JP5501478B2 - Reinforced self-supporting earth retaining structure using arching effect and underground excavation method using it - Google Patents

Description

  The present invention relates to a reinforced self-supporting earth retaining structure using an arching effect and an underground excavation construction method using the same, and more specifically, a back-end earth pressure by vertical excavation is formed by the arching effect. It is related with making it support to a type earth retaining structure.

  Since the reinforced self-supporting earth retaining structure using the arching effect is installed behind the excavation space, the excavation work is efficient without interfering with the excavation work. The lagging inserted in the soldier pile does not act on the backside earth pressure, so it is not only possible to form a self-supporting earth retaining structure, but the weight of the self-supporting structure supports the backside earth pressure. This is a new concept in continuous sheet walls.

  In the present invention, since the reinforced self-supporting earth retaining structure is installed behind the excavation space, the excavation work is not hindered, so the excavation space is widened and excavation is performed in a small space in the city center where high-rise buildings are densely packed. Work is easy and efficient.

  By firmly fixing the connecting part of the seat panel with the upper and lower fixtures so that it becomes a composite cross section, not only the rigidity is increased, but the structure of the upper and lower fixtures is simple, and the binding and disassembly are It is easy to recover the seat panel after the construction is completed.

  During the excavation work for underground structures, the existing temporary earth retaining method to prevent the collapse of the excavation backside soil is to reinforce the insufficient support capacity of the main pile against the excavation backside earth pressure by external force. It is a method to do.

  As a typical construction method against this, there are a strut construction method and a sheet pile construction method.

A) Strut method The strut method is a method of excavating the ground in a top-down manner while the strut 20 reinforces the insufficient horizontal support force of the parent pile 10 against the excavation backside earth pressure ( FIG. 1).

  The excavation back earth pressure is a horizontal force, and the parent pile 10 is a vertical member.

  It is impossible in structural mechanics to support a horizontal force only with a vertical member without a horizontal member. It is the strut 20 that plays a role as a horizontal member for the parent pile 10 that is a vertical member.

The strut 20 is orthogonal to the parent pile 10. The strut 20 is supported by two support points.

  Both support points of the strut 20 are the parent piles 10 usually installed at positions facing each other.

  Thus, since the strut 20 is installed toward the parent pile 10 facing each other, the horizontal strut and the vertical strut intersect each other on the same plane.

  Longitudinal and lateral struts are obstacles for narrowing the work space for equipment entry and excavation of the soil for excavation work.

  In particular, in the city center, because high-rise buildings are built around the excavation space, the struts can only be installed more densely for structural safety.

  On the other hand, since the strut is a temporary facility, after the excavation space is created, the strut must be removed sequentially along with the installation of the permanent structure. Permanent structures are constructed in a bottom-up manner starting from the bottom and gradually up.

  Thereby, strut removal is also performed in stages.

  For example, if the lowest basement floor is B1, in order to construct the B1 floor of a permanent structure, the struts installed on the B1 floor must first be removed.

  At this time, even if the struts on the B1 floor are removed, the struts on the upper floors B2, B3, B4,... Support the earth pressure as it is installed.

  The struts removed from the B1 floor must be removed to the outside, but the struts in the vertical and horizontal directions will be disturbed by the excavation work.

  In addition, for construction on the B1 floor, materials such as concrete mortar and reinforcing bars must descend to the B1 floor via the struts on the B2, B3, B4,. The struts installed on the upper floor hinder the supply of materials, which is a problem that reduces work efficiency.

  B2, B3, B4 ... Even with construction on the floor, such problems remain as they are.

  Therefore, the strut method has the problem that the work space for excavation work and earth removal work becomes narrow because struts must be installed in the excavation space toward the main pile. Because it is a facility, it must be constructed while removing the struts along with the construction of the permanent structure, so the remaining struts obstruct the construction of the permanent structure in sequence, and work efficiency There is a problem that it decreases.

B) Sheet Pile Construction Method “Structure of sheet pile wall structure” of Patent Document 1 as a prior art will be described.

  FIG. 3 of Patent Document 1 is an invention for solving the problems of the interlocks 446 and 448 of Patent Document 2 illustrated in FIG. 2.

As shown in FIG. 2, the soil anchor 444 is coupled by a first interlock 446 of the first seat 440 and a second interlock 448 of the second seat 442. The soil failure plane is the maximum tensile force line T _max -line on which the active earth pressure acts.

  The acting force 450 is a pulling force acting on the soil breaking surface. A soil anchor 444 faces this.

  In Patent Document 1, the problem with Patent Document 2 is that the connecting portion that couples the sheet pile wall section to the anchorage is extremely high in tension due to the earth pressure (earth pressure) that is further maintained from the surrounding area. The structure that can withstand extremely high tension without detaching the connecting portion, that is, the connecting portion in which the first interlock 446 and the second interlock 448 engage with each other It can be confirmed from the description that the purpose of development is.

  The purpose of Patent Document 1 is to form a structure that can withstand extremely high tension without detachment of the connecting portion 16, but the structure is composed solely of the shape and structure of the connecting portion 16. There is.

  In FIG. 3, reference numeral 12 denotes a sheet pile wall section, reference numeral 14 denotes a first anchorage, reference numeral 16 denotes a connecting portion, reference numeral 18 denotes an open cell, reference numeral 22 denotes a flat plate-like assembly, reference numeral 24 denotes a support wall, and reference numeral 26 denotes welding. Part 28 is a double T carrier.

  On the other hand, in Patent Document 1 and Patent Document 2, the basic concepts related to the equilibrium relationship between earth pressure and the opposing force are the same.

  The basic concept of an earth retaining system with a sheet pile is illustrated in FIG. FIG. 4 is shown in Patent Document 2 and is cited in the present invention.

  The basic concept of the earth retaining system will be described with reference to FIG.

  Reference numeral 200 is a typical sheet pile unit cell structure. The unit cell structure 200 is U-shaped. The curved portion of the U-shaped sheet pile is 210, and the straight portion of the sheet pile is 220. The curved portion 210 is closed and the straight portion 220 is opened. The unit cell structure 200 is installed vertically.

  FIG. 4 is a plan view of the unit cell structure 200. The unit cell structure 200 is a structure in which the unit cell structure 200 supports the back surface earth pressure P transmitted through the soil filled therein.

  A structure such as a road is built on the unit cell structure 200.

  P is the back earth pressure with the U-shaped unit cell structure 200 as a boundary condition.

  Referring to FIG. 8, the back surface earth pressure P is located on the back surface. In FIG. 4, this back earth pressure acts on the curved portion 210 of the sheet pile.

  The force balance in FIG. 4 is a concept in which the friction force F = μN corresponds to the backside earth pressure P.

  P and F whose directions of action are opposite to each other are balanced with each other.

  N is a normal force acting on the straight portion 220 of the sheet pile.

  The basic concept of the prior art according to FIG. 4 can be summarized as an earth pressure P acting on the curved portion 210 of the unit cell structure 200 to balance the friction force F.

Korea Public Patent No. 2008-45182

US 6,715,964B2 specification

  The present invention uses an arching effect caused by the frictional force between the soil particles and the seat panel to form a reinforced soil type self-supporting soil mass, and resists earth pressure acting on the excavation space by the weight of the self-supporting soil mass. An object of the present invention is to provide a reinforced self-supporting retaining structure with a new concept. Another purpose is that the reinforced self-supporting earth retaining structure using the arching effect is located at the back of the excavation space, so that the excavation space can be used widely without interfering with the excavation work, and high-rise buildings are densely packed. It is to make excavation work in a small space in the city center easy and efficient. Still another object is to make the joint section of the seat panel a composite cross-section with the upper and lower fixtures to increase the rigidity, and at the same time to bind and disassemble the seat panel joint with the simple structure of the upper and lower fixtures. It is to facilitate the collection of the buried seat panel after the construction is completed, while facilitating.

In order to solve the above-mentioned problem, the present invention includes (a) placing a main pile on a ground surface of a boundary surface to be excavated to a vertical depth H that is a design ground so as to have a spacing B; b) Insert and connect the main pile insertion portion formed on the flange of the main pile and the seat panel projection, and then insert the seat panel projection 22a into the seat panel insertion portion, In addition, the protrusions of the compression support plate are inserted and coupled, but continuous in the range of the soil internal friction angle Φ = 10 to 34 ° and the adhesive force C = 0.0 to 5.0 (ton / m ² ). Connecting the sheet panel length L and the distance B between the sheet panels so that a relationship of 0.5 ≦ L / B ≦ 3.0 is satisfied, and (c) gradually increasing from the ground After excavating to a certain depth h ₁ while proceeding with the middle excavation, the earth retaining plate is moved to the upper end of the parent pile 10. And (d) in a state where excavation at a constant depth h ₁ is performed, further excavation at a constant depth h ₂ and inserting a retaining plate into the parent pile 10 from the upper end, and (e) An underground excavation construction method using a reinforced self-supporting earth retaining structure is provided, including the step of completing underground excavation while repeating the steps (c) and (d).

  The present invention utilizes the arching effect between soil particles and a sheet panel, and forms a self-supporting soil block of a reinforced soil type in which the back earth pressure does not act on the retaining plate, so that the back earth pressure acting on the excavation space can be self-supported. Since it is a new concept that resists by its own weight, it is more efficient and economical than conventional sheet piles.

  The reinforced self-supporting earth retaining structure using the arching effect is located at the back of the excavation space, so that the excavation space can be used widely without interfering with excavation work, and the high-rise buildings are densely populated. Excavation work in space is easy and efficient.

  Since the upper and lower fixing members are configured so that the connecting portion of the seat panel has a composite cross section, not only the rigidity is increased, but also the structure of the upper and lower fixing members is simple. The invention is easy to attach and dismantle, and after construction is completed, the buried seat panel can be easily recovered, and the construction and recovery are efficient and economically useful.

It is the front view which showed the top-down type underground excavation by the conventional strut method. It is the state figure which showed the connection state of the sheet pile junction part by the conventional sheet pile system. It is the top view which showed the connection state of the sheet pile junction part by the conventional sheet pile system. It is the basic conceptual diagram which showed the relationship between the back surface earth pressure and the frictional force by the sheet pile system of FIG.2 and FIG.3. (A)-(b) is the state figure which showed the arch state which stopped by a certain amount through the small hole opened in the lower plate of the hexahedron filled with sand, and then stopped by the arching effect. It is the perspective view of this invention which showed the state by which the soil was filled into the inside where the seat panel is connected following the parent pile. In FIG. 6, it is the perspective view which showed the state from which the soil was removed. It is a unit top view which shows the action state of the force which has balanced this with respect to the back surface earth pressure of FIG. FIG. 9 is a state diagram showing a shear stress distribution shown in the unit plan view of FIG. 8 with respect to the back earth pressure, an arching effect thereby, and a state in which no back earth pressure acts on the A region. It is the perspective view which showed the relationship between the earth lump W formed by the arching effect, and a back surface earth pressure. FIG. 11 is a force balance diagram illustrating the relationship of FIG. 10 on a two-dimensional plane. It is sectional drawing which showed the shearing stress distribution when a soil lump is not formed. It is the perspective view which showed the form of the connection part of the main pile and seat panel of this invention. It is the state figure which showed the state which installed the upper fixing tool in the connection part of the seat panel of this invention. It is other embodiment which showed the form of the connection part of the parent pile and seat panel of this invention. It is the state figure which showed the state which installed the upper fixing tool in the connection part of FIG. It is further another embodiment which showed the form of the connection part of the parent pile and seat panel of this invention. It is a disassembled perspective view of the lower fixture installed in the connection part of the seat panel of this invention. It is the state figure which showed the process in which the lower fixture of this invention was installed, and the installed state. It is the state figure which showed the process in which the lower fixture of this invention was installed, and the installed state. It is sectional drawing which showed the state which the parent pile and seat panel of this invention installed more deeply as the penetration part Hb from the design ground, and received the passive earth pressure. 5 is a distribution diagram of shear stress τ due to frictional force F. FIG. (A)-(c) is the relationship figure which showed the stress-deformation relationship of soil. It is a graph which shows the result of L / B obtained by making internal friction angle (PHI) and adhesive force C into a variable.

  Since the present invention relates to a reinforced self-supporting earth retaining structure utilizing the arching effect, first, a general outline of the arching effect will be described, and then the arching effect will be described from a soil mechanical viewpoint.

A) General Outline of Arching Effect A general outline relating to the arching effect will be described with reference to FIGS. 5 (a) and 5 (b) as follows.

  If a hole having a diameter d formed in the lower bottom plate is made in a state where sand is stacked in a hexahedron having an upper cover plate, the sand is discharged downward through the hole having a diameter d (FIG. 5). (A)).

  By the way, although the hole of diameter d is open, the sand is not continuously discharged and the discharge stops. If the form of the sand is observed while the sand discharge is stopped, it can be seen that an arcuate arch form is formed.

  The sand stacked without a hole having a diameter d is supported by the lower bottom plate. If a hole having a diameter d is opened, the stacked sand is discharged to some extent by the weight W of the sand. Thereafter, sand discharge stops while forming an arcuate arch form.

  In this way, even if the sand's own weight W exists, the phenomenon that is supported by the arc-shaped arch formed on the hole having the diameter d without being discharged any more is referred to as the so-called arching effect. ).

  An arching effect is produced by a balance between the force of sand being discharged from the hole having a diameter d due to its own weight W and the force of suppressing sand discharge due to the frictional force in contact with the four vertical surfaces of the hexahedron.

  It can be said that the arching effect is a state in which the sand is balanced with the friction force generated in close contact with the four vertical surfaces of the hexahedron with respect to the force discharged from the hole having the diameter d. .

  Therefore, the arching effect is produced only when the frictional force and the diameter d are appropriate. If the diameter d is excessively large compared with the magnitude of the frictional force, the arching effect does not occur because the sand is continuously discharged through the hole having the diameter d.

  When the hole having the diameter d is formed, the sand's own weight W acts on the hole having the diameter d, and the sand W is discharged by the acting force W through the hole having the diameter d. However, the sand is not continuously discharged. As shown in FIG. 5B, the sand remains stationary without being discharged any more while forming an arcuate arch form.

  A mutual shear stress is generated between the sand discharged from the hole having the diameter d and the sand particles which are intended to suppress the discharged sand. The mutual shear stress generated in this way supports the acting force W in an arcuate arch form.

  The arcuate arch form is a state in which the sand particles are rearranged due to the shear stress generated between the discharged sand and the sand particles to suppress the discharged sand.

  The arch form is characterized in that an arc is formed on the upper side with respect to the action direction of the sand's own weight W as shown in FIG.

  The sand's own weight W is supported by the arcuate arch form of FIG.

B) Arching effect from the viewpoint of soil mechanics The arching effect by the continuous sheet wall will be described as follows from the viewpoint of soil mechanical characteristics with reference to FIG.

  The stability problem of earth retaining structures is a three-dimensional problem, but is generally interpreted in two dimensions.

  This is because it can be said that an ordinary earth retaining structure having a longer width B and length L than the excavation height H has a substantially two-dimensional boundary condition.

  Even when interpreted in three dimensions, due to the so-called arching effect, the main earth pressure is significantly reduced and the passive earth pressure is increased compared to the two-dimensional state. Results are required.

  FIG. 8 is a two-dimensional plan view relating to the width B and the length L of FIG.

  Since the earth pressure p indicates the earth pressure at the same excavation height H, the magnitude thereof is the same.

  B is the width between the seat panels, and L is the length of the seat panels that are continuously installed.

A frictional force F = μP _O. μ is the coefficient of friction, and _PO is the static earth pressure. The direction of action of _PO is perpendicular to the seat panel.

  A frictional force F is generated by the backside earth pressure p, and the shearing stress τ is distributed by the frictional force F as shown in FIG. The shear stress τ becomes smaller toward the central portion O.

  Since the arc-shaped arch form formed in FIG. 5B is a state in which the sand particles are rearranged, this will be described from a soil mechanical viewpoint.

  When the soil stress-deformation problem is handled as a two-dimensional problem, as shown in FIG. 23 (a), if a stress acts on one element of the soil, only the normal stresses σ1 and σ3 act on the element. There are two orthogonal planes with zero shear stress, namely the II and III-III planes. Normal stresses σ1 and σ3 acting on orthogonal planes (II plane and III-III plane) are called principal stresses. σ1 is called the maximum principal stress and σ3 is called the minimum principal stress.

  As shown in FIG. 23B, the shear stress τ always acts on the surfaces other than the main stress surface (that is, the II surface and the III-III surface) in addition to the normal stress σ.

If the normal stress σ and the shear stress τ on the aa plane inclined counterclockwise from the II plane by an angle α are displayed in a τ-α relationship, the point a in FIG. If the angle α is rotated from 0 to 180 °, the locus of a has a point I displaying the maximum stress σ ₁ around one point A on the σ axis and a point III displaying the minimum principal stress σ _3. Mohr's stress circles C can be drawn, each having a diameter at both ends.

  The result formula for obtaining the normal stress σ and the shear stress τ at point a from the Mohr stress circle C is as follows.

(Number A)
_{σ = 1/2 (σ 1} + σ 3) +1/2 (σ 1 -σ 3) cos2α

(Number B)
τ = 1/2 (σ ₁ −σ ₃ ) sin2α

  When α = 90 °, τ = 0 and σ = σ1.

  Thus, if the soil particles rotate, the shear stress τ at the point a becomes 0, and only the main stress is received.

  The arcuate arch form of FIG. 5B formed by rearrangement of sand particles is a state where the breaking stress τ is 0, that is, a state where only the main stress is received.

  Now, the arcuate arch form shown by the action of the back earth pressure p will be described with reference to FIG.

  If the back surface earth pressure p acts, under the influence of the frictional force F with the seat panel, the soil particles are rearranged while the main stress direction rotates.

  As shown in FIG. 5 (b), by realigning the sand particles, if the shear stress τ = 0, that is, only receiving the main stress, connecting the lines in which the main stress directions are continuous to each other, the arc arch Forms.

  The earth blocks in the same arc shape play the same role as the cross beam supporting the earth pressure in the arch shape.

  In FIG. 5B, the arc-shaped arch form supports the sand load W on the upper part due to such a role of the arch form.

  In FIG. 1, no. 2, no. 3, no. 4, ... No. n is the arcuate arch form shown at regular intervals. No. 1, the back surface earth pressure p is supported most, and the degree of support gradually decreases. No. n, do not receive back earth pressure. No. In the A region of n, the back earth pressure p = 0. Since the earth retaining plate is disposed in the area A, the rear earth pressure p does not reach the earth retaining plate.

  Since the rear earth pressure p does not reach the area A of the earth retaining plate, the earth retaining plate is not a role as a structural material that supports the earth pressure, but merely a protective material that protects the soil from flowing.

  On the other hand, unlike the present invention, the curved portion 210 (FIG. 4) of the unit cell structure 200 (FIG. 4) corresponding to the earth retaining plate is a structural material that must support the back earth pressure p. Therefore, the retaining plate of the present invention and the curved portion 210 of the unit cell structure 200 are completely different in structural mechanical character.

  Due to the arching effect, the back earth pressure p is changed to the arch arc No. 1, no. 2, no. 3, No. Since the surface earth pressure p is gradually decreasing while going to n, and the back surface earth pressure p becomes 0 in the area A before the retaining plate 30, the soil in the seat panels arranged in parallel is a clump. The soil mass functions as a self-supporting structure with respect to the back earth pressure p.

  A self-supporting structure by the arching effect is as shown in FIG.

  The balance of force between the self-supporting structure and the backside earth pressure p is similar to that of reinforced soil. That is, the back surface earth pressure p is a concept that it is supported by the dead weight W of the mass of the self-standing structure.

  The concept of the self-standing structure by the arching effect is a completely different concept from the concept of the U-shaped unit cell structure 200 of FIG.

  Now, the structure of the reinforced self-supporting earth retaining structure of the present invention based on the new concept utilizing the arching effect is as follows.

Referring to FIG. 13 and FIG. 14, in the present invention, the main pile 10 in which the main pile insertion portion 14 a is integrally formed in the longitudinal direction on one flange 12 of the main pile 10 into which the earth retaining plate 30 is inserted, Installed so as to be perpendicular to the ground at the interval B, insert and connect the seat panel protruding portion 22a to the parent pile inserting portion 14a, and then insert the seat panel protruding portion 22a to the seat panel inserting portion 22a ′ However, the compression support plate protrusion 46a is inserted and coupled to the seat panel insertion portion 22a ′, and the soil has an internal friction angle Φ = 10 to 34 ° and adhesive strength C = 0.0 to 5.0. In the range of (ton / m ² ), the length L of the continuous sheet panel 20 and the interval B between the sheet panels 20 are in a relationship of 0.5 ≦ L / B ≦ 3.0, and arching The effect is to prevent the back earth pressure from acting on the front retaining plate. It is reinforced freestanding earth retaining structures configuration using a arching effect characterized by.

  Here, in the range of 0.5 ≦ L / B ≦ 3.0, the internal friction angle Φ of the soil and the adhesive force C are used as variables, and the results calculated by the Rankine earth pressure formula are shown in the graph of FIG. Indicated by.

  If 0.5 ≦ L / B ≦ 3.0 and L / B exceeds 3.0, the length becomes longer and the installation becomes uneconomical. And the recovery of the seat panel 20 becomes difficult.

  If L / B does not reach 0.5, the rigidity of the member such as the seat panel 20 becomes weak, and thus there is a disadvantage that the member force is insufficient.

  According to FIG. 24, the construction is more economical as the size of L / B is reduced in the range of 0.5 ≦ L / B ≦ 3.0. For this purpose, the range 0.5 ≦ L / B ≦ 3.0 is divided into a range 0.5 ≦ L / B ≦ 1.5 and a range 1.5 ≦ L / B ≦ 3.0. It is desirable.

When 0.5 ≦ L / B ≦ 1.5, the soil internal friction angle Φ is in the range of 14 to 22 °, and the adhesive force C is 0.0 to 5.0 (ton / m). ² ).

In the case of 1.5 ≦ L / B ≦ 3.0, the soil internal friction angle Φ is in the range of 10 to 14 °, and the adhesive force C is 0.0 to 5.0 (ton / m). ² ).

  On the other hand, a seat panel insertion portion 22a 'is formed on one side of the seat panel 20, and a seat panel protruding portion 22a is formed on the other side. As another embodiment, an S-shaped bent portion 22b is formed on one side of the seat panel 20, and an S-shaped inverted bent portion 22b 'is formed on the other side (FIG. 15).

  Since the seat panel 20 is connected between the parent pile 10 and the compression support plate 40, the form of the connection portion between the parent pile 10 and the compression support plate 40 varies depending on the form of the connection portion of the seat panel 20.

  For example, when the seat panel protrusion 22a and the parent pile 10 are connected to the seat panel insertion portion 22a ′ and the compression support plate 40, the connection portion form of the parent pile 10 becomes the parent pile insertion portion 14a, and the compression support plate The form of the connection part of 40 must become the compression support plate protrusion part 46a. If it becomes the opposite, the connection part form of the main pile 10 must become the parent pile protrusion part 14a ', and the form of the connection part of the compression support plate 40 must become compression support plate insertion part 46a'.

  Since the main pile protrusion 14a ′ and the compression support plate insertion portion 46a ′ differ depending on the connection portion form of the seat panel 20, the parent pile protrusion 14a ′ and the compression support plate insertion portion 46a ′ in the drawing are omitted. Instead, the parent pile insertion portion 14a and the compression support plate protrusion 46a at the same position are replaced with this.

  Further, when the S-shaped bent portion 22b of the seat panel 20 and the parent pile 10 are connected and the S-shaped inverted bent portion 22b ′ of the seat panel 20 is connected to the compression support plate 40, the connection of the parent pile 10 is performed. The part form must be an S-shaped reverse bent part 14b ', and the form of the connecting part of the compression support plate 40 must be an S-shaped bent part 46b.

  If it becomes the opposite, the connection part form of the main pile 10 must become the S-shaped bending part 14b, and the form of the connection part of the compression support plate 40 must become an S-shaped reverse bending part 46b '.

  Since the S-shaped reverse bent portion 14b 'varies depending on the form of the connecting portion of the seat panel 20, the illustration of the S-shaped reverse bent portion 14b' is omitted in the drawing, and instead, S at the same position as this. This is replaced by the character-shaped bent portion 14b.

  Thus, since the connection form of the pile 10 and the compression support plate 40 changes depending on the left and right connection form of the seat panel 20, here, for convenience of explanation, the seat panel protrusion 22a and the seat panel insertion part 22a ′ are provided. A description will be given using a representative connection form.

  The connection form of the parent pile 10 is the parent pile insertion part 14a or the parent pile protruding part 14a ', or the form of the S-shaped bent part 14b or the S-shaped reverse bent part 14b'.

  The connection form of the compression support plate 40 is the compression support plate protrusion 46a or the compression support plate insertion part 46a ', or the form of the S-shaped bent part 46b or the S-shaped reverse bent part 46b'. Since the S-shaped bent portion 46b and the S-shaped reverse bent portion 46b ′ are selected according to the right and left connection form of the seat panel 20, the S-shaped reverse bent portion 46b ′ is not shown in the drawing. Instead, this is replaced by an S-shaped bent portion 14b located at the same position.

  In order to increase the cross-sectional secondary moment I and the rigidity of the seat panel 20, the seat panel connecting portion 22 is firmly fixed by the upper and lower portion fixtures 50a and 50b.

  The connecting portion of the seat panel 20 is firmly fixed by the upper and lower portion fixtures 50a and 50b. The upper fixing tool 50a is fixed on both sides of the connecting portion of the seat panel 20 by fastening bolts 56a penetrating the seat panel 20, the attachment pad 52a and the fastening plate 54a in a state where the attachment pad 52a and the fastening plate 54a are positioned in that order. Is done. The lower fixture 50b is formed of a first incision 52b and a second incision 56b. The first incision 52b is formed with an upward inclined surface 524b and a locking claw 526b, and the second incision 56b is formed with a rotating plate 54b and a spring 59b. The rotating plate 54b rotates around the hinge shaft 58b. An upper end inclined surface 542b is formed at the upper end, a lower end rotation groove 546b is formed at the lower end, and a vertical insertion groove 544b is formed at the vertical surface. The spring 59b inserted in the spring insertion groove 548b is connected and fixed to the spring mount tool 562b.

  The rotating plate 54b formed in the second incision 56b rotates around the hinge shaft 58b installed at the axis point 582b by the elastic force of the spring 59b, and the upper end inclined surface 542b of the rotating plate 54b is the first inclined surface 542b. It engages with the locking claw 526b of the incision 52b.

  The lower end rotation groove 546b of the rotation plate 54b is formed so deep that the rotation plate 54b smoothly rotates without being applied to the lower end portion of the seat panel 20.

  The lower fixture 50b is configured to be fastened to each other by the first cutout portion 52b and the second cutout portion 56b while being installed at the connecting portion of the two seat panels 20.

  A first cutout 52b is formed in one seat panel 20, and a second cutout 56b is formed in the other sheet panel 20, which are fixed and coupled to each other by the action of the rotating plate 54b.

  Thus, if the upper and lower parts of the seat panel 20 connecting portion are firmly fixed by the upper and lower fixtures 50a and 50b, the two seat panels 20 become one composite cross section, and the cross sectional secondary moment increases. Stiffness increases.

  Next, the relationship between the distance B between the two sheet panels 20 causing the arching effect and the length L of the continuous sheet panels 20 will be described as follows.

  If the rear earth pressure per unit area acting on the interval B of the seat panel 20 is p, the resultant force P of the earth pressure is P = p * B.

(Equation 1)
P = p * B

  That is, the earth pressure P in Equation 1 is an earth pressure that acts on the soil mass between successive sheet panels 20.

  If the weight of the soil mass is W, W is a relationship in which P resists P.

  The back surface earth pressure p per unit area can be obtained by Rankine earth pressure formula 2.

あるいは、
（数２’）

(Equation 2)

Or
(Equation 2 ')

  In the earth pressure p in Expression 2, the adhesive force C and the internal friction angle Φ have a functional relationship.

Here, Ka is Rankine dynamic earth pressure coefficient Ka = tan ² (45 ° −Φ / 2), Φ is an internal friction angle, r is soil unit weight, H is excavation depth, and C is adhesive. It is power.

  If the frictional force between the continuous sheet panel 20 and the soil mass in contact with this is F, the frictional force F is as follows.

(Equation 3)
F = 2 * L (Po * μ + C ′) = 2 * L (r * H * Ko * μ + C ′)

  L is the length of the continuous sheet panel 20, Po is the static earth pressure, μ is the coefficient of friction, and C ′ is the frictional adhesive force.

  If the earth pressure acting on the retaining wall E is Pt, the relationship between the back earth pressure P and the frictional force F is as follows.

(Equation 4)
Pt = PF

  In Equation 4, since the earth pressure does not act on the area A of FIG. 24 due to the arching effect, Pt = 0. That is,

(Equation 5)
PF = 0

  become. In Formula 5, if F is the same as P or larger (F ≧ P), due to the arching effect, the soil mass in the width B and the length L of the continuous sheet panel 20 has its own weight W. Maintain and become independent.

That is,
(Equation 6)
F ≧ P

  Substituting Equation 3 and Equation 2 'into Equation 6 is as follows.

(Equation 7)

  It can be seen that Expression 7 is a variable of the internal friction angle Φ and the adhesive force C.

  Next, when the excavation depth H is 10 m, a lower limit value related to L / B due to a change in the internal friction angle Φ and the adhesive force C is obtained by Expression 7.

[conditions]
Excavation depth H = 10 m, unit weight r = 1.7 (t / m ³ ), friction coefficient μ = [tan (2 / 3Φ)], Rankine main dynamic earth pressure coefficient Ka = tan ² (45 ° −Φ / 2), Rankine main dynamic earth pressure coefficient Kp = tan ² (45 ° + Φ / 2) Ka, adhesive force C (ton / m ² ), friction adhesive force C ′ = [2 / 3C] (ton / m ² ), Static earth pressure coefficient Ko

The calculation result of L / B according to Equation 7 within the above conditions, the range of internal friction angle Φ = 10 to 34 °, and the adhesive force C = 0.0 to 5.0 (ton / m ² ). Is shown as a graph in FIG.

  According to FIG. 24, the following results can be obtained.

(1) The maximum value and the minimum value are shown with the adhesive force C = 0 and C = 5.0 (ton / m ² ) as the boundary line.

(2) When the L / B exceeds 3 in the range of the internal friction angle Φ = 10 to 34 ° of the soil and the range of the adhesive strength C = 0.0 to 5.0 (ton / m ² ), the arching The effect shows that the back earth pressure does not act on the front earth retaining plate.

  (3) However, if L / B exceeds 3, the length of the continuous sheet panel becomes long, which is uneconomical, and if L / B is smaller than 0.5, the sheet panel Therefore, in the present invention, the range of L / B is limited to 0.5 ≦ L / B ≦ 3.0.

(4) That is, the length of the continuous sheet panel 20 within the range of the soil internal friction angle Φ = 10 to 34 ° and the adhesive force C = 0.0 to 5.0 (ton / m ² ). When the relationship between L and the interval B between the seat panels 20 is 0.5 ≦ L / B ≦ 3.0, it can be seen that the back earth pressure does not act on the front earth retaining plate due to the arching effect.

(5) The internal friction angle Φ of the soil is in the range of 14 to 22 °, the adhesive strength C is in the range of 0.0 to 5.0 (ton / m ² ), and the length L of the continuous sheet panel 20 When the relationship with the distance B between the sheet panels 20 is 0.5 ≦ L / B ≦ 1.5, it can be seen that the back earth pressure does not act on the front earth retaining plate due to the arching effect.

(6) The internal friction angle Φ of the soil is in the range of 10 to 14 °, and the adhesive sheet C is in the range of 0.0 to 5.0 (ton / m ² ). When the relationship with the distance B between the seat panels 20 is 1.5 ≦ L / B ≦ 3.0, it can be seen that the back earth pressure does not act on the front earth retaining plate due to the arching effect.

  On the other hand, even if the range of L / B satisfies the range of 0.5 ≦ L / B ≦ 3.0, in the case of the city center, there is insufficient margin space with the boundary line of the adjacent site, or Since there are usually structures adjacent to each other, the length of the continuous sheet panel is subject to construction restrictions that cannot be grounded to meet the above range. As a measure for solving such a construction restriction, in order to replenish the insufficient length of the continuous sheet panel, it is possible to replenish as a passive earth pressure by the penetration depth Hb as shown in FIG. desirable. The penetration depth Hb must be a minimum of 1.0 m in order to maintain increased wall stability and freezing depth.

  The underground excavation construction method using the reinforced self-supporting earth retaining structure of the present invention will be described in detail with reference to the drawings.

(A) placing the main pile 10 to the vertical depth H, which is the design ground, so as to have a distance B on the ground of the boundary surface to be excavated;
(B) Insert and connect the main pile insertion portion 14a formed on the flange 12 of the main pile 10 and the seat panel projection 22a, and then insert the seat panel projection 22a into the seat panel insertion portion 22a ′. While the compression support plate protrusion 46a is inserted and joined to the seat panel insertion portion 22a ′, the soil has an internal friction angle Φ = 10 to 34 ° and an adhesive force C = 0.0 to 5.0. With the range of (ton / m ² ), the relationship between the length L of the continuous sheet panels 20 and the distance B between the sheet panels 20 is such that 0.5 ≦ L / B ≦ 3.0. Connected to the stage,
(C) The step of inserting the retaining plate 30 from the upper end of the parent pile 10 after excavating to a certain depth h ₁ while proceeding with underground excavation gradually from the ground,
(D) In a state where excavation at a constant depth h ₁ is performed, further excavation at a constant depth h ₂ and inserting the earth retaining plate 30 into the parent pile 10 from the upper end;
(E) A step of completing underground excavation while repeating the step (c) and the step (d). Is the method.

Further, in the step (b), a continuous sheet panel 20 having a soil internal friction angle Φ = 14 to 22 ° and an adhesive strength C = 0.0 to 5.0 (ton / m ² ). The relationship between the length L of the sheet and the interval B between the sheet panels 20 includes setting 0.5 ≦ L / B ≦ 1.5.

Further, in the step (b), a continuous sheet panel 20 having a soil internal friction angle Φ = 10 to 14 ° and an adhesive strength C = 0.0 to 5.0 (ton / m ² ). The length L and the distance B between the sheet panels 20 include 1.5 ≦ L / B ≦ 3.0.

  In the case of the city center, it is normal that there is not enough room with the boundary line of the adjacent site, or there is a built structure adjacent to it, so the length of the continuous seat panel should be within the above range. It is subject to construction restrictions that cannot be installed to fit. In this case, as shown in FIG. 21, it is desirable to install the main pile 10 and the root portion Hb of the seat panel 20 deeper than the vertical depth H which is the design ground so as to receive the passive earth pressure. This is to increase the stability and stability of the reinforced self-supporting earth retaining structure against overturning. At this time, if the proper L / B cannot be satisfied, the earth pressure acts on the front earth retaining plate 30, so the thickness must be determined by structural calculation.

  On the other hand, at the stage (b), the upper end of the connecting portion of the seat panel 20 penetrates the seat panel 20, the attachment pad 52a, and the fastening plate 54a in a state where the attachment pad 52a and the fastening plate 54a are positioned on both sides in this order. The upper fixing tool 50a fastened and fixed by the fastening bolt 56a, and the rotating plate 54b formed at the second incision 56b at the lower end thereof are centered on the hinge shaft 58b by the elastic force of the spring 59b. The upper end inclined surface 542b of the rotating plate 54b is configured to be engaged with the locking claw 526b of the first incision 52b. The upper end inclined surface 542b is at the upper end of the rotating plate 54b and the lower end is rotated at the lower end. The groove 546b includes a lower fixture 50b having a vertical insertion groove 544b formed on a vertical surface thereof.

  The method for installing and removing the upper and lower fixtures will be described as follows.

  Insert the seat panel protruding portion 22a (or the S-shaped reverse bent portion 22b 'of the seat panel into the S-shaped bent portion 14b of the main pile) from above into the main pile inserting portion 14a installed on the ground. Then, after the seat panel 20 is inserted and assembled, the compression support plate protrusion 46a is inserted into the seat panel insertion portion 22a ′, and is assembled and installed.

  In the lower fixture 50b, the seat panel 20 in which the first incision portion 52b is formed must first be installed, and then the sheet panel 20 in which the second incision portion 56b is formed must be installed.

  The order of removing the installed seat panel 20 is the same as this. That is, after the sheet panel 20 having the first cutout portion 52b is first removed, the sheet panel 20 formed in the second cutout portion 56b must be removed. If the order is different, the structure is neither installed nor removed.

  The operation of binding and disassembling of the lower fixture 50b will be described as follows.

  First, the binding action of the lower fixture 50b will be described.

  If the seat panel protrusion 22a of the seat panel 20 in which the second incision portion 56b is formed is inserted into the seat panel insertion portion 22a 'of the seat panel 20 in which the first incision portion 52b embedded in the ground is formed. The rotating plate 54b that rotates about the hinge shaft 58b is guided vertically by the vertical sheet panel insertion portion 22a ′ to maintain the vertical state (FIG. 15).

  The hinge shaft 58b is inserted into the shaft point 582b.

  At the moment when the rotating plate 54b that has maintained the vertical state contacts the first incision 52b, the rotating plate 54b is moved by the spring 59b fixed to the spring mount 562b as shown in FIG. The upper inclined surface 542b of the rotating plate 54b is engaged with the locking claw 526b of the first incision 52b while being rotated toward the one incision 52b.

  At this time, the vertical insertion groove 544b of the rotary plate 54b inserted into the second cutout portion 56b of the seat panel 20 and the lower end rotary groove 546b inserted into the lower end portion of the second cutout portion 56b also rotate with the rotation of the rotary plate 54b. Come off.

  In particular, since the rotating plate 54b rotates around the hinge shaft 58b, the lower end rotation groove 546b of the rotating plate 54b has a depth that does not hinder the rotation by the second cutout portion 56b of the seat panel 20. Is formed.

  In this manner, the rotating plate 54b is firmly fixed in a state where the upper end inclined surface 542b is applied.

  The spring 59b is inserted into the spring insertion groove 548b of the rotating plate 54b, and is fixed to the spring mount 562b.

  Next, the disassembling action of the lower fixture 50b will be described.

  In order to disassemble the rotating plate 54b from the state in which the upper end inclined surface 542b of the rotating plate 54b is engaged with the locking claw 526b of the first incision 52b, the seat panel 20 formed with the first incision 52b is first lifted up. For example, the rotating plate 54b is vertically guided by the vertical sheet panel insertion portion 22a ′ to be in a vertical state. While taking out the seat panel 20 in which the first cut-out portion 52b is formed, the vertical insertion groove 544b and the lower end rotation groove 546b of the rotary plate 54b again become the second of the seat panel 20 while maintaining the vertical state of the rotary plate 54b. It is inserted into the incision 56b. As described above, since the rotating plate 54b is not obstructed at all while the seat panel 20 in which the first incision portion 52b is formed is taken out, the seat panel 20 in which the first incision portion 52b is formed can be easily disassembled. Become.

  Since the structure of the lower fixture 50b is simple and the structure is easy to bind and disassemble, the binding and disassembly work and the increase in rigidity are efficient.

Claims (10)

The main pile (10) in which the main pile insertion portion (14a) is integrally formed in the longitudinal direction on the one flange (12) of the main pile (10) into which the earth retaining plate (30) is inserted is placed on the ground at the interval B. Install vertically, insert and connect the seat panel protrusion (22a) to the main pile insertion part (14a), and then insert the sheet panel protrusion (22a) into the seat panel insertion part (22a ') The compression support plate protrusion (46a) is inserted and coupled to the seat panel insertion portion (22a ′), and the range of the internal friction angle Φ = 10 to 34 ° of the soil and the adhesive force C = Within the range of 0.0 to 5.0 (ton / m ² ), the length L of the continuous sheet panel (20) and the interval B between the sheet panels (20) are 0.5 ≦ L / B ≦. 3.0 so that the back earth pressure acts on the front retaining plate by the arching effect. It reinforced freestanding earth retaining structures utilizing the arching effect characterized that no. The length L of the continuous sheet panel (20) in the range of the soil internal friction angle Φ = 14-22 ° and the range of the adhesive strength C = 0.0-5.0 (ton / m ² ), The reinforced self-supporting earth retaining member using the arching effect according to claim 1, characterized in that the relationship with the interval B between the seat panels (20) is 0.5≤L / B≤1.5. Structure. The length L of the continuous sheet panel (20) in the range of the soil internal friction angle Φ = 10 to 14 ° and the adhesive force C = 0.0 to 5.0 (ton / m ² ), The reinforced self-supporting earth retaining member using the arching effect according to claim 1, wherein the relationship with the interval B between the seat panels (20) is 1.5 ≦ L / B ≦ 3.0. Structure.   The connection part of the parent pile (10) is formed from the parent pile insertion part (14a) or the parent pile protrusion part (14a '), and the connection part of the seat panel (20) coupled thereto is the sheet panel protrusion. The reinforced self-supporting earth retaining structure using the arching effect according to claim 1 or 2, wherein the reinforced self-supporting earth retaining structure is formed from a portion (22a) or a seat panel insertion portion (22a ').   The compression support plate (40) is formed of a vertical portion (42) and a horizontal portion, and the connection portion of the compression support plate (40) is a compression support plate protrusion (46a) or a compression support plate insertion portion (46a). The reinforced self-supporting earth retaining structure using the arching effect according to claim 1 or 2, wherein ') is integrally formed with the vertical portion (42).   The connecting part of the seat panel (20) is firmly fixed by the upper and lower part fixing tools (50a, 50b). The upper fixing tool (50a) is attached to both sides of the connecting part of the seat panel (20) by the adhesion pad (52a). And the fastening plate (54a), the lower fixing tool (50b) is fixed by a fastening bolt (56a) penetrating the seat panel (20), the adhesion pad (52a) and the fastening plate (54a). ) Is formed of a first incision portion (52b) and a second incision portion (56b), and the first incision portion (52b) has an upward inclined surface (524b) and a locking claw (526b), A rotary plate (54b) and a spring (59b) are formed in the second incision (56b), and an upper end inclined surface is formed at the upper end of the rotary plate (54b) that rotates about the hinge shaft (58b). (542b) A lower end rotation groove (546b) is formed at the end, and a vertical insertion groove (544b) is formed on the vertical surface thereof. The spring (59b) inserted into the spring insertion groove (548b) is a spring mount tool. The reinforced self-supporting earth retaining structure using the arching effect according to claim 1 or 2, characterized in that it is connected and fixed to (562b). (A) placing the main pile (10) on the ground surface of the boundary surface to be excavated to a vertical depth H of the design ground so as to have a spacing B;
(B) Insert and connect the main pile insertion portion (14a) formed on the flange 12 of the main pile (10) and the seat panel protrusion (22a), and then connect to the seat panel insertion portion (22a '). While inserting the seat panel projection (22a), the compression support plate projection (46a) is inserted and coupled to the seat panel insertion portion (22a ′), but the internal friction angle Φ of soil is 10 to 34. The length L of the continuous sheet panel (20) and the distance B between the sheet panels (20) in the range of ° and the range of adhesive strength C = 0.0 to 5.0 (ton / m ² ) Connecting the relationship so that the relationship is 0.5 ≦ L / B ≦ 3.0;
(C) The step of inserting the retaining plate (30) from the upper end of the parent pile (10) after excavating to a certain depth h ₁ while proceeding with underground excavation gradually from the ground,
(D) In a state where excavation at a constant depth h ₁ has been performed, further excavation at a constant depth h ₂ and inserting the retaining plate (30) into the parent pile (10) from the upper end;
(E) A step of completing underground excavation while repeating the step (c) and the step (d). Method. In the step (b), a continuous sheet panel (20) having a soil internal friction angle Φ = 14 to 22 ° and an adhesive strength C = 0.0 to 5.0 (ton / m ² ). 8) and the relationship of the distance B between the seat panels (20) satisfy 0.5 ≦ L / B ≦ 1.5. Underground excavation construction method using body. In the step (b), a continuous sheet panel (20) having a soil internal friction angle Φ = 10 to 14 ° and an adhesive strength C = 0.0 to 5.0 (ton / m ² ). 8) and a distance B between the seat panels (20) is set to 1.5 ≦ L / B ≦ 3.0. Reinforced self-supporting earth retaining structure according to claim 7 Underground excavation construction method using body. In the step (b), the seat panel (20) and the attachment pad are placed at the upper end of the connecting portion of the seat panel (20) in the state where the attachment pad (52a) and the fastening plate (54a) are positioned in this order. (52a) and an upper fixture (50a) fastened and fixed to the fastening bolt (56a) penetrating the fastening plate (54a),
At the lower end, a rotating plate (54b) formed in the second incision (56b) rotates around the hinge shaft (58b) by the elastic force of the spring (59b), and the rotating plate (54b) The upper end inclined surface (542b) is structured to engage with the locking claw (526b) of the first incision portion (52b). The reinforcing mold according to claim 7 or 8, wherein the lower end rotation groove (546b) includes a lower fixture (50b) having a vertical insertion groove (544b) formed on a vertical surface thereof. An underground excavation method using a self-supporting earth retaining structure.

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