart from one another>Radial reinforcement by slurry jet grouting of single high pressure jet grouting pile>Confirm, and guarantee->；
(3) When reinforcing is performed by adopting a cement-soil mixing pile reinforcing mode, taking the in-pit range reinforcing hole 12 as an example, the mixing reinforcing depth range of the cement-soil mixing pile in a single reinforcing hole 12Is determined by the thickness of the reinforcing region 9 of the counter bottom arch corresponding to the reinforcing hole 12, i.e. +.>Wherein->A horizontal position coordinate corresponding to the reinforcing hole 12 at the position; the reinforcement holes 12 are spaced apart from one another>Stirring reinforcement radius of single cement-soil stirring pile>Confirm, and guarantee->。
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. The foundation pit excavation deformation control process based on the inverted arch reinforcement is characterized by comprising the following steps of:
determining the collapse-bulge damage range of the periphery of the foundation pit according to the width D and the depth H of the foundation pit to be excavated;
determining an upper arch axis boundary and a lower arch axis boundary of a range of a required reverse bottom arch reinforcement area of a foundation pit bottom plate according to the width and the depth of a foundation pit periphery sinking-bulging damage range; the foundation pit periphery sinking-uplift damage range consists of two pit side sinking damage areas above the horizontal plane of the foundation pit bottom plate and an uplift damage area below the horizontal plane of the foundation pit bottom plate; the uplift damage area is positioned from soil in a range below the bottom of the pit side to soil in a range below the bottom of the pit and sequentially comprises a vertical force transmission area, a shearing rotation area and a passive lifting area; the vertical force transfer area is positioned below the sinking damage areas at the two pit sides of the foundation pit, is an inverted isosceles triangle area which is vertically symmetrical, the length of the top edge is equal to the width of the sinking damage area, and the included angle between the waist edge and the top edge isWherein->Is the internal friction angle of the soil body of the foundation pit bottom plate to be excavated; the vertical force transfer area coincides with the corner point of the foundation pit bottom corner at the position of the top corner close to one side in the foundation pit; the passive lifting area is positioned below the horizontal plane of the bottom plate in the foundation pit and is an inverted isosceles triangle area which is vertically symmetrical, and the included angle between the waist edge and the horizontal plane of the bottom plate is +.>The method comprises the steps of carrying out a first treatment on the surface of the The shearing rotation area is a sector-like area positioned between the vertical force transmission area and the passive lifting area, and sector corner points of the sector-like area are respectively corresponding to two bottom corner points of the foundation pit; wherein the arc boundary of the sector-like region is a logarithmic spiral, and the equation of the logarithmic spiral isWherein->The waist edge length of the vertical force transmission area is +.>The start and stop points of the logarithmic spiral are respectively corresponding to the base angle point of the vertical force transmission area and the base angle point of the passive lifting area, and the included angle between the radius of the sector-like area corresponding to any point on the logarithmic spiral and the top edge of the vertical force transmission area is +.>The method comprises the steps of carrying out a first treatment on the surface of the The inverted bottom arch reinforcement area is an inverted arch area, the two arch feet at the top of the inverted bottom arch reinforcement area are respectively supported at the bottoms of the sinking damage areas at the two pit sides, and the curve equation of the upper arch axis boundary of the inverted bottom arch reinforcement area is +.>The curve equation of the lower arch axis boundary of the inverted bottom arch reinforcement region is +.>The shape of the boundary curve is a circular arc arch;
when the arch is formed by an arc arch, the circle centers of the upper arch axis and the lower arch axis are the same circle center, the boundary of the upper arch axis passes through the two base angle points of the foundation pit, and the connecting line of the circle center and the two base angle points of the foundation pit is the radius of the upper arch axisThe method comprises the steps of carrying out a first treatment on the surface of the Lower arch axis boundary penetrationCrossing the two widest position control points of the bulge breaking area, wherein the intersection point of the perpendicular bisectors of the two vertical force transfer areas of the foundation pit bottom plate far away from one side waist edge in the pit is the center of the lower arch axis, and the connecting line of the center and the two widest position control points is the radius of the lower arch axis>；
Uniformly distributing reinforcing holes at intervals along the ground surface according to the range of the reinforcing area of the reverse bottom arch, and determining the reinforcing depth range of the reinforcing holes;
performing reverse bottom arch reinforcement on the peripheral stratum along the range of the foundation pit to be excavated, and forming a reverse bottom arch reinforcement area inside the stratum;
and excavating the foundation pit to be excavated along the surface in a layered and block mode until the foundation pit is excavated.
2. The foundation pit excavation deformation control process based on inverted arch reinforcement according to claim 1, wherein the foundation pit periphery subsidence-uplift failure range is a symmetric region along the vertical center line of the foundation pit floor.
3. The foundation pit excavation deformation control process based on inverted arch reinforcement according to claim 1, wherein the subsidence failure zone is a rectangular area having a set width, and the height of the rectangular area is equal to the depth of excavation of the foundation pit.
4. The foundation pit excavation deformation control process based on inverted bottom arch reinforcement according to claim 1, wherein the boundary curve shape is also a parabolic arch, and when the boundary curve shape is a parabolic arch, the lower arch axis boundary is determined by two widest position control points of a bulge breaking area below the horizontal plane of the foundation pit bottom plate and bottom angle position control points of two vertical force transfer areas together, and the lower arch axis boundary passes through the widest position control points of the bulge breaking area and the bottom angle position control points of the vertical force transfer areas; the boundary of the upper arch axis passes through the corner points of the two bottom corners of the foundation pit, and the included angle between the tangent line of the parabola corresponding to the upper arch axis at the bottom corners of the two foundation pits and the horizontal plane of the bottom plate is。
5. The foundation pit excavation deformation control process based on inverted bottom arch reinforcement as claimed in claim 1, wherein the boundary curve is also a catenary arch, and when the boundary curve is a catenary arch, the upper arch axis boundary is determined by the two bottom corner points of the foundation pit and the bottom corner position control point of the passive lifting area together, and passes through the two bottom corner points of the foundation pit, and the upper arch axis boundary corresponds to a sagittal height at the center position of the upper arch axis boundary as followsThe method comprises the steps of carrying out a first treatment on the surface of the The lower arch axis boundary passes through two widest position control points of the bulge breaking zone, and the corresponding sagittal height of the lower arch axis boundary at the central position is +.>，/>For the included angle between the extension line of the connection line of the widest position control point of the bulge breaking zone and the deepest position control point of the shearing rotation zone and the top edge of the vertical force transmission zone, the arch axis coefficient of the lower arch axis is +>The ratio of the height of the vertical force transfer areas at the two sides of the bottom of the foundation pit to the sagittal height of the boundary of the lower arch axis is determined; upper arch axis coefficient->With the arch axis coefficient of the lower arch>Take the same value.
6. The foundation pit excavation deformation control process based on inverted arch reinforcement according to claim 1, wherein the reinforcement hole is vertically and downwardly punched from the earth's surface, the reinforcement hole is punched to the lower arch axis boundary, the area of the foundation pit to be excavated, in which the reinforcement hole is located between the upper arch axis boundary and the lower arch axis boundary, is the reinforcement depth range of the reinforcement hole, and the area of the foundation pit to be excavated, in which the reinforcement hole is located between the bottom boundary of the subsidence failure area and the lower arch axis boundary, is the reinforcement depth range of the reinforcement hole.
7. The foundation pit excavation deformation control process based on the inverted bottom arch reinforcement according to claim 1, wherein the inverted bottom arch reinforcement area is reinforced by grouting reinforcement or high-pressure jet grouting pile reinforcement or cement-soil mixing pile; the reinforcement depth range of the single reinforcement hole is determined by the thickness of the corresponding reverse bottom arch reinforcement area of the reinforcement hole, and the distance between the reinforcement holes is less than or equal to twice the reinforcement radius of the single grouting pipe or the high-pressure jet grouting pile or the cement mixing pile.
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| JP2007046343A (en) * | 2005-08-10 | 2007-02-22 | Takenaka Komuten Co Ltd | Liquefaction preventive construction method of ground just under existing building |
| CN108049418A (en) * | 2017-11-10 | 2018-05-18 | 浙江理工大学 | Underground parking controls construction method with the Resistant heave of ultra-deep open caisson |
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